UNIVERSE
made of an infinite amount of space,
matter and time.
the start of the universe, the universe
has no beginning and no end; perhaps
the same photons that have always been
in the universe continue to move in the
space that has always been.
particles of light humans have named
"photons". Photons are the base unit
of all matter from the tiniest
particles to the largest galaxies.1
The basic order of matter from smaller
to largest is photons, electrons,
positrons, muons, protons, neutrons,
atoms, molecules, living objects,
planets, stars, globular clusters,
galaxies, galaxtic clusters.2
FOOTNOTES
1. ^ Ted Huntington.
2. ^ Ted Huntington.
meters every second in a line, but as
pieces of matter, can be slightly
slowed from the force of gravity, and
stop for an instant when they collide.1
Photons move 300 million meters every
second in a line but as pieces of
matter their velocity changes slightly
because of gravity, and theoretically
photons bounce off each other, at which
time they come to a complete stop
relative to the rest of the universe
for an instant before bouncing and
accelerating away from each other in
the opposite direction.2
FOOTNOTES
1. ^ Ted Huntington
2. ^ Ted Huntington
and so photons form structures such as
protons, atoms, molecules, molecule
groups (like all of life of earth),
planets, stars, galaxies, and clusters
of galaxies.
Gravity is responsible for photons
forming Hydrogen, Hydrogen forming
nebulas, nebulas forming stars, and
stars forming galaxies.
galaxies we can see are only a tiny
part of the universe. 1 Most of the
galaxies in the universe we will never
see because they are too far away for
even 1 particle of light from them to
be going in the exact direction of our
tiny location, or are captured by atoms
between here and there. 2
One estimate
has 70e21 (sextillion) stars in only
the universe we can see. That is 10
times more stars than grains of sand on
all the earth. 3
FOOTNOTES
1. ^ Carl Sagan, "Cosmos", Carl Sagan
Productions, KCET Los Angeles, (1980).
(estimate of how many galaxies)
2. ^ Ted
Huntington
3. ^
http://edition.cnn.com/2003/TECH/space/0
7/22/stars.survey/
clear. Photons form gas clouds of
Hydrogen and Helium, these gas clouds,
called nebuli condense to form galaxies
of stars. The stars emit photons back
out into the rest of the universe,
where they collect and form clouds
again. Around each star are many
planets and pieces of matter. On many
of those planets intelligent life
evolves. This life moves their stars
out of spiral galaxies to form globular
clusters, and ultimately to transform
spiral galaxies into elliptical
galaxies that travel the universe
looking for more matter to fuel their
movement.
It may very well be that stars at this
scale are photons, spiral galaxies
charged particles, globular galaxies
neutral particles, and galactic
clusters atoms at a much larger scale
in an infinite macro and micro scale.1
FOOTNOTES
1. ^ Ted Huntington
the most distant galaxies we can see
have a lower frequency may be due to
the effects of gravitation and/or
particle collision in the large
distance between source and observer.1
EXPERIMENT: does sound frequency
actually get lower over large
distances?2
FOOTNOTES
1. ^ Ted Huntington.
2. ^ Ted Huntington.
from a gas cloud that formed by
capturing matter in the form of light
from other stars, from the remains of a
previously destroyed galaxy, or some
combination of the two.
5
eventually orbit forms, perhaps in a
nebula, when matter in the nebula
starts accumulating and rotating as a
result of gravity, or from the remains
of an exploded star that condensed
again under the influence of gravity.
My
opinion is that stars contain molten
iron in their center, similar to the
earth. {check with supernova remnants}
The density of the star the earth
rotates is similar to that of a liquid.
The most popular theory to explain how
stars give off so many photons is that
these photons exit as a result of
Hydrogen atomically fusing into Helium,
and I want to add my opinion that
potentially the pressure of gravity
simply separates atoms of Hydrogen and
helium into their source photons.
Perhaps the reaction is similar to the
center of the earth where red hot
liquid iron emits photons. We
obviously do not explain that red hot
molten metal as being the result of
nuclear fusion, but yet it is clearly
not oxygen combustion. Clearly there
are many photons exiting stars every
second, and each star is losing large
amounts of matter in the form of
photons. In addition, the most popular
theory explains that most atoms heavier
than Hydrogen and no heavier than Iron
are made in stars, and atoms larger
than iron can only be made in
supernovae. 1
The current view
theorizes that the iron is made just
before the supernova, in the
gravitational collapse, but I find a
liquid iron core being there for the
lifetime of every star as a more
logical explanation. 2 3 4
FOOTNOTES
1. ^ Ted Huntington
2. ^
http://zebu.uoregon.edu/~imamura/208/mar
1/nucleo.html (with image of onion
skin layers)
3. ^ Ted Huntington
4. ^ another person
declares star inside to be similar to
planets: iron, oxygen, nickel, etc. do
not support standard solar
model. star_inside_iron.pdf
5. ^ Ted Huntington, guess
move closer to the center and lighter
atoms are sent farther out.
Terrestrial planets are red hot, have
surface of melted rock, all lighter
atoms float to the surface of the
molten planets. All the H2O from the
first earth oceans and lakes is in the
atmosphere in gas form.
ways:
1) spherical planet collides with
earth, moon forms from remaining matter
in ring around earth.
2) spherical planet is
caught in earth orbit
3) moon of earth forms
naturally from original matter of star
system in orbit around earth.
The Moon
orbiting 5 degrees from the axis of the
Earth's orbit implies that the Moon was
captured, although 5% is not a
particularly large difference from the
plane of the Earth's rotation.1 That
the Moon orbits in the same direction
as the Earth is evidence in favor of
the Moon forming around the Earth.2
FOOTNOTES
1. ^ Ted Huntington.
2. ^ Ted Huntington.
3 4
4,571 million years old.1 2
FOOTNOTES
1. ^
http://www.sciencemag.org/cgi/content/fu
ll/288/5472/1819?maxtoshow=&HITS=10&hits
=10&RESULTFORMAT=&fulltext=zag+morocco&s
earchid=1129920472874_9236&stored_search
=&FIRSTINDEX=0#RF2
2. ^
http://news.bbc.co.uk/1/hi/sci/tech/7830
48.stm
3. ^
http://www.sciencemag.org/cgi/content/fu
ll/288/5472/1819?maxtoshow=&HITS=10&hits
=10&RESULTFORMAT=&fulltext=zag+morocco&s
earchid=1129920472874_9236&stored_search
=&FIRSTINDEX=0#RF2 (4.7 +- .2 billion
years)
4. ^ sci has 4.7 +- .2 by where did
4.571 come from?
[1] The ''Zag'' meteorite fell to Earth
in 1988 COPYRIGHTED
source: http://news.bbc.co.uk/1/hi/sci/t
ech/783048.stm
Apollo missions (4.53 billions old).
[1]
http://www.nasm.si.edu/exhibitions/attm/
atmimages/S73-15446.f.jpg
http://www.nasm.si.edu/exhibitions/attm/
nojs/wl.br.1.html
source:
earth) rocks date from this time 4.5
billion years before now.
LIFE
2
FOOTNOTES
1. ^ The geological Society of America
ucmp.berkeley.edu
2. ^ Richard Cowen, "History of Life",
(Malden, MA: Blackwell, 2005).
cools into thin crust, H2O condenses
from the atmosphere by raining, filling
the lowest parts of land to make the
first earth oceans, lakes, and rivers.1
FOOTNOTES
1. ^ part about rain and streams going
to bottom of land:
http://www.ersdac.or.jp/Others/geoessay_
htm/geoessay_e/geo_text_09_e.htm
meteorite) zircon yet found on earth,
4.404 billion years old, from Gneiss in
West Australia, is evidence that the
crust and liquid water were on the
surface of earth 4.4 billion years
before now.1
FOOTNOTES
1. ^
http://www.nature.com/nature/links/01011
1/010111-1.html
[1]
http://www.geology.wisc.edu/zircon/Earli
est%20Piece/Images/8.jpg
source:
sugars, the components of living
objects are created on earth. These
molecules are made in the oceans, fresh
water, and or atmosphere of earth (or
other planets) by lightning, photons
with ultraviolet frequency from the
star, or ocean floor volcanos.
nucleotides), proteins (polymers made
of amino acids), carbohydrates
(polymers made of sugars) and lipids
(glycerol attached to fatty acids)
evolved is not clearly known.
Some proteins and nucleic acids have
been formed in labs by using clay which
can dehydrate and which provides long
linear crystal structures to build
proteins and nucleic acids on. Amino
acids join together to form
polypeptides when an H2O molecule is
formed from a Hydrogen (H) on 1 amino
acid and a hydroxyl (OH) on the second.
Are all proteins, carbohydrates, lipids
and DNA the products of living objects?
Is RNA the only molecule of these that
was made without the help of living
objects?
The most popular theory now has RNA
(and potentially lipids) evolving first
before any living objects.
There is still a large amount of
experiment, exploration and education
that needs to be done to understand the
origins of living objects on planet
earth. My opinion is that as soon as
there was liquid water on the earth,
4.4 billion years before now, as zircon
crystals show, the construction of
living objects started on earth.
Perhaps RNA molecules, called
"ribozymes" evolved which can make
copies of RNA, by connecting free
floating nucleotides that match a
nucleotide on the same or a different
RNA, without any proteins. But until
such ribozyme RNA molecules are found,
the only molecule known to copy nucleic
acids are proteins called polymerases.
If such ribozymes exist, then one of
the first coded instructions on the RNA
molecule that was the ancestor of every
living species, must have been the code
to make this ribozyme.
These early RNA molecules
may have been protected by liposomes
(spheres of lipids).
This process of RNA (and then later
DNA) duplication is the most basic
aspect of life on earth, and for all
the diversity, the one common element
of all life is this constant process of
DNA duplication, which will later
evolve to include cell division. This
starts the unbroken thread of copying
and division that connects the earliest
ancestor, some RNA molecule, to all
life on earth that has ever lived.
creation of various Transfer RNA (tRNA)
molecules.
Random mutations in the copying (and
perhaps even in the natural formation)
of RNA molecules probably created a
number of the necessary tRNAs (transfer
RNA, an RNA molecule responsible for
matching free floating amino acid
molecules to 3 nucleotide sequences on
other RNA molecules).
This would be a precellular protein
assembly system, where tRNA (transfer
RNA) molecules can build polypeptide
chains of amino acids by linking
directly to other RNA strands.
Part of each tRNA molecule bonds with a
specific amino acid, and a 3 nucleotide
sequence from a different part of the
tRNA molecule bonds with the opposite
matching 3 nucleotide sequence on an
(m)RNA molecule.
Since there are tRNA molecules for each
amino acid (although some tRNAs can
attach to more than one amino acid?),
there must have been a slow
accumulation of various tRNA molecules
for each of the 20 amino acids used in
constructing polypeptides in cells
living now. Perhaps after the
evolution of the first tRNA, the first
polypeptides were chains of all the
same one amino acid. With the
evolution of a second tRNA polypeptides
would have more variety because now two
amino acids would be available to build
polypeptides.
This polypeptide assembly system may
exist freely in water, or within a
liposome1 . This sytem builds many
more proteins than would be built
without such a system. The mRNA with
the code to make copier RNA, now also
contains the code to produce various
tRNA molecules. These molecules
function as a unit, and proto-cell,
with the rest of the mRNA initially
containing random codes for random
proteins.
For the first time, RNA code represents
a template for other RNA molecules, but
also a template for building proteins
with the help of tRNA molecules.
There is some question of where the
origin of the first cell took place,
near volcanos on the ocean floor, or in
fresh water lakes and tidal pools near
volcanos on land, because unprotected
nucleic acids cannot exist for much
time in the ocean because of Sodium and
Chlorine.
What were the first amino acids
connected as proteins? Were the first
proteins all made with the same amino
acid?
Ribosomal RNA moves down mRNA molecules
functioning as a platform for bringing
the mRNA and tRNA molecules together to
assemble polypeptides (proteins).
This rRNA serves as an early ribosome;
objects that serve as sites for
building polypeptides and are found in
every cell. As time continues the
ribosome will grow to include two more
RNA molecules, some protein molecules,
and a second half that will make
polypeptide construction more
efficient.
The rRNA serves the purpose of bringing
amino acids close enough to bond with
each other to form polypeptides.
As an rRNA moves down an mRNA, tRNA
molecules bond with the mRNA and on the
opposite side of the tRNA, a matching
amino acid (separates? from the tRNA
and) attaches to a growing polypeptide
chain.
Now the mRNA that is the
ancestral/progenitor of all of life,
contains the code for the copier RNA,
tRNAs, and the rRNA molecule. These
nucleic acids function as a unit, and
proto-cell.
importance is built, an RNA polymerase.
A molecule that can more efficiently
copy RNA.
The first protein of real
importance is evolved by RNA and
assembled by the early ribosome, an RNA
polymerase. A molecule that can more
efficiently copy RNA.
is built by the early ribosome protein
making protocell. This protein changes
ribonucleotides into
deoxyribonucleotides. This allows the
first DNA molecule on earth to be
assembled.
Ribonucleotide reductase may be the
molecule that allowed DNA to be the
template for the line of cells that
survived to now.
to copy DNA by assembling DNA
nucleotides from other DNA molecules.
causes the early ribosome to create
reverse transcriptase, a protein that
can assemble DNA molecules from an RNA
molecule template.
With this advance, a DNA molecule can
be constructed that has all of the code
that was stored on the long evolved RNA
molecule. DNA now serves as a more
stable template for making mRNA, each
tRNA, rRNA, and the RNA and DNA
polymerases.
RNA polymerase proteins build RNA
molecules using the new DNA template,
that still perform their original
polypeptide building function together
with the tRNA and rRNA molecules, but
are labeled "mRNA" (Messenger RNA)
because they move from DNA to ribosome.
Why DNA
serves as the template for all cells
and not mRNA is not fully understood,
but DNA is a more stable molecule than
the single stranded RNA. Perhaps the 2
legs of DNA serve some other important
reasons, for example, two legs may
allow two processes to happen at one
time.
around DNA, made of proteins. This
membrane holds water inside a cell.
This is the first cell. rRNA
comparison shows that this is most
likely a eubacterium.1
DNA produces instructions for
cytoplasm, the cytoplasm is assembled
from proteins made by the ribosome.
For the first time, DNA and ribosomes
are building cell structure. The
templates for each tRNA, rRNA, mRNA and
DNA polymerase proteins are already
coded in a central strand of DNA. DNA
protected by cytoplasm is more likely
to survive and copy. This cell is
heterotrophic and has no metabolism to
produce ATP. Amino acids, nucleotides,
H2O, and other molecules enter and exit
the cytoplasm only because of a
difference in concentration from inside
and outside the cell (passive
transport) and represent the beginnings
of the first digestive system. This
either happens in fresh water lakes or
in salty oceans, perhaps near lava
vents on or under the ocean floor. As
this line of DNA continues to make
copies of itself, all copies now have
cytoplasm. The DNA is composed mainly
of instructions to assemble the nucleic
acids and proteins needed to build
ribosomes, polymerases and cytoplasm.
This cell structure forms the basis of
all future cells of every living object
on earth. These first cells are
anaerobic (do not require free oxygen)
and heterotrophic, meaning that they do
not make their own food: amino acids,
nucleotides, phosphates, and sugars.
These bacteria depend on these
molecules and photons in the form of
heat to reproduce and grow.
A system of division must evolve which
attaches the original and newly
synthesized copy of DNA to the
cytoplasm, so that as the cell grows,
the two copies of DNA can be separated
and the first membraned cells can
divide into two cells. This is the
beginning of the "binary fission"
method of cell division. Division of
the cell begins with the division of
the DNA membrane-attachment site and
separates by the growth of new
cytoplasm.
DNA has 2 functions, 1) to be copied
by the polymerase protein, 2) to serve
as a code for assembling proteins.
Two
important evolutionary steps evolve:
DNA duplication in cytoplasm, and cell
(DNA with cytoplasm) division.
The process of DNA duplication is
probably similar if not the same
process using the same proteins that
were used to duplicate DNA without
cytoplasm.
circle allows the DNA polymerase to
make continuous copies of the cell.
In
theory prokaryote cells do not
deteroiate from the effect of aging,
but they do endure mutations (from
photons with ultraviolet frequency, for
example), however, there are many other
ways prokaryotes can be destroyed (loss
of water, physically damaged by
nonliving objects, eaten by other
organisms, and other mechanisms).
molecules into and out of the cytoplasm
(facilitative diffusion) evolve.1
FOOTNOTES
1. ^
http://www.cat.cc.md.us/~gkaiser/biotuto
rials/eustruct/cmeu.html
[1] Uniporters are transport proteins
that transport a substance across a
membrane down a concentration gradient
from an area of greater concentration
to lesser concentration. The transport
is powered by the potential energy of a
concentration gradient and does not
require metabolic energy.
source: http://www.cat.cc.md.us/~gkaiser
/biotutorials/eustruct/cmeu.html
[2] Channel proteins transport water
or certain ions down a concentration
gradient from an area of higher
concentration to an area of lower
concentration. In the case of water,
the channel proteins are called
aquaporins. Water molecules are small
enough that they can also pass between
the phospholipids in the cytoplasmic
membrane by passive diffusion.
source:
from bacteria, or are initially
bacteria. These cells depend on the
DNA duplicating and protein producing
systems of other cells to reproduce
themselves. Over time, more effective,
and efficient virus designs will
survive.1
FOOTNOTES
1. ^
http://cellbio.utmb.edu/cellbio/rer2.htm
cytoplasm. Cells can now make ATP from
glucose and eventually other
monosaccharides, the end product is
pyruvate.
The glycolysis equation is:
C6H12O6
(glucose) + 2 NAD+ + 2 ADP + 2 P
-----> 2 pyruvic acid, (CH3(C=O)COOH +
2 ATP + 2 NADH + 2 H+
cytoplasm. Cells (all anaerobic) can
now make more ATP and convert pyruvate
(the final product of glycolysis) to
lactate (an ionized form of lactic
acid).1
FOOTNOTES
1. ^
http://216.239.63.104/search?q=cache:3s2
stckAJoMJ:www.nmc.edu/~ftank/115f04/Ch%2
5209%2520Notes.pdf+cellular+respiration+
oldest&hl=en
evolves in the cytoplasm. Cells (all
anaerobic) can now convert pyruvate
(the final product of glycolysis) to
ethanol.1
FOOTNOTES
1. ^
http://216.239.63.104/search?q=cache:3s2
stckAJoMJ:www.nmc.edu/~ftank/115f04/Ch%2
5209%2520Notes.pdf+cellular+respiration+
oldest&hl=en
1
that can assemble lipids.
FOOTNOTES
1. ^ find biomarker evidence
metabolism (ATP) to transport molecules
into and out of the cytoplasm (active
transport) evolve.1
FOOTNOTES
1. ^
http://www.cat.cc.md.us/~gkaiser/biotuto
rials/eustruct/cmeu.html
[1] TP: not clear what the red circles
are, some kind of molecule I
guess. Antiporters are transport
proteins that simultaneously transport
two substances across the membrane in
opposite directions; one against the
concentration gradient and one with the
concentration gradient. Antiporters
typically use proton motive force to
transport a substrate across the
membrane. The movement of protons
across the membrane (proton motive
force) provides the energy for
transporting the substrate across the
membrane against its concentration
gradient..
source: http://www.cat.cc.md.us/~gkaiser
/biotutorials/eustruct/cmeu.html
[2] Symporters are transport proteins
that simultaneously transport two
substances across the membrane in the
same direction; one against the
concentration gradient and one with the
concentration gradient. Symporters
often use proton motive force to
transport a substrate across the
membrane. The movement of protons
across the membrane (proton motive
force) provides the energy for
transporting the substrate.
source:
be created with an early precellular
protein production system must have
been a protein (like RNA polymerase)
that can make copies of RNA from mRNA
molecules. This protein may have
outperformed a ribozyme that was
performing the copying function.
Eventually mRNA that coded for tRNA
molecules and mRNA that coded for rRNA
molecules merged to form a template.
Now the entire protein production
system (the mRNA itself, tRNAs, rRNAs,
and the RNA polymerase) could be copied
many times by the RNA polymerase
protein.
This is before cytoplasm or any cell
wall has evolved. RNA and DNA copying
happens in water, the first cell has
not evolved yet.
evolves in prokaryotes. Now some
prokaryotes can exchange circular
pieces of DNA (plasmids), through tubes
(pili). Conjugation may be the process
that led to sex (cellular fusion) and
also the transition from a circle of
DNA to chromosomes in eukaryotes, since
some protists (cilliates and some
algae) reproduce sexually by
conjugation.1
Archaeal flagellins are
related to members of the type IV
pilin/transport superfamily widespread
in bacteria.
In addition to pili and conjugation,
proteins evolve that can assist in
splitting DNA and also proteins that
assist in merging two strands of DNA
together, since some times the DNA in
split and the new plasmid is connected
and the DNA circle is sown back
together.2
FOOTNOTES
1. ^ conjugation in protists, flagella
in eukaryotes: Michael Sleigh,
"Protozoa and Other Protists", (London;
New York: Edward Arnold, 1989).
2. ^
prokaryote pili and archaea flagella
related:
http://www.queens-pfd.ca/people/index.cf
m?meds=profile&profile=12
[1] the fertility factor or F factor is
a very large (94,500 bp) circular dsDNA
plasmid; it is generally independent of
the host chromosome. COPYRIGHTED
source: http://www.mun.ca/biochem/course
s/3107/images/Fplasmidmap.gif
[2] conjugation (via pilus)
COPYRIGHTED EDU
source: http://www.bio.miami.edu/dana/16
0/conjugation.jpg
Perha
ps pili evolved into flagella, flagella
into pili, or the two systems are
unrelated.2
Proteins in Archaebacteria flagella are
related to pili in bacteria.
This may be the beginning of motility.
Now for the first time, cells are not
completely controlled by surrounding
matter, but can make limited choices
about their location.
FOOTNOTES
1. ^ conjugation in protists, flagella
in eukaryotes: Michael Sleigh,
"Protozoa and Other Protists", (London;
New York: Edward Arnold, 1989).
2. ^
prokaryote pili and archaea flagella
related:
http://www.queens-pfd.ca/people/index.cf
m?meds=profile&profile=12
allow certain proteins coded by DNA to
not be built, evolve. Proteins bind
with these DNA sequences to stop RNA
polymerase from building mRNA molecules
which would be translated into
proteins. Operons allow a bacterium to
produce certain proteins only when
necessary. Bacteria before now can
only build a constant stream of all
proteins encoded in their DNA.1 2
FOOTNOTES
1. ^
http://info.bio.cmu.edu/Courses/03441/Te
rmPapers/99TermPapers/GenEvo/operon.html
2. ^
http://web.indstate.edu/thcme/mwking/gen
e-regulation.html#table
eubacteria.
Without bacteria that convert N2 into
nitrogen compounds, the supply of
nitrogen necessary for much of life
would be seriously limited and would
drastically slow evolution on earth.
Nitrogen
fixation is the process by which
nitrogen is taken from its relatively
inert molecular form (N2) in the
atmosphere and converted into nitrogen
compounds useful for other chemical
processes (such as, notably, ammonia,
nitrate and nitrogen dioxide).1
Nitrogen fixation is performed
naturally by a number of different
prokaryotes, including bacteria, and
actinobacteria certain types of
anaerobic bacteria. Many higher plants,
and some animals (termites), have
formed associations with these
microorganisms.2
The best-known are
legumes (such as clover, beans, alfalfa
and peanuts,) which contain symbiotic
bacteria called rhizobia within nodules
in their root systems, producing
nitrogen compounds that help the plant
to grow and compete with other plants.
When the plant dies, the nitrogen helps
to fertilize the soil. The great
majority of legumes have this
association, but a few genera (e.g.,
Styphnolobium) do not. 3
FOOTNOTES
1. ^ "Nitrogen fixation". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Nitrogen_fi
xation
2. ^ "Nitrogen fixation". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Nitrogen_fi
xation
3. ^ "Nitrogen fixation". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Nitrogen_fi
xation
[1] This is an image of nitrogen cycle
taken from this [1] EPA website. PD
source: http://en.wikipedia.org/wiki/Ima
ge:Nitrogen_Cycle.jpg
filment growth evolves in prokaryotes.
Cyanobacteria
grow in filaments.
Unlike eukaryotes, there is no
communication between cells in
prokaryote filments.
2
prokaryotes evolve. Heterocysts evolve
in cyanobacteria.
Heterocysts are specialized
nitrogen-fixing cells formed by some
filamentous cyanobacteria during
nitrogen starvation.
What cell differentiation is
first is unknown, perhaps cells that
form spores, or cysts, or perhaps cell
differentiation that is observes in
cyanobacterial filamentous cells.
Heterocysts are specialized
nitrogen-fixing cells formed by some
filamentous cyanobacteria, such as
Nostoc punctiforme and Anabaena
sperica, during nitrogen starvation.
They fix nitrogen from dinitrogen (N2)
in the air using the enzyme
nitrogenase, in order to provide the
cells in the filament with nitrogen for
biosynthesis. Nitrogenase is
inactivated by oxygen, so the
heterocyst must create a microanaerobic
environment. The heterocysts' unique
structure and physiology requires a
global change in gene expression. For
example, heterocysts:
* produce three additional cell
walls, including one of glycolipid that
forms a hydrophobic barrier to oxygen
*
produce nitrogenase and other proteins
involved in nitrogen fixation
* degrade
photosystem II, which produces oxygen
* up
regulate glycolytic enzymes, which use
up oxygen and provide energy for
nitrogenase
* produce proteins that scavenge
any remaining oxygen
Cyanobacteria usually obtain a fixed
carbon (carbohydrate) by
photosynthesis. The lack of photosystem
II prevents heterocysts from
photosynthesising, so the vegetative
cells provide them with carbohydrates,
which is thought to be sucrose. The
fixed carbon and nitrogen sources are
exchanged though channels between the
cells in the filament. Heterocysts
maintain photosystem I, allowing them
to generate ATP by cyclic
photophosphorylation.
Single heterocysts develop about every
9-15 cells, producing a one-dimensional
pattern along the filament. The
interval between heterocysts remains
approximately constant even though the
cells in the filament are dividing. The
bacterial filament can be seen as a
multicellular organism with two
distinct yet interdependent cell types.
Such behaviour is highly unusual in
prokaryotes and may have been the first
example of multicellular patterning in
evolution. Once a heterocyst has
formed, it cannot revert to a
vegetative cell, so this
differentiation can be seen as a form
of apoptosis. Certain
heterocyst-forming bacteria can
differentiate into spore-like cells
called akinetes or motile cells called
hormogonia, making them the most
phenotyptically versatile of all
prokaryotes.
The mechanism of controlling
heterocysts is thought to involve the
diffusion of an inhibitor of
differentiation called PatS. Heterocyst
formation is inhibited in the presence
of a fixed nitrogen source, such as
ammonium or nitrate. The bacteria may
also enter a symbiotic relationship
with certain plants. In such a
relationship, the bacteria do not
respond to the availability of
nitrogen, but to signals produced by
the plant. Up to 60% of the cells can
become heterocysts, providing fixed
nitrogen to the plant in return for
fixed carbon.
The cyanobacteria that form heterocysts
are divided into the orders Nostocales
and Stigonematales, which form simple
and branching filaments respectively.
Together they form a monophyletic
group, with very low genetic
variability.1
FOOTNOTES
1. ^ "Heterocyst". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Heterocyst
2. ^ Ted Huntington, a tital guess my
friends
[1] Anabaena COPYRIGHTED EDU
source: http://home.manhattan.edu/~franc
es.cardillo/plants/monera/anabaena.gif
[2] Anabaena smitthi COPYRIGHTED
FRANCE
source: http://www.ac-rennes.fr/pedagogi
e/svt/photo/microalg/anabaena.jpg
can produce some if not all of their
own food (amino acids, nucleotides,
sugars, phophates, lipids, and
carbohydrates), but require phosphorus,
nitrogen, CO2, water and light in the
form of heat.1
There are only 2 kinds of autotrophy:
Lithotrophy and Photosynthesis. These
are lithotrophic cells that change
inorganic (abiotic) molecules into
organic molecules. These cells are
archaebacteria, called methanogens that
perform the reaction: 4H2 + CO2 -> CH4
+ 2H2O. They convert CO2 into Methane.
Methane is better than CO2 for
trapping heat, and could have
contributed to heating the earth.
FOOTNOTES
1. ^ Richard Cowen, "History of Life",
(Malden, MA: Blackwell, 2005).
cells only have Photosystem I.
Photosynthesis Photosystem I evolves in
early anaerobic prokaryote cells. One
of two photosythesis systems,
photosystem I uses a pigment
chlorophyll A, absorbs photons in 700
nm wave lengths best, breaking the bond
betwenn H2 and S. They are anaerobic
and perform the reaction: H2S
(Hydrogen Sulfide) + CO2 + light ->
CH2O (Formaldehyde) + 2S.
Only 5 phyla of
eubacteria can photosynthesize.1
FOOTNOTES
1. ^ Battistuzzi, Feijao, Hedges, "A
Genomic timescale of prokaryote
evolution: insights into the origin of
methanogenesis, phototrophy, and the
colonization of land", BMC Evolutionary
Biology, (2004).
evolves in early prokaryote cells.
Photosystem 2 absorbs photons best at
680nm wavelengths, a higher frequency
of light than Photosystem I. These
cells can break the strong Hydrogen
bonds between Hydrogen and Oxygen in
water molecules (more abundant than
Sulphur). This system emits free
Oxygen.1
The simple equation of photosynthesis
is: 6 H2O + 6 CO2 + photons = C6H12O6
(glucose) + 6O2. The detailed steps of
photosynthesis are called the "Calvin
Cycle". Prokaryote cells can now
produce their own glucose to store and
be converted to ATP by glycolysis and
fermentation later.
This sytem is the main system
responsible for producing the Oxygen
now in the air of earth.
Of the 5 phyla of
eubacteria that can photosynthesize,
only 1, cyanobacteria, produces oxygen.
1
the "Citric Acid Cycle", and the "Krebs
Cycle") evolves, probably in
cyanobacteria, as a substitute for
fermentaton, by using oxygen to break
down the products of glycolysis,
pyruvic acid, to CO2 and H2O, producing
18 more ATP molecules.1
This is the
first aerobic cell, a cell that has an
oxygen based metabolism. This cell
uses oxygen to convert glucose (and
eventually other sugars and fats) into
CO2, H2O and ATP. For example, cells
that oxidize glucose perform the
reaction:
C6H12O6 + 6 O2 + 38 ADP + 38 phosphate
-> 6 CO2 + 6 H2O + 38 ATP
This reaction
(with glycolysis) can produce up to 36
ATP molecules. Cellular respiration is
the opposite (although the specific
reactions differ) of photosynthesis
which starts with H2O and CO2 and
produces glucose.
Steps are:
Glycolysis preparatory
phase
Glycolysis pay-off phase
Oxidative
carboxylation
Krebs cycle
FOOTNOTES
1. ^ "Aerobic organism". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Aerobic_org
anism
[1] kreb cycle from
http://people.unt.edu/~hds0006/tca/
source:
for a cell wall. The cell wall only
protects bacteria and does not filter
any molecules as the cytoplasm does.
is
first gram-negative cell wall?
1. Only contain a few layers of
peptidoglycan -- the building block for
strong, rigid cell walls
2. Contain an
outer membrane, external to the
peptidoglycan, called the
lipopolysaccharide
3. The space between the layers of
peptidoglycan and the secondary cell
membrane is called periplasmatic space
4.
The S-layer is directly attached to the
outer membrane, rather than the
peptidoglycan
5. Any flagella, if present, have 4
supporting rings instead of two
6. No
teichoic acids are present"
[1] one is indirectly
from http://www.cvm.uiuc.edu/courses/vp
331/index.html
source: file:/root/web/Structures_in_pat
hogenesi1.html
source: http://www.mansfield.ohio-state.
edu/~sabedon/biol1080.htm
secondary processes in cells that are
not fully understood yet.
to be found, more DNA needs to be
sequenced, and more bacteria found and
grown to fully understand when bacteria
parts evolved. For example:
flagella
plasmids
pili and "conjugation" the trade of
pieces of plasmid DNA (this may be the
earliest form of sex {or syngamy})
changing into
spores
When gram-stain positive cell walls
evolved.
When the various shapes evolved:
spherical
(coccus,cocci)
rod (bacillus,bacilli)
spiral (spirilla)
other:
short rods (coccobacilli).
commas (vibrii).
squares (rare)
stars (rare)
irregula
r (rare)
Which specific bacteria of the Archaea
(if any) were first, which of the
Eubacteria and Cyanobacteria came
next.
When the "Nitrogen Cycle" or "Nitrogen
Fixing" evolved. Few cells can
separate N2 into N, (needed for nucleic
acids?1 ). The waste product urea is
converted by one bacteria to ammonia, a
second bacteria converts the ammonia to
N2.
FOOTNOTES
1. ^ Ted Huntington.
1 2 3 4 5 6 7
estimates of when the first Eubacteria
and Archaea evolved. Eubacteria and
Archaea (also called Archaebacteria)
are the two major lines of Prokaryotes.
Prokaryotes are the most primitive
living objects ever found. In contrast
to the later evolved Eukaryotes,
Prokaryotes have a circle of DNA
located in their cytoplasm (not
chromosomes) and have no nucleus. At
least one genetic comparison shows
Eubacteria and Archaea evolving now.1 2
3 4 5 6 7
After the full genomes of all living
species are known, and understood we
will have more certainty about the
history of evolution. Many genetic
trees are based on DNA genes (sequences
of DNA that define nucleic acids or
proteins). In particular the genes for
ribosomal RNA are thought to be very
conserved over time, although perhaps
genes for reproduction, or cytoplasm,
for example may later prove to be more
conserved over time.
Only when the full
genomes of all living species are
known, and understood will we have
strong certainty about the history of
evolution. Many genetic trees are
based on DNA genes (sequences of DNA
that define nucleic acids or proteins),
in particular ribosomal RNA which is
thought to be highly conserved over the
eons of time. Ribosomal RNA may be the
best record of evolutionary history,
but perhaps other genes, for example,
those involved with reproduction, or
cytoplasm will prove to be more
conserved or better estimates of
evolutionary history. For example, I
think the method of reproduction would
be the most conserved, since that
process is the most necessary for
survival, changes to those genes may
stop continued existence, where changes
to rrna may not be as serious. In
addition, the vast diversity and change
in reproductive method over time,
should tell us that similar large scale
changes could have happened for rrna,
cytoplasm, and indeed any part of a
cell.
These early Archaea and Eubacteria are
"thermophile" bacteria, bacteria that
are found and grow best in hot water
(80+ degrees Celsius). That genetic
evidence puts these prokaryotes as the
oldest living prokaryotes is evidence
that the first prokaryotes on earth may
have lived in hot water, perhaps near
thermal springs or near ocean floor
volcanos. Perhaps the water on the
early earth was hot when these first
prokaryotes evolved.
Archaea are similar to
other prokaryotes in most aspects of
cell structure and metabolism. However,
their genetic transcription and
translation are very similar to those
of eukaryotes.
FOOTNOTES
1. ^
http://www.nature.com/nrg/journal/v3/n11
/full/nrg929_fs.html
2. ^ Russell F. Doolittle, Da-Fei Feng,
Simon Tsang, Glen Cho, Elizabeth
Little, "Determining Divergence Times
of the Major Kingdoms of Living
Organisms with a Protein Clock",
Science, (1996). 2142-1873my
(2142-1873my)
3. ^ Richard Dawkins, "The Ancestor's
Tale", (Boston, MA: Houghton Mifflin
Company, 2004). 2300my (2300my)
4. ^
Battistuzzi, Feijao, Hedges, "A Genomic
timescale of prokaryote evolution:
insights into the origin of
methanogenesis, phototrophy, and the
colonization of land", BMC Evolutionary
Biology, (2004). 4100my (has arche b4
eu) (4100my)
5. ^ Osawa, S., Honjo,
"Archaebacteria vs Metabacteria :
Phylogenetic tree of organisms
indicated by comparison of 5S ribosomal
RNA sequences.", (Tokyo: Springer,
Tokyo/ Berlin eds.:"Evolution of Life",
pp. 325-336,, 1991). 1800my (1800my)
6. ^ S.
Blair Hedges, "The Origin and Evolution
of Model Organisms", Nature Reviews
Genetics 3, 838-849 (2002);
doi:10.1038/nrg929, (2002). 4000my
(4000my)
7. ^ S. Blair Hedges and Sudhir Kumar,
"Genomic clocks and evolutionary
timescales", Trends in Genetics
Volume 19, Issue 4 , April 2003, Pages
200-206, (2003). 3970my (3970my)
[1] Figure 1) Changing views of the
tree and timescale of life. a) An
early-1990s view, with the tree
determined mostly from ribosomal RNA
(rRNA) sequence analysis. This tree
emphasizes vertical (as opposed to
horizontal) evolution and the close
relationship between eukaryotes and the
Archaebacteria. The deep branching
(>3.5 Giga (109) years ago, Gya) of
CYANOBACTERIA (Cy) and other Eubacteria
(purple), the shallow branching
(approx1 Gya) of plants (Pl), animals
(An) and fungi (Fu), and the early
origin of mitochondria (Mi), were based
on interpretations of the geochemical
and fossil record7, 8. Some deeply
branching amitochondriate (Am) species
were believed to have arisen before the
origin of mitochondria44. Major
symbiotic events (black dots) were
introduced to explain the origin of
eukaryotic organelles42, but were not
assumed to be associated with large
transfers of genes to the host nucleus.
They were: Eu, joining of an
archaebacterium host with a eubacterium
(presumably a SPIROCHAETE) to produce
an amitochondriate eukaryote; Mi,
joining of a eukaryote host with an
alpha-proteobacterium (Ap) symbiont,
leading to the origin of mitochondria,
and plastids (Ps), joining of a
eukaryote host with a cyanobacterium
symbiont, forming the origin of
plastids on the plant lineage and
possibly on other lineages. b) The
present view, based on extensive
genomic analysis. Eukaryotes are no
longer considered to be close relatives
of Archaebacteria, but are genomic
hybrids of Archaebacteria and
Eubacteria, owing to the transfer of
large numbers of genes from the
symbiont genome to the nucleus of the
host (indicated by coloured arrows).
Other new features, largely derived
from molecular-clock studies16, 39 (Box
1), include a relatively recent origin
of Cyanobacteria (approx2.6 Gya) and
mitochondria (approx1.8 Gya), an early
origin (approx1.5 Gya) of plants,
animals and fungi, and a close
relationship between animals and fungi.
Coloured dashed lines indicate
controversial aspects of the present
view: the existence of a
premitochondrial symbiotic event and of
living amitochondriate eukaryotes,
ancestors of which never had
mitochondria. c) The times of
divergence of selected model organisms
from humans, based on molecular clocks.
For the prokaryotes (red), because of
different possible origins through
symbiotic events, divergence times
depend on the gene of interest.
source: http://www.nature.com/nrg/journa
l/v3/n11/full/nrg929_fs.html
[2] Figure 2 A phylogeny of
prokaryotes. The relationships of
selected prokaryote model organisms
based on recent studies14-19. Times of
divergence (million years ago (Mya)
plusminus one standard error) are
indicated at nodes in the tree16, 39.
Branch lengths are not proportional to
time. Phyla and phylum-level groupings
are indicated on the right.
source: http://www.nature.com/nrg/journa
l/v3/n11/full/nrg929_fs.html
1
evolve.1 2 3
Genetic comparison shows
the Archaea Phylum, Euryarchaeotes
evolving now.
The Euryarchaeota are a major group of
Archaea. They include the methanogens,
which produce methane and are often
found in intestines, the halobacteria,
which survive extreme concentrations of
salt, and some extremely thermophilic
aerobes and anaerobes. They are
separated from the other archaeans
based mainly on rRNA sequences.4
Euryarchaeota may contain the most
ancient DNA of any living object on
earth.
PHYLUM Euryarchaeota
CLASS Archaeoglobi
CLASS Halobacteria
CLASS
Methanobacteria
CLASS Methanococci
CLASS Methanomicrobia
CLASS Methanopyri
CLASS
Methanosarcinae
CLASS Thermococci
CLASS Thermoplasmata
FOOTNOTES
1. ^ Richard Dawkins, "The Ancestor's
Tale", (Boston, MA: Houghton Mifflin
Company, 2004).
[1] tree of archaebacteria (archaea)
COPYRIGHTED
source: http://www.uni-giessen.de/~gf126
5/GROUPS/KLUG/Stammbaum.html
[2] A phylogenetic tree of living
things, based on RNA data, showing the
separation of bacteria, archaea, and
eukaryotes. Trees constructed with
other genes are generally similar,
although they may place some
early-branching groups very
differently, thanks to long branch
attraction. The exact relationships of
the three domains are still being
debated, as is the position of the root
of the tree. It has also been suggested
that due to lateral gene transfer, a
tree may not be the best representation
of the genetic relationships of all
organisms. NASA
source: http://en.wikipedia.org/wiki/Ima
ge:PhylogeneticTree.jpg
1
evolves.1 2 3
Genetic comparison shows
Archaea Phylum, Crenarchaeotes evolving
now.
The phylum Crenarchaeota, commonly
referred to as the crenarchaea, in the
domain Archaea, contains many extremely
thermophilic and psychrophilic
organisms. They were originally
separated from the other archaeons
based on rRNA sequences, since then
physiological features, such as lack of
histones have supported this division.
Until recently all cultured crenarchaea
have been thermophilic or
hyperthermophilic organisms, some of
which have the ability to grow up to
113 degrees C. These organisms stain
gram negative and are morphologically
diverse having rod, cocci, filamentous
and unusually shaped cells.4
PHYLUM
Crenarchaeotes
ORDER Caldisphaerales
ORDER Cenarchaeales
ORDER
Desulfurococcales
ORDER Sulfolobales
ORDER Thermoproteales
FOOTNOTES
1. ^ Richard Dawkins, "The Ancestor's
Tale", (Boston, MA: Houghton Mifflin
Company, 2004).
[1] tree of archaea ?
source: http://www.uni-giessen.de/~gf126
5/GROUPS/KLUG/Stammbaum.html
[2] Microscopia elettronica a
scansione dell'archeobatterio
termoacidofilo Sulfolobus solfataricus
COPYRIGHT ITALY
source: http://www.area.fi.cnr.it/r&f/n6
/ingrand.htm
Acasta and Great Slave Lake in the
North West territories of Canada dates
from this time, 4030 million years
before now.1 2 3 4
FOOTNOTES
1. ^
http://pubs.usgs.gov/gip/geotime/age.htm
l
2. ^
http://www.geol.umd.edu/~tholtz/G102/102
arch1.htm
3. ^
http://chigaku.ed.gifu-u.ac.jp/chigakuhp
/dem/tec/history/isua.html
4. ^
http://www.mediaworkshop.org/techcamp/gr
oupc/geology/geohome.htm
source: http://www.regione.emilia-romagn
a.it/geologia/divulgazione/pianeta_terra
/09_paesaggio/img/app/c09_a01_01.jpg
source:
4
(Aquifex, Thermotoga, etc.) evolve
now.1 2
Genetic comparison shows that
Eubacteria "Hyperthermophiles"
(Aquifex, Thermotoga, etc.) evolve now.
This may be the living object with the
most primitive DNA found on earth
(depending on the age of the archaea).
This group of eubacteria includes the
Phyla "Aquificae",
"Thermodesulfobacteria", and
"Thermotogae".
The Aquificae phylum is a diverse
collection of bacteria that live in
harsh environmental settings. They have
been found in hot springs, sulfur
pools, and thermal ocean vents. Members
of the genus Aquifex, for example, are
productive in water between 85 to 95
°C. They are the dominant members of
most terrestrial neutral to alkaline
hot springs above 60 degrees celsius.
They are autotrophs, and are the
primary carbon fixers in these
environments. They are true bacteria
(domain eubacteria) as opposed to the
other inhabitants of extreme
environments, the Archaea.
Thermotoga are thermophile or
hyperthermophile bacteria whose cell is
wrapped in an outer "toga" membrane.
They metabolize carbohydrates. Species
have varying amounts of salt and oxygen
tolerance. Thermotoga subterranea
strain SL1 was found in a 70°C deep
continental oil reservoir in the East
Paris Basin, France. It is anaerobic
and reduces cystine and thiosulfate to
hydrogen sulfide.3
FOOTNOTES
1. ^ Battistuzzi, Feijao, Hedges, "A
Genomic timescale of prokaryote
evolution: insights into the origin of
methanogenesis, phototrophy, and the
colonization of land", BMC Evolutionary
Biology, (2004).
2. ^ Brocks, Buick, "A
reconstruction of Archean biological
diversity based on", Geochimica et
cosmochimica acta, (2003).
3. ^ "Aquifex".
Wikipedia. Wikipedia, 2008.
http://en.wikipedia.org/wiki/Aquifex
4. ^ Battistuzzi, Feijao, Hedges, "A
Genomic timescale of prokaryote
evolution: insights into the origin of
methanogenesis, phototrophy, and the
colonization of land", BMC Evolutionary
Biology, (2004).
[1] Aquifex pyrophilus (platinum
shadowed). © K.O. Stetter & Reinhard
Rachel, University of Regensburg.
source: http://biology.kenyon.edu/Microb
ial_Biorealm/bacteria/aquifex/aquifex.ht
m
[2] Aquifex aeolicus. © K.O. Stetter
& Reinhard Rachel, University of
Regensburg.
source: http://biology.kenyon.edu/Microb
ial_Biorealm/bacteria/aquifex/aquifex.ht
m
also the oldest Banded Iron Formation,
on Akilia Island in Western Greenland.
The oldest evidence for life on earth
was found in this rock by measuring the
ratio of carbon 12 to carbon 13 in
grains of apatite (calcium phosphate)
from this rock. Life uses the lighter
Carbon-12 isotope and not Carbon-13 and
so the ratio of carbon-12 to carbon-13
is different from a nonliving source
(calcium carbonate or limestone).1 2
FOOTNOTES
1. ^ Mojzsis, et al. nature nov 7,
1996
http://www.nature.com/cgi-taf/DynaPage.t
af?file=/nature/journal/v384/n6604/index
.html, 2:102,
2. ^
http://jersey.uoregon.edu/~mstrick/Rogue
ComCollege/RCC_Lectures/Banded_Iron.html
source: nature 11/7/96
Banded Iron Formation Rocks. These
rocks are sedimentary. They are made
of iron rich chert (silicates, like
SiO2). These rocks have alternative
bands of orange or yellow and black.
In the red parts the iron is oxydized
(contains iron oxides, either hematite
{Fe2O3 = rust} or magnetite {Fe3O4]}).1
2 3 4 5
These bands may have formed because
photosynthetic bacteria (in
stromatolites found in shallow ocean
shores, and purple bacteria floating in
water) produce oxygen from CO2 during
photosynthesis. When the level of
oxygen in the water became too high,
many bacteria died, and this cycle
created the BIF. But BIF also may form
naturally when photons in uv
frequencies split H2O into H2 and O2.
So perhaps the BIF bands represent
cycles of more or less uv light
reaching the earth. Perhaps the
alternating phenomenon is similar to
eukaryotic algal blooms. In any event,
this free oxygen bonded with the many
tons of iron dissolved in the water to
form insoluable iron oxide which then
fell to the ocean floor to form the
orange layers of Banded Iron Formation.
How these alternating bands are made
is not clear and has not yet been
duplicated in a lab.
This cycle of alternating orange and
black bands will continue for 2 billion
years until 1,800 million years before
now. This is the beginning of oxygen
production on earth, the atmosphere of
earth still has only small amounts of
oxygen at this time.
It is amazing that
people are still not certain what was
the cause of the oxygen, and the cycles
that deposited the banded Iron
Formation.
source: nature 11/7/96
formation, SW Greenland.1 2
FOOTNOTES
1. ^ Hans D. Pflug, "Earliest organic
evolution. Essay to the memory of
Bartholomew Nagy",Precambrian
Research Volume 106, Issues 1-2, 1
February 2001, Pages
79-91. http://www.sciencedirect.com/sci
ence?_ob=ArticleURL&_udi=B6VBP-42G6M5T-7
&_user=4422&_coverDate=02%2F01%2F2001&_f
mt=full&_orig=browse&_cdi=5932&view=c&_a
cct=C000059600&_version=1&_urlVersion=0&
_userid=4422&md5=d61bf36f008d6b2cba3ba5d
bd5a628d7&ref=full#bib9
2. ^ Schopf, J.W., 1993. Microfossils
from the early Archean Apex chert: New
evidence of the antiquity of life.
Science 260, pp. 640-646.
Abstract-GEOBASE Abstract-MEDLINE
[1] Fig. 5. (a) Carbonaceous
microstructure from Isua Banded iron
formation, SW-Greenland (ca 3.85 Ga).
(b) Laser mass spectrum (negative ions)
from similar specimen. Field of
measurement ca 1 small mu, Greekm
diameter.
source: http://www.sciencedirect.com/sci
ence?_ob=MiamiCaptionURL&_method=retriev
e&_udi=B6VBP-42G6M5T-7&_image=fig7&_ba=7
&_user=4422&_coverDate=02%2F01%2F2001&_f
mt=full&_orig=browse&_cdi=5932&view=c&_a
cct=C000059600&_version=1&_urlVersion=0&
_userid=4422&md5=fe1052cbc18dba545ec95c2
e7ff3090b
2
FOOTNOTES
1. ^ The geological Society of America
ucmp.berkeley.edu
2. ^ Richard Cowen, "History of Life",
(Malden, MA: Blackwell, 2005).
3
Greenland Banded Iron Formation
sediment are evidence of the existence
of Archaea.1 2
FOOTNOTES
1. ^
http://www.ucmp.berkeley.edu/archaea/arc
haeafr.html
2. ^ Jürgen Hahn & Pat Haug. 1986.
Traces of Archaebacteria in ancient
sediments. System. Appl. Microbiol. 7:
178-183. (Archaebacteria '85
Proceedings).
3. ^
http://www.ucmp.berkeley.edu/archaea/arc
haeafr.html
2
and Hydrocarbon molecules (alkanes)
detected in 3760 billion year old Isua
Banded Iron Formation, indicate the
possibility of photosynthetic sulfate
reducing bacteria (Archaea, for example
Sulpholobus) and Cyanobacteria living
at that time.1
FOOTNOTES
1. ^ Systematic and Applied
Microbiology, Vol 7, pp 178-183 1986
2. ^
Systematic and Applied Microbiology,
Vol 7, pp 180-189 1986
2
in Isua, Greenland Banded Iron
Formation evidence of prokaryote Oxygen
photosynthesis.1
FOOTNOTES
1. ^ Earth and Planetary Science
Letters Volume 217, Issues 3-4 , 15
January 2004, Pages 237-244U-rich
"Archaean sea-floor sediments from
Greenland - indications of >3700 Ma
oxygenic photosynthesis" Minik T.
Rosing and Robert Frei
2. ^ Earth and
Planetary Science Letters Volume 217,
Issues 3-4 , 15 January 2004, Pages
237-244U-rich "Archaean sea-floor
sediments from Greenland - indications
of >3700 Ma oxygenic
photosynthesis" Minik T. Rosing and
Robert Frei
2
sediment in Australia shown to be
consistent with planktonic
photosynthesizing organisms.1
FOOTNOTES
1. ^ 13C-Depleted Carbon
Microparticles in >3700-Ma Sea-Floor
Sedimentary Rocks from West Greenland
http://www.sciencemag.org/cgi/content/
full/283/5402/674 Science 29 January
1999: Vol. 283. no. 5402, pp. 674 -
676 DOI: 10.1126/science.283.5402.674
2. ^ 13C-Depleted Carbon
Microparticles in >3700-Ma Sea-Floor
Sedimentary Rocks from West Greenland
http://www.sciencemag.org/cgi/content/
full/283/5402/674 Science 29 January
1999: Vol. 283. no. 5402, pp. 674 -
676 DOI: 10.1126/science.283.5402.674
[1] Figure 1. (A) Turbidite sedimentary
rocks from the Isua supracrustal belt,
west Greenland. The notebook is 17 cm
wide. (B) A close-up of finely
laminated slate representing pelagic
mud. The hammer is 70 cm long. (C)
Photomicrograph of sample 810213,
showing finely laminated pelagic mud.
The variation in color is mainly due to
variations in C abundance. (D)
Photomicrograph of C grains arranged
along a buckled stringer. (E)
Backscattered electron image of a
polished surface (sample 810213),
showing the distribution of C grains as
black areas. (F) Backscattered electron
image of a polished surface (sample
810213), showing the rounded shape of C
grains (black).
source: http://www.sciencemag.org/cgi/co
ntent/full/283/5402/674
3
Archaebacteria (Archaea) Phylum,
Korarchaeotes evolving now.1 2
FOOTNOTES
1. ^ Richard Dawkins, "The Ancestor's
Tale", (Boston, MA: Houghton Mifflin
Company, 2004).
2. ^ Battistuzzi, Feijao,
Hedges, "A Genomic timescale of
prokaryote evolution: insights into
the origin of methanogenesis,
phototrophy, and the colonization of
land", BMC Evolutionary Biology,
(2004).
3. ^ Battistuzzi, Feijao, Hedges, "A
Genomic timescale of prokaryote
evolution: insights into the origin of
methanogenesis, phototrophy, and the
colonization of land", BMC Evolutionary
Biology, (2004). and image 1
MORE INFO
[1] also see nature v417 n6886
[1] DNA tree
source: http://www.uni-giessen.de/~gf126
5/GROUPS/KLUG/Stammbaum.html
[2] Scanning electron micrograph of
the Obsidian Pool enrichment culture.
Barns et al. discovered the
Korarchaeota lineage in Obsidian Pool
over a decade ago, using what were
highly innovative methods for the time.
Since their discovery, the Korarchaeota
group of microorganisms still remains
mostly uncharacterized. The group is
primarily defined only by 16S ribosomal
RNA sequences obtained from a variety
of marine and terrestrial hydrothermal
environments. The 16S-rRNA-based
phylogeny of the Korarchaeota suggests
that this group forms a very deep,
kingdom-level, major lineage within the
archaeal domain. PD
source: http://www.jgi.doe.gov/sequencin
g/why/CSP2006/korarchaeota.jpg
yet found. Stromatolites made by
photosynthetic bacteria found in both
Warrawoona, Western Australia, and Fig
Tree Group, South Africa.1 2
FOOTNOTES
1. ^ nature feb 6, 1986
2. ^ nature apr 3,
1980
[1] image on left is from swaziland
source: nature feb 6
source: 1986
thought to be cyanobacteria, found in
3,500 Million Year old chert from South
Africa and 3,465 Million year old Apex
chert of north-western Australia.1 2 3
4 5
Oldest fossils of an organism,
thought to be cyanobacteria, found in
3,500 Million Year old chert from South
Africa and 3,465 Million year old Apex
chert of the Pilbara Supergroup,
Warrawoona Group, northwestern Western
Australia.
Some people argue that these are not
fossils of bacteria but abiotic
material. Most genetic timelines put
the origin of cyanobacteria much later
around 2,700mybn.
Cyanobacteria evolved
multicellularity where cellular
differentiation occurs.6 7
FOOTNOTES
1. ^ warrawoona Nature416, 73 - 76
(07 Mar 2002) Letters to Nature
http://www.nature.com/nature/journal/v
416/n6876/full/416073a_fs.html
2. ^ swaziland Nature 314, 530-532
(11 Apr 1985) Letters to
Editor "Filamentous microfossils from
the 3,500-Myr-old Onverwacht Group,
Barberton Mountain Land, South Africa"
3. ^
argues that these are not
fossils: http://www.nature.com/nature/j
ournal/v420/n6915/full/420476b.html
"we contend that the Raman spectra of
Schopf et al.1 indicate that these are
disordered carbonaceous materials of
indeterminate origin. We maintain that
Raman spectroscopy cannot be used to
identify microfossils unambiguously,
although it is a useful technique for
pinpointing promising microscopic
entities for further investigation."
4. ^
http://www.nature.com/news/2002/020304/f
ull/020304-6.html "Gloves are coming
off in ancient bacteria bust-up." 2002
5. ^
http://www.nature.com/nature/journal/v41
6/n6876/full/416076a.html braiser et
al. "Questioning the evidence for
Earth's oldest fossils"
6. ^ BIO415 (Author?
University?) Multicelluarity.pdf (t3:
multicellularity of cyanobacteria)
7. ^ t3:
http://www.mansfield.ohio-state.edu/~sab
edon/biol3018.htm multiceullarity.
"Some cyanobacteria species exist in a
truly, though primitive, multicellular
form in which cellular differentiation
occurs."
[1] Figure 1 Optical photomicrographs
showing carbonaceous (kerogenous)
filamentous microbial fossils in
petrographic thin sections of
Precambrian cherts. Scale in a
represents images in a and c-i; scale
in b represents image in b. All parts
show photomontages, which is
necessitated by the three-dimensional
preservation of the cylindrical sinuous
permineralized microbes. Squares in
each part indicate the areas for which
chemical data are presented in Figs 2
and 3. a, An unnamed cylindrical
prokaryotic filament, probably the
degraded cellular trichome or tubular
sheath of an oscillatoriacean
cyanobacterium, from the 770-Myr
Skillogalee Dolomite of South
Australia12. b, Gunflintia grandis, a
cellular probably oscillatoriacean
trichome, from the 2,100-Myr Gunflint
Formation of Ontario, Canada13. c, d,
Unnamed highly carbonized filamentous
prokaryotes from the 3,375-Myr Kromberg
Formation of South Africa14: the poorly
preserved cylindrical trichome of a
noncyanobacterial or oscillatoriacean
prokaryote (c); the disrupted,
originally cellular trichomic remnants
possibly of an Oscillatoria- or
Lyngbya-like cyanobacterium (d). e-i,
Cellular microbial filaments from the
3,465-Myr Apex chert of northwestern
Western Australia: Primaevifilum
amoenum4,5, from the collections of The
Natural History Museum (TNHM), London,
specimen V.63164[6] (e); P. amoenum4
(f); the holotype of P.
delicatulum4,5,15, TNHM V.63165[2] (g);
P. conicoterminatum5, TNHM V63164[9]
(h); the holotype of Eoleptonema apex5,
TNHM V.63729[1] (i).
source: Nature416
[2] Fig. 3 Filamentous microfossils:
a, cylindrical microfossil from
Hooggenoeg sample; b, threadlike and
tubular filaments extending between
laminae, Kromberg sample; c,d,e,
tubular filamnets oriented subparallel
to bedding, Kromberg sample; f,
threadlike filament flattened parallel
to bedding, Kromberg sample.
source: 73 - 76 (07 Mar 2002) Letters
to Nature
http://www.nature.com/nature/journal/v41
6/n6876/fig_tab/416073a_F1.html
3 4
eukaryotes happened here at 3.5 bybn.1
2
FOOTNOTES
1. ^ Michael Sleigh, "Protozoa and
Other Protists", (London; New York:
Edward Arnold, 1989).
2. ^ Carl R. Woese,
"Bacterial Evolution", Microbiological
Reviews, June 1877, p. 221-271.
woese1987b.pdf
3. ^ Michael Sleigh, "Protozoa and
Other Protists", (London; New York:
Edward Arnold, 1989).
4. ^ Carl R. Woese,
"Bacterial Evolution", Microbiological
Reviews, June 1877, p. 221-271.
woese1987b.pdf
2
evidence of moderate thermophile
sulphur reducing prokaryotes from North
Pole, Australia.1
FOOTNOTES
1. ^
http://www.nature.com/cgi-taf/DynaPage.t
af?file=/nature/journal/v410/n6824/full/
410077a0_fs.html
2. ^
http://www.nature.com/cgi-taf/DynaPage.t
af?file=/nature/journal/v410/n6824/full/
410077a0_fs.html
[1] get larger image
source: file:///root/web/fossils_biomark
er_science_v67_i22_nov_15_2003.html#bib9
9
2
bacteria.1
FOOTNOTES
1. ^
http://www.nature.com/nature/journal/v41
0/n6824/full/410077a0.html
2. ^
http://www.nature.com/nature/journal/v41
0/n6824/full/410077a0.html
[1] The tree is modified from ref. 2,
and abstracted from phylogenetic trees
presented in refs 26 and 27. The time
calibration points are from ref. 30,
with our additional constraint of 3.47
Gyr placed in the Bacterial domain.
Lineages housing sulphate-reducers
metabolizing at temperatures > 70 °C
are shown by broken black lines, while
lineages supporting sulphate-reducers
metabolizing at < 70 °C are shown by heavy black lines.
source: http://www.nature.com/nature/jou
rnal/v410/n6824/fig_tab/410077a0_F4.html
1
photosynthetic bacteria found in
Pilbara Craton, Australia.
Strelley Pool Chert
FOOTNOTES
1. ^
http://www.nature.com/nature/journal/v44
1/n7094/full/nature04764.html
[1] a-c, 'Encrusting/domical
laminites'; d-f, 'small crested/conical
laminites'; g-i, 'cuspate swales'; j-l,
'large complex cones' (dashed lines in
k trace lamina shape and show outlines
of intraclast conglomerate piled
against the cone at two levels). m-o,
'Egg-carton laminites'; p, q, 'wavy
laminites'; r-t, 'iron-rich laminites'
(t is a cut slab). The scale card in b,
h and i is 18 cm. The scale card
increments in c, e, k, l, n and s are 1
cm. The scale bar in o is about 1 cm.
The scale bars in the remaining
pictures are about 5 cm. COPYRIGHTED
source: http://www.nature.com/nature/jou
rnal/v441/n7094/fig_tab/nature04764_F1.h
tml
2
photosynthetic, probably anoxygenic,
bacteria that lived in mats in the
ocean date to this time.1
FOOTNOTES
1. ^
http://www.nature.com/nature/journal/v43
1/n7008/full/nature02888.html
2. ^
http://www.nature.com/nature/journal/v43
1/n7008/full/nature02888.html
[1] a, Dark carbonaceous laminations
draping an underlying coarse detrital
carbonaceous grain (a), showing
internal anastomosing and draping
character (b) and, at the top (c)
draping irregularities in underlying
carbonaceous laminations. b, Dark
carbonaceous laminations that have been
eroded and rolled up by currents. c,
Bundled filaments in the rolled
laminations in b [tp: they should
have clearly indicated that they are
saying that these filaments are
bacteria].
source: http://www.nature.com/nature/jou
rnal/v431/n7008/fig_tab/nature02888_F4.h
tml
Swaziland System, South Africa.1
FOOTNOTES
1. ^
http://www.sciencedirect.com/science?_ob
=ArticleURL&_udi=B6VBP-42G6M5T-7&_user=4
422&_coverDate=02%2F01%2F2001&_fmt=full&
_orig=browse&_cdi=5932&view=c&_acct=C000
059600&_version=1&_urlVersion=0&_userid=
4422&md5=d61bf36f008d6b2cba3ba5dbd5a628d
7&ref=full#bib9
MORE INFO
[1] maybe evidence: Nagy, B. and
Nagy, L.A., 1969. Early Precambrian
microstructures: possibly the oldest
fossils on Earth?. Nature 223, pp.
1226-1229.?
[1] Fig. 3. (a,b) Organic
microstructures from Kromberg
Formation, Swaziland System, South
Africa (ca 3.4 Ga). TEM-micrographs of
demineralized specimens. (c) Portion of
organic microstructure from Bulawaya
stromatolite (see Fig. 2). (d) Portion
of the mucilagenous sheath of recent
Anabaena sp., cyanobacteria (Fig. d
after Leak, 1967). For magnification of
Fig. c see scale of Fig. a.
source: http://www.sciencedirect.com/sci
ence?_ob=MiamiCaptionURL&_method=retriev
e&_udi=B6VBP-42G6M5T-7&_image=fig9&_ba=9
&_user=4422&_coverDate=02%2F01%2F2001&_f
mt=full&_orig=browse&_cdi=5932&view=c&_a
cct=C000059600&_version=1&_urlVersion=0&
_userid=4422&md5=27a45a0804747bb4b74eaac
305df2905
1
Different from binary division, where a
cell is split in half, in budding, a
new complete cell is made in the
original cell, and the new cell bursts
through the cell wall, the original
cell wall must then be repaired.
Budding is the
only other method of reproduction known
in prokaryotes besides binary fission.
The only major difference between
prokaryote budding and binary division
are that one or more new cells are
completely formed inside the original
cell, where in binary division part of
the original cell wall is used to make
the new cell.
In budding, a complete new cell is
synthesized from a DNA template, where
in binary division only the DNA is
duplicated and more cytoplasm and cell
wall is synthesized. So, budding
preserves organelles made by the main
DNA template that cannot duplicate
themselves and would not get duplicated
or synthesized in binary division, for
example, flagella.
Although it is very unlikely,
the possibility does exist that
prokaryote budding evolved from a
eukaryote that lost it's nucleus.
FOOTNOTES
1. ^ Record ID 191. "Universe, life,
Science Future". Ted Huntington. (based
on my own estimate based on fossils
from id191) (3.4)
[1] Evolutionary relationships of model
organisms and bacteria that show
unusual reproductive strategies. This
phylogenetic tree (a) illustrates the
diversity of organisms that use the
alternative reproductive strategies
shown in (b). Bold type indicates
complete or ongoing genome projects.
Intracellular offspring are produced by
several low-GC Gram-positive bacteria
such as Metabacterium polyspora,
Epulopiscium spp. and the segmented
filamentous bacteria (SFB). Budding and
multiple fission are found in the
proteobacterial genera Hyphomonas and
Bdellovibrio, respectively. In the case
of the Cyanobacteria, Stanieria
produces baeocytes and Chamaesiphon
produces offspring by budding.
Actinoplanes produce dispersible
offspring by multiple fission of
filaments within the sporangium.
source: http://www.nature.com/nrmicro/jo
urnal/v3/n3/full/nrmicro1096_fs.html
(Nature Reviews Microbiology 3
[2] Electron micrograph of a
Pirellula bacterium from giant tiger
prawn tissue (Penaeus monodon). Notice
the large crateriform structures (C) on
the cell surface and flagella. From
Fuerst et al.
source: 214-224 (2005);
doi:10.1038/nrmicro1096)
South Africa are oldest evidence of
procaryotes that reproduce by budding
and not binary fission.1
FOOTNOTES
1. ^
http://www.sciencedirect.com/science?_ob
=ArticleURL&_udi=B6VBP-42G6M5T-7&_user=4
422&_coverDate=02%2F01%2F2001&_fmt=full&
_orig=browse&_cdi=5932&view=c&_acct=C000
059600&_version=1&_urlVersion=0&_userid=
4422&md5=d61bf36f008d6b2cba3ba5dbd5a628d
7&ref=full#bib9
MORE INFO
[1] (maybe
evidence): ZENTRALBLATT FUR
BAKTERIOLOGIE MIKROBIOLOGIE UND HYGIENE
I ABTEILUNG Pflug, H.D., 1982. Early
diversification of life in the Archean.
Zbl. Bakt. Hyg. I.Abt. Orig. C3, pp.
53-64.?
[1] Fig. 4. (a-d) Organic
microstructures from Swartkoppie chert,
South Africa (ca 3.25 Ga).
TEM-micrographs of demineralized
specimen (a,b) Laser mass spectra
(negative ions) from clusters of
similar specimens. Field of measurement
ca 1 small mu, Greekm diameter. (c,d)
TEM-micrographs from demineralized Thin
section. (e) Recent budding iron
bacterium Pedomicrobium sp. (Fig. e
from Ghiorse and Hirsch, 1979).
source: http://www.sciencedirect.com/sci
ence?_ob=MiamiCaptionURL&_method=retriev
e&_udi=B6VBP-42G6M5T-7&_image=fig6&_ba=6
&_user=4422&_coverDate=02%2F01%2F2001&_f
mt=full&_orig=browse&_cdi=5932&view=c&_a
cct=C000059600&_version=1&_urlVersion=0&
_userid=4422&md5=801178ddb930bd041063bae
7a3e0e204
found in 3235 million year old deep-sea
volcanogenic massive sulphide deposits
from the Pilbara Craton of Australia
may be oldest Archaea fossils.1
FOOTNOTES
1. ^ Nature 405, 676 - 679 (08 June
2000);
doi:10.1038/35015063 Filamentous
microfossils in a
3,235-million-year-old volcanogenic
massive sulphide deposit BIRGER
RASMUSSEN
[1] Photomicrographs of filaments from
the Sulphur Springs VMS deposit. Scale
bar, 10 µm. a-f, Straight, sinuous and
curved morphologies, some densely
intertwined. g, Filaments parallel to
the concentric layering. h, Filaments
oriented sub-perpendicular to
banding.
source:
1
G+C {Guanine and Cytosine count} Gram
positive) evolve.1 2 3
Genetic
comparison shows Eubacteria Phylum
Firmicutes (low G+C {Guanine and
Cytosine count} Gram positive) evolving
here.
Firmicutes include the Classes:
Bacillus (anthrax), Listeria,
Mollicutes, and Stephylococcus.
Firmicutes may be the
first rod shaped bacteria, and first
bacteria to have a gram positive cell
wall.
The peptidoglycan layer is thicker in
Gram-positive bacteria (20 to 80 nm)
than in Gram-negative bacteria (7 to 8
nm)
Firmicultes form endospores, and is the
only phlyum of bacteria that evolved
the ability to build endospores.
The Firmicutes
are a division of bacteria, most of
which have Gram-positive stains. A few,
the Mollicutes or mycoplasmas, lack
cell walls altogether and so do not
respond to Gram staining, but still
lack the second membrane found in other
Gram-negative forms. Originally the
Firmicutes were taken to include all
Gram-positive bacteria, but more
recently they tend to be restricted to
a core group of related forms, called
the low G+C group in contrast to the
Actinobacteria. They have round cells,
called cocci (singular coccus), or
rod-shaped forms.
Many Firmicutes produce endospores,
which are resistant to desiccation and
can survive extreme conditions. They
are found in various environments, and
some notable pathogens. Those in one
family, the heliobacteria, produce
energy through photosynthesis.
Firmicutes include:
CLASS Bacilli (rod shaped)
ORDER
Bacillales (anthrax)
ORDER Lactobacillales
CLASS Clostridia
ORDER
Clostridiales
ORDER Halanaerobiales
ORDER
Thermoanaerobacteriales
CLASS Mollicutes
ORDER Mycoplasmatales
ORDER
Entomoplasmatales
ORDER Anaeroplasmatales
ORDER Acholeplasmatales
FOOTNOTES
1. ^ Richard Dawkins, "The Ancestor's
Tale", (Boston, MA: Houghton Mifflin
Company, 2004).
MORE INFO
[1]
http://en.wikipedia.org/wiki/Peptidoglyc
an
[2] firmicutes only bacteria to make
endospores
http://en.wikipedia.org/wiki/Endospore
[3]
http://en.wikipedia.org/wiki/Firmicutes
[1] Listeria monocytogenes is a
Gram-positive bacterium, in the
division Firmicutes, named for Joseph
Lister. It is motile by means of
flagella. Some studies suggest that 1
to 10% of humans may carry L.
monocytogenes in their
intestines. Researchers have found L.
monocytogenes in at least 37 mammalian
species, both domesticated and feral,
as well as in at least 17 species of
birds and possibly in some species of
fish and shellfish. Laboratories can
isolate L. monocytogenes from soil,
silage, and other environmental
sources. L. monocytogenes is quite
hardy and resists the deleterious
effects of freezing, drying, and heat
remarkably well for a bacterium that
does not form spores. Most L.
monocytogenes are pathogenic to some
degree.
source: http://en.wikipedia.org/wiki/Ima
ge:Listeria.jpg
[2] These are bacteria (about 0.3 µm
in diameter) that do not have outer
walls, only cytoplasmic membranes.
However, they do have cytoskeletal
elements that give them a distinct
non-spherical shape. They look like
schmoos that are pulled along by their
heads. How they are able to glide is a
mystery.
source: http://webmac.rowland.org/labs/b
acteria/projects_glide.html
1
abililty to form endpospores.1
An
endospore is any spore that is produced
within an organism (usually a
bacterium). Most bacterium produce only
one spore, as this is not a
reproduction process. This is in
contrast to exospores, which are rather
produced by growth or budding. The
primary function of most endospores is
to ensure the survival of a colony
through periods of environmental
stress. Endospores are therefore
resistant to desiccation, temperature,
starvation, ultraviolet and gamma
radiation, and chemical disinfectants.
One of the great questions of this time
is: "what is the process behind cell
differentiation and cell growth?" How
is each stage initiated and stopped?
There are a number of theories. One
theory presumes the entire DNA strand
is accessible at all times. In this
view operons are used sequentially,
while many proteins are supressed, some
operons are active, which results in
one set of proteins developing the
cell, at some point, the first group of
operons are inhibited and a different
operon (or set of operons) is turned
on, signalling a new set of proteins to
be built which effects the growth and
shape of the cell. An abundance of a
first stage protein might initiate the
second stage. A second theory is that
DNA is read like a computer program
with some proteins moving along the DNA
strand, one part at a time. In this
way, one portion of the DNA may reflect
one life stage, while the next portion
represents the next (and perhaps very
different) life stage.
The endospore-forming bacteria belong
to the Firmicutes.
FOOTNOTES
1. ^ "Endospore". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Endospore
[1] Spore forming inside a bacterium.
Stahly, MicrobeLibrary COPYRIGHTED
source: http://www.microbe.org/microbes/
spores.asp
1
ancestor of all Proteobacteria
(Rickettsia {mitochondria}, gonorrhoea,
Salmonella, E coli) evolving now.1 2 3
4
Proteobacteria include 5 Classes:
CLASS Alpha
Proteobacteria (Rickettsia Prowazekii
{mitochondria/typhus})
CLASS Beta Proteobacteria (Neisseria
gonorrhoeae {gonorrhoea})
CLASS Gamma Proteobacteria
(Salmonella and Escherichia coli.)
CLASS Delta
Proteobacteria
CLASS Epsilon Proteobacteria
The Proteobacteria are a major group of
bacteria. They include a wide variety
of pathogens, such as Escherichia,
Salmonella, Vibrio, Helicobacter, and
many other notable genera. Others are
free-living, and include many of the
bacteria responsible for nitrogen
fixation. The group is defined
primarily in terms of ribosomal RNA
(rRNA) sequences, and is named for the
Greek god Proteus, who could change his
shape, because of the great diversity
of forms found in it.
All Proteobacteria are Gram-negative,
with an outer membrane mainly composed
of lipopolysaccharides. Many move about
using flagella, but some are non-motile
or rely on bacterial gliding. The last
include the myxobacteria, a unique
group of bacteria that can aggregate to
form multicellular fruiting bodies.
There is also a wide variety in the
types of metabolism. Most members are
facultatively or obligately anaerobic
and heterotrophic, but there are
numerous exceptions. A variety of
genera, which are not closely related,
can photosynthesize. These are called
purple bacteria, referring to their
mostly reddish pigmentation.
The delta-proteobacteria Myxobacteria
is capable of colonial multicellularity
and some view as possibly being the
bacteria that formed the cytoplasm in
eukaryotes.
CLASS Alpha Proteobacteria (Rickettsia
Prowazekii {mitochondria/typhus})
CLASS Beta Proteobacteria
(Neisseria gonorrhoeae {gonorrhoea})
CLASS Gamma
Proteobacteria (Salmonella, Escherichia
coli., fireblight {Erwinia amylovora},
one form of dysentery {Shigella
dysenteriae}, Legionaires' disease
{Legionella pneumophilia}, Haemophilus
influenzae {first free living organism
to have entire genome sequenced},
Pseudomonas, the largest known bacteria
{Thiomargarita namibiensis}, Cholera
{Vibrio cholerae})
The number of individual E.
coli bacteria in the feces that one
human passes in one day averages
between 100 billion and 10 trillion.
CLA
SS Delta Proteobacteria (Bdellovibrio
{parasite on other bacteria}, Geobacter
{can oxydize uranium, may be used as
battery that runs on waste},
myxobacteria {form multicellular bodies
that make spores, have large genome}
CLASS
Epsilon Proteobacteria (Helicobacter
{spiral bacteria})
FOOTNOTES
1. ^ Battistuzzi, Feijao, Hedges, "A
Genomic timescale of prokaryote
evolution: insights into the origin of
methanogenesis, phototrophy, and the
colonization of land", BMC Evolutionary
Biology, (2004).
MORE INFO
[1] multicellularity.
http://www.mansfield.ohio-state.edu/~sab
edon/biol3018.htm multicellularity.
Multicellularity.pdf
http://en.wikipedia.org/wiki/Escherichia
_coli
http://en.wikipedia.org/wiki/Proteobacte
ria
[1] Figure 1. Transmission electron
micrograph of the ELB agent in XTC-2
cells. The rickettsia are free in the
cytoplasm and surrounded by an electron
transparent halo. Original
magnification X 30,000. CDC PD
source: www.cdc.gov/ncidod/
eid/vol7no1/raoultG1.htm
[2] Caulobacter crescentus. From
http://sunflower.bio.indiana.edu/~ybrun/
L305.html COPYRIGHTED EDU was in wiki
but appears to be removed
source: http://upload.wikimedia.org/wiki
pedia/en/4/42/Caulobacter.jpg
1
Eubacteria Phylum, Planctomycetes
(Planctobacteria) evolving now.1
Planct
omycetes are a possible ancestor of all
eukaryotes because the circle of DNA
can sometimes be enclosed in a double
membrane.
Planctomycetes is a small phylum with
only 4 Genera, require oxygen for
growth (obligately aerobic), are found
in fresh and salt water. They reproduce
by budding. They have holdfast (stalk)
at the nonreproductive end that helps
them to attach to each other during
budding.
The life cycle involves alternation
between sessile cells and flagellated
swarmer cells. The sessile cells bud to
form the flagellated swarmer cells
which swim for a while before settling
down to attach and begin reproduction.
It is also possible, although unlikely,
that planctomycetes are descended from
a very early eukaryote that lost the
nucleus but retained the cytoplasmic
DNA, since budding may have evolved as
a method to duplicate a eukaryote cell
from the nucleus. (ok this is out
there...maybe t3)
The organisms belonging
to this group lack murein in their cell
wall Murein is an important
heteropolymer present in most bacterial
cell walls that serves as a protective
component in the cell wall skeleton.
Instead their walls are made up of
glycoprotein rich in glutamate.
Planctomycetes have internal structures
that are more complex than would be
typically expected in prokaryotes.
While they don't have a nucleus in the
eukaryotic sense, the nuclear material
can sometimes be enclosed in a double
membrane. In addition to this nucleoid,
there are two other membrane-separated
compartments; the pirrellulosome or
riboplasm, which contains the ribosome
and related proteins, and the
ribosome-free paryphoplasm.
FOOTNOTES
1. ^ Battistuzzi, Feijao, Hedges, "A
Genomic timescale of prokaryote
evolution: insights into the origin of
methanogenesis, phototrophy, and the
colonization of land", BMC Evolutionary
Biology, (2004).
MORE INFO
[1] s10
http://ijs.sgmjournals.org/cgi/reprint/5
0/6/1965
[2]
http://genomebiology.com/2002/3/6/resear
ch/0031
[3]
http://en.wikipedia.org/wiki/Planctomyce
tes
[1] Electron micrographs of cells of
new Gemmata-like and Isosphaera-like
isolates. (A) Negatively stained cell
of the Gemmata-like strain JW11-2f5
showing crateriform structures
(arrowhead) and coccoid cell
morphology. Bar marker, 200 nm. (B)
Negatively stained budding cell of
Isosphaera-like strain CJuql1 showing
uniform crateriform structures
(arrowhead) on the mother cell and
coccoid cell morphology. Bar marker,
200 nm. (C) Thin section of
Gemmata-like cryosubstituted cell of
strain JW3-8s0 showing the
double-membrane-bounded nuclear body
(NB) and nucleoid (N) enclosed within
it. Bar marker, 200 nm. (D) Thin
section of Isosphaera-like strain C2-3
possessing a fibrillar nucleoid (N)
within a cytoplasmic compartment
bounded by a single membrane (M) only.
Bar marker, 200 nm. Appl Environ
Microbiol. 2002 January; 68(1):
417-422. doi:
10.1128/AEM.68.1.417-422.2002.
source: http://www.pubmedcentral.gov/art
iclerender.fcgi?tool=pubmed&pubmedid=117
72655
[2] Evolutionary distance tree
derived from comparative analysis of
16S rDNAs from freshwater and soil
isolates and reference strains of the
order Planctomycetales. Database
accession numbers are shown in
parentheses after species, strain, or
clone names. Bootstrap values of
greater than 70% from 100 bootstrap
resamplings from the distance analysis
are presented at nodes. Thermotoga
maritima was used as an outgroup.
Isolates from this study and
representative named species of the
planctomycetes are indicated in bold.
The scale bar represents 0.1 nucleotide
substitution per nucleotide
position. Appl Environ Microbiol.
2002 January; 68(1): 417-422. doi:
10.1128/AEM.68.1.417-422.2002.
source: http://florey.biosci.uq.edu.au/m
ypa/images/fuerst2.gif
1
Eubacteria Phylum, Actinobacteria (high
G+C, Gram positive) evolving now.1 2 3
4 5
Actinobacteria have 5 Orders:
ORDER
Acidimicrobiales
ORDER Actinobacteriales
ORDER Coriobacteriales
ORDER Rubrobacteriales
ORDER
Sphaerobacteriales
Actinobacteria include the causes of
tuberculosis (Mycobacteria
tuberculosis) and leprosy (Mycobacteria
leprae).
The Actinobacteria or Actinomycetes are
a group of Gram-positive bacteria. Most
are found in the soil, and they include
some of the most common soil life,
playing an important role in
decomposition of organic materials,
such as cellulose and chitin. This
replenishes the supply of nutrients in
the soil and is an important part of
humus formation. Other Actinobacteria
inhabit plants and animals, including a
few pathogens, such as Mycobacterium.
Some
Actinobacteria form braching filaments,
which somewhat resemble the mycelia of
the unrelated fungi, among which they
were originally classified under the
older name Actinomycetes. Most members
are aerobic, but a few, such as
Actinomyces israelii, can grow under
anaerobic conditions. Unlike the
Firmicutes, the other main group of
Gram-positive bacteria, they have DNA
with a high GC-content
{guanine-cytosine content} and some
Actinomycetes species produce external
spores.
Mycobacterium bovis (the bacterium
responsible for bovine TB) in
particular has been estimated to be
responsible, for the period of the
first half of the 20th century, for
more losses among farm animals than all
other infectious diseases combined.
Infection occurs if the bacterium is
ingested.
Actinobacteria are unsurpassed in their
ability to produce many compounds that
have pharmaceutically useful
properties. In 1940 Selman Waksman
discovered that the soil bacteria he
was studying made actinomycin, a
discovery which granted him a Nobel
Prize. Since then hundreds of naturally
occurring antibiotics have been
discovered in these terrestrial
microorganisms, especially from the
genus Streptomyces.
When M.leprae was discovered by G.A.
Hansen in 1873, it was the first
bacterium to be identified as causing
disease in man. Although Leprosy is
contagious, it is not widespread
because 95% of the population have
immune systems able to cope with the
bacteria.
FOOTNOTES
1. ^ Richard Dawkins, "The Ancestor's
Tale", (Boston, MA: Houghton Mifflin
Company, 2004).
[1] Frankia is a genus of
nitrogen-fixing soil bacteria, which
possesses a set of features that are
unique amongst symbiotic
nitrogen-fixing microorganisms,
including rhizobia, making it an
attractive taxon to study. These
heterotrophic Gram-positive bacteria
which are able to induce symbiotic
nitrogen-fixing root nodules
(actinorhizas) in a wide range of
dicotyledonous species (actinorhizal
plants), have also the capacity to fix
atmospheric nitrogen in culture and
under aerobic conditions.
source: http://www.ibmc.up.pt/webpagesgr
upos/cam/Frankia.htm
[2] Aerial mycelium and spore of
Streptomyces coelicolor. The mycelium
and the oval spores are about 1µm
wide, typical for bacteria and much
smaller than fungal hyphae and spores.
(Scanning electron micrograph, Mark
Buttner, Kim Findlay, John Innes
Centre). COPYRIGHT UK
source: http://www.sanger.ac.uk/Projects
/S_coelicolor/micro_image4.shtml
1
Eubacteria Phylum, Spirochaetes
(Syphilis, Lyme disease) evolving now.1
Includes leptospirosis (leptospira),
Lyme disease (Borrelia burgdorferi),
and Syphilis (Treponema pallidum).
Spirochaetes
only have one order:
ORDER Spirochaetales
This is when the first spiral shaped
bacteria evolve.
The spirochaetes (or spirochetes) are a
phylum of distinctive bacteria, which
have long, helically coiled cells. They
are distinguished by the presence of
flagella running lengthwise between the
cell membrane and cell wall, called
axial filaments. These cause a twisting
motion which allows the spirochaete to
move about. Most spirochaetes are
free-living and anaerobic, but there
are numerous exceptions.
Spirochaetes only have
one order:
ORDER Spirochaetales
and 3 families.
FOOTNOTES
1. ^ Battistuzzi, Feijao, Hedges, "A
Genomic timescale of prokaryote
evolution: insights into the origin of
methanogenesis, phototrophy, and the
colonization of land", BMC Evolutionary
Biology, (2004).
MORE INFO
[1] Tree of Life.
http://tolweb.org/tree/
[2] Richard Dawkins, "The Ancestor's
Tale", (Boston, MA: Houghton Mifflin
Company, 2004).
[1] Syphilis is a complex, sexually
transmitted disease (STD) with a highly
variable clinical course. The disease
is caused by the bacterium, Treponema
pallidum. In the United States, 32,871
cases of syphilis, including 432 cases
of congenital syphilis, were detected
by public health officials in 2002.
Eight of the ten states with the
highest rates of syphilis are located
in the southern region of the United
States.
source: http://www.cdc.gov/nchstp/od/tus
kegee/syphilis.htm
[2] leptospirose 200x magnified with
dark-field microscope photo taken by
bluuurgh at the dutch royal tropical
institute (www.kit.nl) PD
source: http://uhavax.hartford.edu/bugl/
images/Treponema%20pallidum.jpg
4 5
Eubacteria Phyla Bacteroidetes and
Chlorobi (green sulphur bacteria)
evolving now.1 2
PHYLUM Bacteroidetes
CLASS
Bacteroides
ORDER Bacteroidales
CLASS Flavobacteria
ORDER
Flavobacteriales
CLASS Sphingobacteria
ORDER Sphingobacteriales
PHLYUM Chlorobi (Green sulphur)
CLASS Chlorobia
ORDER
Chlorobiales3
The phylum Bacteroidetes is composed of
three large groups of bacteria. By far,
more is written about and known about
the Bacteroides class, than the other
two, the Flavobacteria and the
Sphingobacteria classes. They are
related by the similarity in the
composition of the small 16S subunit of
their ribosomes. Members of the
bacteroides class are human commensals
(they benefit but humans receive no
effect) and sometimes pathogens.
Members of the other two classes are
rarely pathogenic to humans.
Chlorobi are the "green sulphur
bacteria", are a family of phototrophic
(photosynthesizing) bacteria. Green
sulfur bacteria are generally nonmotile
(one species has a flagellum), and come
in spheres, rods, and spirals. Their
environment must be oxygen-free, and
they need light to grow. They engage in
photosynthesis, using
bacteriochlorophylls c, d, and e in
vesicles called chlorosomes attached to
the membrane. They use sulfide ions as
electron donor, and in the process the
sulfide gets oxidized, producing
globules of elemental sulfur outside
the cell, which may then be further
oxidized. (By contrast, the
photosynthesis in plants uses water as
electron donor and produces oxygen.)
A species of green sulfur bacteria has
been found living near a black smoker
off the coast of Mexico at a depth of
2,500 meters beneath the surface of the
Pacific Ocean. At this depth, the
bacteria, designated GSB1, lives off
the dim glow of the thermal vent since
no sunlight can penetrate to that
depth.
FOOTNOTES
1. ^ Richard Dawkins, "The Ancestor's
Tale", (Boston, MA: Houghton Mifflin
Company, 2004).
2. ^ Battistuzzi, Feijao,
Hedges, "A Genomic timescale of
prokaryote evolution: insights into
the origin of methanogenesis,
phototrophy, and the colonization of
land", BMC Evolutionary Biology,
(2004).. ^
3. ^
http://sn2000.taxonomy.nl/Taxonomicon/Ta
xonTree.aspx?id=563
4. ^ estimate from Richard Dawkins,
"The Ancestor's Tale", (Boston, MA:
Houghton Mifflin Company, 2004).
5. ^ estimate
from Battistuzzi, Feijao, Hedges, "A
Genomic timescale of prokaryote
evolution: insights into the origin of
methanogenesis, phototrophy, and the
colonization of land", BMC Evolutionary
Biology, (2004).
MORE INFO
[1] Tree of Life
[2]
http://en.wikipedia.org/wiki/Bacteroidet
es
[3]
http://en.wikipedia.org/wiki/Chlorobi
[1] Bacteroides fragilis . From the
Zdravotni University
source: http://biology.kenyon.edu/Microb
ial_Biorealm/bacteria/bacteroidete_chlor
ob_group/bacteroides/bacteroides.htm
[2] Cross section of a Bacteroides
showing an outer membrane, a
peptidoglycan layer, and a cytoplasmic
membrane. From New-asthma
source: http://phil.cdc.gov/phil/details
.asp
1
Eubacteria Phyla Chlamydiae and
Verrucomicrobia evolving now.1
Chlamydi
ae includes (clamydia, trachoma
{Chlamydia trachomatis}, a form of
pneumonia {Chlamydophila pneumoniae},
psittacosis {Chlamydophila psittaci}.
CLASS Chlamydiae
ORDER Chlamydiales
PHYLA Verrucomicrobia
ORDER Verrucomicrobiales
The Chlamydiae are a group of bacteria,
all of which are intracellular
parasites of eukaryotic cells. Most
described species infect mammals and
birds, but some have been found in
other hosts, such as amoebae.
Chlamydiae have a
life-cycle involving two distinct
forms. Infection takes place by means
of elementary bodies (EB), which are
metabolically inactive. These are taken
up within a cellular vacuole, where
they grow into larger reticulate bodies
(RB), which reproduce. Ultimately new
elementary bodies are produced and
expelled from the cell.
Verrucomicrobia is a recently described
phylum of bacteria. This phylum
contains only a few described species
(Verrucomicrobia spinosum, is an
example, the phylum is named after
this). The species identified have been
isolated from fresh water and soil
environments and human feces. A number
of as-yet uncultivated species have
been identified in association with
eukaryotic hosts including extrusive
explosive ectosymbionts of protists and
endosymbionts of nematodes residing in
their gametes.
Evidence suggests that verrucomicrobia
are abundant within the environment,
and important (especially to soil
cultures). This phylum is considered to
have two sister phyla Chlamydiae and
Lentisphaera.
There are three main species of
chlamydiae that infect humans:
* Chlamydia trachomatis, which
causes the eye-disease trachoma and the
sexually transmitted infection
chlamydia;
* Chlamydophila pneumoniae, which
causes a form of pneumonia;
* Chlamydophila
psittaci, which causes psittacosis.
FOOTNOTES
1. ^ Battistuzzi, Feijao, Hedges, "A
Genomic timescale of prokaryote
evolution: insights into the origin of
methanogenesis, phototrophy, and the
colonization of land", BMC Evolutionary
Biology, (2004).
MORE INFO
[1] Tree of Life.
http://tolweb.org/tree/
[2] Richard Dawkins, "The Ancestor's
Tale", (Boston, MA: Houghton Mifflin
Company, 2004).
[3]
http://en.wikipedia.org/wiki/Chlamydiae
[4]
http://en.wikipedia.org/wiki/Verrucomicr
obia
[1] Chlamydia trachomatis wiki, is
copyrighted
source: http://en.wikipedia.org/wiki/Chl
amydia_trachomatis
[2] wiki, public domain
source: http://en.wikipedia.org/wiki/Ima
ge:Chlamydophila_pneumoniae.jpg
1
cell membrane folds around some
molecules to form a spherical vesicle
which enters the cytoplasm, and
exocytosis, the opposite process, where
a vesicle combines with a call membrane
to empty molecules outside a cell both
evolve in an early eukaryote cell.
Eukaryote cells can now swallow
bacteria (phagocytosis) and liquid
(pinocytosis). The cells can then
(heterotrophically) use the molecules
injested (for example a bacterium) for
copying and to make ATP. This is the
first time one cell can eat a different
living cell.
How similar endocytosis is to
conjugation is unknown at this time.
FOOTNOTES
1. ^ guess based on Cav-Smith saving
endo before cytoskeleton
[1] Pinocytosis In the process of
pinocytosis the plasma membrane froms
an invagination. What ever substance
is found within the area of
invagination is brought into the
cell. In general this material will
be dissolved in water and thus this
process is also refered to as
''cellular drinking'' to indicate that
liquids and material dissolved in
liquids are ingested by the
cell. This is opposed to the
ingestion of large particulate material
like bacteria or other cells or cell
debris.
source: http://academic.brooklyn.cuny.ed
u/biology/bio4fv/page/endocytb.htm
1
cytoplasm.1 2 3
One theory is that the
cytoskeleton formed from the eukaryote
flagella (cilia, undulipodia) tubules.
Cytoskelet
on is a single body with the
endoplasmic reticulum and nuclear
membrane?
FOOTNOTES
1. ^ Cavalier-Smith, annals of Botony
2005 vol95 issue 1
12
4 5 6 7 8 9 10 This cell has a
nucleus, with either single strands or
a circle of DNA inside. This is a
single anaerobic cell. This is the
first protist.
This cell evolves either by:
1) two or more
bacteria joined, one with flagella
(perhaps a eubacteria) formed the
nucleus, a second formed the cytoplasm
outside the nucleus, eventually the
code to build the entire cell including
the instructions to build the symbiotic
captured bacteria was included in the
new nucleus,
2) the nucleus formed as
part of the cytoplasm lattice, perhaps
the outer wall folded in on itself
creating a double membrane, or a
membrane grew around the DNA (for
example like planctobacteria) which
provided more protection for the DNA
from the movement and digestive
activities of cytoplasm now without a
rigid cell wall,
3) a bacteria with
flagella that grew cytoplasm and a
secondary cell wall outside the
original cell wall,
4) a virus,
5) a
DNA strand from conjugation with a
different prokaryote stored in a
vesicle.
There are key features that are
different from eukaryotes and
prokaryotes:
1) Eukaryotes have a nucleus,
prokaryotes do not.
2) DNA in eukaryotes is
in the form of chromosomes, in
prokaryotes the DNA is in a circle.
3)
Eukaryotes can do endocytosis, fold
their cell membrane around some
external object and injest the object,
prokaryotes can not.
4) Eukaryotes have a
membrane lattice of proteins, actin and
myacin, prokaryotes do not.
5) Eukaryotes
have an endoplasmic reticulum and golgi
body.
6) Eukaryotes reproduce asexually by
dual binary division (both nucleus and
cell divide by binary division),
budding, or mitosis, prokaryotes
reproduce by budding or binary
division.
If the nucleus is an engulfed
prokaryote, this cell inherits the
processes of nuclear DNA duplication
and nucleus division (karyokinesis)
from prokaryote binary division.
Initially, both the nucleus and cell
divide by binary division.
Support for the
nucleus forming from a prokaryote is
that chromosomes in parabasalia and
dinoflagellates remain permanently
anchored to the nuclear membrane
(envelope?) by the kinetochores, the
same way prokaryote DNA anchors to the
cell membrane (wall?) during cell
division.
A theory of an archaebacteria (perhaps
an eocyte) forming the first eukaryote
nucleus and a gram-negative eubacteria
forming the cytoplasm of the first
eukaryote is supported by genetic
evidence.
This cell reproduces asexually by
either binary fission (both nucleus and
cytoplasm) or budding, or sexually by
conjugation or both cell and nuclei
fully merging.
If this cell has chromosomes, this is
the first (haploid) organism with
chromosomes.
Perhaps a sperm-like flagellated
prokaryote merged with an ovum-like
prokaryote from the same or a different
species, perhaps by the ovum opening a
pilus and the sperm-like cell entering
the pilus, and once inside opening a
pilus through which the DNA from the
two cells could merge. Many
diplomonads look like sperm cells stuck
in an ovum, with the still flagellated
sperm forming the nucleus, and some
diplomonads, for example, the oxymonad,
Saccinobaculus reproduce sexually.
An important evolutionary step had to
evolve here, and that is the evolution
of the prokaryote binary division
system: 1) duplicating DNA in the
cytoplasm, 2) separating the two copies
of DNA, and 3) the division of
cytoplasm into two cells to an adapted
process of eukaryote cell division: 1)
duplicating DNA in the nucleus, 2)
separating the DNA in the nucleus, 3)
dividing the nucleus into two nuclei,
4) separating the two nuclei, and then
5) dividing the cytoplasm into two
cells.
It appears in early eukaryote nuclei
(as seen in closed mitosis, where the
nuclear membrane persistes through
mitosis) that the nuclei divide by a
process similar to binary division (as
opposed to budding), which adds to the
support for the first nucleus being a
prokaryote and continuing to divide by
binary division.
Most people accept that the centrioles
from which grow the microtubule
spindles that pull apart chromosomes in
mitosis, evolved from the base pairs
which originally were, and on some
species still are, connected to a
cilium.
Perhaps there are some eukaryote nuclei
that duplicate by budding, although
this has never been found to my
knowledge. If ever found, that would
imply that budding evolved before the
first eukaryote, but could have
possibly evolved after by simply
dropping the instructions to copy
anything other than the nucleus.
Binary cell division in the most basic
form only synthesizes more cytoplasm
and cell wall, where budding reproduces
the entire body plan of a cell (or
nucleus in this case).
evidence for
prokaryote=eukaryote nucleus
1) flagella
connected to nucleus of metamonads.
a) flagella
hints that nucleus prokaryote may have
been a male gamete (and the cytoplasm
the female gamete).
b) flagella are presumably
outside the double membrane, indicates
that came after capture? Maybe
flagella penetrate double
membrane...perhaps were initialy inside
or partially inside and outside.
2) nucleus
division does not need to be recreated,
can be basically the same inherited
prokaryote cell division (perhaps with
minor adjustments), only within a cell
membrane.
3) conjugation already existed as a
form of exchanging DNA before the first
eukaryote, it is possible that a
complete bacterium could be taken in
through a pilus. Some eukaryotes like
spyrogrya still reproduce sexually
through conjugation.
4) DNA was splitting and
merging with conjugation in prokaryotes
before eukaryotes.
5) division of nucleus and
cytoplasm is different, just like
mitochondria, when the cytoplasm
divides is signalled by molecules (as
far as I know), and a nucleus may
divide without the cytoplasm dividing
(immediately or perhaps ever) in some
protists. (Clearly many metamonads have
multiple nuclei). It's interesting
that some metamonads have muliple
nuclei (mastigonts), because when they
reproduce it is all integrated, each
nuceli is rebuilt (as far as I know).
Maybe that shows how simple throwing
together nuclei and cytoplasm is for
DNA for put together and reproduce.
6) two layer
membrane around nucleus, is evidence of
a prokaryote being captured in a
vacuole.
7) happened for mitochondria,
chloroplasts, (and later red algae and
green algae), that is support for a
prokaryote similar to rikettsia, or
cyanobacteria being engulfed and
forming nucleus.
8) "all eukaryotic HSP70
homologs share in common with the
Gram-negative group of eubacteria a
number of sequence features that are
not present in any archaebacterium or
Gram-positive bacterium, indicating
their evolution from this group of
organisms."
9) Most genes related to the nucleus
are related to archaebacteria, while
those relating to the cytoplasm are
related to eubacteria.
Perhaps there was a long period of time
where the future eukaryote nucleus was
only an organelle, reproducing
initially like mitochondria and
chloroplasts do, by themselves, but
initiated by the nuclear duplication
and cytoplasmic division (check).
Somehow the binary division process of
the cytoplasm DNA and the binary
division process of the
nucleus-organelle had to merge into one
process.
Either the spindle chromosome
method (mitosis) evolved before or
after the nucleus-organelle has taken
over the cytoplasm building function.
As time continued, the process of
spindle separation evolved for the
nucleus-organelle. As time continued,
the building of the nucleus-organelle
was taken over by the cytoplasmic DNA,
still reproducing by binary fission.
I
could see how budding would be a
natural evolution for a cell nucleus
that starts as an organelle, is
reproduced by cytoplasm DNA and then
the DNA is tranfered back into the
nucleus-organelle. The
nucelus-organelle would then recreate
the entire cell inside the nucleus
(including the cytoplasm DNA
presumably), and presumably it would
burst out and continue to copy that
way. Perhaps budding prokaryotes were
budding eukaryotes that still had their
cytoplasm DNA that actually lost their
nucleus-organelle. Then budding
perhaps evolved into mitosis. I think
that mitosis is more similar to binary
division than budding is.
It seems clear that the
nucleus-organelle copied itself.
Potentially the same proteins that
initiate DNA duplication and cell
division for the cytoplasm DNA
simulteously initiate DNA duplication
and cell (nucleus-organelle) division
in the nucleus-organelle. So the
nucleus-organelle may have been exactly
like a mitochondrion for many years.
Although there are uncertainties, this
first eukaryote is thought to be a
member of the broad group of single
celled eukaryotes called "flagellates".
It is theorized that later will evolve
the unicellular "ameobozoid" and
"ciliate" groups. (this is a little
vague and I am not sure it really
covers algae, and the other alveolates,
but it does reduce the complexity of
protists11 )
FOOTNOTES
1. ^ Nature 396, 109 - 110 (12
November 1998);
doi:10.1038/24030 Rickettsia, typhus
and the mitochondrial
connection MICHAEL W. GRAY
2. ^ Richard
Cowen, "History of Life", (Malden, MA:
Blackwell, 2005).
3. ^ Nature 392, 15 - 16 (05
March 1998); doi:10.1038/32033 A
paradigm gets shifty W. FORD
DOOLITTLE
4. ^ (h2 symbiosis) The chimeric
eukaryote: Origin of the nucleus from
the karyomastigont in amitochondriate
protists Lynn Margulis*, Michael F.
Dolan* , and Ricardo
Guerrero file:/root/web/euk_nucleo6954.
5. ^ "Planctomycetes a phylum of
emerging interest for microbial
evolution and ecology John A.
Fuerst" planctomycetes_a1.pdf and
fuerst1.pdf
6. ^ Nature 392, 37 - 41 (05 March
1998); doi:10.1038/32096 The hydrogen
hypothesis for the first
eukaryote WILLIAM MARTIN* AND MIKLÓS
MÜLLER
7. ^ Nature 431, 152 - 155 (09
September 2004);
doi:10.1038/nature02848 The ring of
life provides evidence for a genome
fusion origin of eukaryotes MARIA C.
RIVERA1,3,4 AND JAMES A. LAKE1,2,4
8. ^ Science,
Vol 305, Issue 5685, 766-768 , 6 August
2004 EVOLUTIONARY BIOLOGY: The Birth
of the Nucleus Elizabeth Pennisi
9. ^ Richard
Cowen, "History of Life", (Malden, MA:
Blackwell, 2005).0) origin of nuclear
membrane/envelope, is anaerobic
eukorig1 thru eukorig7
10. ^ S Blair Hedges,
Hsiong Chen, Sudhir Kumar, Daniel YC
Wang, Amanda S Thompson and Hidemi Wa,
"A genomic timescale for the origin of
eukaryotes", BMC Evolutionary Biology
2001, 1:4
doi:10.1186/1471-2148-1-4, (2001).
11. ^ Ted
Huntington.
12. ^ S Blair Hedges, Hsiong Chen,
Sudhir Kumar, Daniel YC Wang, Amanda S
Thompson and Hidemi Wa, "A genomic
timescale for the origin of
eukaryotes", BMC Evolutionary Biology
2001, 1:4
doi:10.1186/1471-2148-1-4, (2001).
[1]
http://www.regx.de/m_organisms.php#planc
to
source: http://www.regx.de/m_organisms.p
hp#plancto
[2]
http://www.mansfield.ohio-state.edu/~sab
edon/biol1080.htm
source: http://www.mansfield.ohio-state.
edu/~sabedon/biol1080.htm
6
single circular chromosome to linear
chromosomes.1 2 3 4
Possibly the prokaryote ancestor of the
first eukaryote had linear chromosomes
since some prokaryotes (although very
few) are known to have linear
chromosomes instead of or in addition
to a single circular chromosome.
Perhaps a DNA
strand entered a cell by conjugation,
the circle of DNA was cut to insert the
new DNA (plasmid), but the new DNA
strand was not sewn back into the
original strand of DNA creating two
strands of DNA which eventually evolved
into the first 2 chromosomes.
Perhaps the first eukaryote nucleus was
a virus, many of which have linear
chromosomes.
This includes the evolution of
histones, proteins which are packed in
between nucleotides in each
chromosome.
Presumably DNA duplication (sythesis)
of chromosomes (in the nucleus) is
initially identical to DNA duplication
of DNA strands or circular DNA.
Some prokaryotes do not have just one
circle of DNA.5 Brucella melitensis
has 2 circlular chromosomes.
Agrobacterium tumefaciens has a
circular and a linear chromosome.
Streptomyces griseus can have one
linear chromosome. Borrelia
burgdorferi contains a linear
chromosome and a number of variable
circular and linear plasmids. Most
eukaryote orgenelles have a single
circular chromosome except for the
mitochondria of most cnidarians and
some other forms which have linear
chromosomes.
FOOTNOTES
1. ^ not all prokaryotes has circle of
DNA: http://arjournals.annualreviews.or
g/doi/full/10.1146/annurev.ecolsys.28.1.
391;jsessionid=npo4ogeI2anbnHbeKO
2. ^ Jumas-Bilak E, Maugard C,
Michaux-Charachon S, Allardet-Servent
A, Perrin A, et al. 1995. Study of the
organization of the genomes of
Escherichia coli, Brucella melitensis
and Agrobacterium tumefaciens by
insertion of a unique restriction site.
Microbiology 141:2425-32 (Medline)
3. ^ Lezhava
A, Kameoka D, Sugino H, Goshi K,
Shinkawa H, et al. 1997. Chromosomal
deletions in Streptomyces griseus that
remove the afsA locus. Mol. Gen. Genet.
253:478-83
4. ^ Marconi RT, Casjens S, Munderloh
UG, Samuels DS. 1996. Analysis of
linear plasmid dimers in Borrelia
burgdorferi sensu lato isolates:
implications concerning the potential
mechanisms of linear plasmid
replication. J. Bact. 178:3357-61
5. ^ not all
prokaryotes has circle of
DNA: http://arjournals.annualreviews.or
g/doi/full/10.1146/annurev.ecolsys.28.1.
391;jsessionid=npo4ogeI2anbnHbeKO
6. ^ Ted Huntington, my guess due to
absence of published info
undulipodium) evolves on early single
cell eukaryotes.
The eukaryote cilia (flagella,
undulipodia) may evolve from a
prokaryote flagella connected to the
nucleus, from the cytoskeleten, or a
symbiotic prokaryote.
Cilia and eukaryote flagella are
structurally the same, but have minor
functional differences. Cilia are a
special class of eukaryote flagella.
The
eukarote flagellum is different from
prokayote flagellum. The prokaryote
flagallum is a solid structures, made
of the protein flagellin, which
protrudes through the plasma membrane.
The eukaryote flagellum (and cilium)
contains a "9 plus 2 array", 9
microtubules in a circle with 2
microtubules in the center. Some
people think that the eukaryote
flagella and cilia should be called
"undulipodia".
In some species the spindles used in
mitosis connect to the bases of the
eukaryote cilia (undulipodia), which
leads some people to think that the
spindles of mitosis may have evolved
from the eukaryote cilia.
Some people think that the eukaryote
cilium (flagellum, undulipodia) was a
spirochete (prokaryote) that formed a
symbiotic relationship with a eukaryote
host, whose DNA was transfered to the
host nucleus. Other possibilities are
that the eukaryote flagellum evolved
from prokaryote flagellum, or simply
evolved over time through natural
selection.
The eukaryote flagellum protein
"tubulin" is thought to be related to a
bacterial replication/cytoskeletal
protein "FtsZ" found in some
archaebacteria (archaea).
What method of reproduction this first
nucleated cell used is a great mystery.
Among the choices are binary division,
budding, or mitosis. My own feeling is
that budding or dual binary division
(both nucleus and cytoplasm) was how
this cell initially copied.
The eukaryote
flagellum (cilium, undulipodium) is the
same inherited and found on sperm
cells.
constantly synthesizing DNA and then
having a division period (as is the
case for all known prokaryotes), but
this cell has a period in between cell
division and DNA synthesis where DNA
synthesis is not performed. Later some
cells develop a stage after synthesis
and before cell division.1
For the
first time, a cell is not constantly
synthesizing DNA (S) and then having a
division period (D) (as is the case for
all known prokaryotes), but this cell
has a period in between cell division
and DNA synthesis where DNA synthesis
is not performed (G1) . Later some
cells develop a stage after synthesis
and before cell division (G2).
1
a prokaryote, synchronized duplication
and division of organelle-nucleus and
cytoplasm of early eukaryote cell
evolves. Before this, eukaryote cell
division usually results in one cell
with no organelle-nuclei and a second
cell with 2 organelle-nuclei. Perhaps
the organelle-nuclei attach to the
outer cell membrane in the same way the
cytoplasmic DNA do, which allows new
cytoplasm growth to separate the two
organelle-nucleus in addition to the
cytoplasmic DNA.1 2
Or perhaps the
first system of organized nuclei
separation originated with the
organelle-nucleus flagella microtubules
grewing into the cytoskeleton, and
organized system spindles and mitosis.
If the nuclear membrane was formed
around the DNA within a prokaryote,
then binary division had to adapt to
separate the duplicated DNA within the
proto-nucleus (not within the entire
cell) which may have been very simple
to evolve. If the cytoplasm grew
outside the cell wall of a prokaryote,
binary division would have to adapt to
separate that external cytoplasm.
FOOTNOTES
1. ^ Michael Sleigh, "Protozoa and
Other Protists", (London; New York:
Edward Arnold, 1989).
source:
source:
haploid (single set of chomosomes)
eukaryote nucleus, evolves in
eukaryotes. Before mitosis, there is a
synthesis stage where DNA in the form
of chromosomes are duplicated in the
nucleus before the nucleus and cell
divide.1 2
explain basic process of
mitosis:
prophase, metaphase, anaphase,
telophase
Presumably no prokaryotes have ever
reproduced through mitosis. Only
eukaryotes reproduce asexually using
mitosis.
Most people accept that some protists
were sexual and later lost that
ability. But the majority view now is
that the first eukaryotes were asexual,
and that some protists still living now
have never had sexual ability.
Because mitosis is complex and similar
in detail in all species that do
mitosis, people think that mitosis only
evolved once, and was inherited by all
species that do mitosis.
The major differences between this new
method of copying, mitosis and the
older method, binary fission (add
budding?) are:
1) In mitosis, microtubule
spindles attach to the kinetochore (the
protein structure in eukaryotes which
assembles on the centromere and links
the chromosome to microtubule polymers
from the mitotic spindle during
mitosis) and pull apart the two DNA
copies, where in binary fission the DNA
(single chromosome) attaches to a part
of the cytoplasm which pulls apart the
two cells.
2) Chromosomes (linear pieces of
DNA), not a circle of DNA is being
copied.
People speculate that early mitosis had
spindles outside the nucleus, with
chromosomes fastened to the nuclear
membrane, as can still be seen in
parabasalia and dinoflagellates, which
appear to have primitive nuclei.
In more ancient species the nuclear
membrane persists through mitosis
(closed mitosis), but in more recent
species, like metazoa, land plants, and
many kinds of protists, the nuclear
membrane disintegrates before mitosis
and is rebuilt after (open mitosis).
Most people think that extranuclear
spindles (spindles that originate
outside of the nucleus) and closed
mitosis evolved first. Only later did
pleuromitosis (spindles rotate 90
degrees, nucleus can be semi-open, or
closed) and then orthomitosis (spindles
are on both sides of nucleus and
separate chromosomes in a straight
line, nucleus can be open, semi-open or
closed) evolve in later eukaryotes.
It is
interesting to think about how how
binary fission (or potentially budding)
of prokaryote cells with no nucleus
evolved into mitosis and the use of
spindles.
Mitosis, budding, and binary fission
are the only asexual methods of
reproduction known.
Perhaps mitosis evolved first only
copying the nucleus then later evolved
to make not only a new nucleus but also
a new cell around that nucleus.
[1] Mitosis divides genetic information
during cell division Source:
http://www.ncbi.nlm.nih.gov/About/primer
/genetics_cell.html This image is
from the Science Primer, a work of the
National Center for Biotechnology
Information, part of the National
Institutes of Health. As a work of the
U.S. federal government, the image is
in the public domain.
source: http://en.wikipedia.org/wiki/Mit
osis
[2] Prophase: The two round objects
above the nucleus are the centrosomes.
Note the condensed chromatin. from
Gray's Anatomy. Unless stated
otherwise, it is from the online
edition of the 20th U.S. edition of
Gray's Anatomy of the Human Body,
originally published in 1918. Online
editions can be found on Bartleby and
also on Yahoo!
source:
division evolves. Two eukaryote cells
can merge into one cell with 2 nuclei
and then divide back into single 1
nucleus cells.
Possibly two cells that fuse
cytoplasms but not nuclei, may still
retain the system of cytoplasmic DNA
and organelle-nucleus attachment to
cell membrane (wall?), but on each half
of the new cell, therefore making dual
haploid mitosis (potentially of both
cytoplasmic DNA and organelle-nucleus
in synchronized duplication) a simple
evolutionary next step.
1 2
syngamy, gametogamy) evolves in
protists. Haploid (1 set of
chromosomes) eukaryote cells merge and
then their nuclei merge (karyogamy) to
form the first diploid (2 sets of
chromosomes) cells (the first zygote).1
2
This fusion of 2 haploid cells results
in the first diploid single-celled
organism, which then immediately
divides (both nucleus and cytoplasm by
single-division meiosis) back to two
haploid cells.
Possibly first, only cytoplasmic
merging happened with nuclear merging
(karyogamy) and nuclear division
(karyokinesis) evolving later.
Now, two cells
with different DNA can mix providing
more chance of variety/mutation. Two
chromosome sets provides a backup copy
of important genes (sequences that code
for proteins, or nucleic acids) that
might be lost with only a set of single
chromosomes.
The life cycle of future organisms will
now have two phases, a gamophase (from
n to 2n (until syngamy3 )), and
zygophase (from 2n to n (until meiosis4
)). Gamoid cells are not haploid in
polyploid organisms.
Potentially sexual cell and
genetic fusion is what made the first
eukaryote cell, and sex in protists may
be directly descended from conjugation
in prokaryotes, in other words not
evolved from a different method
independently of conjugation, because
some metamonads, for example
Saccinobaculus reproduce sexually, and
look very much like a prokaryote sperm
cell which formed the nucleus captured
in an ovum cell.
For sexual species there are 3 basic
life cycles:
1) Haploid (Haplontic) life cycle:
zygotic meiosis. Life as haploid
cells, cell division immediately after
creation of zygote from fusion. (All
fungi, Some green algae, Many
protozoa)
2) Diploid (Diplontic) life cycle:
gametic meiosis. Instead of immediate
cell division, zygote reproduces by
mitosis. Haploid gametes never copy by
mitosis. (animals, some brown algae)
3)
Haplodiploid (Haplodiplontic,
Diplohaplontic, Diplobiontic) life
cycle: sporic meiosis. Diploid cell
(sporocyte) meiosis results in 2
haploid sporophytes (gamonts), not 2
haploid gametes. These haploid cells
then differentiate? or mitosis? to form
haploid gametes. Haplodiplontic
organisms have alternation of
generations, one generation involves
diploid spore-producing single or
multicellular sporophytes (makes
spores) and the other generation
involves haploid single or
multicellular gamete-producing
multicellular gametophytes (makes
gametes). Pants and many algae have
this haplodiplontic life cycle.
These first sexual cells are haplontic,
with zygotic meiosis; they reproduce
asexually through mitosis as haploid
cells, fusing to a diploid cell without
mitosis, then dividing back into
haploid cells.
An important evolutionary step evolves
here in that now two cells can
completely merge into one cell. This
merge not only includes their nuclei,
but also their cytoplasm (althought the
DNA do not merge). Before now, as far
as has ever been observed, no two cells
have ever completely merged, although,
through conjugation some prokaryotes
have been observed to exchange DNA.
This marks the beginning of the
"haplonic lifestyle" with "zygotic
meosis", where the organism is haploid
until cell fusion which is immediately
followed by (one-step) meiosis of the
zygote, after which the haploid cells
continues to reproduce through
mitosis.
Possibly the first sexual organism
merged through a form of "autogamy"
(both haploid gametes originate from
the same individual, the opposite of
"allogamy" where the gametes originate
from different individuals). Some
species reproduce by a form of autogamy
(intracellular autogamy), where nuclei
(also called pronuclei) divide and then
merge within the same cell before the
entire cell divides. Some metamonads
(earliest still living eukaryotes),
like Oxymonas and Saccinobaculus can
reproduce asexually by mitosis, but
also can reproduce sexually using this
form of autogamy. This may be evidence
that some prokaryote could also merge
two entire cells (if the eukaryote
nucleus was a prokaryote). Perhaps
prokaryotes evolved full cellular
fusion before the first eukaryote. If
that is true, then this initial form of
nuclei dividing and merging
(intracellular autogamy) may have
existed for some time before full
eukaryote cell merging and synchronized
eukayote nucleus and cytoplasm division
evolved. It is difficult to see what
selective advantage autogamy could
possibly have since no new DNA is ever
introduced into the next generation of
organism, as opposed to "allogamy",
where DNA from different individuals is
merged, and which has a clear selective
advantage. So perhaps autogamy evolved
after allogamy, although to me it
appears that allogamy is more complex
than autogamy, and autogamy would be a
perfect starting step to develop the
needed proteins and processes for the
more complicated allogamy (autogamy
only involves the duplication and
merging of two nuclei, where allogamy
involves the merging of the cell walls,
and cytoplasm in addition to the two
nuclei.)
This is the beginning of the label
"gamete" for haploid cells that can
merge to form a diploid zygote. In
addition, the label "gametocyte" or
"gamont" is any polyploid cell that
divides (meiosis) into haploid gamete
cells which can merge to form a zygote.
Perhaps
there is a relationship between
prokaryote spore formation and the
phenomenon of diploid zygotes forming a
thick cell wall.
Perhaps the first sex (full cell
nucleus and cytoplasm fusion) was
interchangeably isogamous (both gametes
are identical and interchangable), with
only one gender, in other words, the
first sex on earth was homosexual.
Then later heterogamous gametes
evolved, where there were two distinct
haploid gamete cells, usually a large
female cell and a smaller flagellated
male cell.
Sex also allows organisms to choose
reproductive partners that are more
likely to make new organisms that are
more likely to survive.
An alternative theory is that a failed
mitosis could result in a diploid
nucleus.
What advantage might autogamy of
intercellular nuclei have, the added
chance of mistakes in the merging of
two nuclei? In addition, why would
such a system (intracellular autogamy)
persist if there was no selective
advantage? Why wouldn't oxymonas or
saccinobacculus reduce totally to
asexual mitosis and or allogamous
sexual reproduction and either never
make use of or lose intracellular
autogamous sexual reproduction
completely?
This is the first eukaryote cell to
have a life cycle that involves two
different kinds of cells.
FOOTNOTES
1. ^ Sir Gavin De Beer, "Atlas of
Evolution", (London: Nelson, 1964).
2. ^
estimate based on diplomonads having
sex repro, and origin of euk being (is
now)
[1] Zygotic Meiosis. GNU
source: http://en.wikipedia.org/wiki/Ima
ge:Zygotic_meiosis.png
[2] Gametic Meiosis. GNU
source: http://en.wikipedia.org/wiki/Ima
ge:Gametic_meiosis.png
duplication and a cell division of a
diploid cell into 2 haploid cells)
evolves.1 2
detail one-step meiosis:
The is no DNA crossover or chiasma
formation in one-division meiosis,
apparently because either duplication
of chromosomes or separation of
chromatids does not occurred.
As far as I know, mitosis and one-step
meiosis are the same with the only
exceptions that 1) in meiosis two
haploid cells join before cell
division, and 2) in mitosis the DNA is
duplicated before cell division, but in
meiosis the DNA is not duplicated
before cell division.
Meiosis can be one step (one DNA
duplication and then one cell division)
or two step (two DNA duplications and
then two divisions). Probably one step
meosis evolved first and two step
meiosis later.
Meiosis can only function on cells with
two or more sets of chromosomes.
The Protists
Pyrsonympha and Dinenympha has up to a
four step meiosis.
Because meiosis is similar and complex
in detail in all species that do
meiosis, people think that meiosis only
evolved once, and was inherited by all
species that do meiosis.
[1] GametoGenesis. COPYRIGHTED EDU
source: http://www.bio.miami.edu/dana/10
4/gametogenesis.jpg
[2] Sexual cycle oxymonas, identical
to saccinobaculus, one step meiosis.
haploid. COPYRIGHTED CANADA
source: http://www.zoology.ubc.ca/~redfi
eld/clevelan/oxymonas.GIF
2 haploid cells fuse) evolves.
This is required
for diploid mitosis.
Duplication of diploid DNA may be very
similar to duplication of haploid DNA.
Initially perhaps the diploid DNA
duplicated, but still divided in
one-division meiosis.
This begins the "diplontic" life cycle
(with gametic meiosis), where diploid
cells (a zygote) can copy asexually
through mitosis after merging. This
organism, when haploid, cannot do
mitosis (presumably haploid gamete
mitosis will evolve much later in brown
algae), and this is still true in all
descendents (including humans) of this
single celled organism.
The proteins and
mechanism of mitosis of diploid cells
is probably very similar to mitosis of
haploid cells. The most primitive
organisms still alive that are
diplontic are the metamonads (e.g.
Oxymonads: Notila, Hypermastigotes:
Urinympha, Macrospironympha,
Rhynchonympha).
(cell and nucleus fusion) between two
isogamous (same size) gametes but which
have 2 different (+ and -) forms
(genders).1
Perhaps the invention of
two different genders originated when a
flagellated cell (or nucleus) divided
by binary division and only one half of
the two new cells retained the
flagellum. Then to differentiate the
two cells even more, but still keep the
same DNA template, different proteins
could be weighted on one half of the
cell during division to activate
various operons in one gender but not
the other once the two DNA pairs are
separated.
Perhaps sex where the gametes are the
same size but cannot merge themselves
should be called "specific" or
"gendered" isogamy, and where any two
same sized gametes can merge called
"nonspecific" or "nongendered" isogamy.
between two different size gamete cells
(heterogamy or anisogamy) evolves in
protists.1
Some species are
heterogamous but two of the same sized
(gender) gametes can fuse to form a
zygote.
between one flagellated gamete and an
unflagellated gamete (oogamy, a form of
heterogamy) evolves in protists.1
This
system is the system humans inherited.
sterols, molecules made by mitochondria
in eukaryotes) found in northwestern
Australia.1 2
FOOTNOTES
1. ^ Richard Cowen, "History of Life",
(Malden, MA: Blackwell, 2005).
2. ^ Science,
Vol 285, Issue 5430, 1033-1036 , 13
August 1999 Archean Molecular Fossils
and the Early Rise of
Eukaryotes Jochen J. Brocks, 1,2*
Graham A. Logan, 2 Roger Buick, 1 Roger
E. Summons 2
stromatolite, Zimbabwe.1
FOOTNOTES
1. ^
http://www.sciencedirect.com/science?_ob
=ArticleURL&_udi=B6VBP-42G6M5T-7&_user=4
422&_coverDate=02%2F01%2F2001&_fmt=full&
_orig=browse&_cdi=5932&view=c&_acct=C000
059600&_version=1&_urlVersion=0&_userid=
4422&md5=d61bf36f008d6b2cba3ba5dbd5a628d
7&ref=full#bib9 Nagy, L.A. and
Zumberge, J.E., 1976. Fossil
microorganisms from the approximately
2800-2500 million-year-old Bulawaya
stromatolites: Application of
ultramicrochemical analyses. Proc.
Natl. Acad. Sci. Wash. 73, pp.
2973-2976.
[1] Fig. 2. Organic microstructure from
the Bulawaya stromatolite, Zimbabwe (ca
2.7 Ga). (a) TEM-micrograph from
demineralized rock section. (b) Laser
mass spectrum from individual specimen
of the same population (negative ions).
Field of measurement ca 1 small mu,
Greekm diameter. Attribution of
signals: 12: C−, 13: CH−,
14: CH−2, 16: O−, 17:
OH−, 19: F−, 24: C−2,
25: C2H−, 26: CN−, 28:
Si−, 36: C−3, 37:
C3H−, 40-42, 45: fragmental
carbonaceous groups, 48: C−4, 49:
C4H−, 50: C4H−2, 60:
SiO−2, resp. C−5, 61:
C5H−.
source: http://www.sciencedirect.com/sci
ence?_ob=MiamiCaptionURL&_method=retriev
e&_udi=B6VBP-42G6M5T-7&_image=fig5&_ba=5
&_user=4422&_coverDate=02%2F01%2F2001&_f
mt=full&_orig=browse&_cdi=5932&view=c&_a
cct=C000059600&_version=1&_urlVersion=0&
_userid=4422&md5=d9195635e48bcf1f817c009
69102189f
cyanobacteria, 2alpha -methylhopanes,
indicate that oxygenic photosynthesis
evolved well before the atmosphere
became oxidizing.1
FOOTNOTES
1. ^ Science, Vol 285, Issue 5430,
1033-1036 , 13 August 1999, Archean
Molecular Fossils and the Early Rise of
Eukaryotes Jochen J. Brocks, 1,2*
Graham A. Logan, 2 Roger Buick, 1 Roger
E. Summons 2
evolves.1 2 3 4
Only a few species
exhibit this property (e.g. the
Oxymonad Notilla, Diatoms, Dasicladales
{Acetabularia}, in many foraminiferans,
and in gregarines).
Gamontogamy may have evolved into
two-step meiosis.
The vast majority of eukaryotes living
now that reproduce sexually fuse
haploid cells. All "gametes" are
haploid cells that can merge, diploid
cells that can merge are gamonts.
Gamonts (Meiocytes) are cells that
produce gametes.
In theory this should be very similar
if not exactly like haploid cell
fusion, so perhaps this is not a major
evolutionary step.
[1] The Oxymonad, Notila (diploid
Pacific form) life cycle. COPYRIGHTED
source: http://www.zoology.ubc.ca/~redfi
eld/clevelan/notila.GIF
cell divisions with no stage in between
which result in one diplid cell
dividing into four haploid cells)
evolves.1
Meiosis and mitosis are
similar in being process of nucleus and
cell division, but are different.
Diff
erences between meiosis and mitosis:
1) At least
one crossover per homologous pair
happens in 2 step meiosis but crossover
usually does not happen in mitosis.
2) Two step
meiosis involves cell divisions that
happen one after the other, where
mitosis only happens after one DNA
duplication (there are never 2 mitoses
together without a DNA duplication
between them to my knowledge).
The cell division in two step meiosis
that involves a separation of sister
chromatids (not homologous chromosome
pairs) is basically identical to
mitosis. For two step meiosis, this is
the second nucleus and cell division.
Later
multistep meiosis evolves, where there
may be as many as 4 divisions (for
example in the protists Pyrsonympha and
Dinenympha).
[1] GametoGenesis. COPYRIGHTED EDU
source: http://www.bio.miami.edu/dana/10
4/gametogenesis.jpg
[2] Sexual cycle oxymonas, identical
to saccinobaculus, one step meiosis.
haploid. COPYRIGHTED CANADA
source: http://www.zoology.ubc.ca/~redfi
eld/clevelan/oxymonas.GIF
2
FOOTNOTES
1. ^ Battistuzzi, Feijao, Hedges, "A
Genomic timescale of prokaryote
evolution: insights into the origin of
methanogenesis, phototrophy, and the
colonization of land", BMC Evolutionary
Biology, (2004).
2. ^ Battistuzzi, Feijao,
Hedges, "A Genomic timescale of
prokaryote evolution: insights into
the origin of methanogenesis,
phototrophy, and the colonization of
land", BMC Evolutionary Biology,
(2004). (2600-2700my)
1
(Thermus Aquaticus {used in PCR},
Deinococcus radiodurans {can survive
long exposure to radiation}) evolve
now.1
PHYLUM Deinococcus-Thermus
CLASS Deinococci
ORDER
Deinococcales
ORDER Thermales
The Deinococcus-Thermus are a small
group of bacteria comprised of cocci
highly resistant to environmental
hazards. There are two main groups. The
Deinococcales include a single genus,
Deinococcus, with several species that
are resistant to radiation; they have
become famous for their ability to eat
nuclear waste and other toxic
materials, survive in the vacuum of
space and survive extremes of heat and
cold. The Thermales include several
genera resistant to heat. Thermus
aquaticus was important in the
development of the polymerase chain
reaction where repeated cycles of
heating DNA to near boiling make it
advantageous to use a thermo-stable DNA
polymerase enzyme. These bacteria have
thick cell walls that give them
gram-positive stains, but they include
a second membrane and so are closer in
structure to those of gram-negative
bacteria.
FOOTNOTES
1. ^ Battistuzzi, Feijao, Hedges, "A
Genomic timescale of prokaryote
evolution: insights into the origin of
methanogenesis, phototrophy, and the
colonization of land", BMC Evolutionary
Biology, (2004).
MORE INFO
[1] Tree of Life.
http://tolweb.org/tree/
[2] Richard Dawkins, "The Ancestor's
Tale", (Boston, MA: Houghton Mifflin
Company, 2004).
[1] D. radiodurans growing on a
nutrient agar plate. The red color is
due to carotenoid pigment. Links to
816x711-pixel, 351KB JPG. Credit: M.
Daly, Uniformed Services University of
the Health Sciences NASA
source: http://science.nasa.gov/newhome/
headlines/images/conan/D_rad_dish.jpg
[2] Photomicrograph of Deinococcus
radiodurans, from
www.ornl.gov/ORNLReview/ v34 The Oak
Ridge National Laboratory United
States Federal Government This work
is in the public domain because it is a
work of the United States Federal
Government. This applies worldwide. See
Copyright.
source: http://en.wikipedia.org/wiki/Ima
ge:Deinococcus.jpg
1 2
Eubacteria phylum, Cyanobacteria
(ancestor of all eukaryote chloroplasts
{plastids}) evolving now. There is a
conflict between the interpretation of
the geological and the genetic evidence
as to if oxygen photosynthesis and
cyanobacteria evolved earlier around
3800mybn or here at 2500mybn.1 2
Cyanob
acteria get their energy from
photosythesis.
Cyanobacteria include unicellular,
colonial, and filamentous forms. Some
filamentous cyanophytes form
differentiated cells, called
heterocysts, that are specialized for
nitrogen fixation, and resting or spore
cells called akinetes. Each individual
cell typically has a thick, gelatinous
cell wall, which stains gram-negative.
The cyanophytes lack flagella, but may
move about by gliding along surfaces.
Most are found in fresh water, while
others are marine, occur in damp soil,
or even temporarily moistened rocks in
deserts. A few are endosymbionts in
lichens, plants, various protists, or
sponges and provide energy for the
host.
Chloroplasts found in eukaryotes (algae
and higher plants) most likely
represent reduced endosymbiotic
cyanobacteria. This endosymbiotic
theory is supported by various
structural and genetic similarities.
Primary chloroplasts are found among
the green plants, where they contain
chlorophyll b, and among the red algae
and glaucophytes, where they contain
phycobilins. It now appears that these
chloroplasts probably had a single
origin. Other algae likely took their
chloroplasts from these forms by
secondary endosymbiosis or ingestion.
tenative:
CLASS Chroobacteria
CLASS Hormogoneae
CLASS
Gloeobacteria
Some live in the fur of sloths,
providing a form of camouflage.
FOOTNOTES
1. ^ Battistuzzi, Feijao, Hedges, "A
Genomic timescale of prokaryote
evolution: insights into the origin of
methanogenesis, phototrophy, and the
colonization of land", BMC Evolutionary
Biology, (2004).
2. ^ S. Blair Hedges and
Sudhir Kumar, "Genomic clocks and
evolutionary timescales", Trends in
Genetics Volume 19, Issue 4 , April
2003, Pages 200-206, (2003).
MORE INFO
[1] Tree of Life.
http://tolweb.org/tree/
[2] Richard Dawkins, "The Ancestor's
Tale", (Boston, MA: Houghton Mifflin
Company, 2004).
[3] Journal of Molecular
Evolution Publisher: Springer-Verlag
New York ISSN: 0022-2844 (Paper)
1432-1432 (Online) Issue: Volume 42,
Number 2 Date: February 1996 Pages:
194 - 200
[4] Phylogenetic Relationships of
Nonaxenic Filamentous Cyanobacterial
Strains Based on 16S rRNA Sequence
Analysis jme_42_2_1996.pdf
[5]
http://en.wikipedia.org/wiki/Cyanobacter
ia
[1] Oscillatoria COPYRIGHTED EDU
source: http://www.stcsc.edu/ecology/alg
ae/oscillatoria.jpg
[2] Lyngbya COPYRIGHTED EDU
source: http://www.stanford.edu/~bohanna
n/Media/LYNGB5.jpg
3
Non-Sulphur) evolve now.1
PHYLUM
Chloroflexi
CLASS Chloroflexi
CLASS
Thermomicrobia2
The Chloroflexi are a group of bacteria
that produce ATP through
photosynthesis. They make up the bulk
of the green non-sulfur bacteria,
though some are classified separately
in the Phylum Thermomicrobia. They are
named for their green pigment, usually
found in photosynthetic bodies called
chlorosomes.
Chloroflexi are typically filamentous,
and can move about through bacterial
gliding. They are facultatively
aerobic, but do not produce oxygen
during photosynthesis, and have a
different method of carbon fixation
than other photosynthetic bacteria.
Phylogenetic trees indicate that they
had a separate origin.
FOOTNOTES
1. ^ Battistuzzi, Feijao, Hedges, "A
Genomic timescale of prokaryote
evolution: insights into the origin of
methanogenesis, phototrophy, and the
colonization of land", BMC Evolutionary
Biology, (2004).
2. ^ "Chloroflexi". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Chloroflexi
3. ^ Battistuzzi, Feijao, Hedges, "A
Genomic timescale of prokaryote
evolution: insights into the origin of
methanogenesis, phototrophy, and the
colonization of land", BMC Evolutionary
Biology, (2004).
MORE INFO
[1] Richard Dawkins, "The
Ancestor's Tale", (Boston, MA: Houghton
Mifflin Company, 2004).
[2] Tree of Life
http://tolweb.org/tree/
[1] Chloroflexus photomicrograph from
Doe Joint Genome Institute of US Dept
Energy PD
source: http://en.wikipedia.org/wiki/Ima
ge:Chlorofl.jpg
Era.1 2
FOOTNOTES
1. ^ The geological Society of America
ucmp.berkeley.edu
2. ^ Richard Cowen, "History of Life",
(Malden, MA: Blackwell, 2005).
appear in many places.1 2
FOOTNOTES
1. ^ Richard Cowen, "History of Life",
(Malden, MA: Blackwell, 2005).
2. ^
greenspirit.uk
million years starts now.1
FOOTNOTES
1. ^ Richard Cowen, "History of Life",
(Malden, MA: Blackwell, 2005).
1
nucleus that makes ribosomes, evolves.1
In some eukaryotes (thought to be more
ancient), the nucleolus just divides
during mitosis, but in other eukaryotes
the mitosis is dissolved and rebuilt
after nuclear division.
In euglenids, kinetoplastids,
dinoflagellates, some amoebae and some
coccidians, the nucleolus remains
visible throughout mitosis and divides
into two, but in the majority of groups
the nucleolus dissapears and reforms at
telophase. That the nucleolus can
divide by itself suggests that it was
once a free living cell.
FOOTNOTES
1. ^ Michael Sleigh, "Protozoa and
Other Protists", (London; New York:
Edward Arnold, 1989).: p48 nucleolus
divides
[1] Nucleolus, COPYRIGHTED
source: http://www.eccentrix.com/members
/chempics/Slike/cell/Nucleolus.jpg
[2] With the combination of x-rays
from the Advanced Light Source and a
new protein-labeling technique,
scientists can see the distribution of
the nucleoli within the nucleus of a
mammary epithelial cell. USG PD
source: http://www.lbl.gov/Science-Artic
les/Archive/xray-inside-cells.html
reticulum evolves in eukaryote cell.
Rough
and smooth endoplasmic reticulum
evolves in eukaryote cell.
The rough ER manufactures and
transports proteins destined for
membranes and secretion. It synthesizes
membrane, organellar, and excreted
proteins. Minutes after proteins are
synthesized most of them leave to the
Golgi apparatus within vesicles. The
rough ER also modifies, folds, and
controls the quality of proteins.
The smooth ER has functions in several
metabolic processes. It takes part in
the synthesis of various lipids (e.g.,
for building membranes such as
phospholipids), fatty acids and
steroids (e.g., hormones), and also
plays an important role in carbohydrate
metabolism, detoxification of the cell
(enzymes in the smooth ER detoxify
chemicals), and calcium storage. It
also is a large transporter of nutrient
found in each cell.
[1] Figure 1 : Image of nucleus,
endoplasmic reticulum and Golgi
apparatus. (1) Nucleus. (2) Nuclear
pore. (3) Rough endoplasmic reticulum
(RER). (4) Smooth endoplasmic reticulum
(SER). (5) Ribosome on the rough ER.
(6) Proteins that are transported. (7)
Transport vesicle. (8) Golgi apparatus.
(9) Cis face of the Golgi apparatus.
(10) Trans face of the Golgi apparatus.
(11) Cisternae of the Golgi
apparatus. I am the copyright holder
of that image (I might even have the
CorelDraw file around somewhere:-), and
I hereby place the image and all
partial images created from it in the
public domain. So, you are free to use
it any way you like. In fact, I am
delighted that one of my drawings makes
it into print! I can mail you the
.cdr file, if you like (and if I can
find it), if you need a better
resolution for printing. Yours, Magnus
Manske Source: [1]. See also
User:Magnus Manske
source: http://en.wikipedia.org/wiki/Ima
ge:Nucleus_ER_golgi.jpg
dictyosome) evolves in eukaryote cell.
The
primary function of the Golgi apparatus
is to process proteins targeted to the
plasma membrane, lysosomes or
endosomes, and those that will be
formed from the cell, and sort them
within vesicles. It functions as a
central delivery system for the cell.
Most of the transport vesicles that
leave the endoplasmic reticulum (ER),
specifically rough ER, are transported
to the Golgi apparatus, where they are
modified, sorted, and shipped towards
their final destination. The Golgi
apparatus is present in most eukaryotic
cells, but tends to be more prominent
where there are many substances, such
as proteins, being secreted. For
example, plasma B cells, the
antibody-secreting cells of the immune
system, have prominent Golgi complexes.
[1] Figure 1: Image of nucleus,
endoplasmic reticulum and Golgi
apparatus: (1) Nucleus, (2) Nuclear
pore, (3) Rough endoplasmic reticulum
(RER), (4) Smooth endoplasmic reticulum
(SER), (5) Ribosome on the rough ER,
(6) Proteins that are transported, (7)
Transport vesicle, (8) Golgi apparatus,
(9) Cis face of the Golgi apparatus,
(10) Trans face of the Golgi apparatus,
(11) Cisternae of the Golgi apparatus,
(12) Secretory vesicle, (13) Plasma
membrane, (14) Exocytosis, (15)
Cytoplasm, (16) Extracellular space.
source: http://en.wikipedia.org/wiki/Ima
ge:Nucleus_ER_golgi_ex.jpg
makes lysosomes which fuse with
endosomes. The various molecules in
lysosomes digest the contents of the
endosome, which then exits the cell as
waste.
[1] Figure 1: Image of nucleus,
endoplasmic reticulum and Golgi
apparatus: (1) Nucleus, (2) Nuclear
pore, (3) Rough endoplasmic reticulum
(RER), (4) Smooth endoplasmic reticulum
(SER), (5) Ribosome on the rough ER,
(6) Proteins that are transported, (7)
Transport vesicle, (8) Golgi apparatus,
(9) Cis face of the Golgi apparatus,
(10) Trans face of the Golgi apparatus,
(11) Cisternae of the Golgi apparatus,
(12) Secretory vesicle, (13) Plasma
membrane, (14) Exocytosis, (15)
Cytoplasm, (16) Extracellular space.
source: http://sun.menloschool.org/~cwea
ver/cells/e/lysosomes/
source: http://en.wikipedia.org/wiki/Ima
ge:Nucleus_ER_golgi_ex.jpg
that can only live in other bacteria,
closely related to Rickettsia
prowazekii, an aerobic
alpha-proteobacteria that causes
louse-borne typhus, enters an early
eukaryote cell. As time continues a
symbiotic relationship evolves, where
the Rickettsia forms the mitochondria,
organelles of every euokaryote cell.
The mitochondria perform the Acid
Citric Cycle (Krebs Cycle), using
oxygen to breakdown glucose into CO2
and H2O, and provide up 38 ATP
molecules. Mitochondria reproduce by
themselves, and are not created by the
DNA in the cell nucleus. As time
continues some of the DNA from the
mitochondria merges with the cell
nucleus DNA. Mitochondria produce
sterol used to make the eukaryote cell
wall flexible. Because mitochondria
need Oxygen, but the level of oxygen is
very low on earth, oxygen may be
provided by photosynthesizing
cyanobacteria living near these cells.
All eukaryotes alive today either have
mitochondria except the amitochondriate
excavates (metamonads), the most
ancient of the eukaryotes alive today.
That parabasalids have hydrogenosomes,
anaerobic organelles that seem to have
evolved from mitochondria, many people
think amitochondriate species lost
their mitochondria over time.1
This
changes the eukaryote cell from an
anaerobic to aerobic unicellular
organism.
This early mitochondria may have
"tubular christae".
Perhaps there was a period of
time where a system evolved to make
sure both halves received mitochondria
during cell division.
Protists with discoidal mitochondrial
cristea will later evolve from the
Bikont tubular mitochondrial christae
branch.
For the most part:
1) Excavates, Amoebozoa,
and Chromealveolates have or had
tubular christae,
2) Discicristata
(Euglenozoa) have discoidal christae.
3)
Cryptomonads, Glaucophytes, Red Algae,
Green Algae, Plants, Fungi, Animals all
have flat christae.
From this point on, all eukaryotes will
need Oxygen to use mitochondria and
receive the ATP made by mitochondria. 2
One theory is that, as more O2 is
produced at the surface of the ocean,
protists (which require oxygen for
mitochondria) can move to the ocean
floor. 3
FOOTNOTES
1. ^
http://comenius.susqu.edu/BI/202/Protist
s/EUKARYA-DOMAIN.htm
2. ^ Richard Cowen, "History of Life",
(Malden, MA: Blackwell, 2005).
3. ^ Richard
Cowen, "History of Life", (Malden, MA:
Blackwell, 2005).
[1] Phylogenetic hypothesis of the
eukaryotic lineage based on
ultrastructural and molecular data.
Organisms are divided into three main
groups distinguished by mitochondrial
cristal shape (either discoidal,
flattened or tubular). Unbroken lines
indicate phylogenetic relationships
that are firmly supported by available
data; broken lines indicate
uncertainties in phylogenetic
placement, resolution of which will
require additional data. Color coding
of organismal genus names indicates
mitochondrial genomes that have been
completely (Table 1), almost completely
(Jakoba, Naegleria and
Thraustochytrium) or partially (*)
sequenced by the OGMP (red), the FMGP
(black) or other groups (green). Names
in blue indicate those species whose
mtDNAs are currently being sequenced by
the OGMP or are future candidates for
complete sequencing. Amitochondriate
retortamonads are positioned at the
base of the tree, with broken arrows
denoting the endosymbiotic origin(s) of
mitochondria from a Rickettsia-like
eubacterium. Macrophar.,
Macropharyngomonas.
source: http://nar.oxfordjournals.org/co
ntent/vol26/issue4/images/gkb18201.gif
[2] Figure 1 Phylogenetic tree of
eukaryotes based on ultrastructural and
molecular data. Organisms are
sub-divided into main groups as
discussed in the text. Only a few
representative species for which
complete (or almost complete) mtDNA
sequences are known are shown in each
lineage. In some cases, line drawings
or actual pictures of the organisms are
provided (Acanthamoeba, M. Nagata; URL:
http://protist.i.hosei.ac.jp/PDB/PCD3379
/htmls/21.html; Allomyces, Tom Volk;
URL:
http://botit.botany.wisc.edu/images/332/
Chytridiomycota/Allomyces_r_So_pa/A._arb
uscula_pit._sporangia_tjv.html;
Amoebidium, URL:
http://cgdc3.igmors.upsud.fr/microbiolog
ie/mesomycetozoaires.htm; Marchantia,
URL:
http://www.science.siu.edu/landplants/He
patophyta/images/March.female.JPEG
Scenedesmus, Entwisle et al.,
http://www.rbgsyd.gov.au/_data/page/1824
/Scenedesmus.gif). The color-coding of
the main groups (alternating between
dark and light blue) on the outer
circle corresponds to the color-coding
of the species names. Unbroken lines
indicate phylogenetic relationships
that are firmly supported by available
molecular data; broken lines indicate
uncertainties in phylogenetic
placement, resolution of which will
require additional sequence data. [t:
why not color code or add which type of
mito?]
source: http://arjournals.annualreviews.
org/doi/full/10.1146/annurev.genet.37.11
0801.142526
1
Unikonts (one cilium). Bikonts (also
called anterokonts for having anterior
{forward facing} cilia) will evolve
into the vast majority of the Protist
and all of the Plant Kingdoms. The
Unikonts will evolve into the ameobozoa
(tenatively), and the opisthokonts
(ancestrally posterior cilium) which
include the entire Fungi and Animal
Kingdoms.1 2 3
Since members of both the unikont
(animals, fungi) and bikont
(metamonads, plants) can reproduce
sexually, sex had to evolve before this
branching, presuming sexual
reproduction is strictly inherited and
did not evolve twice.
FOOTNOTES
1. ^ Nucleic Acids Research Pages
865-878 v26 4 865 MW Gray, BF Lang,
R Cedergren, GB Golding, C Lemieux, D
Sankoff, M Turmel, N Brossard, E
Delage, TG Littlejohn, I Plante, P
Rioux, D Saint-Louis, Y Zhu, and G
Burger
MORE INFO
[1] THOMAS CAVALIER-SMITH,
"Economy, Speed and Size Matter:
Evolutionary Forces Driving Nuclear
Genome Miniaturization and Expansion",
* Oxford Journals * Life
Sciences * Annals of Botany *
Volume 95, Number 1 *, (2005).
[2] Thomas
Cavalier-Smith and Ema E. -Y. Chao,
"Phylogeny of Choanozoa, Apusozoa, and
Other Protozoa and Early Eukaryote
Megaevolution", Springer New York,
(2003).
[3] Michael W. Gray, B. Franz Lang,
Robert Cedergren, G. Brian Golding,
Claude Lemieux, David San, "Genome
structure and gene content in protist
mitochondrial DNAs", Oxford Journals,
(1997).
[1] Figure 1. Phylogenetic hypothesis
of the eukaryotic lineage based on
ultrastructural and molecular data.
Organisms are divided into three main
groups distinguished by mitochondrial
cristal shape (either discoidal,
flattened or tubular). Unbroken lines
indicate phylogenetic relationships
that are firmly supported by available
data; broken lines indicate
uncertainties in phylogenetic
placement, resolution of which will
require additional data. Color coding
of organismal genus names indicates
mitochondrial genomes that have been
completely (Table 1), almost completely
(Jakoba, Naegleria and
Thraustochytrium) or partially (*)
sequenced by the OGMP (red), the FMGP
(black) or other groups (green). Names
in blue indicate those species whose
mtDNAs are currently being sequenced by
the OGMP or are future candidates for
complete sequencing. Amitochondriate
retortamonads are positioned at the
base of the tree, with broken arrows
denoting the endosymbiotic origin(s) of
mitochondria from a Rickettsia-like
eubacterium. Macrophar.,
Macropharyngomonas.
source:
a mineral that cannot exist for much
time if exposed to oxygen, indicating
that free oxygen is accumulating in the
air of earth for the first time.1
FOOTNOTES
1. ^ Richard Cowen, "History of Life",
(Malden, MA: Blackwell, 2005).
on land, begin here and are evidence of
more free oxygen in the air of earth.1
2
FOOTNOTES
1. ^ Richard Cowen, "History of Life",
(Malden, MA: Blackwell, 2005).
2. ^
http://www.es.ucsc.edu/~pkoch/lectures/l
ecture5.html
[1]
http://www.kgs.ukans.edu/Extension/redhi
lls/redhills.html
source:
10 11 12
oldest line of eukaryotes still in
existence, the oldest living protists,
in the Phylum "Metamonada" (Excavates)
originating now. 1 2 3 This is where
the eukaryote line is created and
separates from the archaebacteria
(archaea) line. Most of these species
have an excavated ventral feeding
groove, and all lack mitochondria.
Mitochondria are thought to have been
lost secondarily, although this is not
certain.
PHYLUM Metamonada
ORDER Carpediemondida
ORDER
Diplomonadida
ORDER Retortamonadida
CLASS Parabasalia
ORDER
Trichomonadida
ORDER Hypermastigida
CLASS Anaeromonada
ORDER Oxymonadida
ORDER Trimastigida
Includes Diplomonad
"Giardia", and Parabasalid "Trichomonas
vaginalis".
The trophozoite form of Giardia does
age and die.
Most Metamonads reproduce
asexually through closed (the nuclear
membrane does not dissolve during
mitosis) mitosis (and involves an
external spindle? is pluromitosis?),
but some species are "faculatively
sexual" (can reproduce sexually in
addition to asexually). So already by
the time of these most ancient of the
now living eukaryotes, sex had evolved.
eat bacteria?
Some people have this phylum as
part of the group "Excavates" which
includes the Phyla (Metamonada,
Percolozoa, and Euglenozoa).
The classification of the protists is
far from complete and settled. There
are currently more than one existing
classification scheme for the protists.
features of parabasalia and metamonada:
gamete type: flagellated
haplontic and
diplontic
condensed chromosomes in some
species
mitotic spindle:
parabasalia:
external
metamonadea: internal
polar
structures:
parabasalia: flagellar
root
metamonadea: kinetosome
flagella:
parabasalia: 4 to many
metamonadea:
2,44
heterokont, isokont, anisokont:
anisokont 5 (Anisokont flagella are
those flagella that are unequal in
length, form, or direction. 6 )
(Isokont flagella are those flagella
that are equal in length, form, and
direction.7 )
(The name heterokont
refers to the characteristic form of
these cells, which typically have two
unequal flagella. The anterior or
tinsel flagellum is covered with
lateral bristles or mastigonemes, while
the other flagellum is whiplash, smooth
and usually shorter, or sometimes
reduced to a basal body. The flagella
are inserted subapically or laterally,
and are usually supported by four
microtubule roots in a distinctive
pattern. 8 )
flagellate stages: trophic
li
fe forms:
unicellular: flagellated
multi
cellular: none
cell covering: naked 9
FOOTNOTES
1. ^ S Blair Hedges, Jaime E Blair,
Maria L Venturi and Jason L Shoe, "A
molecular timescale of eukaryote
evolution and the rise of complex
multicellular life", BMC Evolutionary
Biology 2004, 4:2
doi:10.1186/1471-2148-4-2, (2004).
2. ^ Richard
Dawkins, "The Ancestor's Tale",
(Boston, MA: Houghton Mifflin Company,
2004).
3. ^ S. Blair Hedges, "The Origin and
Evolution of Model Organisms", Nature
Reviews Genetics 3, 838-849;
doi:10.1038/nrg929, (2002).
4. ^ Michael
Sleigh, "Protozoa and Other Protists",
(London; New York: Edward Arnold,
1989). p98-99
5. ^ Michael Sleigh, "Protozoa
and Other Protists", (London; New York:
Edward Arnold, 1989). p98-99
6. ^
http://comenius.susqu.edu/bi/202/Protist
s/terms/anisokont.htm
7. ^
http://comenius.susqu.edu/bi/202/Protist
s/terms/anisokont.htm
8. ^ "Heterokonts". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Heterokonts
9. ^ Michael Sleigh, "Protozoa and
Other Protists", (London; New York:
Edward Arnold, 1989). p98-99
10. ^ S Blair
Hedges, Jaime E Blair, Maria L Venturi
and Jason L Shoe, "A molecular
timescale of eukaryote evolution and
the rise of complex multicellular
life", BMC Evolutionary Biology 2004,
4:2 doi:10.1186/1471-2148-4-2,
(2004).
11. ^ Richard Dawkins, "The Ancestor's
Tale", (Boston, MA: Houghton Mifflin
Company, 2004).
12. ^ S. Blair Hedges, "The
Origin and Evolution of Model
Organisms", Nature Reviews Genetics 3,
838-849; doi:10.1038/nrg929, (2002).
[1] Giardia lamblia, a parasitic
flagellate that causes giardiasis.
Image from public domain source at
http://www.nigms.nih.gov/news/releases/i
mages/para.jpg
source: http://www.nigms.nih.gov/news/re
leases/images/para.jpg
[2] . The cysts are hardy and can
survive several months in cold water.
Infection occurs by the ingestion of
cysts in contaminated water, food, or
by the fecal-oral route (hands or
fomites) . In the small intestine,
excystation releases trophozoites (each
cyst produces two trophozoites) .
Trophozoites multiply by longitudinal
binary fission, remaining in the lumen
of the proximal small bowel where they
can be free or attached to the mucosa
by a ventral sucking disk .
Encystation occurs as the parasites
transit toward the colon. The cyst is
the stage found most commonly in
nondiarrheal feces . Because the cysts
are infectious when passed in the stool
or shortly afterward, person-to-person
transmission is possible. While
animals are infected with Giardia,
their importance as a reservoir is
unclear.
source: http://www.dpd.cdc.gov/dpdx/HTML
/Giardiasis.asp?body=Frames/G-L/Giardias
is/body_Giardiasis_page1.htm
2
shows the eubacteria and archaebacteria
line separating here at 2,156 mybn,
first archaebacteria.1
FOOTNOTES
1. ^ Russell F. Doolittle, Da-Fei
Feng, Simon Tsang, Glen Cho, Elizabeth
Little, "Determining Divergence Times
of the Major Kingdoms of Living
Organisms with a Protein Clock",
Science, (1996).
2. ^ Russell F. Doolittle,
Da-Fei Feng, Simon Tsang, Glen Cho,
Elizabeth Little, "Determining
Divergence Times of the Major Kingdoms
of Living Organisms with a Protein
Clock", Science, (1996).
1 2 3 4
Eukaryote Phylum "Loukozoa" (Jakobea
and Malawimonadea) originating now.
These species have mitochondria with
tubular cristae, and are the most
ancient species that still have
mitochondria.1 2 3 4
This species is the most ancient known
species to have a shell. This first
hard shells (lorika) made of calcium
carbonate (Calcite CaCO3), plates of
silica (SiO2), or carbon-based
molecules evolve around the
single-celled species living in the
ocean. 5
Perhaps this shell served to protect
the cell from external damage from
being eaten by other eukaryotes
(zooplankton), infection by bacteria or
viruses, control of buoyancy, to filter
UV light, against damage by non-living
sources. 6
Jakobids and Malawimonads
are also grouped as Excavates because
they have a ventral feeding groove.
Jakobids are flagellates with two
flagella located at the anterior end of
a ventral feeding groove (i.e., are
excavate), with mitochondria, freely
swimming or loricate (with protective
shell).
Flagellar apparatus with two basal
bodies giving rise to two major
microtubular roots, which support the
margins of the ventral groove. Other
cytoskeletal microtubules arise
directly or indirectly from the basal
bodies, no extrusomes.
Jakobids have tubular mitochondrial
cristae (transforming to flat cristae
in Jakoba libera). (1) This indicates
that flat evolved from tubular
cristae.
PHYLUM Loukozoa
ORDER Jakobida
ORDER
Malawimonadida
Reproduction=mitosis?
ORDER Jakobida
FAMILY Histionidae
The jakobid family
"Histionidae" reproduce asexually by
binary fission. In this family no
sexual reproduction has been observed
yet. (1)
FAMILY Jakobidae
FOOTNOTES
1. ^ S Blair Hedges, Jaime E Blair,
Maria L Venturi and Jason L Shoe, "A
molecular timescale of eukaryote
evolution and the rise of complex
multicellular life", BMC Evolutionary
Biology 2004, 4:2
doi:10.1186/1471-2148-4-2, (2004).
2. ^ Richard
Dawkins, "The Ancestor's Tale",
(Boston, MA: Houghton Mifflin Company,
2004).
3. ^ S. Blair Hedges, "The Origin and
Evolution of Model Organisms", Nature
Reviews Genetics 3, 838-849;
doi:10.1038/nrg929, (2002).
4. ^ estimate from
S. L. Baldauf, "The Deep Roots of
Eukaryotes", Science 13 June
2003: Vol. 300. no. 5626, pp. 1703 -
1706 DOI: 10.1126/science.1085544,
(2003).
[1] Histiona. This drawing was made by
D. J. Patterson. COPYRIGHTED EDU
source: http://microscope.mbl.edu/script
s/microscope.php?func=imgDetail&imageID=
3479
[2] Histiona (hist-ee-own-a) is a
jakobid flagellate related to Jakoba.
As with other excavates, there is a
ventral groove and the flagella insert
at the head of the groove. There are
two flagella, one lying in the groove
and one curving outwards from the point
of insertion. The margins of the groove
can be mistaken for flagella. Unlike
most other excavates, Histiona sits in
a stalked lorica when feeding. Lorica
with a cyst is evident. Phase contrast.
This picture was taken by David
Patterson, Linda Amaral Zettler, Mike
Peglar and Tom Nerad from cultures and
other materials maintained at the
American Type Culture Collection during
2001. COPYRIGHTED EDU
source: http://microscope.mbl.edu/script
s/microscope.php?func=imgDetail&imageID=
435
mitochondria split from the tubular
christae line.1
This is the origin of the
Discicristata: species that have
discoid mitochondrial cristae and, in
some cases, a deep (excavated) ventral
feeding groove.2
The Discicristata are
Acrasid slime molds, vahlkampfiid
amoebas, euglenoids, trypanosomes, and
leishmanias.
[1] Figure 1. Phylogenetic hypothesis
of the eukaryotic lineage based on
ultrastructural and molecular data.
Organisms are divided into three main
groups distinguished by mitochondrial
cristal shape (either discoidal,
flattened or tubular). Unbroken lines
indicate phylogenetic relationships
that are firmly supported by available
data; broken lines indicate
uncertainties in phylogenetic
placement, resolution of which will
require additional data. Color coding
of organismal genus names indicates
mitochondrial genomes that have been
completely (Table 1), almost completely
(Jakoba, Naegleria and
Thraustochytrium) or partially (*)
sequenced by the OGMP (red), the FMGP
(black) or other groups (green). Names
in blue indicate those species whose
mtDNAs are currently being sequenced by
the OGMP or are future candidates for
complete sequencing. Amitochondriate
retortamonads are positioned at the
base of the tree, with broken arrows
denoting the endosymbiotic origin(s) of
mitochondria from a Rickettsia-like
eubacterium. Macrophar.,
Macropharyngomonas.
source: http://nar.oxfordjournals.org/co
ntent/vol26/issue4/images/gkb18201.gif
Diplobiontic) life cycle (organism with
both diploid and haploid "alternate
life stages" that reproduce asexually
by mitosis) with "sporic meiosis"
evolves.
In this life cycle haploid gametes fuse
to form a diploid zygote which divides
by meiosis producing haploid spores
that produce (differentiate?) gametes,
starting the cycle again.
Initially these species are single
celled in both stages (like
Haptophyta).
All plants, most brown algae,
blastocladiid chytrids, many red algae,
and some filamentous green algae (e.g.
Cladophora) and foraminifera have
haplodiploid life cycles.
Initially, these organisms are single
celled, but later the mitosis stages
will become multicellular when the
cells that result from mitosis stick
together. The only? example of this
is Haptophyta, where diploid cells
divide in sporic meiosis, into haploid
cells (gamonts) which then divide into
gametes.
Of the diplohaplonic species, those
where the haploid and diploid stages
look the same are called "isomorphic"
and those where the two stages look
different are called "heteromorphic".
In land plants the haploid
(gametophyte) stage is reduced to only
a few cells. Since double DNA
chromosomes (diploid) provides more
possibilities than a single chromosome,
diploid organisms have a selective
advantage over haploid organisms. 1
FOOTNOTES
1. ^ Raven, Evert, Eichhorn, "Biology
of Plants", (New York: Worth
Publishers, 1992).
[1] Figure 23.1.Plants have
haplodiplontic life cycles that involve
mitotic divisions (resulting in
multicellularity) in both the haploid
and diploid generations (paths A and
D). Most animals are diplontic and
undergo mitosis only in the diploid
generation (paths B and D).
Multicellular organisms with haplontic
life cycles follow paths A and C.
COPYRIGHTED EDU
source: http://zygote.swarthmore.edu/pla
ntfig1.gif
[2] Drawn by self for Biological life
cycle Based on Freeman & Worth's
Biology of Plants (p. 171). GNU
source: http://en.wikipedia.org/wiki/Ima
ge:Sporic_meiosis.png
3
with flat christae evolve from those
with tubular christae.1 2
FOOTNOTES
1. ^
http://nar.oxfordjournals.org/cgi/conten
t/full/26/4/865
2. ^
http://microscope.mbl.edu/scripts/protis
t.php?func=integrate&myID=P1901&chinese_
flag=&system=&version=&documentID=&exclu
deNonLinkedIn=&imagesOnly=
3. ^ guess based on one jakobid having
tubular that change to flat, aside from
that cryptomonads are firs
[1] Figure 1. Phylogenetic hypothesis
of the eukaryotic lineage based on
ultrastructural and molecular data.
Organisms are divided into three main
groups distinguished by mitochondrial
cristal shape (either discoidal,
flattened or tubular). Unbroken lines
indicate phylogenetic relationships
that are firmly supported by available
data; broken lines indicate
uncertainties in phylogenetic
placement, resolution of which will
require additional data. Color coding
of organismal genus names indicates
mitochondrial genomes that have been
completely (Table 1), almost completely
(Jakoba, Naegleria and
Thraustochytrium) or partially (*)
sequenced by the OGMP (red), the FMGP
(black) or other groups (green). Names
in blue indicate those species whose
mtDNAs are currently being sequenced by
the OGMP or are future candidates for
complete sequencing. Amitochondriate
retortamonads are positioned at the
base of the tree, with broken arrows
denoting the endosymbiotic origin(s) of
mitochondria from a Rickettsia-like
eubacterium. Macrophar.,
Macropharyngomonas.
source: http://nar.oxfordjournals.org/co
ntent/vol26/issue4/images/gkb18201.gif
1 2 3
primitive living members of the Phylum
"Euglenozoa" (euglenids, leishmania,
trypanosomes, kinetoplastids) evolved
at this time.1 2 3
This is the oldest eukaryote to exhibit
colonialism. Perhaps eukaryote
colonialism is partially or fully
inherited from prokaryotes, but
colonialism may have evolved
independently again in eukaryotes.
This is the most ancient species known
to have a cell covering, which is of
the type "pellicle".
No examples of sexual
reproduction in the group have been
found. 4 Reproduction is through
closed mitosis and involves an internal
spindle. 5 At least one account of a
sexual cycle has been reported in
Scytomonas. 6
The chloroplasts are contained in three
membranes and are pigmented similarly
to the plants, suggesting they were
retained from some captured green
alga.
All Euglenozoa have mitochondria with
discoid cristae, which in the
kinetoplastids characteristically have
a DNA-containing granule or kinetoplast
associated with the flagellar bases.
I think
they are still haploid, mitosis
duplicates in nucleus?
Euglenozoa age?
This group is sometimes called
"Discicristates" because all members
have mitochondria with "discoidal
cristae". 7
Euglenids are the first eukaryotes with
an eyespot. Most colored euglenids
also have a stigma or eyespot, which is
a small splotch of red pigment on one
side of the flagellar pocket. This
shades a collection of light sensitive
crystals near the base of the leading
flagellum, so the two together act as a
sort of directional eye. Euglenozoa
eyepots evolved from chloroplasts.
This is the beginning of a light
sensory system which evolves to eyes?
A small number of euglinids have
chloroplasts and can photosynthesize.
In these species, the chloroplasts
contain three membranes and are thought
to have evolved at least 900 million
years later from a captured green alga.
Euglenoids, however, share reproductive
habits with their kinetoplastid
relations by reproducing mainly by
asexual binary fission. Euglenoids
reproduce very rapidly, absorbing their
flagellum and dividing haploid cells
through mitosis. Mitosis produces 4-8
flagellated haploid cells, called
zoospores. The zoospores then break out
of the parent cell and grow to full
size. 8
condensed chromosomes: yes in all
kinetoplasts, and some euglenophyta. 9
polar structures: none 10
number of
flagella: kinetoplastids=(1 in some) 2,
euglenophyta=2 (4 in some) 11
life
forms: 12
unicellular: flagellated 13
multicellular: colonial 14
cell
covering: pellicle 15
2. Euglenoids are small (10-500
µm) freshwater unicellular organisms.
3.
One-third of all genera have
chloroplasts; those that lack
chloroplasts ingest or absorb their
food.
4. Their chloroplasts are
surrounded by three rather than two
membranes.
a. Their chloroplasts
resemble those of green algae.
b.
They are probably derived from a green
algae through endosymbiosis.
5. The pyrenoid
outside the chloroplast produces an
unusual type of carbohydrate polymer
(paramylon)
not seen in green algae.
6. They possess two flagella, one of
which typically is much longer and than
the other and projects
out of a
vase-shaped invagination; it is called
a tinsel flagellum because it has hairs
on it.
7. Near the base of the
longer flagellum is a red eyespot that
shades a photoreceptor for detecting
light.
8. They lack cell walls, but
instead are bounded by a flexible
pellicle composed of protein strips
side-by-side.
9. A contractile vacuole,
similar to certain protozoa, eliminates
excess water.
10. Euglenoids reproduce
by longitudinal cell division; sexual
reproduction is not known to occur. 16
PHYLUM Euglenozoa
CLASS Euglenoidea
CLASS Diplonemea
CLASS
Kinetoplastea
CLASS Postgaardea
Those Euglnozoa that do not
photosynthesize feed on bacteria
(phagocytosis) or feed through
absorption (osmosis) of nutrients.
Most are small,
around 15-40 µm in size, although many
euglenids get up to 500 µm long.
Most Euglenozoa have two flagella,
usually one leading and one trailing.
Some euglenozoa cause parasitic disease
in other species.
A kinetoplastid member of
Euglenozoa, such as trypanosoma brucei
which causes African sleeping sickness,
is transmitted from host to host by a
vector, most commonly the tsetse fly.
In
most forms there is an associated
cytostome (mouth) supported by one of
three microtubule groups that arise
from the flagellar bases.
Average life cycle=? days
Average age of
euglenozoa life=? days
Trypanosomes (Kinetoplastids) typically
have complex life-cycles involving more
than one host, and go through various
morphological stages.
1000 Species of Euglenoids
(euglenophyta).
FOOTNOTES
1. ^ S Blair Hedges, Jaime E Blair,
Maria L Venturi and Jason L Shoe, "A
molecular timescale of eukaryote
evolution and the rise of complex
multicellular life", BMC Evolutionary
Biology 2004, 4:2
doi:10.1186/1471-2148-4-2, (2004).
2. ^ Richard
Dawkins, "The Ancestor's Tale",
(Boston, MA: Houghton Mifflin Company,
2004). (1600mybn)
3. ^ Russell F. Doolittle,
Da-Fei Feng, Simon Tsang, Glen Cho,
Elizabeth Little, "Determining
Divergence Times of the Major Kingdoms
of Living Organisms with a Protein
Clock", Science, (1996). (1800-1900 for
eukaryote/prokaryote separation)
[1] euglena
source: http://www.fcps.k12.va.us/Stratf
ordLandingES/Ecology/mpages/euglena.htm
[2] euglena
source: http://protist.i.hosei.ac.jp/PDB
/Images/Mastigophora/Euglena/genus1L.jpg
21 22 23
Phylum "Percolozoa" (also called
"Heterolobosea"1 ) (acrasid slime
molds) evolved at this time.2 3 4
Perco
lozoa are a group of heterotrophic
colourless protozoa, including many
that can transform between amoeboid,
flagellate, and encysted stages. These
are collectively referred to as
amoeboflagellates, schizopyrenids, or
vahlkampfids. They also include the
acrasids, a group of social amoebae
that aggregate to form sporangia.5 6 7
Very closely related to Euglenozoa.
All
characteristics are like Euglenozoa:
Percolozoa
have mitochondria with discoid
christae.
No examples of sexual reproduction in
the group have been found.
Reproduction is through closed mitosis
and involves an internal spindle. 8
No
chloroplasts (check) or (The
chloroplasts are contained in three
membranes and are pigmented similarly
to the plants, suggesting they were
retained from some captured green
alga.9 )
I think they are still haploid,
mitosis duplicates in nucleus?
Percolozoa age?
Pe
rcolozoa are sometimes included in the
group "Discicristates" because all
members have mitochondria with
"discoidal cristae".
No eyespots.
closed mitosis with internal spindle.
10
The Percolozoa are the most ancient
species to have members that move by
pseudopodia, like amoeba.
PHYLUM Percolozoa 11
CLASS
Heterolobosea
ORDER Schizopyrenida Singh, 1952
ORDER Acrasida Shröter, 1886
(acrasids, cellular slime molds)
ORDER
Lyromonadida Cavalier-Smith, 1993
CLASS
Percolatea 12
ORDER Acrasida (acrasids, cellular
slime molds):
a. Cellular slime
molds (Phylum Acrasiomycota) (ORDER
Acrasida13 ) exist as individual
amoeboid cells. (Plasmodial slime
molds, mycetozoa, which evolve later,
exist as a plasmodium. )
b.
They live in soil and feed on bacteria
and yeast.
c. As food runs out,
amoeboid cells release a chemical that
causes them to aggregate into a
pseudoplasmodium.
d. The pseudoplasmodium
stage is temporary; it gives rise to
sporangia that produce spores.
e.
Spores survive until more favorable
environmental conditions return; then
they germinate.
f. Spore germinate to
release haploid amoeboid cells, which
is again the beginning of asexual
cycle.
g. Asexual cycle occurs
under very moist conditions. 14
Percolo
zoa feed on bacteria (phagocytosis) or
feed through absorption (osmosis) of
nutrients. (check)
Most are small, around 15-40
µm in size, although many euglenids
get up to 500 µm long.
The flagellate stage is slightly
smaller, with two or four anterior
flagella anterior to the feeding
groove.
Average life cycle=? days
Average age of
Percolozoa life=? days
Most Percolozoa are found as
bacterivores in soil, freshwater, and
on feces. There are a few marine and
parasitic forms, including the species
Naegleria fowleri, which can become
pathogenic in humans and is often
fatal. The group is closely related to
the Euglenozoa, and share with them the
unusual though not unique
characteristic of having mitochondria
with discoid cristae. The presence of a
ventral feeding groove in the
flagellate stage, as well as other
features, suggests that they are part
of the excavate group.15
The amoeboid stage is roughly
cylindrical, typically around 20-40
μm in length. They are
traditionally considered lobose
amoebae, but are not related to the
others and unlike them do not form true
lobose pseudopods. Instead, they
advance by eruptive waves, where
hemispherical bulges appear from the
front margin of the cell, which is
clear. The flagellate stage is slightly
smaller, with two or four anterior
flagella anterior to the feeding
groove.16
Usually the amoeboid form is taken when
food is plentiful, and the flagellate
form is used for rapid locomotion.
However, not all members are able to
assume both forms. The genera
Percolomonas, Lyromonas, and
Psalteriomonas are known only as
flagellates, while Vahlkampfia,
Pseudovahlkampfia, and the acrasids do
not have flagellate stages. As
mentioned above, under unfavourable
conditions, the acrasids aggregate to
form sporangia. These are superficially
similar to the sporangia of the
dictyostelids, but the amoebae only
aggregate as individuals or in small
groups and do not die to form the
stalk.17
The Heterolobosea were first defined by
Page and Blanton in 1985 as a class of
amoebae, and so only included those
forms with amoeboid stages.
Cavalier-Smith created the phylum
Percolozoa for the extended group,
together with the enigmatic flagellate
Stephanopogon. (currently I have
stephanopogon colpoda images under
ciliates...18 ) He maintained the
Heterolobosea as a class for amoeboid
forms, but most others have expanded
them to include the flagellates as
well.19
Stephanopogon closely resembles certain
ciliates and was originally classified
with them, but is now considered a
flagellate. 20
FOOTNOTES
1. ^ Ted Huntington.
2. ^ S Blair Hedges, Jaime E
Blair, Maria L Venturi and Jason L
Shoe, "A molecular timescale of
eukaryote evolution and the rise of
complex multicellular life", BMC
Evolutionary Biology 2004, 4:2
doi:10.1186/1471-2148-4-2, (2004).
1961mybn
3. ^ Richard Dawkins, "The Ancestor's
Tale", (Boston, MA: Houghton Mifflin
Company, 2004). 1600 mybn
4. ^ Russell F.
Doolittle, Da-Fei Feng, Simon Tsang,
Glen Cho, Elizabeth Little,
"Determining Divergence Times of the
Major Kingdoms of Living Organisms with
a Protein Clock", Science, (1996).
1800-1900 mybn
5. ^ "Percolozoa". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Percolozoa
6. ^
http://microscope.mbl.edu/scripts/protis
t.php?func=integrate&myID=P2989
7. ^ Raven, Evert, Eichhorn, "Biology
of Plants", (New York: Worth
Publishers, 1992). p178
8. ^ Michael Sleigh,
"Protozoa and Other Protists", (London;
New York: Edward Arnold, 1989). p98-99
9. ^
Ted Huntington.
10. ^
http://microscope.mbl.edu/scripts/protis
t.php?func=integrate&myID=P2989
11. ^
http://sn2000.taxonomy.nl/Taxonomicon/Ta
xonTree.aspx?id=114287
12. ^
http://sn2000.taxonomy.nl/Taxonomicon/Ta
xonTree.aspx?id=114287
13. ^ Ted Huntington.
14. ^
http://www.sirinet.net/~jgjohnso/apbio30
.html
15. ^ "Percolozoa". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Percolozoa
16. ^ "Percolozoa". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Percolozoa
17. ^ "Percolozoa". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Percolozoa
18. ^ Ted Huntington.
19. ^ "Percolozoa".
Wikipedia. Wikipedia, 2008.
http://en.wikipedia.org/wiki/Percolozoa
20. ^ "Stephanopogon". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Stephanopog
on
21. ^ S Blair Hedges, Jaime E Blair,
Maria L Venturi and Jason L Shoe, "A
molecular timescale of eukaryote
evolution and the rise of complex
multicellular life", BMC Evolutionary
Biology 2004, 4:2
doi:10.1186/1471-2148-4-2, (2004).
1961mybn (1961)
22. ^ Richard Dawkins, "The
Ancestor's Tale", (Boston, MA: Houghton
Mifflin Company, 2004). 1600 mybn
(1600mybn)
23. ^ Russell F. Doolittle, Da-Fei
Feng, Simon Tsang, Glen Cho, Elizabeth
Little, "Determining Divergence Times
of the Major Kingdoms of Living
Organisms with a Protein Clock",
Science, (1996). 1800-1900 mybn
(1800-1900(for eukaryote/prokaryote
separation)
[1] Stages of Naegleria fowleri, a
member of the Percolozoa. Adapted from
Image:Free-living amebic
infections.gif, which is from the CDC.
PD
source: http://en.wikipedia.org/wiki/Ima
ge:Naegleria.png
[2] CLASS Heterolobosea ORDER
Schizopyrenida Heteramoeba: The
flagellated form is large (30
�m), two flagella, an elongate
cytostome curving around the anterior
of the cell and forming a groove.
Nucleus with peripheral chromatin.
Probably feeds and divides as a
flagellate. One species. This genus is
most like Paratetramitus from which it
can be distinguished by peripheral
location of chromatin material. Cysts
without pores, excystment through a
weak region of wall. Marine.
Heteramoeba (het-err-a-me-ba) a naked
heterolobose amoeba, distinguished from
other types of naked amoebae with
lobose pseudopodia largely by
ultrastructural features, but trophic
heterolobose amoebae tend to form their
pseudopodially suddenly rather than
progressively. Phase contrast. This
picture was taken by David Patterson,
Linda Amaral Zettler, Mike Peglar and
Tom Nerad from cultures and other
materials maintained at the American
Type Culture Collection during 2001.
NONCOMMERCIAL USE
source: http://microscope.mbl.edu/script
s/microscope.php?func=imgDetail&imageID=
413
1
protist.
Multicellularity is a very important
event in the evolution of life on
earth. With multicellular organisms,
larger sized organisms could evolve.
There are many uncertainties
surrounding the origin of
multicellularity. Multicellularity may
have evolved independently for Plants,
Fungi and Animals, or multicellularity
may have evolved only once in
eukaryotes.
The key feature of this cell is that a
multicellular organism is made from a
single cell and the multicellular
organism is not a collection of
independent cells (colonialism). The
main difference between this organism
and single-celled organisms is the way
the cells stay fastened together after
cell division.
Which species was the first
multicellular species is not clear.
Multicellularity is found in all 3 life
cycles (haplontic, diplontic,
haplodiplontic). The 3 main life cycle
types (haplontic, etc.) probably
evolved in single cell species before
multicellularity evolved. If
multicellularity evolved once and is
inherited, perhaps all multicellular
organism descended from a single
haplodiplontic organism.
These multicellular organisms have
undifferentiated cells in the
multicellular stage (all cells in the
haploid or diploid multicellular
organism are made of one kind of cell).
Dinoph
yta, and Fungi are multicellular
Haplontic species.
Most animals are
multicellular Diplontic species.
Most brown
algae and all plants are multicellular
Haplodiplontic species.
The vast majority of multicellular
organisms reproduce only through sex,
although there are exceptions (like
some plants and rotifers) which have
lost the ability to sexually reproduce
or can also reproduce asexually. In
multicellularity, one cell goes on to
produce all the cells in a
multicellular species, so that each
individual organism is genetically
unique. This cell is usually a diploid
zygote, but can be a haploid cell.
This protist is most likely sexual, and
multicellularity evolved only in a
species that reproduces sexually.
Some describe algae multicellularity as
"filamentous".1
The first multicellular eukaryuotes are
presumably undifferentiated. For
haplontic these cells are all gametes,
for diplontic these cells are all
capable of meiosis to form gametes, for
haplodiplontic, in the haploid stage
the cells are all gamete producing, in
the diploid stage the cells are all
spore producing.
Some people think that multicellular
organisms arose at least six times: in
animals, fungi and several groups of
algae. 2
What did the first
multicellular organism look like?
Perhaps it was a haplontic protist that
only did one or more haploid mitoses,
but this time the cells stuck together
(perhaps similar to the way bacteria
form filaments).
An interesting aspect of multicellular
organisms is that oxygen must still
reach each cell for mitochondria to
work, and so this requires that the
cells be only 1 cell thick, or if
thicker have some kind of (circulatory)
system for oxygen to reach each cell.
FOOTNOTES
1. ^ Michael Sleigh, "Protozoa and
Other Protists", (London; New York:
Edward Arnold, 1989).
1
differentiation evolves.
Multicellular organisms are no longer
all haploid or diploid gamete producing
cells (or spore producing if
haplodiplontic), but are made of gamete
(or spore) producing cells in addition
to somatic cells which copy asexually
through mitosis.
Now, in addition to being large
multicell organisms, multicellular
organisms can have differentiated cells
that form a variety of different shaped
structures, and perform different
functions.
This process will evolve to the
metazoan multicellular differentiation
that arises from a single zygote cell,
where cells have different functions
and shapes.
Differentiation evolves for a
second time in eukaryotes?
this is not the first
monoadmulti one cell leading to a
multicellular organism (attached, free,
interchangible)?
where a multicellular organism is made
from one cell (interchangable, specific
cells: genetic specificity).
It is unknown how multicellular life
stages happen. For example, why one
specific cell line of many produced
from mitosis of a zygote will go on to
do meiosis producing the haploid gamete
cells which will fuse to form the next
zygote, but the many other cells made
from, for example, one of the two cells
made after the zygote divides, will not
contain the line of cells that
ultimately make the gamete producing
cells which continue the life cycle of
the organism. Since presumably each
cell in an organism contains an
identical genome, perhaps a gamete
producing cell can be made from any
cell if specific proteins are present,
or perhaps there is a protein which
simply points to a certain location in
the DNA which is located at a different
location in the DNA for every cell, or
perhaps some other explanation answers
the question of how cell
differentiation can happen when each
cell has the same genome.
A (diploid) zygote cell (the cell made
by two merging gamete cells) now
divides to form all cells in the
differentiated multicellular organism,
and is said to be "totipotent".
Totipotent cells differentiate into
"pluripotent" cells which can make most
but not all cells in the organism.
Pluripotent cells differentiate into
"multipotent" (can make a number of
cells) or "unipotent" cells (can only
make one kind of cell).
FOOTNOTES
1. ^ Ted Huntington. guess. is after
haploid mitosis? after fusion?
plants, this is where the plant kingdom
begins with the evolution of brown
algae (phaeophyta).1
FOOTNOTES
1. ^ Michael Sleigh, "Protozoa and
Other Protists", (London; New York:
Edward Arnold, 1989).
1 2 3
ancestor of the "Chromalveolates"
evolving now. Chromalveolates include
the Chromista and Alveolata. The
Chromista include the 3 Phyla
Haptophyta, Cryptophyta (Cryptomonads),
and Heterokontophyta (brown algae
{kelp}, diatoms, water molds).
Alveolata include the 3 Phyla
Dinoflagellata, Apicomplexa (Malaria,
Toxoplasmosis), and Ciliophora
(ciliates).1 2 3
Chromealveolates have
mitochondria with tubular cristae.
Thomas Cavalier-Smith writes: "The
chromalveolate clade (Cavalier-Smith
1999) and its constituent taxa, kingdom
Chromista (Cavalier-Smith 1981) and
protozoan infrakingdom Alveolata
(Cavalier-Smith 1991b), were all
proposed based on morphological,
biochemical, and evolutionary reasoning
about protein targeting before there
was sequence evidence for any of them.
Now all are strongly supported by such
evidence. Chromalveolates comprise all
algae with chlorophyll c (the
chromophyte algae) and all their
nonphotosynthetic descendants. They
arose by a single symbiogenetic event
in which an early unicellular red alga
was phagocytosed by a biciliate host
and enslaved to provide photosynthate
(Cavalier-Smith 1999, 2002c, 2003a).
The strongest evidence that this
occurred once only in their cenancestor
is the replacement of the red algal
plastid glyceraldehyde phosphate
dehydrogenase (GAPDH) by a duplicate of
the gene for the cytosolic version of
this enzyme in all four chromalveolate
groups with plastids: the alveolate
sporozoa and dinoflagellates and the
chromist cryptomonads and chromobiotes
(Fast et al. 2001). It would be
incredible for such gene duplication,
retargeting by acquiring bipartite
targeting sequences, and loss of the
original red algal gene to have
occurred convergently in four groups,
but it was already pretty incredible
that these groups would all have
evolved a similar protein-targeting
system independently and all happened
to enslave a red alga, evolve
chlorophyll c, and place their plastids
within the rough endoplasmic reticulum
(ER) independently. Yet many assumed
just this because of the false dogma
that symbiogenesis is easy and the
failure of all these groups to cluster
in rRNA trees. For chromobiotes this
retargeting of GAPDH has been
demonstrated only for
heterokonts-information is lacking for
haptophytes. However, there are five
strong synapomorphies for Chromobiota,
making it highly probable that the
group is holophyletic (Cavalier-Smith
1994). They share the presence of the
periplastid reticulum in the
periplastid space instead of a
nucleomorph like cryptomonads, they
uniquely make the carotenoid
fucoxanthin and chlorophyll c3, they
uniquely have a single autofluorescent
cilium, and they have tubular
mitochondrial cristae with an
intracristal filament. Five plastid
genes now extremely robustly support
the monophyly of both chromists and
chromobiotes (Yoon et al. 2002). We are
confident that comparable sequence
evidence from nuclear genes will also
eventually catch up with the general
biological evidence for the holophyly
of chromobiotes to convince even the
most skeptical, who ignore or discount
such valuable evidence that
chromobiotes are holophyletic." 4
Chromista include phyla:
Heterokontophyta
(heterokonts) (many classes) (includes
colored: golden algae, axodines,
diatoms, yellow-green algea, brown
algae, colorless: water moulds, slime
nets)
Haptophyta
Cryptophyta (cryptomonads) (many
genera)
Alveolates include the phyla:
Dinoflagellata
(Dinoflagellates)
Apicomplexa (Apicomplexans)
Ciliophora (ciliates)
In 1981 Cavalier-Smith created a new
kingdom called "Chromista" in which all
chromalveolates are placed. 5
There
are a number of classification schemes
for the kingdom Protista and no one
system has emerged as most popular yet.
FOOTNOTES
1. ^ S Blair Hedges, Jaime E Blair,
Maria L Venturi and Jason L Shoe, "A
molecular timescale of eukaryote
evolution and the rise of complex
multicellular life", BMC Evolutionary
Biology 2004, 4:2
doi:10.1186/1471-2148-4-2, (2004).
2. ^ Richard
Dawkins, "The Ancestor's Tale",
(Boston, MA: Houghton Mifflin Company,
2004). (1600mybn)
3. ^ Sandra L. Baldauf, A. J.
Roger, I. Wenk-Siefert, W. F.
Doolittle, "A Kingdom-Level Phylogeny
of Eukaryotes Based on Combined Protein
Data", Science, Vol 290, num 5493, p
972, (2000). has heterkonts before
ciliophora and apicomplexa branch
MORE INFO
[1] "Brown alga". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Brown_alga
[1] Fig. 1. A consensus phylogeny of
eukaryotes. The vast majority of
characterized eukaryotes, with the
notable exception of major subgroups of
amoebae, can now be assigned to one of
eight major groups. Opisthokonts (basal
flagellum) have a single basal
flagellum on reproductive cells and
flat mitochondrial cristae (most
eukaryotes have tubular ones).
Eukaryotic photosynthesis originated in
Plants; theirs are the only plastids
with just two outer membranes.
Heterokonts (different flagellae) have
a unique flagellum decorated with
hollow tripartite hairs (stramenopiles)
and, usually, a second plain one.
Cercozoans are amoebae with filose
pseudopodia, often living with in tests
(hard outer shells), some very
elaborate (foraminiferans). Amoebozoa
are mostly naked amoebae (lacking
tests), often with lobose pseudopodia
for at least part of their life cycle.
Alveolates have systems of cortical
alveoli directly beneath their plasma
membranes. Discicristates have discoid
mitochondrial cristae and, in some
cases, a deep (excavated) ventral
feeding groove. Amitochondrial
excavates lack substantial molecular
phylogenetic support, but most have an
excavated ventral feeding groove, and
all lack mitochondria. The tree shown
is based on a consensus of molecular
(1-4) and ultrastructural (16, 17) data
and includes a rough indication of new
ciPCR ''taxa'' (broken black lines)
(7-11). An asterisk preceding the taxon
name indicates probable paraphyletic
group
source: http://www.sciencemag.org/cgi/co
ntent/full/300/5626/1703
[2] Beautiful marine diatoms as seen
through a microscope. These tiny
phytoplankton are encased within a
silicate cell wall. Image ID: corp2365,
NOAA Corps Collection Photographer: Dr.
Neil Sullivan, University of Southern
Calif. NOAA This image is a work of
the National Oceanic and Atmospheric
Administration, taken or made during
the course of an xxxxx? official
duties. As works of the U.S. federal
government, all NOAA images are in the
public domain.
source: http://en.wikipedia.org/wiki/Ima
ge:Diatoms_through_the_microscope.jpg
1 2 3
ancestor of Chromalveolate Phlyum
Haptophyta evolving now.1 2 3
Some
Haptophytes are haplodiploid (alternate
between haploid and diploid cycles that
both have mitosis), and this group is
the most primitive with a haplodiploid
life cycle.
Haptophytes are single cellular.4
Haptophytes are found only in all
oceans (marine) and are flagellates,
almost all with plastids with
chlorophylls a and c, with two flagella
and one additional locomotor/feeding
organelle, the haptonema.5
Haptophyta are a group of algae
(phytoplankton).
The chloroplasts are pigmented
similarly to those of the heterokonts,
such as golden algae, but the structure
of the rest of the cell is different,
so it may be that they are a separate
line whose chloroplasts are derived
from similar endosymbionts.6
The cells
typically have two slightly unequal
flagella, both of which are smooth, and
a unique organelle called a haptonema,
which is superficially similar to a
flagellum but differs in the
arrangement of microtubules and in its
use.7
Haptophytes have tubular
mitochondria cristae.8
Most haptophytes
are coccolithophores, which live
strictly in the oceans (marine) and are
ornmmented with calcified scales called
coccoliths, which are sometimes found
as microfossils. Other planktonic
haptophytes of note include
Chrysochromulina and Prymnesium, which
periodically form toxic marine algal
blooms. Both molecular and
morphological evidence supports their
division into five orders.9 10
Emiliania is a small organism that is
famous for turning huge portions of the
ocean bright turquoise during its
blooms. They are also known for
contributing to the white cliffs of
Dover because of the calcite in their
coccolith cell structure. They play a
very important role in the carbon cycle
in the ocean because they form calcium
carbonate exoskeletons that sink to the
bottom of the ocean floor when they
die. They are also one of the worlds
major calcite producers.11
Sexual reproduction: Asexual, Open
mitosis with spindle nucleating
(originating?12 ) in cytoplasm.13
Phaeoc
ystis colonial cells diploid, motile
cells haploid or diploid; reproduction
by vegetative division of non-motile
cells and fragmentation of colonies,
vegetative division of motile cells, or
by fusion of gametes.14
Members of the Haptophytes Genus
"Phaocystis" form colonies (see photo15
).
Haptophytes are also called
"Prymnesiophytes" 16
Some Haptophyta have hard shell made of
calcium carbonate evolves around the
single-celled species living in the
ocean.
KINGDOM Protista (Chromalveolata)
PHYLUM Haptophyta
CLASS
Pavlovophyceae
ORDER Pavlovales
CLASS Prymnesiophyceae
ORDER Prymnesiales
ORDER Phaeocystales
ORDER
Isochrysidales
ORDER Coccolithales
FOOTNOTES
1. ^ S Blair Hedges, Jaime E Blair,
Maria L Venturi and Jason L Shoe, "A
molecular timescale of eukaryote
evolution and the rise of complex
multicellular life", BMC Evolutionary
Biology 2004, 4:2
doi:10.1186/1471-2148-4-2, (2004).
2. ^ Richard
Dawkins, "The Ancestor's Tale",
(Boston, MA: Houghton Mifflin Company,
2004). (1600mybn)
3. ^ Sandra L. Baldauf, A. J.
Roger, I. Wenk-Siefert, W. F.
Doolittle, "A Kingdom-Level Phylogeny
of Eukaryotes Based on Combined Protein
Data", Science, Vol 290, num 5493, p
972, (2000). (has heterkonts before
ciliophora and apicomplexa branch)
[1] Fig. 1. A consensus phylogeny of
eukaryotes. The vast majority of
characterized eukaryotes, with the
notable exception of major subgroups of
amoebae, can now be assigned to one of
eight major groups. Opisthokonts (basal
flagellum) have a single basal
flagellum on reproductive cells and
flat mitochondrial cristae (most
eukaryotes have tubular ones).
Eukaryotic photosynthesis originated in
Plants; theirs are the only plastids
with just two outer membranes.
Heterokonts (different flagellae) have
a unique flagellum decorated with
hollow tripartite hairs (stramenopiles)
and, usually, a second plain one.
Cercozoans are amoebae with filose
pseudopodia, often living with in tests
(hard outer shells), some very
elaborate (foraminiferans). Amoebozoa
are mostly naked amoebae (lacking
tests), often with lobose pseudopodia
for at least part of their life cycle.
Alveolates have systems of cortical
alveoli directly beneath their plasma
membranes. Discicristates have discoid
mitochondrial cristae and, in some
cases, a deep (excavated) ventral
feeding groove. Amitochondrial
excavates lack substantial molecular
phylogenetic support, but most have an
excavated ventral feeding groove, and
all lack mitochondria. The tree shown
is based on a consensus of molecular
(1-4) and ultrastructural (16, 17) data
and includes a rough indication of new
ciPCR ''taxa'' (broken black lines)
(7-11). An asterisk preceding the taxon
name indicates probable paraphyletic
group
source: http://www.sciencemag.org/cgi/co
ntent/full/300/5626/1703
[2] Emiliania huxleyi, a
coccolithophore. Photo courtesy Dr.
Markus Geisen - photographer, and The
Natural History Museum. PD
source: http://en.wikipedia.org/wiki/Ima
ge:Emiliania_huxleyi_3.jpg
1 2 3
ancestor of the Chromalveolate Phylum
"Cryptophyta" (Cryptomonads) evolving
now.1 2 3
The cryptomonads are a small
group of flagellates, most of which
have chloroplasts. They are common in
freshwater, and also occur in marine
and brackish habitats. Each cell has an
anterior groove or pocket with
typically two slightly unequal flagella
at the edge of the pocket. 4
Cryptomonad
s distinguished by the presence of
characteristic extrusomes called
ejectisomes, which consist of two
connected spiral ribbons held under
tension. If the cells are irritated
either by mechanical, chemical or light
stress, they discharge, propelling the
cell in a zig-zag course away from the
disturbance. Large ejectisomes, visible
under the light microscope, are
associated with the pocket; smaller
ones occur elsewhere on the cell. 5
Cryp
tomonads have one or two chloroplasts,
except for Chilomonas which has
leucoplasts and Goniomonas which lacks
plastids entirely. These contain
chlorophylls a and c, together with
phycobilins and other pigments, and
vary in color from brown to green. Each
is surrounded by four membranes, and
there is a reduced cell nucleus called
a nucleomorph between the middle two.
This indicates that the chloroplast was
derived from a eukaryotic symbiont,
shown by genetic studies to have been a
red alga. 6
A few cryptomonads, such as
Cryptomonas, can form palmelloid
stages, but readily escape the
surrounding mucus to become free-living
flagellates again. Cryptomonad flagella
are inserted parallel to one another,
and are covered by bipartite hairs
called mastigonemes, formed within the
endoplasmic reticulum and transported
to the cell surface. Small scales may
also be present on the flagella and
cell body. The mitochondria have flat
cristae, and mitosis is open; sexual
reproduction has also been reported.7
Originally the cryptomonads were
considered close relatives of the
dinoflagellates because of their
similar pigmentation. Later botanists
treated them as a separate division,
Cryptophyta, while zoologists treated
them as the flagellate order
Cryptomonadida. There is considerable
evidence that cryptomonad chloroplasts
are closely related to those of the
heterokonts and haptophytes, and the
three groups are sometimes united as
the Chromista. However, the case that
the organisms themselves are related is
not very strong, and they may have
acquired chloroplasts independently.8
Crytomonads often forms blooms in
greater depths of lakes, or during
winter beneath the ice. The cells are
usually brownish in color, and have a
slit-like furrow at the anterior. They
are not known to produce any toxins and
are used to feed small zooplankton,
which is the food source for small fish
in fish farming. 9
Reproduction:
Number of species:
Size and shape: 10-50 μm
in size and flattened in shape
Mitochondria
Christae: flat 10 11 12 (which is
unusual, as most chromalveolates have
tubular christae). Cryotphyta may be
more closely related to the Plant
Kingdom and nearest Glaucophyta which
also have flat christae.
After one species of jakobid that
changes tubular to flat christae,
cryptophyta are the most ancient phylum
to have flat christae. 13 14
KINGDOM
Protista (Chromalveolata)
PHYLUM Cryptophyta
CLASS
Cryptomonadea
ORDER Pyrenomonadales Novarino &
Lucas, 1993
ORDER Cryptomonadales
Pascher, 1913
FOOTNOTES
1. ^ S Blair Hedges, Jaime E Blair,
Maria L Venturi and Jason L Shoe, "A
molecular timescale of eukaryote
evolution and the rise of complex
multicellular life", BMC Evolutionary
Biology 2004, 4:2
doi:10.1186/1471-2148-4-2, (2004).
2. ^ Richard
Dawkins, "The Ancestor's Tale",
(Boston, MA: Houghton Mifflin Company,
2004). (1600mybn)
3. ^ Sandra L. Baldauf, A. J.
Roger, I. Wenk-Siefert, W. F.
Doolittle, "A Kingdom-Level Phylogeny
of Eukaryotes Based on Combined Protein
Data", Science, Vol 290, num 5493, p
972, (2000). has heterkonts before
ciliophora and apicomplexa branch
[1] Fig. 1. A consensus phylogeny of
eukaryotes. The vast majority of
characterized eukaryotes, with the
notable exception of major subgroups of
amoebae, can now be assigned to one of
eight major groups. Opisthokonts (basal
flagellum) have a single basal
flagellum on reproductive cells and
flat mitochondrial cristae (most
eukaryotes have tubular ones).
Eukaryotic photosynthesis originated in
Plants; theirs are the only plastids
with just two outer membranes.
Heterokonts (different flagellae) have
a unique flagellum decorated with
hollow tripartite hairs (stramenopiles)
and, usually, a second plain one.
Cercozoans are amoebae with filose
pseudopodia, often living with in tests
(hard outer shells), some very
elaborate (foraminiferans). Amoebozoa
are mostly naked amoebae (lacking
tests), often with lobose pseudopodia
for at least part of their life cycle.
Alveolates have systems of cortical
alveoli directly beneath their plasma
membranes. Discicristates have discoid
mitochondrial cristae and, in some
cases, a deep (excavated) ventral
feeding groove. Amitochondrial
excavates lack substantial molecular
phylogenetic support, but most have an
excavated ventral feeding groove, and
all lack mitochondria. The tree shown
is based on a consensus of molecular
(1-4) and ultrastructural (16, 17) data
and includes a rough indication of new
ciPCR ''taxa'' (broken black lines)
(7-11). An asterisk preceding the taxon
name indicates probable paraphyletic
group COPYRIGHTED
source: http://www.sciencemag.org/cgi/co
ntent/full/300/5626/1703
[2] Figure 1. Phylogenetic hypothesis
of the eukaryotic lineage based on
ultrastructural and molecular data.
Organisms are divided into three main
groups distinguished by mitochondrial
cristal shape (either discoidal,
flattened or tubular). Unbroken lines
indicate phylogenetic relationships
that are firmly supported by available
data; broken lines indicate
uncertainties in phylogenetic
placement, resolution of which will
require additional data. Color coding
of organismal genus names indicates
mitochondrial genomes that have been
completely (Table 1), almost completely
(Jakoba, Naegleria and
Thraustochytrium) or partially (*)
sequenced by the OGMP (red), the FMGP
(black) or other groups (green). Names
in blue indicate those species whose
mtDNAs are currently being sequenced by
the OGMP or are future candidates for
complete sequencing. Amitochondriate
retortamonads are positioned at the
base of the tree, with broken arrows
denoting the endosymbiotic origin(s) of
mitochondria from a Rickettsia-like
eubacterium. Macrophar.,
Macropharyngomonas. COPYRIGHTED
source: http://nar.oxfordjournals.org/cg
i/content/full/26/4/865
1 2 3
ancestor of the Chromalveolate Phylum
"Heterokontophyta" (Heterokonts also
called Stramenopiles) evolving now.
Heterokonts include brown algae,
diatoms, golden algae, axodines,
yellow-green algae, water moulds and
slime nets.1 2 3
Heterkonts evolved
very near the same time as the
Euglinozoa did.
Heterokonts all have
mitochondria with tubular christae.
The motile cells of heterokonts all
have two unequal cilia (flagella), one
"tinsel" (covered with hairs
{mastigonemes}) cilium and one
"whiplash" (free of hair) cilium.4
KING
DOM Protista (Chromalveolata)
PHYLUM Heterokontophyta
Colored groups
CLASS
Chrysophyceae (golden algae)
CLASS
Synurophyceae
CLASS Actinochrysophyceae
(axodines)
CLASS Pelagophyceae
CLASS
Phaeothamniophyceae
CLASS Bacillariophyceae (diatoms)
CLASS
Raphidophyceae
CLASS Eustigmatophyceae
CLASS Xanthophyceae
(yellow-green algae)
CLASS Phaeophyceae
(brown algae)
Colorless groups
CLASS
Oomycetes(water moulds)
CLASS
Hypochytridiomycetes
CLASS Bicosoecea
CLASS
Labyrinthulomycetes(slime nets)
CLASS
Opalinea
CLASS Proteromonadea
FOOTNOTES
1. ^ S Blair Hedges, Jaime E Blair,
Maria L Venturi and Jason L Shoe, "A
molecular timescale of eukaryote
evolution and the rise of complex
multicellular life", BMC Evolutionary
Biology 2004, 4:2
doi:10.1186/1471-2148-4-2, (2004).
2. ^ Richard
Dawkins, "The Ancestor's Tale",
(Boston, MA: Houghton Mifflin Company,
2004). (1600mybn)
3. ^ Sandra L. Baldauf, A. J.
Roger, I. Wenk-Siefert, W. F.
Doolittle, "A Kingdom-Level Phylogeny
of Eukaryotes Based on Combined Protein
Data", Science, Vol 290, num 5493, p
972, (2000). has heterkonts before
ciliophora and apicomplexa branch
[1] Fig. 1. A consensus phylogeny of
eukaryotes. The vast majority of
characterized eukaryotes, with the
notable exception of major subgroups of
amoebae, can now be assigned to one of
eight major groups. Opisthokonts (basal
flagellum) have a single basal
flagellum on reproductive cells and
flat mitochondrial cristae (most
eukaryotes have tubular ones).
Eukaryotic photosynthesis originated in
Plants; theirs are the only plastids
with just two outer membranes.
Heterokonts (different flagellae) have
a unique flagellum decorated with
hollow tripartite hairs (stramenopiles)
and, usually, a second plain one.
Cercozoans are amoebae with filose
pseudopodia, often living with in tests
(hard outer shells), some very
elaborate (foraminiferans). Amoebozoa
are mostly naked amoebae (lacking
tests), often with lobose pseudopodia
for at least part of their life cycle.
Alveolates have systems of cortical
alveoli directly beneath their plasma
membranes. Discicristates have discoid
mitochondrial cristae and, in some
cases, a deep (excavated) ventral
feeding groove. Amitochondrial
excavates lack substantial molecular
phylogenetic support, but most have an
excavated ventral feeding groove, and
all lack mitochondria. The tree shown
is based on a consensus of molecular
(1-4) and ultrastructural (16, 17) data
and includes a rough indication of new
ciPCR ''taxa'' (broken black lines)
(7-11). An asterisk preceding the taxon
name indicates probable paraphyletic
group COPYRIGHTED
source: http://www.sciencemag.org/cgi/co
ntent/full/300/5626/1703
[2] Figure 1. Phylogenetic hypothesis
of the eukaryotic lineage based on
ultrastructural and molecular data.
Organisms are divided into three main
groups distinguished by mitochondrial
cristal shape (either discoidal,
flattened or tubular). Unbroken lines
indicate phylogenetic relationships
that are firmly supported by available
data; broken lines indicate
uncertainties in phylogenetic
placement, resolution of which will
require additional data. Color coding
of organismal genus names indicates
mitochondrial genomes that have been
completely (Table 1), almost completely
(Jakoba, Naegleria and
Thraustochytrium) or partially (*)
sequenced by the OGMP (red), the FMGP
(black) or other groups (green). Names
in blue indicate those species whose
mtDNAs are currently being sequenced by
the OGMP or are future candidates for
complete sequencing. Amitochondriate
retortamonads are positioned at the
base of the tree, with broken arrows
denoting the endosymbiotic origin(s) of
mitochondria from a Rickettsia-like
eubacterium. Macrophar.,
Macropharyngomonas. COPYRIGHTED
source: http://nar.oxfordjournals.org/cg
i/content/full/26/4/865
6 7 8
Algae (Phaeophyta) evolves now.1 2 3
Brown Algae is the most genetically
ancient multicellular organism still
living on earth. In addition to being
first to evolve multicellularity, cell
differentiation (cells of different
types) is already present in all brown
algae.
Genetic comparison shows the ancestor
of the Chromalveolate Heterokont Brown
Algae (Phaeophyta) evolving now.
Brown Algae is the most genetically
ancient multicellular organism still
living on earth. In addition to being
first to evolve multicellularity, cell
differentiation (cells of different
types) is already present in all brown
algae.
Brown algae belong to a large group
called the heterokonts, most of which
are colored flagellates. Most contain
the pigment fucoxanthin, which is
responsible for the distinctive
greenish-brown color that gives brown
algae their name. Brown algae are
unique among heterokonts in developing
into multicellular forms with
differentiated tissues, but they
reproduce by means of flagellate
spores, which closely resemble other
heterokont cells. Genetic studies show
their closest relatives are the
yellow-green algae. 4
Most Brown algae are haplodiplontic.
KINGDOM Protista
(Chromalveolata)
PHYLUM Heterokontophyta
Colored groups
CLASS Phaeophyceae
(brown algae)
Some people view brown algae as being
in the plant kingdom, and others as
being a multicellular protist in the
protist kingdom.
2. Brown algae range from small
forms with simple filaments to large
multicellular (50-100 m long) seaweeds.
(Fig. 30.8)
3. Brown algae have
chlorophylls a and c and a fucoxanthin
that give them their color.
4. Their
reserve food is a carbohydrate called
laminarin.
5. Seaweed refers to any large,
complex alga.
6. Their cell walls
contain a mucilaginous water-retaining
material that inhibits desiccation.
7.
Laminaria is an intertidal kelp that is
unique among protists; this genus shows
tissue differentiation.
8. Nereocystis and
Macrocystis are giant kelps found in
deeper water anchored to the bottom by
their holdfasts.
9. Individuals of the
genus Sargassum sometimes break off
from their holdfasts and form floating
masses.
10. Brown algae provide food
and habitat for marine organisms, and
they are also important to humans.
a. Brown algae are harvested for human
food and for fertilizer in several
parts of the world.
b. They are a
source of algin, a pectin-like
substance added to give foods a stable,
smooth consistency.
11. Most have an
alternation of generations life cycle.
12. Fucus is an intertidal rockweed;
meiotic cell division produces gametes
and adult is always diploid. 5
FOOTNOTES
1. ^ S Blair Hedges, Jaime E Blair,
Maria L Venturi and Jason L Shoe, "A
molecular timescale of eukaryote
evolution and the rise of complex
multicellular life", BMC Evolutionary
Biology 2004, 4:2
doi:10.1186/1471-2148-4-2, (2004).
2. ^ Richard
Dawkins, "The Ancestor's Tale",
(Boston, MA: Houghton Mifflin Company,
2004).
3. ^ Sandra L. Baldauf, A. J. Roger, I.
Wenk-Siefert, W. F. Doolittle, "A
Kingdom-Level Phylogeny of Eukaryotes
Based on Combined Protein Data",
Science, Vol 290, num 5493, p 972,
(2000). has heterkonts before
ciliophora and apicomplexa branch
4. ^
"Phaeophyta". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Phaeophyta
5. ^
http://www.sirinet.net/~jgjohnso/apbio30
.html
6. ^ S Blair Hedges, Jaime E Blair,
Maria L Venturi and Jason L Shoe, "A
molecular timescale of eukaryote
evolution and the rise of complex
multicellular life", BMC Evolutionary
Biology 2004, 4:2
doi:10.1186/1471-2148-4-2, (2004).
(1973mybn)
7. ^ Richard Dawkins, "The Ancestor's
Tale", (Boston, MA: Houghton Mifflin
Company, 2004). (1600mybn)
8. ^ Sandra L. Baldauf,
A. J. Roger, I. Wenk-Siefert, W. F.
Doolittle, "A Kingdom-Level Phylogeny
of Eukaryotes Based on Combined Protein
Data", Science, Vol 290, num 5493, p
972, (2000). has heterkonts before
ciliophora and apicomplexa branch
[1] Fig. 1. A consensus phylogeny of
eukaryotes. The vast majority of
characterized eukaryotes, with the
notable exception of major subgroups of
amoebae, can now be assigned to one of
eight major groups. Opisthokonts (basal
flagellum) have a single basal
flagellum on reproductive cells and
flat mitochondrial cristae (most
eukaryotes have tubular ones).
Eukaryotic photosynthesis originated in
Plants; theirs are the only plastids
with just two outer membranes.
Heterokonts (different flagellae) have
a unique flagellum decorated with
hollow tripartite hairs (stramenopiles)
and, usually, a second plain one.
Cercozoans are amoebae with filose
pseudopodia, often living with in tests
(hard outer shells), some very
elaborate (foraminiferans). Amoebozoa
are mostly naked amoebae (lacking
tests), often with lobose pseudopodia
for at least part of their life cycle.
Alveolates have systems of cortical
alveoli directly beneath their plasma
membranes. Discicristates have discoid
mitochondrial cristae and, in some
cases, a deep (excavated) ventral
feeding groove. Amitochondrial
excavates lack substantial molecular
phylogenetic support, but most have an
excavated ventral feeding groove, and
all lack mitochondria. The tree shown
is based on a consensus of molecular
(1-4) and ultrastructural (16, 17) data
and includes a rough indication of new
ciPCR ''taxa'' (broken black lines)
(7-11). An asterisk preceding the taxon
name indicates probable paraphyletic
group COPYRIGHTED
source: http://www.sciencemag.org/cgi/co
ntent/full/300/5626/1703
[2] Figure 1. Phylogenetic hypothesis
of the eukaryotic lineage based on
ultrastructural and molecular data.
Organisms are divided into three main
groups distinguished by mitochondrial
cristal shape (either discoidal,
flattened or tubular). Unbroken lines
indicate phylogenetic relationships
that are firmly supported by available
data; broken lines indicate
uncertainties in phylogenetic
placement, resolution of which will
require additional data. Color coding
of organismal genus names indicates
mitochondrial genomes that have been
completely (Table 1), almost completely
(Jakoba, Naegleria and
Thraustochytrium) or partially (*)
sequenced by the OGMP (red), the FMGP
(black) or other groups (green). Names
in blue indicate those species whose
mtDNAs are currently being sequenced by
the OGMP or are future candidates for
complete sequencing. Amitochondriate
retortamonads are positioned at the
base of the tree, with broken arrows
denoting the endosymbiotic origin(s) of
mitochondria from a Rickettsia-like
eubacterium. Macrophar.,
Macropharyngomonas. COPYRIGHTED
source: http://nar.oxfordjournals.org/cg
i/content/full/26/4/865
21 22 23
evolve.1 2 3
Genetic comparison shows
the ancestor of the Chromalveolate
Heterokont Diatoms evolving now.
Diatoms are diplontic. 4
Diatoms are a very common types of
phytoplankton. Most diatoms are
unicellular, although some form chains
or simple colonies. A characteristic
feature of diatom cells is that they
are encased within a unique cell wall
made of silica. These walls show a wide
diversity in form, some quite beautiful
and ornate, but usually consist of two
symmetrical sides with a split between
them, hence the group name. 5
Life Cycle
When a cell divides each new cell
takes as its epitheca a valve of the
parent frustule, and within ten to
twenty minutes builds its own
hypotheca; this process may occur
between one and eight times per day.
Availability of dissolved silica limits
the rate of vegetative reproduction,
but also because this method
progressively reduces the average size
of the diatom frustule in a given
population there is a certain threshold
at which restoration of frustule size
is neccesary. Auxospores are then
produced, which are cells that posses a
different wall structure lacking the
siliceous frustule and swell to the
maximum frustule size. The auxospore
then forms an initial cell which forms
a new frustule of maximum size within
itself. 6
KINGDOM Protista
(Chromalveolata)
PHYLUM Heterokontophyta
Colored groups
CLASS
Bacillariophyceae (diatoms)
There are more than 200 genera of
living diatoms, and it is estimated
that there are approximately 100 000
extant species (Round & Crawford,
1990). Diatoms are a widespread group
and can be found in the oceans, in
freshwater, in soils and on damp
surfaces. 7
Their chloroplasts are typical of
heterokonts, with four membranes and
containing pigments such as
fucoxanthin. Individuals usually lack
flagella, but they are present in
gametes and have the usual heterokont
structure, except they lack the hairs
(mastigonemes) characteristic in other
groups. 8
Most diatom species are non-motile but
some are capable of an oozing motion.
As their relatively dense cell walls
cause them to readily sink, planktonic
forms in open water usually rely on
turbulent mixing of the upper layers by
the wind to keep them suspended in
sunlit surface waters. Some species
actively regulate their buoyancy to
counter sinking. 9
Diatoms cells are contained within a
unique silicate (silicic acid) cell
wall comprised of two separate valves
(or shells). The biogenic silica that
the cell wall is composed of is
synthesised intracellularly by the
polymerisation of silicic acid
monomers. This material is then
extruded to the cell exterior and added
to the wall. Diatom cell walls are also
called frustules or tests, and their
two valves typically overlap one other
like the two halves of a petri dish. In
most species, when a diatom divides to
produce two daughter cells, each cell
keeps one of the two valves and grows a
smaller valve within it. As a result,
after each division cycle the average
size of diatom cells in the population
gets smaller. Once such cells reach a
certain minimum size, rather than
simply divide vegetatively, they
reverse this decline by forming an
auxospore. This expands in size to give
rise to a much larger cell, which then
returns to size-diminishing divisions.
Auxospore production is almost always
linked to meiosis and sexual
reproduction. 10
Diatoms are traditionally divided into
two orders: centric diatoms
(Centrales), which are radially
symmetric, and pennate diatoms
(Pennales), which are bilaterally
symmetric. The former are paraphyletic
to the latter. A more recent
classification is that of Round &
Crawford (1990), who divide the diatoms
into three classes: centric diatoms
(Coscinodiscophyceae), pennate diatoms
without a raphe (Fragilariophyceae),
and pennate diatoms with a raphe
(Bacillariophyceae). It is probable
there will be further revisions as our
understanding of their relationships
increases. 11
Planktonic forms in freshwater and
marine environments typically exhibit a
"bloom and bust" lifestyle. When
conditions in the upper mixed layer
(nutrients and light) are favourable
(e.g. at the start of spring) their
competitive edge (Furnas, 1990) allows
them to quickly dominate phytoplankton
communities ("bloom"). 12
When conditions turn unfavourable,
usually upon depletion of nutrients,
diatom cells typically increase in
sinking rate and exit the upper mixed
layer ("bust"). This sinking is induced
by either a loss of buoyancy control,
the synthesis of mucilage that sticks
diatoms cells together, or the
production of heavy resting spores.13
In the open ocean, the condition that
typically causes diatom (spring) blooms
to end is a lack of silicon. Unlike
other nutrients, this is only a major
requirement of diatoms so it is not
regenerated in the plankton ecosystem
as efficiently as, for instance,
nitrogen or phosphorus nutrients. This
can be seen in maps of surface nutrient
concentrations - as nutrients decline
along gradients, silicon is usually the
first to be exhausted (followed
normally by nitrogen then
phosphorus).14
Heterokont chloroplasts appear to be
derived from those of red algae, rather
than directly from prokaryotes as
occurs in plants. This suggests they
had a more recent origin than many
other algae. However, fossil evidence
is scant, and it is really only with
the evolution of the diatoms themselves
that the heterokonts make a serious
impression on the fossil record. 15
The earliest known fossil diatoms date
from the early Jurassic (~185 Ma;
Kooistra & Medlin, 1996), although
recent genetic (Kooistra & Medlin,
1996) and sedimentary (Schieber,
Krinsley & Riciputi, 2000) evidence
suggests an earlier origin. Medlin et
al. (1997) suggest that their origin
may be related to the end-Permian mass
extinction (~250 Ma), after which many
marine niches were opened. The gap
between this event and the time that
fossil diatoms first appear may
indicate a period when diatoms were
unsilicified and their evolution was
cryptic (Raven & Waite, 2004). Since
the advent of silicification, diatoms
have made a significant impression on
the fossil record, with major deposits
of fossil diatoms found as far back as
the early Cretaceous, and some rocks
(diatomaceous earth, diatomite,
kieselguhr) being composed almost
entirely of them. 16
Although the
diatoms may have existed since the
Triassic, the timing of their
ascendancy and "take-over" of the
silicon cycle is more recent. 17
3. Diatoms are the most numerous
unicellular algae in the oceans. (Fig.
30.6a)
4. They are extremely numerous
and an important source of food and O2
in aquatic systems.
5. Diatom cell walls
consist of two silica-impregnated
halves or valves.
a. When diatoms
reproduce asexually, each received one
old valve.
b. The new valve fits
inside the old one; therefore, the new
diatom is smaller than the original
one.
c. This continues until
they are about 30 percent of their
original size.
d. Then they
reproduce sexually; a zygote grows and
divides mitotically to form diatoms of
normal size.
6. The cell wall has an
outer layer of silica (glass) with a
variety of markings formed by pores.
7. Diatom remains accumulate on the
ocean floor and are mined as
diatomaceous earth for use as filters,
abrasives, etc. 18
Life Cycle (cont.)
Many neritic planktonic
diatoms alternate between a vegetative
reproductive phase and a thicker walled
resting cyst or statospore stage. The
siliceous resting spore commonly forms
after a period of active vegetative
reproduction when nutrient levels have
been depleted. Statospores may remain
entirely within the the parent cell,
partially within the parent cell or be
isolated from it. An increase in
nutreint levels and/or length of
daylight cause the statospore to
germinate and return to its normal
vegatative state. Seasonal upwelling is
therefore a vital part of many diatoms
life cycle as a provider of nutrients
and as a transport mechanism which
brings statospores or their vegetative
products up into the photic zone.19
The
resting spore morphology of some
species is similar to that of the
corresponding vegetative cell, whereas
in other species the resting spores and
the vegetative cells differ strongly.
The two valves of a resting spore may
be similar or distinctly different.
Often the first valve formed is more
similar to the valves of the vegetative
cells than the second valve. 20
FOOTNOTES
1. ^ S Blair Hedges, Jaime E Blair,
Maria L Venturi and Jason L Shoe, "A
molecular timescale of eukaryote
evolution and the rise of complex
multicellular life", BMC Evolutionary
Biology 2004, 4:2
doi:10.1186/1471-2148-4-2, (2004).
2. ^ Richard
Dawkins, "The Ancestor's Tale",
(Boston, MA: Houghton Mifflin Company,
2004).
3. ^ Sandra L. Baldauf, A. J. Roger, I.
Wenk-Siefert, W. F. Doolittle, "A
Kingdom-Level Phylogeny of Eukaryotes
Based on Combined Protein Data",
Science, Vol 290, num 5493, p 972,
(2000). has heterkonts before
ciliophora and apicomplexa branch
4. ^ Michael
Sleigh, "Protozoa and Other Protists",
(London; New York: Edward Arnold,
1989). p98-99
5. ^ "Diatom". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Diatom
6. ^
http://www.ucl.ac.uk/GeolSci/micropal/di
atom.html
7. ^ "Diatom". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Diatom
8. ^ "Diatom". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Diatom
9. ^ "Diatom". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Diatom
10. ^ "Diatom". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Diatom
11. ^ "Diatom". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Diatom
12. ^ "Diatom". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Diatom
13. ^ "Diatom". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Diatom
14. ^ "Diatom". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Diatom
15. ^ "Diatom". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Diatom
16. ^ "Diatom". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Diatom
17. ^ "Diatom". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Diatom
18. ^
http://www.sirinet.net/~jgjohnso/apbio30
.html
19. ^
http://www.ucl.ac.uk/GeolSci/micropal/di
atom.html
20. ^
http://www.ucl.ac.uk/GeolSci/micropal/di
atom.html
21. ^ S Blair Hedges, Jaime E Blair,
Maria L Venturi and Jason L Shoe, "A
molecular timescale of eukaryote
evolution and the rise of complex
multicellular life", BMC Evolutionary
Biology 2004, 4:2
doi:10.1186/1471-2148-4-2, (2004).
(1973mybn)
22. ^ Richard Dawkins, "The Ancestor's
Tale", (Boston, MA: Houghton Mifflin
Company, 2004). (1600mybn)
23. ^ Sandra L.
Baldauf, A. J. Roger, I. Wenk-Siefert,
W. F. Doolittle, "A Kingdom-Level
Phylogeny of Eukaryotes Based on
Combined Protein Data", Science, Vol
290, num 5493, p 972, (2000). has
heterkonts before ciliophora and
apicomplexa branch
[1] Fig. 1. A consensus phylogeny of
eukaryotes. The vast majority of
characterized eukaryotes, with the
notable exception of major subgroups of
amoebae, can now be assigned to one of
eight major groups. Opisthokonts (basal
flagellum) have a single basal
flagellum on reproductive cells and
flat mitochondrial cristae (most
eukaryotes have tubular ones).
Eukaryotic photosynthesis originated in
Plants; theirs are the only plastids
with just two outer membranes.
Heterokonts (different flagellae) have
a unique flagellum decorated with
hollow tripartite hairs (stramenopiles)
and, usually, a second plain one.
Cercozoans are amoebae with filose
pseudopodia, often living with in tests
(hard outer shells), some very
elaborate (foraminiferans). Amoebozoa
are mostly naked amoebae (lacking
tests), often with lobose pseudopodia
for at least part of their life cycle.
Alveolates have systems of cortical
alveoli directly beneath their plasma
membranes. Discicristates have discoid
mitochondrial cristae and, in some
cases, a deep (excavated) ventral
feeding groove. Amitochondrial
excavates lack substantial molecular
phylogenetic support, but most have an
excavated ventral feeding groove, and
all lack mitochondria. The tree shown
is based on a consensus of molecular
(1-4) and ultrastructural (16, 17) data
and includes a rough indication of new
ciPCR ''taxa'' (broken black lines)
(7-11). An asterisk preceding the taxon
name indicates probable paraphyletic
group COPYRIGHTED
source: http://www.sciencemag.org/cgi/co
ntent/full/300/5626/1703
[2] Figure 1. Phylogenetic hypothesis
of the eukaryotic lineage based on
ultrastructural and molecular data.
Organisms are divided into three main
groups distinguished by mitochondrial
cristal shape (either discoidal,
flattened or tubular). Unbroken lines
indicate phylogenetic relationships
that are firmly supported by available
data; broken lines indicate
uncertainties in phylogenetic
placement, resolution of which will
require additional data. Color coding
of organismal genus names indicates
mitochondrial genomes that have been
completely (Table 1), almost completely
(Jakoba, Naegleria and
Thraustochytrium) or partially (*)
sequenced by the OGMP (red), the FMGP
(black) or other groups (green). Names
in blue indicate those species whose
mtDNAs are currently being sequenced by
the OGMP or are future candidates for
complete sequencing. Amitochondriate
retortamonads are positioned at the
base of the tree, with broken arrows
denoting the endosymbiotic origin(s) of
mitochondria from a Rickettsia-like
eubacterium. Macrophar.,
Macropharyngomonas. COPYRIGHTED
source: http://nar.oxfordjournals.org/cg
i/content/full/26/4/865
23 24 25
molds (Oomycetes OemISETEZ) evolve.1 2
3
Genetic comparison shows the
ancestor of the Chromalveolate
Heterokont Water molds (Oomycetes
OemISETEZ) evolving now.
Oomycetes (Water molds), with about 580
species, vary from unicellular, to
multicellular highly brached
filamentous forms. 4 The filamentous
form is called "coenocytic" (grows as a
large multinucleate cell that results
from multiple nuclear divisions without
cell divisions, also called "mycelium"
in fungi) 5 6 Oomycetes grow by
closed (or nearly closed) mitosis with
pairs of centrioles near the poles 7 .
Filamentous forms grow by mitosis, but
only the nucleus is duplicated
(karyokinesis), no septa (horizontal
cell wall) is constructed, making these
multinucleate very large single cells.
Technically, filamentous oomycetes are
3 celled multicellular organisms
because a septa forms between the
vegetative filament and the diploid
sporangium (and oogonium) cells (and
the haploid antheridium multinucleate
cells are not free swimming), but many
people label oomycetes as single celled
organism. But it appears clear that
oomycetes would be constructed of many
cells if a cell wall was built at
mitosis. Sexual forms are diploid and
reproduce by conjugation.
Water Molds are microscopic organisms
that reproduce both sexually and
asexually and are composed of mycelia,
or a tube-like vegetative body (all of
an organism's mycelia are called its
thallus). The name "water mould" refers
to the fact that they thrive under
conditions of high humidity and running
surface water. 8
Water molds were originally classified
as fungi, but are now known to have
developed separately and show a number
of differences. Their cell walls are
composed of cellulose rather than
chitin and lack septa (a wall that
divides two spaces) except where
reproductive cells are produced, in
addition to having gene sequences more
closely related to brown algae than
fungi.9 Also, in the vegetative state
they have diploid nuclei, whereas fungi
have haploid nuclei. 10 11
The oomycetes include the water molds,
white rusts and the downy mildews. Many
oomycetes are multinucleate filaments
(hyphae) that resemble fungi. These
hyphae have no cross walls, but are one
long hollow tube and are called
"coenocytic". They were once thought to
be related to the fungi, but their cell
walls are made of cellulose, not chitin
as they are in the true fungi. The
superficial resemblance of the fungi
and the oomycetes is likely a case of
convergent evolution. Both groups have
a filamentous (hyphal) body form with a
high surface area to volume ration
which facilitates uptake of nutrients
from their surroundings. 12
The oomycetes are saprobic and
parasitic forms, including water molds
like Saprolegnia and downey mildews
like Peronospora. 13
1. These organisms (and slime
molds) resemble fungi but all have
flagellated cells which fungi never
do.
2. Water molds possess a cell
wall but it is made of cellulose, not
chitin as in fungi.
3. Water molds
produce diploid (2n) zoospores and
meiosis produces the gametes. 14
2. Aquatic water molds
parasitize fishes, forming furry
growths on their gills, and decompose
remains.
3. Terrestrial water molds
parasitize insects and plants; a water
mold caused the 1840s Irish potato
famine.
4. Water molds have a
filamentous body but cell walls are
composed largely of cellulose.
5. During
asexual reproduction, they produce
diploid motile spores (2n zoospores)
with flagella.
6. Unlike fungi, the adult
is diploid; gametes are produced by
meiosis.
7. Eggs are produced in
enlarged oogonia. 15
KINGDOM Protista
(Chromalveolata)
PHYLUM Heterokontophyta
Colorless groups
CLASS Oomycetes
(water moulds)
Oomycetes have mitochondria with
tubular christae. 16
Water mould motile cells are produced
as asexual spores called zoospores,
which capitalize on surface water
(including precipitation on plant
surfaces) for movement. The Zoospores
have 2 unequal anterior (apical)
flagella. They also produce sexual
spores, called oospores, that are
translucent double-walled spherical
structures used to survive adverse
environmental conditions. 17
The water molds are among the most
important plant pathogenic (capable of
causing disease) organisms that may be
facultatively or obligately parasitic.
The majority can be divided into three
groups, although more exist. 18 19
* The Phytophthora group is a genus
that causes diseases such as dieback,
potato blight (caused the potato famine
in Ireland), sudden oak death and
rhododendron root rot. 20
* The Pythium group is a genus that
is more ubiquitous than Phytophythora
and individual species have larger host
ranges, usually causing less damage.
Pythium damping off is a very common
problem in greenhouses where the
organism kills newly emerged seedlings.
Mycoparasitic members of this group
(e.g. P. oligandrum) parasitise other
oomycetes and fungi and have been
employed as biocontrol agents . One
Pythium species, Pythium insidiosum is
also known to infect mammals. 21
* The third group are the downy
mildews, which are easily identifable
by the appearance of white "mildew" on
leaf surfaces (although this group can
be confused with the unrelated powdery
mildews). 22
A male nuclei from a multinucleate
haploid cell is transfered to into the
haploid egg cell; the male gamete is
not free moving, only the female
gametes are although contained within
the oogonium.
FOOTNOTES
1. ^ S Blair Hedges, Jaime E Blair,
Maria L Venturi and Jason L Shoe, "A
molecular timescale of eukaryote
evolution and the rise of complex
multicellular life", BMC Evolutionary
Biology 2004, 4:2
doi:10.1186/1471-2148-4-2, (2004).
2. ^ Richard
Dawkins, "The Ancestor's Tale",
(Boston, MA: Houghton Mifflin Company,
2004).
3. ^ Sandra L. Baldauf, A. J. Roger, I.
Wenk-Siefert, W. F. Doolittle, "A
Kingdom-Level Phylogeny of Eukaryotes
Based on Combined Protein Data",
Science, Vol 290, num 5493, p 972,
(2000). has heterkonts before
ciliophora and apicomplexa branch
4. ^ Raven,
Evert, Eichhorn, "Biology of Plants",
(New York: Worth Publishers, 1992).
5. ^
http://www.ilmyco.gen.chicago.il.us/Term
s/coeno128.html#coeno128
6. ^ "Coenocyte". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Coenocyte
7. ^ Michael Sleigh, "Protozoa and
Other Protists", (London; New York:
Edward Arnold, 1989).
8. ^ "Water moulds".
Wikipedia. Wikipedia, 2008.
http://en.wikipedia.org/wiki/Water_mould
s
9. ^
http://users.rcn.com/jkimball.ma.ultrane
t/BiologyPages/P/Protists.html#Water_Mol
ds
10. ^ "Water moulds". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Water_mould
s
11. ^
http://www.plantbio.uga.edu/zoosporicfun
gi/oomycete.htm
12. ^
http://kentsimmons.uwinnipeg.ca/16cm05/1
116/16protists.htm
13. ^ Michael Sleigh, "Protozoa and
Other Protists", (London; New York:
Edward Arnold, 1989).
14. ^
http://www.sirinet.net/~jgjohnso/apbio30
.html
15. ^
http://www.sirinet.net/~jgjohnso/apbio30
.html
16. ^
http://microscope.mbl.edu/scripts/protis
t.php?func=integrate&myID=P2734&chinese_
flag=&system=&version=&documentID=&exclu
deNonLinkedIn=&imagesOnly=
17. ^ "Water moulds". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Water_mould
s
18. ^ "Water moulds". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Water_mould
s
19. ^
http://www.plantbio.uga.edu/zoosporicfun
gi/oomycete.htm
20. ^ "Water moulds". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Water_mould
s
21. ^ "Water moulds". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Water_mould
s
22. ^ "Water moulds". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Water_mould
s
23. ^ S Blair Hedges, Jaime E Blair,
Maria L Venturi and Jason L Shoe, "A
molecular timescale of eukaryote
evolution and the rise of complex
multicellular life", BMC Evolutionary
Biology 2004, 4:2
doi:10.1186/1471-2148-4-2, (2004).
(1973mybn)
24. ^ Richard Dawkins, "The Ancestor's
Tale", (Boston, MA: Houghton Mifflin
Company, 2004). (1600mybn)
25. ^ Sandra L.
Baldauf, A. J. Roger, I. Wenk-Siefert,
W. F. Doolittle, "A Kingdom-Level
Phylogeny of Eukaryotes Based on
Combined Protein Data", Science, Vol
290, num 5493, p 972, (2000). has
heterkonts before ciliophora and
apicomplexa branch
[1] Fig. 1. A consensus phylogeny of
eukaryotes. The vast majority of
characterized eukaryotes, with the
notable exception of major subgroups of
amoebae, can now be assigned to one of
eight major groups. Opisthokonts (basal
flagellum) have a single basal
flagellum on reproductive cells and
flat mitochondrial cristae (most
eukaryotes have tubular ones).
Eukaryotic photosynthesis originated in
Plants; theirs are the only plastids
with just two outer membranes.
Heterokonts (different flagellae) have
a unique flagellum decorated with
hollow tripartite hairs (stramenopiles)
and, usually, a second plain one.
Cercozoans are amoebae with filose
pseudopodia, often living with in tests
(hard outer shells), some very
elaborate (foraminiferans). Amoebozoa
are mostly naked amoebae (lacking
tests), often with lobose pseudopodia
for at least part of their life cycle.
Alveolates have systems of cortical
alveoli directly beneath their plasma
membranes. Discicristates have discoid
mitochondrial cristae and, in some
cases, a deep (excavated) ventral
feeding groove. Amitochondrial
excavates lack substantial molecular
phylogenetic support, but most have an
excavated ventral feeding groove, and
all lack mitochondria. The tree shown
is based on a consensus of molecular
(1-4) and ultrastructural (16, 17) data
and includes a rough indication of new
ciPCR ''taxa'' (broken black lines)
(7-11). An asterisk preceding the taxon
name indicates probable paraphyletic
group COPYRIGHTED
source: http://www.sciencemag.org/cgi/co
ntent/full/300/5626/1703
[2] Figure 1. Phylogenetic hypothesis
of the eukaryotic lineage based on
ultrastructural and molecular data.
Organisms are divided into three main
groups distinguished by mitochondrial
cristal shape (either discoidal,
flattened or tubular). Unbroken lines
indicate phylogenetic relationships
that are firmly supported by available
data; broken lines indicate
uncertainties in phylogenetic
placement, resolution of which will
require additional data. Color coding
of organismal genus names indicates
mitochondrial genomes that have been
completely (Table 1), almost completely
(Jakoba, Naegleria and
Thraustochytrium) or partially (*)
sequenced by the OGMP (red), the FMGP
(black) or other groups (green). Names
in blue indicate those species whose
mtDNAs are currently being sequenced by
the OGMP or are future candidates for
complete sequencing. Amitochondriate
retortamonads are positioned at the
base of the tree, with broken arrows
denoting the endosymbiotic origin(s) of
mitochondria from a Rickettsia-like
eubacterium. Macrophar.,
Macropharyngomonas. COPYRIGHTED
source: http://nar.oxfordjournals.org/cg
i/content/full/26/4/865
1 2 3
(Ciliates, Dinoflagellates,
Apicomplexans) evolve.1 2 3
Genetic
comparison shows the ancestor of the
Chromalveolate Alveolata (Ciliates,
Dinoflagellates, Apicomplexans)
evolving now.
The alveolates are a major line of
protists. There are three main groups,
which are very divergent in form, but
are now known to be close relatives
based on various ultrastructural and
genetic similarities:
Ciliates Very common protozoa,
with many short cilia arranged in rows
Apicom
plexa Parasitic protozoa that lack
locomotive structures except in
gametes
Dinoflagellates Mostly marine
flagellates, many of which have
chloroplasts4
The most notable shared characteristic
is the presence of cortical alveoli,
flattened vesicles packed into a
continuous layer supporting the
membrane, typically forming a flexible
pellicle. In dinoflagellates they often
form armor plates. Alveolates have
mitochondria with tubular cristae, and
their flagella or cilia have a distinct
structure.5
The Apicomplexa and dinoflagellates may
be more closely related to each other
than to the ciliates. Both have
plastids, and most share a bundle or
cone of microtubules at the top of the
cell. In apicomplexans this forms part
of a complex used to enter host cells,
while in some colorless dinoflagellates
it forms a peduncle used to ingest
prey. 6
DOMAIN Eukaryota - eukaryotes
KINGDOM
Protozoa (Goldfuss, 1818) R. Owen, 1858
- protozoa
SUBKINGDOM Biciliata
INFRAKINGDOM
Alveolata Cavalier-Smith, 1991
PHYLUM Myzozoa Cavalier-Smith & Chao,
2004
PHYLUM Ciliophora (Doflein,
1901) Copeland, 1956 - ciliates
Relationships between some of these the
major groups were suggested during the
1980s, and between all three by
Cavalier-Smith, who introduced the
formal name Alveolata in 1991. They
were confirmed by a genetic study by
Gajadhar et al. Some studies suggested
the haplosporids, mostly parasites of
marine invertebrates, might belong here
but they lack alveoli and are now
placed among the Cercozoa.
The development of plastids among the
alveolates is uncertain. Cavalier-Smith
proposed the alveolates developed from
a chloroplast-containing ancestor,
which also gave rise to the Chromista
(the chromalveolate hypothesis).
However, as plastids only appear in
relatively advanced groups, others
argue the alveolates originally lacked
them and possibly the dinoflagellates
and Apicomplexa acquired them
separately.
FOOTNOTES
1. ^ S Blair Hedges, Jaime E Blair,
Maria L Venturi and Jason L Shoe, "A
molecular timescale of eukaryote
evolution and the rise of complex
multicellular life", BMC Evolutionary
Biology 2004, 4:2
doi:10.1186/1471-2148-4-2, (2004).
2. ^ Richard
Dawkins, "The Ancestor's Tale",
(Boston, MA: Houghton Mifflin Company,
2004). (1600mybn)
3. ^ Sandra L. Baldauf, A. J.
Roger, I. Wenk-Siefert, W. F.
Doolittle, "A Kingdom-Level Phylogeny
of Eukaryotes Based on Combined Protein
Data", Science, Vol 290, num 5493, p
972, (2000). has heterkonts before
ciliophora and apicomplexa branch
[1] Fig. 1. A consensus phylogeny of
eukaryotes. The vast majority of
characterized eukaryotes, with the
notable exception of major subgroups of
amoebae, can now be assigned to one of
eight major groups. Opisthokonts (basal
flagellum) have a single basal
flagellum on reproductive cells and
flat mitochondrial cristae (most
eukaryotes have tubular ones).
Eukaryotic photosynthesis originated in
Plants; theirs are the only plastids
with just two outer membranes.
Heterokonts (different flagellae) have
a unique flagellum decorated with
hollow tripartite hairs (stramenopiles)
and, usually, a second plain one.
Cercozoans are amoebae with filose
pseudopodia, often living with in tests
(hard outer shells), some very
elaborate (foraminiferans). Amoebozoa
are mostly naked amoebae (lacking
tests), often with lobose pseudopodia
for at least part of their life cycle.
Alveolates have systems of cortical
alveoli directly beneath their plasma
membranes. Discicristates have discoid
mitochondrial cristae and, in some
cases, a deep (excavated) ventral
feeding groove. Amitochondrial
excavates lack substantial molecular
phylogenetic support, but most have an
excavated ventral feeding groove, and
all lack mitochondria. The tree shown
is based on a consensus of molecular
(1-4) and ultrastructural (16, 17) data
and includes a rough indication of new
ciPCR ''taxa'' (broken black lines)
(7-11). An asterisk preceding the taxon
name indicates probable paraphyletic
group COPYRIGHTED
source: http://www.sciencemag.org/cgi/co
ntent/full/300/5626/1703
[2] Figure 1. Phylogenetic hypothesis
of the eukaryotic lineage based on
ultrastructural and molecular data.
Organisms are divided into three main
groups distinguished by mitochondrial
cristal shape (either discoidal,
flattened or tubular). Unbroken lines
indicate phylogenetic relationships
that are firmly supported by available
data; broken lines indicate
uncertainties in phylogenetic
placement, resolution of which will
require additional data. Color coding
of organismal genus names indicates
mitochondrial genomes that have been
completely (Table 1), almost completely
(Jakoba, Naegleria and
Thraustochytrium) or partially (*)
sequenced by the OGMP (red), the FMGP
(black) or other groups (green). Names
in blue indicate those species whose
mtDNAs are currently being sequenced by
the OGMP or are future candidates for
complete sequencing. Amitochondriate
retortamonads are positioned at the
base of the tree, with broken arrows
denoting the endosymbiotic origin(s) of
mitochondria from a Rickettsia-like
eubacterium. Macrophar.,
Macropharyngomonas. COPYRIGHTED
source: http://nar.oxfordjournals.org/cg
i/content/full/26/4/865
12 13 14
Genetic
comparison shows the ancestor of the
Chromalveolate Alveolata Ciliates
evolving now.
The ciliates are one of the most
important groups of protists, common
almost everywhere there is water -
lakes, ponds, oceans, and soils, with
many ecto- (lives on host) and
endosymbiotic (lives in host) members,
as well as some obligate (depends on
host for survival) and opportunistic
parasites (does not depend on host for
survival). Ciliates tend to be large
protists, a few reaching 2 mm in
length, and are some of the most
complex in structure. The name ciliate
comes from the presence of hair-like
organelles called cilia, which are
identical in structure to flagella but
typically shorter and present in much
larger numbers. Cilia occur in all
members of the group, although the
peculiar suctoria only have them for
part of the life-cycle, and are
variously used in swimming, crawling,
attachment, feeding, and sensation.4
Unlike other eukaryotes, ciliates have
two different sorts of nuclei: a small,
diploid micronucleus (reproduction),
and a large, polyploid macronucleus
(general cell regulation). The latter
is generated from the micronucleus by
amplification of the genome and heavy
editing. The high degree of polyploidi
allows the cell to sustain an
appropriate level of transcription.
Division of the macronucleus does not
occur by a mitotic process but
segregation of the chromosomes is by a
different process, whose mechanism is
unknown. This process is not perfect,
and after about 200 generations the
cell shows signs of aging (has so many
mutations that it does not function
properly). Periodically the macronuclei
is (must be?) regenerated from the
micronuclei. In most, this occurs
during sexual reproduction, which is
not usually through syngamy but through
conjugation. Here two cells line up,
the micronuclei undergo meiosis, some
of the haploid daughters are exchanged
and then fuse to form new micro- and
macronuclei.5
With a few exceptions, there is a
distinct cytostome or mouth where
ingestion takes place. Food vacuoles
are formed through phagocytosis and
typically follow a particular path
through the cell as their contents are
digested and broken down via lysosomes
so the substances the vacuole contains
are then small enough to diffuse
through the membrane of the food
vacuole into the cell. Anything left in
the food vacuole by the time it reaches
the cytoproct (anus) is discharged via
exocytosis. Most ciliates also have one
or more prominent contractile vacuoles,
which collect water and expel it from
the cell to maintain osmotic pressure,
or in some function to maintain ionic
balance. These often have a distinctive
star-shape, with each point being a
collecting tube.6
Most ciliates feed on smaller organisms
(heterotrophic), such as bacteria and
algae, and detritus swept into the
mouth by modified oral cilia. These
usually include a series of
membranelles to the left of the mouth
and a paroral membrane to its right,
both of which arise from polykinetids,
groups of many cilia together with
associated structures. This varies
considerably, however. Some ciliates
are mouthless and feed by absorption,
while others are predatory and feed on
other protozoa and in particular on
other ciliates. This includes the
suctoria, which feed through several
specialized tentacles.7
Ciliates and Amoeboids have in common:
Food is
digested in food vacuoles.
Excess water is
expelled by contractile vacuoles. 8
DOM
AIN Eukaryota - eukaryotes
KINGDOM Protozoa
(Goldfuss, 1818) R. Owen, 1858 -
protozoa
SUBKINGDOM Biciliata
INFRAKINGDOM
Alveolata Cavalier-Smith, 1991
PHYLUM Ciliophora (Doflein, 1901)
Copeland, 1956 - ciliates
CLASS
Karyorelictea
CLASS Heterotrichea
CLASS
Spirotrichea
CLASS Litostomatea
CLASS
Phyllopharyngea
CLASS Nassophorea
CLASS
Colpodea {possibly in phylum
percolozoa}
CLASS Prostomatea
CLASS
Oligohymenophorea
CLASS Plagiopylea
In some forms there are also body
polykinetids, for instance, among the
spirotrichs where they generally form
bristles called cirri. More often body
cilia are arranged in mono- and
dikinetids, which respectively include
one and two kinetosomes (basal bodies),
each of which may support a cilium.
These are arranged into rows called
kineties, which run from the anterior
to posterior of the cell. The body and
oral kinetids make up the
infraciliature, an organization unique
to the ciliates and important in their
classification, and include various
fibrils and microtubules involved in
coordinating the cilia.9
The infraciliature is one of the main
component of the cell cortex. Another
are the alveoli, small vesicles under
the cell membrane that are packed
against it to form a pellicle
maintaining the cell's shape, which
varies from flexible and contractile to
rigid. Numerous mitochondria and
extrusomes are also generally present.
The presence of alveoli, the structure
of the cilia, the form of mitosis and
various other details indicate a close
relationship between the ciliates,
Apicomplexa, and dinoflagellates. These
superficially dissimilar groups make up
the alveolates.10
Ciliates move by coordinated strokes of
hundreds of cilia projecting through
holes in a semirigid pellicle.
They discharge
long, barbed trichocysts for defense
and for capturing prey; toxicysts
release a poison.
Most are holozoic and ingest
food through a gullet and eliminate
wastes through an anal pore.
During asexual
reproduction, ciliates divide by
transverse binary fission.
Ciliates possess two
types of nuclei-a large macronucleus
and one or more small micronuclei.
a. The
macronucleus controls the normal
metabolism of the cell.
b. The
micronucleus are involved in sexual
reproduction.
1) The macronucleus disintegrates
and the micronucleus undergoes
meiosis.
2) Two ciliates then exchange a
haploid micronucleus.
3) The micronuclei give
rise to a new macronucleus containing
only housekeeping genes.
Ciliates are
diverse.
a. Members of the genus Paramecium
are complex. (Fig. 30.13b)
b. The
barrel-shaped didinia expand to consume
paramecia much larger than themselves.
c.
Suctoria rest on a stalk and paralyze
victims, sucking them dry.
d. Stentor
resembles a giant blue vase with
stripes. (Fig. 30.13a) 11
Could the 2 nuclei in ciliates be the
result of an earlier fusion (or
engulfing) of 2 prokaryotes?
FOOTNOTES
1. ^ S Blair Hedges, Jaime E Blair,
Maria L Venturi and Jason L Shoe, "A
molecular timescale of eukaryote
evolution and the rise of complex
multicellular life", BMC Evolutionary
Biology 2004, 4:2
doi:10.1186/1471-2148-4-2, (2004).
2. ^ Richard
Dawkins, "The Ancestor's Tale",
(Boston, MA: Houghton Mifflin Company,
2004).
3. ^ Sandra L. Baldauf, A. J. Roger, I.
Wenk-Siefert, W. F. Doolittle, "A
Kingdom-Level Phylogeny of Eukaryotes
Based on Combined Protein Data",
Science, Vol 290, num 5493, p 972,
(2000). has heterkonts before
ciliophora and apicomplexa branch
4. ^
"Ciliates". Wikipedia. Wikipedia, 2008.
http://en.wikipedia.org/wiki/Ciliates
5. ^ "Ciliates". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Ciliates
6. ^ "Ciliates". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Ciliates
7. ^ "Ciliates". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Ciliates
8. ^
http://www.sirinet.net/~jgjohnso/apbio30
.html
9. ^ "Ciliates". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Ciliates
10. ^ "Ciliates". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Ciliates
11. ^
http://www.sirinet.net/~jgjohnso/apbio30
.html
12. ^ S Blair Hedges, Jaime E Blair,
Maria L Venturi and Jason L Shoe, "A
molecular timescale of eukaryote
evolution and the rise of complex
multicellular life", BMC Evolutionary
Biology 2004, 4:2
doi:10.1186/1471-2148-4-2, (2004).
(1973mybn)
13. ^ Richard Dawkins, "The Ancestor's
Tale", (Boston, MA: Houghton Mifflin
Company, 2004). (1600mybn)
14. ^ Sandra L.
Baldauf, A. J. Roger, I. Wenk-Siefert,
W. F. Doolittle, "A Kingdom-Level
Phylogeny of Eukaryotes Based on
Combined Protein Data", Science, Vol
290, num 5493, p 972, (2000). has
heterkonts before ciliophora and
apicomplexa branch
[1] Fig. 1. A consensus phylogeny of
eukaryotes. The vast majority of
characterized eukaryotes, with the
notable exception of major subgroups of
amoebae, can now be assigned to one of
eight major groups. Opisthokonts (basal
flagellum) have a single basal
flagellum on reproductive cells and
flat mitochondrial cristae (most
eukaryotes have tubular ones).
Eukaryotic photosynthesis originated in
Plants; theirs are the only plastids
with just two outer membranes.
Heterokonts (different flagellae) have
a unique flagellum decorated with
hollow tripartite hairs (stramenopiles)
and, usually, a second plain one.
Cercozoans are amoebae with filose
pseudopodia, often living with in tests
(hard outer shells), some very
elaborate (foraminiferans). Amoebozoa
are mostly naked amoebae (lacking
tests), often with lobose pseudopodia
for at least part of their life cycle.
Alveolates have systems of cortical
alveoli directly beneath their plasma
membranes. Discicristates have discoid
mitochondrial cristae and, in some
cases, a deep (excavated) ventral
feeding groove. Amitochondrial
excavates lack substantial molecular
phylogenetic support, but most have an
excavated ventral feeding groove, and
all lack mitochondria. The tree shown
is based on a consensus of molecular
(1-4) and ultrastructural (16, 17) data
and includes a rough indication of new
ciPCR ''taxa'' (broken black lines)
(7-11). An asterisk preceding the taxon
name indicates probable paraphyletic
group COPYRIGHTED
source: http://www.sciencemag.org/cgi/co
ntent/full/300/5626/1703
[2] Figure 1. Phylogenetic hypothesis
of the eukaryotic lineage based on
ultrastructural and molecular data.
Organisms are divided into three main
groups distinguished by mitochondrial
cristal shape (either discoidal,
flattened or tubular). Unbroken lines
indicate phylogenetic relationships
that are firmly supported by available
data; broken lines indicate
uncertainties in phylogenetic
placement, resolution of which will
require additional data. Color coding
of organismal genus names indicates
mitochondrial genomes that have been
completely (Table 1), almost completely
(Jakoba, Naegleria and
Thraustochytrium) or partially (*)
sequenced by the OGMP (red), the FMGP
(black) or other groups (green). Names
in blue indicate those species whose
mtDNAs are currently being sequenced by
the OGMP or are future candidates for
complete sequencing. Amitochondriate
retortamonads are positioned at the
base of the tree, with broken arrows
denoting the endosymbiotic origin(s) of
mitochondria from a Rickettsia-like
eubacterium. Macrophar.,
Macropharyngomonas. COPYRIGHTED
source: http://nar.oxfordjournals.org/cg
i/content/full/26/4/865
50 51 52
Genet
ic Ribosomal RNA comparison shows
Chromalveolate Alveolata,
Dinoflagellates evolve.
Dinoflagellates
reproduce mainly by haploid mitosis,
but also reproduce sexually.
In dinoflagellates, the chromosomes are
always visible and do not condense
prior to mitosis. The chromosomes are
attached to the nuclear envelope, which
persists during mitosis. 4
The main method of reproduction of the
dinoflagellates is by longitudinal cell
division, with each daughter cell
receiving one of the flagella ad a
portion of the theca and then
constructing the missing parts in a
very intricate sequence. Some
nonmotile species form zoospores, which
may be colonial. A number of species
reproduce sexually, mostly by isogamy,
but a few species reproduce by
heterogamy (anisogamy). 5
Dinoflagellate zygotes are similar to
some acritarchs (early eukaryote
fossils). 6
Some Dinoflagellates produce cysts. 7
The dinoflagellates are a large group
of flagellate protists. Most are marine
plankton, but they are common in fresh
water habitats as well; their
populations are distributed depending
on temperate, saltiness, or depth.
About half of all dinoflagellates are
photosynthetic, and these make up the
largest group of eukaryotic algae aside
from the diatoms. Being primary
producers make them an important part
of the food chain. Some species, called
zooxanthellae, are endosymbionts of
marine animals and protozoa, and play
an important part in the biology of
coral reefs. Other dinoflagellates are
colorless predators on other protozoa,
and a few forms are parasitic. 8
Some dinoflagellates are reported to be
filamentous (multicellular). 9
Mitochond
ria christae are tubular. 10
Dinoflagel
lates are haploid (haplontic). 11
DOMA
IN Eukaryota - eukaryotes
KINGDOM Protozoa
(Goldfuss, 1818) R. Owen, 1858 -
protozoa
SUBKINGDOM Biciliata
INFRAKINGDOM
Alveolata Cavalier-Smith, 1991
PHYLUM Dinoflagellata Bütschli, 1885
CLASS Dinophyceae (Bütschli,
1885) Pascher, 1914
CLASS
Blastodiniophyceae Fensome et al.,
1993
CLASS Noctiluciphyceae
Fensome et al., 1993
CLASS
Syndiniophyceae Loeblich III, 1976 12
Most dinoflagellates are unicellular
forms with two dissimilar flagella. One
of these extends towards the posterior,
called the longitudinal flagellum,
while the other forms a lateral circle,
called the transverse flagellum. In
many forms these are set into grooves,
called the sulcus and cingulum. The
transverse flagellum provides most of
the force propelling the cell, and
often imparts to it a distinctive
whirling motion, which is what gives
the name dinoflagellate refers to
(Greek dinos, whirling). The
longitudinal acts mainly as the
steering wheel, but providing little
propulsive force as well. 13
Dinoflagellates have a complex cell
covering called an amphiesma, composed
of flattened vesicles, called alveoli.
In some forms, these support
overlapping cellulose plates that make
up a sort of armor called the theca.
These come in various shapes and
arrangements, depending on the species
and sometimes stage of the
dinoflagellate. Fibrous extrusomes are
also found in many forms. Together with
various other structural and genetic
details, this organization indicates a
close relationship between the
dinoflagellates, Apicomplexa, and
ciliates, collectively referred to as
the alveolates. 14
The chloroplasts in most photosynthetic
dinoflagellates are bound by three
membranes, suggesting they were
probably derived from some ingested
alga, and contain chlorophylls a and c
and fucoxanthin, as well as various
other accessory pigments. However, a
few have chloroplasts with different
pigmentation and structure, some of
which retain a nucleus. This suggests
that chloroplasts were incorporated by
several endosymbiotic events involving
already colored or secondarily
colorless forms. The discovery of
plastids in Apicomplexa have led some
to suggest they were inherited from an
ancestor common to the two groups, but
none of the more basal lines have them.
15
All the same, the dinoflagellate still
consists of the more common organelles
such as rough and smooth endoplasmic
reticulum, Golgi apparatus,
mitochondria, lipid and starch grains,
and food vacuoles. Some have even been
found with light sensitive organelle
such as the eyespot or a larger nucleus
containing a prominent nucleolus. 16
Life-cycle
Dinoflagellates have a peculiar form of
nucleus, called a dinokaryon, in which
the chromosomes are attached to the
nuclear membrane. These lack histones
and remained condensed throughout
interphase rather than just during
mitosis, which is closed and involves a
unique external spindle. This sort of
nucleus was once considered to be an
intermediate between the nucleoid
region of prokaryotes and the true
nuclei of eukaryotes, and so were
termed mesokaryotic, but now are
considered advanced rather than
primitive traits.17
In most dinoflagellates, the nucleus is
dinokaryotic throughout the entire life
cycle. They are usually haploid, and
reproduce primarily through fission,
but sexual reproduction also occurs.
This takes place by fusion of two
individuals to form a zygote, which may
remain mobile in typical dinoflagellate
fashion or may form a resting cyst,
which later undergoes meiosis to
produce new haploid cells.18
However, when the conditions become
desperate, usually starvation or no
light, their normal routines change
dramatically. Two dinoflagellates will
fuse together forming a planozygote.
Next is a stage not much different from
hibernation called hypnozygote when the
organism takes in excess fat and oil.
At the same time its shape is getting
fatter and the shell gets harder.
Sometimes even spikes are formed. When
the weathers allows it, these
dinoflagellates break out of their
shell and are in a temporary stage,
planomeiocyte, when they quickly
reforms their individual thecas and
return to the dinoflagellates at the
beginning of the process.19
Ecology and fossils
Dinoflagellates sometimes
bloom in concentrations of more than a
million cells per millilitre. Some
species produce neurotoxins, which in
such quantities kill fish and
accumulate in filter feeders such as
shellfish, which in turn may pass them
on to people who eat them. This
phenomenon is called a red tide, from
the color the bloom imparts to the
water. Some colorless dinoflagellates
may also form toxic blooms, such as
Pfiesteria. It should be noted that not
all dinoflagellate blooms are
dangerous. Bluish flickers visible in
ocean water at night often come from
blooms of bioluminescent
dinoflagellates, which emit short
flashes of light when disturbed.20
Dinoflagellate cysts are found as
microfossils from the Triassic period,
and form a major part of the
organic-walled marine microflora from
the middle Jurassic, through the
Cretaceous and Cenozoic to the present
day. Arpylorus, from the Silurian of
North Africa was at one time considered
to be a dinoflagellate cyst, but this
palynomorph is now considered to be
part of the microfauna. It is possible
that some of the Paleozoic acritarchs
also represent dinoflagellates.21
Chloroplast features: 22
Chloroplasts:
Brown 23
Mitochondria christae are
tubular. 24
Nuclear features: 25
Gamete type:
flagellated 26
Dinoflagellates are
haploid (haplontic). 27
has condensed
chromosomes. 28
Mitotic spindle:
external. 29
polar structures: none,
and centrioles 30
Flagellar features: 31
Number of
flagella: 2 32
Heterokont, isokont, or
anisokont: anisokont 33
shaft
features: paraxial rod, hairs 34
flagel
late stages: gamete, trophic, zoospore
35
trophic: (trophozoites) The
activated, feeding stage in the life
cycle of protozoan parasites. 36
A
protozoan, especially of the class
Sporozoa, in the active stage of its
life cycle. 37
The feeding stage of a
protozoan (as distinct from
reproductive or encysted stages). 38
zoo
spore: A zoospore is a motile asexual
spore utilizing a flagellum for
locomotion. Also called a swarm spore,
these spores are used by some algae and
fungi to propagate themselves.39
Golgi type: dictyosome 40
Food stores: 41
carbohydrate: alpha 1-4
glucan 42
fat=yes 43
extrusomes: tricocysts, nematocysts 44
eyespot type: cytoplasmic stigma, ? 45
Life Forms: 46
unicellular: flagellate,
amoeboid, coccoid 47
multicellular:
filementous 48
Cell covering: pellicle with plates. 49
FOOTNOTES
1. ^ Richard Dawkins, "The Ancestor's
Tale", (Boston, MA: Houghton Mifflin
Company, 2004).
2. ^ Sandra L. Baldauf, A. J.
Roger, I. Wenk-Siefert, W. F.
Doolittle, "A Kingdom-Level Phylogeny
of Eukaryotes Based on Combined Protein
Data", Science, Vol 290, num 5493, p
972, (2000). has heterkonts before
ciliophora and apicomplexa branch
3. ^ Richard
Dawkins, "The Ancestor's Tale",
(Boston, MA: Houghton Mifflin Company,
2004).
4. ^
http://microscope.mbl.edu/scripts/protis
t.php?func=integrate&myID=P8047&chinese_
flag=&system=&version=&documentID=&exclu
deNonLinkedIn=&imagesOnly=
5. ^
http://microscope.mbl.edu/scripts/protis
t.php?func=integrate&myID=P8047&chinese_
flag=&system=&version=&documentID=&exclu
deNonLinkedIn=&imagesOnly=
6. ^
http://microscope.mbl.edu/scripts/protis
t.php?func=integrate&myID=P8047&chinese_
flag=&system=&version=&documentID=&exclu
deNonLinkedIn=&imagesOnly=
7. ^ Raven, Evert, Eichhorn, "Biology
of Plants", (New York: Worth
Publishers, 1992). p98-99
8. ^
http://sn2000.taxonomy.nl/Taxonomicon/Ta
xonTree.aspx?id=199167&tree=0.1
9. ^ "Dinoflagellate". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
10. ^ "Dinoflagellate". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
11. ^ "Dinoflagellate". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
12. ^ "Trophozoites". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Trophozoite
s
13. ^
http://sn2000.taxonomy.nl/Taxonomicon/Ta
xonTree.aspx?id=199167&tree=0.1
14. ^
http://sn2000.taxonomy.nl/Taxonomicon/Ta
xonTree.aspx?id=199167&tree=0.1
15. ^
http://sn2000.taxonomy.nl/Taxonomicon/Ta
xonTree.aspx?id=199167&tree=0.1
16. ^
http://sn2000.taxonomy.nl/Taxonomicon/Ta
xonTree.aspx?id=199167&tree=0.1
17. ^
http://sn2000.taxonomy.nl/Taxonomicon/Ta
xonTree.aspx?id=199167&tree=0.1
18. ^
http://sn2000.taxonomy.nl/Taxonomicon/Ta
xonTree.aspx?id=199167&tree=0.1
19. ^
http://sn2000.taxonomy.nl/Taxonomicon/Ta
xonTree.aspx?id=199167&tree=0.1
20. ^
http://sn2000.taxonomy.nl/Taxonomicon/Ta
xonTree.aspx?id=199167&tree=0.1
21. ^
http://sn2000.taxonomy.nl/Taxonomicon/Ta
xonTree.aspx?id=199167&tree=0.1
22. ^ "Dinoflagellate". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
23. ^ "Dinoflagellate". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
24. ^ "Dinoflagellate". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
25. ^ "Dinoflagellate". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
26. ^ "Dinoflagellate". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
27. ^ "Dinoflagellate". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
28. ^ "Dinoflagellate". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
29. ^ "Dinoflagellate". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
30. ^ "Dinoflagellate". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
31. ^ "Dinoflagellate". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
32. ^ "Dinoflagellate". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
33. ^ "Dinoflagellate". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
34. ^ "Dinoflagellate". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
35. ^ "Dinoflagellate". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
36. ^
http://www.yourdictionary.com/ahd/t/t037
8700.html
37. ^
http://www.biology-online.org/dictionary
/trophozoite
38. ^ "Zoospore". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Zoospore
39. ^ S Blair Hedges, Jaime E Blair,
Maria L Venturi and Jason L Shoe, "A
molecular timescale of eukaryote
evolution and the rise of complex
multicellular life", BMC Evolutionary
Biology 2004, 4:2
doi:10.1186/1471-2148-4-2, (2004).
40. ^
"Dinoflagellate". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
41. ^ "Dinoflagellate". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
42. ^ "Dinoflagellate". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
43. ^ "Dinoflagellate". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
44. ^ "Dinoflagellate". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
45. ^ "Dinoflagellate". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
46. ^ "Dinoflagellate". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
47. ^ "Dinoflagellate". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
48. ^ "Dinoflagellate". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
49. ^ "Dinoflagellate". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dinoflagell
ate
50. ^ Richard Dawkins, "The Ancestor's
Tale", (Boston, MA: Houghton Mifflin
Company, 2004). (1973mybn)
51. ^ Sandra L.
Baldauf, A. J. Roger, I. Wenk-Siefert,
W. F. Doolittle, "A Kingdom-Level
Phylogeny of Eukaryotes Based on
Combined Protein Data", Science, Vol
290, num 5493, p 972, (2000). has
heterkonts before ciliophora and
apicomplexa branch (1600mybn)
52. ^ Richard
Dawkins, "The Ancestor's Tale",
(Boston, MA: Houghton Mifflin Company,
2004).
[1] Fig. 1. A consensus phylogeny of
eukaryotes. The vast majority of
characterized eukaryotes, with the
notable exception of major subgroups of
amoebae, can now be assigned to one of
eight major groups. Opisthokonts (basal
flagellum) have a single basal
flagellum on reproductive cells and
flat mitochondrial cristae (most
eukaryotes have tubular ones).
Eukaryotic photosynthesis originated in
Plants; theirs are the only plastids
with just two outer membranes.
Heterokonts (different flagellae) have
a unique flagellum decorated with
hollow tripartite hairs (stramenopiles)
and, usually, a second plain one.
Cercozoans are amoebae with filose
pseudopodia, often living with in tests
(hard outer shells), some very
elaborate (foraminiferans). Amoebozoa
are mostly naked amoebae (lacking
tests), often with lobose pseudopodia
for at least part of their life cycle.
Alveolates have systems of cortical
alveoli directly beneath their plasma
membranes. Discicristates have discoid
mitochondrial cristae and, in some
cases, a deep (excavated) ventral
feeding groove. Amitochondrial
excavates lack substantial molecular
phylogenetic support, but most have an
excavated ventral feeding groove, and
all lack mitochondria. The tree shown
is based on a consensus of molecular
(1-4) and ultrastructural (16, 17) data
and includes a rough indication of new
ciPCR ''taxa'' (broken black lines)
(7-11). An asterisk preceding the taxon
name indicates probable paraphyletic
group COPYRIGHTED
source: http://www.sciencemag.org/cgi/co
ntent/full/300/5626/1703
[2] Figure 1. Phylogenetic hypothesis
of the eukaryotic lineage based on
ultrastructural and molecular data.
Organisms are divided into three main
groups distinguished by mitochondrial
cristal shape (either discoidal,
flattened or tubular). Unbroken lines
indicate phylogenetic relationships
that are firmly supported by available
data; broken lines indicate
uncertainties in phylogenetic
placement, resolution of which will
require additional data. Color coding
of organismal genus names indicates
mitochondrial genomes that have been
completely (Table 1), almost completely
(Jakoba, Naegleria and
Thraustochytrium) or partially (*)
sequenced by the OGMP (red), the FMGP
(black) or other groups (green). Names
in blue indicate those species whose
mtDNAs are currently being sequenced by
the OGMP or are future candidates for
complete sequencing. Amitochondriate
retortamonads are positioned at the
base of the tree, with broken arrows
denoting the endosymbiotic origin(s) of
mitochondria from a Rickettsia-like
eubacterium. Macrophar.,
Macropharyngomonas. COPYRIGHTED
source: http://nar.oxfordjournals.org/cg
i/content/full/26/4/865
8 9 10
Genetic
comparison shows Apicomplexans evolve.
The Apicomplexa are a large group of
protozoa, characterized by the presence
of an apical complex at some point in
their life-cycle. They are exclusively
parasitic, and completely lack flagella
or pseudopods except for certain gamete
stages. Diseases caused by Apicomplexa
include:4
* Babesiosis (Babesia)
*
Cryptosporidiosis (Cryptosporidium)
* Malaria
(Plasmodium)
* Toxoplasmosis (Toxoplasma
gondii)5
Most members have a complex life-cycle,
involving both asexual and sexual
reproduction. Typically, a host is
infected by ingesting cysts, which
divide to produce sporozoites that
enter its cells. Eventually, the cells
burst, releasing merozoites which
infect new cells. This may occur
several times, until gamonts are
produced, forming gametes that fuse to
create new cysts. There are many
variations on this basic pattern,
however, and many Apicomplexa have more
than one host.6
DOMAIN Eukaryota -
eukaryotes
KINGDOM Protozoa (Goldfuss, 1818) R.
Owen, 1858 - protozoa
SUBKINGDOM Biciliata
INFRAKINGDOM Alveolata Cavalier-Smith,
1991
PHYLUM Apicomplexa
CLASS
Conoidasida Levine, 1988
CLASS
Aconoidasida Mehlhorn, Peters &
Haberkorn, 1980
CLASS
Metchnikovellea Weiser, 1977
CLASS
Blastocystea Cavalier-Smith, 1998 7
FOOTNOTES
1. ^ S Blair Hedges, Jaime E Blair,
Maria L Venturi and Jason L Shoe, "A
molecular timescale of eukaryote
evolution and the rise of complex
multicellular life", BMC Evolutionary
Biology 2004, 4:2
doi:10.1186/1471-2148-4-2, (2004).
2. ^ Richard
Dawkins, "The Ancestor's Tale",
(Boston, MA: Houghton Mifflin Company,
2004).
3. ^ Sandra L. Baldauf, A. J. Roger, I.
Wenk-Siefert, W. F. Doolittle, "A
Kingdom-Level Phylogeny of Eukaryotes
Based on Combined Protein Data",
Science, Vol 290, num 5493, p 972,
(2000). has heterkonts before
ciliophora and apicomplexa branch
4. ^
"Apicomplexa". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Apicomplexa
5. ^ "Apicomplexa". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Apicomplexa
6. ^ "Apicomplexa". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Apicomplexa
7. ^
http://sn2000.taxonomy.nl/Taxonomicon/Ta
xonTree.aspx?id=199436&tree=0.1
8. ^ S Blair Hedges, Jaime E Blair,
Maria L Venturi and Jason L Shoe, "A
molecular timescale of eukaryote
evolution and the rise of complex
multicellular life", BMC Evolutionary
Biology 2004, 4:2
doi:10.1186/1471-2148-4-2, (2004).
(1973mybn)
9. ^ Richard Dawkins, "The Ancestor's
Tale", (Boston, MA: Houghton Mifflin
Company, 2004). (1600mybn)
10. ^ Sandra L.
Baldauf, A. J. Roger, I. Wenk-Siefert,
W. F. Doolittle, "A Kingdom-Level
Phylogeny of Eukaryotes Based on
Combined Protein Data", Science, Vol
290, num 5493, p 972, (2000). has
heterkonts before ciliophora and
apicomplexa branch
MORE INFO
[1]
http://www.sirinet.net/~jgjohnso/apbio30
.html
[1] Fig. 1. A consensus phylogeny of
eukaryotes. The vast majority of
characterized eukaryotes, with the
notable exception of major subgroups of
amoebae, can now be assigned to one of
eight major groups. Opisthokonts (basal
flagellum) have a single basal
flagellum on reproductive cells and
flat mitochondrial cristae (most
eukaryotes have tubular ones).
Eukaryotic photosynthesis originated in
Plants; theirs are the only plastids
with just two outer membranes.
Heterokonts (different flagellae) have
a unique flagellum decorated with
hollow tripartite hairs (stramenopiles)
and, usually, a second plain one.
Cercozoans are amoebae with filose
pseudopodia, often living with in tests
(hard outer shells), some very
elaborate (foraminiferans). Amoebozoa
are mostly naked amoebae (lacking
tests), often with lobose pseudopodia
for at least part of their life cycle.
Alveolates have systems of cortical
alveoli directly beneath their plasma
membranes. Discicristates have discoid
mitochondrial cristae and, in some
cases, a deep (excavated) ventral
feeding groove. Amitochondrial
excavates lack substantial molecular
phylogenetic support, but most have an
excavated ventral feeding groove, and
all lack mitochondria. The tree shown
is based on a consensus of molecular
(1-4) and ultrastructural (16, 17) data
and includes a rough indication of new
ciPCR ''taxa'' (broken black lines)
(7-11). An asterisk preceding the taxon
name indicates probable paraphyletic
group COPYRIGHTED
source: http://www.sciencemag.org/cgi/co
ntent/full/300/5626/1703
[2] Figure 1. Phylogenetic hypothesis
of the eukaryotic lineage based on
ultrastructural and molecular data.
Organisms are divided into three main
groups distinguished by mitochondrial
cristal shape (either discoidal,
flattened or tubular). Unbroken lines
indicate phylogenetic relationships
that are firmly supported by available
data; broken lines indicate
uncertainties in phylogenetic
placement, resolution of which will
require additional data. Color coding
of organismal genus names indicates
mitochondrial genomes that have been
completely (Table 1), almost completely
(Jakoba, Naegleria and
Thraustochytrium) or partially (*)
sequenced by the OGMP (red), the FMGP
(black) or other groups (green). Names
in blue indicate those species whose
mtDNAs are currently being sequenced by
the OGMP or are future candidates for
complete sequencing. Amitochondriate
retortamonads are positioned at the
base of the tree, with broken arrows
denoting the endosymbiotic origin(s) of
mitochondria from a Rickettsia-like
eubacterium. Macrophar.,
Macropharyngomonas. COPYRIGHTED
source: http://nar.oxfordjournals.org/cg
i/content/full/26/4/865
8 9
(the Phyla "Radiolaria", "Cercozoa",
and "Foraminifera") evolve now.1 2
This marks the beginning of the
protists described as "amoeboid",
because they have pseudopods.
5. Amoeboids
phagocytize their food; pseudopods
surround and engulf prey.
6. Food is digested
inside food vacuoles.
7. Freshwater amoeboids
have contractile vacuoles to eliminate
excess water. 3
Some foraminifera are haplodiploid
(alternate between haploid and diploid
cycles that both have mitosis).
The Rhizaria are a major line of
protists. They vary considerably in
form, but for the most part they are
amoeboids with filose, reticulose, or
microtubule-supported pseudopods. Many
produce shells or skeletons, which may
be quite complex in structure, and
these make up the vast majority of
protozoan fossils. Nearly all have
mitochondria with tubular cristae. 4
The
re are three main groups of Rhizaria:
Cercozoa
Various amoebae and flagellates,
usually with filose pseudopods and
common in soil
Foraminifera Amoeboids with
reticulose pseudopods, common as marine
benthos
Radiolaria Amoeboids with axopods,
common as marine plankton 5
The name Rhizaria was created recently
by Cavalier-Smith in 2002. Most are
biciliate amoeboflagellates at some
point in the life cycle. Pseudopodia
are root-like reticulopodia, filopodia
and/or axopodia - not broad lobopodia
as in Amoeba. All of these features
can, however, be found in members of
other clades. Nevertheless, the
Rhizaria are supported by both rRNA and
actin trees (Cavalier-Smith & Chao,
2003; Nikolaev et al. 2004). 6
A few
other groups may be included in the
Cercozoa, but on some trees appear
closer to the Foraminifera. These are
the Phytomyxea and Ascetosporea,
parasites of plants and animals
respectively, and the peculiar amoeba
Gromia. The different groups of
Rhizaria are considered close relatives
based mainly on genetic similarities,
and have been regarded as an extension
of the Cercozoa. The name Rhizaria for
the expanded group was introduced by
Cavalier-Smith in 2002, who also
included the centrohelids and Apusozoa.
7
FOOTNOTES
1. ^ Richard Dawkins, "The Ancestor's
Tale", (Boston, MA: Houghton Mifflin
Company, 2004).
2. ^ S Blair Hedges, Jaime E
Blair, Maria L Venturi and Jason L
Shoe, "A molecular timescale of
eukaryote evolution and the rise of
complex multicellular life", BMC
Evolutionary Biology 2004, 4:2
doi:10.1186/1471-2148-4-2, (2004).
3. ^
http://www.sirinet.net/~jgjohnso/apbio30
.html
4. ^ "Rhizaria". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Rhizaria
5. ^ "Rhizaria". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Rhizaria
6. ^
http://www.palaeos.com/Eukarya/Units/Rhi
zaria/Rhizaria.html
7. ^ "Rhizaria". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Rhizaria
8. ^ Richard Dawkins, "The Ancestor's
Tale", (Boston, MA: Houghton Mifflin
Company, 2004). has 1600my for
excavates, discricristales, rhizaria,
chromalveolates, (1600my)
9. ^ S Blair Hedges,
Jaime E Blair, Maria L Venturi and
Jason L Shoe, "A molecular timescale of
eukaryote evolution and the rise of
complex multicellular life", BMC
Evolutionary Biology 2004, 4:2
doi:10.1186/1471-2148-4-2, (2004). I
use this estimate
[1] FIG. 2. The tree of life based on
molecular, ultrastructural and
palaeontological evidence. Contrary to
widespread assumptions, the root is
among the eubacteria, probably within
the double-enveloped Negibacteria, not
between eubacteria and archaebacteria
(Cavalier-Smith, 2002b); it may lie
between Eobacteria and other
Negibacteria (Cavalier-Smith, 2002b).
The position of the eukaryotic root has
been nearly as controversial, but is
less hard to establish: it probably
lies between unikonts and bikonts (Lang
et al., 2002; Stechmann and
Cavalier-Smith, 2002, 2003). For
clarity the basal eukaryotic kingdom
Protozoa is not labelled; it comprises
four major groups (alveolates, cabozoa,
Amoebozoa and Choanozoa) plus the small
bikont phylum Apusozoa of unclear
precise position; whether Heliozoa are
protozoa as shown or chromists is
uncertain (Cavalier-Smith, 2003b).
Symbiogenetic cell enslavement occurred
four or five times: in the origin of
mitochondria and chloroplasts from
different negibacteria, of
chromalveolates by the enslaving of a
red alga (Cavalier-Smith, 1999, 2003;
Harper and Keeling, 2003) and in the
origin of the green plastids of
euglenoid (excavate) and chlorarachnean
(cercozoan) algae-a green algal cell
was enslaved either by the ancestral
cabozoan (arrow) or (less likely) twice
independently within excavates and
Cercozoa (asterisks) (Cavalier-Smith,
2003a). The upper thumbnail sketch
shows membrane topology in the
chimaeric cryptophytes (class
Cryptophyceae of the phylum Cryptista);
in the ancestral chromist the former
food vacuole membrane fused with the
rough endoplasmic reticulum placing the
enslaved cell within its lumen (red) to
yield the complex membrane topology
shown. The large host nucleus and the
tiny nucleomorph are shown in blue,
chloroplast green and mitochondrion
purple. In chlorarachneans (class
Chlorarachnea of phylum Cercozoa) the
former food vacuole membrane remained
topologically distinct from the ER to
become an epiplastid membrane and so
did not acquire ribosomes on its
surface, but their membrane topology is
otherwise similar to the cryptophytes.
The other sketches portray the four
major kinds of cell in the living world
and their membrane topology. The upper
ones show the contrasting ancestral
microtubular cytoskeleton (ciliary
roots, in red) of unikonts (a cone of
single microtubules attaching the
single centriole to the nucleus, blue)
and bikonts (two bands of microtubules
attached to the posterior centriole and
an anterior fan of microtubules
attached to the anterior centriole).
The lower ones show the single plasma
membrane of unibacteria (posibacteria
plus archaebacteria), which were
ancestral to eukaryotes and the double
envelope of negibacteria, which were
ancestral to mitochondria and
chloroplasts (which retained the outer
membrane, red).
source: http://aob.oxfordjournals.org/cg
i/content/full/95/1/147/FIG2
[2] Fig. 1. A consensus phylogeny of
eukaryotes. The vast majority of
characterized eukaryotes, with the
notable exception of major subgroups of
amoebae, can now be assigned to one of
eight major groups. Opisthokonts (basal
flagellum) have a single basal
flagellum on reproductive cells and
flat mitochondrial cristae (most
eukaryotes have tubular ones).
Eukaryotic photosynthesis originated in
Plants; theirs are the only plastids
with just two outer membranes.
Heterokonts (different flagellae) have
a unique flagellum decorated with
hollow tripartite hairs (stramenopiles)
and, usually, a second plain one.
Cercozoans are amoebae with filose
pseudopodia, often living with in tests
(hard outer shells), some very
elaborate (foraminiferans). Amoebozoa
are mostly naked amoebae (lacking
tests), often with lobose pseudopodia
for at least part of their life cycle.
Alveolates have systems of cortical
alveoli directly beneath their plasma
membranes. Discicristates have discoid
mitochondrial cristae and, in some
cases, a deep (excavated) ventral
feeding groove. Amitochondrial
excavates lack substantial molecular
phylogenetic support, but most have an
excavated ventral feeding groove, and
all lack mitochondria. The tree shown
is based on a consensus of molecular
(1-4) and ultrastructural (16, 17) data
and includes a rough indication of new
ciPCR ''taxa'' (broken black lines)
(7-11). An asterisk preceding the taxon
name indicates probable paraphyletic
group.
source: http://www.sciencemag.org/cgi/co
ntent/full/300/5626/1703
29 30
now.1 2
The Cercozoa are a group of
protists, including most amoeboids and
flagellates that feed by means of
filose pseudopods. These may be
restricted to part of the cell surface,
but there is never a true cytostome or
mouth as found in many other protozoa.
They show a variety of forms and have
proven difficult to define in terms of
structural characteristics, although
their unity is strongly supported by
genetic studies.3
The best-known
Cercozoa are the euglyphids, filose
amoebae with shells of siliceous scales
or plates, which are commonly found in
soils, nutrient-rich waters, and on
aquatic plants. Some other filose
amoebae produce organic shells,
including the tectofilosids and Gromia.
They were formerly classified with the
euglyphids as the Testaceafilosia. This
group is not monophyletic, but nearly
all studied members fall in or near the
Cercozoa, related to similarly shelled
flagellates.4
Another important group placed here are
the chlorarachniophytes, strange
amoebae that form a reticulating net.
They are set apart by the presence of
chloroplasts, which apparently
developed from an ingested green alga.
They are bound by four membranes and
still possess a vestigial nucleus,
called a nucleomorph. As such, they
have been of great interest to
researchers studying the endosymbiotic
origins of organelles.5
Other notable cercozoans include the
cercomonads, which are common soil
flagellates. Two groups traditionally
considered heliozoa, the dimorphids and
desmothoracids, belong here. Recently
the marine Phaeodarea have also been
included. The Cercozoa are closely
related to the Foraminifera and
Radiolaria, amoeboids that usually have
complex shells, and together with them
form a supergroup called the Rhizaria.
Their exact composition and
relationships are still being worked
out. 6
PHYLUM Cercozoa (Cavalier-Smith 1998)
7
CLASS Spongomonadea
CLASS Proteomyxidea -
desmothoracids, dimorphids,
gymnophryids, etc.
CLASS Sarcomonadea -
cercomonads
CLASS Imbricatea - euglyphids and
thaumatomonads
CLASS Thecofilosea - tectofilosids
and cryomonads
CLASS Phaeodarea
CLASS Chlorarachnea
(Hibberd & Norris, 1984)
Class Spongomonadea
Chlorarachniophytes
are a small group of algae occasionally
found in tropical oceans. They are
typically mixotrophic, ingesting
bacteria and smaller protists as well
as conducting photosynthesis. Normally
they have the form of small amoebae,
with branching cytoplasmic extensions
that capture prey and connect the cells
together, forming a net. They may also
form flagellate zoospores, which
characteristically have a single
subapical flagellum that spirals
backwards around the cell body, and
walled coccoid cells.8
The chloroplasts were presumably
acquired by ingesting some green alga.
They are surrounded by four membranes,
the outermost of which is continuous
with the endoplasmic reticulum, and
contain a small nucleomorph between the
middle two, which is a remnant of the
alga's nucleus. This contains a small
amount of DNA and divides without
forming a mitotic spindle. The origin
of the chloroplasts from green algae is
supported by their pigmentation, which
includes chlorophylls a and b, and by
genetic similarities. The only other
group of algae that contain
nucleomorphs are the cryptomonads, but
their chloroplasts seem to be derived
from a red alga.9
The chlorarachniophytes only include
five genera, which show some variation
in their life-cycles and may lack one
or two of the stages described above.
Genetic studies place them among the
Cercozoa, a diverse group of amoeboid
and amoeboid-like protozoa.10
Class Proteomyxidea
Order Desmothoracida (Hertwig &
Lesser 1874)
The desmothoracids are a group
of heliozoan protists, usually sessile
and found in freshwater environments.
Each adult is a spherical cell around
10-20 μm in diameter surrounded by
a perforated organic lorica or shell,
with many radial pseudopods projecting
through the holes to capture food.
These are supported by small bundles of
microtubules that arise near a point on
the nuclear membrane. Unlike other
heliozoans, the microtubules are not in
any regular geometric array, there does
not appear to be a microtubule
organizing center, and there is no
distinction between the outer and inner
cytoplasm. 11
Reproduction takes place by the budding
off of small motile cells, usually with
two flagella. Later these are lost, and
pseudopods and a lorica are formed.
Typically a single lengthened pseudopod
will secrete a hollow stalk that
attached the adult to the substrate.
The form of the flagella, the tubular
cristae within the mitochondria, and
other characters led to the suggestion
that the desmothoracids belong among
what is now the Cercozoa, which has now
been confirmed by genetic studies. 12
Order Heliomonadida
Genus Dimorpha
The dimorphids or
heliomonads are a small group of
heliozoa that are unusual in possessing
flagella throughout their life-cycle.
There are two genera: Dimorpha, a tiny
organism found in freshwater, and the
larger Tetradimorpha, which is
distinguished by having four rather
than two flagella. Bundles of
microtubules, typically in square
array, arise from a body near the
flagellar bases and support the
numerous axopods that project from the
cell surface. 13
Dimorphids have a single nucleus, and
mitochondria with tubular cristae.
Genetic studies place them among the
Cercozoa, a group including various
other flagellates that form pseudopods.
14
Order Reticulosida
Family Gymnophryidae
(Mikrjukov & Mylnikov, 1996)
The gymnophryids
are a small group of amoeboids that
lack shells and produce thin,
reticulose pseudopods. These contain
microtubules and have a granular
appearance, owing to the presence of
extrusomes, but are distinct from the
pseudopods of Foraminifera. They are
included among the Cercozoa, but differ
from other cercozoans in having
mitochondria with flat cristae, rather
than tubular cristae. 15
Gymnophrys cometa, found in freshwater
and soil, is representative of the
group. The cell body is under 10
μm in size, and has a pair of
reduced flagella, which are smooth and
insert parallel to one another. It may
also produce motile zoospores and
cysts. Gymnophrys and Borkovia are the
only confirmed genera, but other naked
reticulose amoebae such as Biomyxa may
be close relatives. 16
Class Sarcomonadea
Order Cercomonadida (Poche,
1913)
Cercomonads are small flagellates,
widespread in aqueous habitats and
especially common in soils. The cells
are generally around 10 μm in
length, without any shell or covering.
They produce filose pseudopods to
capture bacteria, but do not use them
for locomotion, which usually takes
place by gliding along surfaces. Most
members have two smooth flagella, one
directed forward and one trailing under
the cell, inserted at right angles near
its anterior. The nucleus is connected
to the flagellar bases and accompanied
by a characteristic paranuclear body.
17
Genetic studies place the cercomonads
among the core Cercozoa, a diverse
group of amoeboid and flagellate
protozoans. They are divided into two
families. The Heteromitidae tend to be
relatively rigid, and produce only
temporary pseudopods. The
Cercomonadidae are more plastic, and
when food supplies are plentiful may
become amoeboid and even multinucleate.
The classification of genera and
species continues to undergo revision.
Some genera have been merged, like
Cercomonas and Cercobodo, and some have
been moved to other groups. 18
Class Imbricatea
Order Euglyphida (Copeland,
1956)
The euglyphids are a prominent group of
filose amoebae that produce shells or
tests from siliceous scales, plates,
and sometimes spines. These elements
are created within the cell and then
assembled on its surface in a more or
less regular arrangement, giving the
test a textured appearance. There is a
single opening for the long slender
pseudopods, which capture food and pull
the cell across the substrate. 19
Euglyphids are common in soils,
marshes, and other organic-rich
environments, feeding on tiny organisms
such as bacteria. The test is generally
30-100 μm in length, although the
cell only occupies part of this space.
During reproduction a second shell is
formed opposite the opening, so both
daughter cells remain protected.
Different genera and species are
distinguished primarily by the form of
the test. Euglypha and Trinema are the
most common. 20
The euglyphids are traditionally
grouped with other amoebae. However,
genetic studies instead place them with
various amoeboid and flagellate groups,
forming an assemblage called the
Cercozoa. Their closest relatives are
the thaumatomonads, flagellates that
form similar siliceous tests. 21
Class Thecofilosea
Order Tectofilosida
(Cavalier-Smith & Chao, 2003)
The
tectofilosids or amphitremids are a
group of filose amoebae with shells.
These are composed of organic materials
and sometimes collected debris, in
contrast to the euglyphids, which
produce shells from siliceous scales.
The shell usually has a single opening,
but in Amphitrema and a few other
genera it has two on opposite ends. The
cell itself occupies most of the shell.
They are most often found on marsh
plants such as Sphagnum. 22
This group was previously classified as
the Gromiida or Gromiina. However,
molecular studies separate Gromia from
the others, which must therefore be
renamed. They are placed among the
Cercozoa, and presumably developed from
flagellates like Cryothecomonas, which
has a similar test. However, only a few
have been studied in detail, so their
relationships and monophyly are not yet
certain. 23
Class: Phaeodarea (Haeckel, 1879)
The
Phaeodarea are a group of amoeboid
protists. They are traditionally
considered radiolarians, but in
molecular trees do not appear to be
close relatives of the other groups,
and are instead placed among the
Cercozoa. They are distinguished by the
structure of their central capsule and
by the presence of a phaeodium, an
aggregate of waste particles within the
cell. 24
Phaeodarea produce hollow skeletons
composed of amorphous silica and
organic material, which rarely
fossilize. The endoplasm is divided by
a cape with three openings, of which
one gives rise to feeding pseudopods,
and the others let through bundles of
microtubules that support the axopods.
Unlike other radiolarians, there are no
cross-bridges between them. They also
lack symbiotic algae, generally living
below the photic zone, and do not
produce any strontium sulphate. 25
CLASS Chlorarachnea
Chlorarachniophytes are a small
group of algae occasionally found in
tropical oceans. They are typically
mixotrophic, ingesting bacteria and
smaller protists as well as conducting
photosynthesis. Normally they have the
form of small amoebae, with branching
cytoplasmic extensions that capture
prey and connect the cells together,
forming a net. They may also form
flagellate zoospores, which
characteristically have a single
subapical flagellum that spirals
backwards around the cell body, and
walled coccoid cells. 26
The chloroplasts were presumably
acquired by ingesting some green alga.
They are surrounded by four membranes,
the outermost of which is continuous
with the endoplasmic reticulum, and
contain a small nucleomorph between the
middle two, which is a remnant of the
alga's nucleus. This contains a small
amount of DNA and divides without
forming a mitotic spindle. The origin
of the chloroplasts from green algae is
supported by their pigmentation, which
includes chlorophylls a and b, and by
genetic similarities. The only other
group of algae that contain
nucleomorphs are the cryptomonads, but
their chloroplasts seem to be derived
from a red alga. 27
The chlorarachniophytes only include
five genera, which show some variation
in their life-cycles and may lack one
or two of the stages described above.
Genetic studies place them among the
Cercozoa, a diverse group of amoeboid
and amoeboid-like protozoa. 28
FOOTNOTES
1. ^ Richard Dawkins, "The Ancestor's
Tale", (Boston, MA: Houghton Mifflin
Company, 2004). has 1600mybn for
excavates, discricristales, rhizaria,
chromalveolates
2. ^ S Blair Hedges, Jaime E Blair,
Maria L Venturi and Jason L Shoe, "A
molecular timescale of eukaryote
evolution and the rise of complex
multicellular life", BMC Evolutionary
Biology 2004, 4:2
doi:10.1186/1471-2148-4-2, (2004).
3. ^
"Cercozoa". Wikipedia. Wikipedia, 2008.
http://en.wikipedia.org/wiki/Cercozoa
4. ^ "Cercozoa". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Cercozoa
5. ^ "Cercozoa". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Cercozoa
6. ^ "Cercozoa". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Cercozoa
7. ^ "Cercozoa". Wikipedia. Wikipedia,
2008.
http://en.wikipedia.org/wiki/Cercozoa
8. ^ "Chlorarachniophyte". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Chlorarachn
iophyte
9. ^ "Chlorarachniophyte". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Chlorarachn
iophyte
10. ^ "Chlorarachniophyte". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Chlorarachn
iophyte
11. ^ "Desmothoracid". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Desmothorac
id
12. ^ "Desmothoracid". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Desmothorac
id
13. ^ "Dimorphid". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dimorphid
14. ^ "Dimorphid". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Dimorphid
15. ^ "Gymnophryid". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Gymnophryid
16. ^ "Gymnophryid". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Gymnophryid
17. ^ "Cercomonad". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Cercomonad
18. ^ "Cercomonad". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Cercomonad
19. ^ "Euglyphid". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Euglyphid
20. ^ "Euglyphid". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Euglyphid
21. ^ "Euglyphid". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Euglyphid
22. ^ "Tectofilosid". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Tectofilosi
d
23. ^ "Tectofilosid". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Tectofilosi
d
24. ^ "Phaeodarea". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Phaeodarea
25. ^ "Phaeodarea". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Phaeodarea
26. ^ "Chlorarachniophyte". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Chlorarachn
iophyte
27. ^ "Chlorarachniophyte". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Chlorarachn
iophyte
28. ^ "Chlorarachniophyte". Wikipedia.
Wikipedia, 2008.
http://en.wikipedia.org/wiki/Chlorarachn
iophyte
29. ^ Richard Dawkins, "The Ancestor's
Tale", (Boston, MA: Houghton Mifflin
Company, 2004). has 1600mybn for
excavates, discricristales, rhizaria,
chromalveolates (1600mybn)
30. ^ S Blair Hedges,
Jaime E Blair, Maria L Venturi and
Jason L Shoe, "A molecular timescale of
eukaryote evolution and the rise of
complex multicellular life", BMC
Evolutionary Biology 2004, 4:2
doi:10.1186/1471-2148-4-2, (2004).
[1] FIG. 2. The tree of life based on
molecular, ultrastructural and
palaeontological evidence. Contrary to
widespread assumptions, the root is
among the eubacteria, probably within
the double-enveloped Negibacteria, not
between eubacteria and archaebacteria
(Cavalier-Smith, 2002b); it may lie
between Eobacteria and other
Negibacteria (Cavalier-Smith, 2002b).
The position of the eukaryotic root has
been nearly as controversial, but is
less hard to establish: it probably
lies between unikonts and bikonts (Lang
et al., 2002; Stechmann and
Cavalier-Smith, 2002, 2003). For
clarity the basal eukaryotic kingdom
Protozoa is not labelled; it comprises
four major groups (alveolates, cabozoa,
Amoebozoa and Choanozoa) plus the small
bikont phylum Apusozoa of unclear
precise position; whether Heliozoa are
protozoa as shown or chromists is
uncertain (Cavalier-Smith, 2003b).
Symbiogenetic cell enslavement occurred
four or five times: in the origin of
mitochondria and chloroplasts from
different negibacteria, of
chromalveolates by the enslaving of a
red alga (Cavalier-Smith, 1999, 2003;
Harper and Keeling, 2003) and in the
origin of the green plastids of
euglenoid (excavate) and chlorarachnean
(cercozoan) algae-a green algal cell
was enslaved either by the ancestral
cabozoan (arrow) or (less likely) twice
independently within excavates and
Cercozoa (asterisks) (Cavalier-Smith,
2003a). The upper thumbnail sketch
shows membrane topology in the
chimaeric cryptophytes (class
Cryptophyceae of the phylum Cryptista);
in the ancestral chromist the former
food vacuole membrane fused with the
rough endoplasmic reticulum placing the
enslaved cell within its lumen (red) to
yield the complex membrane topology
shown. The large host nucleus and the
tiny nucleomorph are shown in blue,
chloroplast green and mitochondrion
purple. In chlorarachneans (class
Chlorarachnea of phylum Cercozoa) the
former food vacuole membrane remained
topologically distinct from the ER to
become an epiplastid membrane and so
did not acquire ribosomes on its
surface, but their membrane topology is
otherwise similar to the cryptophytes.
The other sketches portray the four
major kinds of cell in the living world
and their membrane topology. The upper
ones show the contrasting ancestral
microtubular cytoskeleton (ciliary
roots, in red) of unikonts (a cone of
single microtubules attaching the
single centriole to the nucleus, blue)
and bikonts (two bands of microtubules
attached to the posterior centriole and
an anterior fan of microtubules
attached to the anterior centriole).
The lower ones show the single plasma
membrane of unibacteria (posibacteria
plus archaebacteria), which were
ancestral to eukaryotes and the double
envelope of negibacteria, which were
ancestral to mitochondria and
chloroplasts (which retained the outer
membrane, red).
source: http://aob.oxfordjournals.org/cg
i/content/full/95/1/147/FIG2
[2] Fig. 1. A consensus phylogeny of
eukaryotes. The vast majority of
characterized eukaryotes, with the
notable exception of major subgroups of
amoebae, can now be assigned to one of
eight major groups. Opisthokonts (basal
flagellum) have a single basal
flagellum on reproductive cells and
flat mitochondrial cristae (most
eukaryotes have tubular ones).
Eukaryotic photosynthesis originated in
Plants; theirs are the only plastids
with just two outer membranes.
Heterokonts (different flagellae) have
a unique flagellum decorated with
hollow tripartite hairs (stramenopiles)
and, usually, a second plain one.
Cercozoans are amoebae with filose
pseudopodia, often living with in tests
(hard outer shells), some very
elaborate (foraminiferans). Amoebozoa
are mostly naked amoebae (lacking
tests), often with lobose pseudopodia
for at least part of their life cycle.
Alveolates have systems of cortical
alveoli directly beneath their plasma
membranes. Discicristates have discoid
mitochondrial cristae and, in some
cases, a deep (excavated) ventral
feeding groove. Amitochondrial
excavates lack substantial molecular
phylogenetic support, but most have an
excavated ventral feeding groove, and
all lack mitochondria. The tree shown
is based on a consensus of molecular
(1-4) and ultrastructural (16, 17) data
and includes a rough indication of new
ciPCR ''taxa'' (broken black lines)
(7-11). An asterisk preceding the taxon
name indicates probable paraphyletic
group.
source: http://www.sciencemag.org/cgi/co
ntent/full/300/5626/1703
30 31
evolve now.1 2
Ribosomal RNA indicates
that Rhizaria Phylum "Radiolaria"
evolve now.
Radiolarians (also radiolaria) are
amoeboid protozoa that produce
intricate mineral skeletons, typically
with a central capsule dividing the
cell into inner and outer portions,
called endoplasm and ectoplasm. They
are found as plankton throughout the
ocean, and their shells are important
fossils found from the Cambrian
onwards.3
Move by pseudopodia. 4
external tests
made of silica (glass). 5
Radiolaria have a test composed of
silica or strontium sulfate.
Most have a radial
arrangement of spines.
Pseudopods (actinopods)
project from an external layer of
cytoplasm and are supported by rows of
microtubules.
Tests of dead foraminiferans and
radiolarians form deep layers of ocean
floor sediment.
Back to the Precambrian, each
layer has distinctive foraminiferans
which helps date rocks.
Over hundreds of
millions of years, the CaCO3 shells
have contributed to the formation of
chalk deposits (i.e. White Cliffs of
Dover, limestone of pyramids). 6
Lifecycle
Simple asexual fission of radiolarian
cells has been observed. Sexual
reproduction has not been confirmed but
is assumed to occur; possible
gametogenesis has been observed in the
form of "swarmers" being expelled from
swellings in the cell. Swarmers are
formed from the central capsule after
the ectoplasm has been discarded. The
central capsule sinks through the water
column to depths hundreds of meters
greater than the normal habitat and
swells, eventually rupturing and
releasing the flagellated cells.
Recombination of these cells, which are
assumed to be haploid, to produce
diploid "adults" has not been observed
however and is only inferred to occur.
Comparisons of standing crops within
the water column and sediment trap
samples have ascertained that the
average life span of radiolarians is
about two weeks, ranging from a few
days to a few weeks. 7
All
radiolarians secrete strontium sulphate
at some point in the life cycle - as
the adult shell in Acantharea, and as
crystals in swarmer cells" produced
during asexual reproduction in
Polycystinea. 8
Large, planktonic forms
that produce a glassy, intricate shell.
9
Radiolarians have many needle-like
pseudopods supported by microtubules,
called axopods, which aid in flotation.
The nuclei and most other organelles
are in the endoplasm, while the
ectoplasm is filled with frothy
vacuoles and lipid droplets, keeping
them buoyant. Often it also contains
symbiotic algae, especially
zooxanthellae, that provide most of the
cell's energy. Some of this
organization is found among the
heliozoa, but those lack central
capsules and only produce simple scales
and spines. 10
The main class of radiolarians are the
Polycystinea, which produce siliceous
skeletons. These include the majority
of fossils. They also include the
Acantharea, which produce skeletons of
strontium sulfate. Despite some initial
suggestions to the contrary, genetic
studies place these two groups close
together. They also include the
peculiar genus Sticholonche, which
lacks an internal skeleton and so is
usually considered a heliozoan. 11
Traditionally the radiolarians also
include the Phaeodarea, which produce
siliceous skeletons but differ from the
polycystines in several other respects.
However, on molecular trees they branch
with the Cercozoa, a group including
various flagellate and amoeboid
protists. The other radiolarians appear
near, but outside, the Cercozoa, so the
similarity is due to convergent
evolution. The radiolarians and
Cercozoa are included within a
supergroup called the Rhizaria. 12
German biologist Ernst Haeckel produced
exquisite (and perhaps somewhat
exaggerated) drawings of radiolaria,
helping to popularize these protists
among Victorian parlor microscopists
alongside foraminifera and diatoms. 13
PHYLUM Radiolaria (Müller 1858 emend.)
14
CLASS Polycystinea 15 16
CLASS
Acantharea (Haeckel, 1881) 17
CLASS
Sticholonchea 18
(CLASS Phaeodarea
Haeckel, 1879 19 )?
CLASS Polycystinea:
The polycystines are a group of
radiolarian protists. They include the
vast majority of the fossil radiolaria,
as their skeletons are abundant in
marine sediments, making them one of
the most common groups of microfossils.
These skeletons are composed of opaline
silica. In some it takes the form of
relatively simple spicules, but in
others it forms more elaborate
lattices, such as concentric spheres
with radial spines or sequences of
conical chambers. 20
Class Acantharea
The Acantharea are a small group
of radiolarian protozoa, distinguished
mainly by their skeletons. These are
composed of strontium sulfate crystals,
which do not fossilize, and take the
form of either ten diametric or twenty
radial spines. The central capsule is
made up of microfibrils arranged into
twenty plates, each with a hole through
which one spine projects, and there is
also a microfibrillar cortex linked to
the spines by myonemes. These assist in
flotation, together with the vacuoles
in the ectoplasm, which often contain
zooxanthellae. 21
The axopods are fixed
in number. Reproduction takes place by
formation of spores, which may be
flagellate. These develop into
mononucleate amoebae; adults are
usually multinucleate. 22
Class Sticholonchea
Sticholonche is a peculiar genus
of protozoan with a single species, S.
zanclea, found in open oceans at depths
of 100-500 metres. It is generally
considered a heliozoan, placed in its
own order, called the Taxopodida.
However it has also been classified as
an unusual radiolarian, and this has
gained support from genetic studies,
which place it near the Acantharea.23
Sticholonche are usually around 200
μm, though this