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Single-Celled Species' Genome As Complex As Ours?
An anonymous reader writes: "A new paper reports on the sequencing and analysis of the genome of a single-celled species known as Tetrahymena thermophila. This ciliate (like the Paramecium people look at in school) has some 27,000 genes, or nearly as many as humans. And despite existing as a single cell, this spcies encodes fantastic complexity and unusual features. For example, it has a primitive immune system that prevents the invasion of foreign DNA. Also, it is able to cordon off its germ cell lineage much as humans do with sperm and eggs. But Tetrahymena does this by having two nuclei within each cell, with one of the nuclei being held in reserve for sex. Basically, this species uses its genome complexity to function like a single celled chameleon, changing its shape and its properties in response to the changing environment. For example, when a new nutrient shows up in its neighborhood this species can build a kit to suck the nutrient in, degrade it, and turn it into cellular biomass quickly. Thus whereas humans use their genomic complexity in part to create a stable environment for the body, this species simply uses a genomic swiss army kit to make do with whatever environment it encounters."
I predict that companies will start looking at these gene sequences for application in drug development and to investigate the application of these "novel genes" in DNA repair therapies, metabolism and other applications.
I am actually pretty interested in this species from a metabolomic perspective. Organisms that can tune their physiology have a lot to teach us about the ability of metabolic networks to respond to environmental challenge or optimize their function in response to stress/disease.
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The more examples of what evolution produces, the faster we can reverse engineer our own genome and engineer/re-engineer our own cells using nanotech in the next decade to reverse aging in our own cells...after all, all the baby boomer's, who are now starting to get a sampling of what it's like to get old and infirm.
The advantage we have over previous generations, is that we now have the tools to investigate and control our own metabolic processes. After all, it would have been impossible 25 years ago to approach these questions because the cheap computing power was not available and the technology of automatic gene sequencing had yet to be developed...not to mention a great deal of the population is used to dealing with complex systems (look how many people know about programming complex computer architectures and software, which back in 1975 would have been only found at universities and industry/military environments). The best way for science to advance is to compare one system to another, so more examples of how nature evolved cellular systems speeds our understanding and control possibilities even faster!
I always find it odd that people think our DNA would be the most complex. It's really a rather stunning conceit. Single cell organisms have had millions of years to eveolve too, why shouldn't their DNA be as rich?
Very true.
Yet again I'm reminded that evolution doesn't stop and that these "simple" organisms have had just as much selection applied to their genome as the more "complex" organisms. People think of evolution as simple bacteria turning into more complicated multicellular organisms, which then turned into more complex animals and eventually the pinnacle of evolution, people.
The reality is that evolution doesn't have a goal and that single celled life is just as rich and complex as any of the more supposedly advanced life forms.
I think what the previous commenter was getting at is more of a realization that humans were not some inevitable grand finale of evolution. Much of what makes us what we are evolved as a result of chance events, and random occurances. While our minds have allowed us to thrive and deal with challenges, our physical form is by no means the last word in biological efficiency or toughness.
Were things to get really bad, (Eg: A bigass comet smashing into the earth), there are plenty of "lesser" species whos chances of survival are much better than ours. Evolution has not made humans perfect, nor made humanity invincible.
One time I threw a brick at a duck.
The human eye has a "design" error, in that the photosensitive layer is not in front, there are other cells above them. This means that the neurons that do the image processing functions in the retina must be transparent, and even so there is some absorption and scattering of light. Also, we have a blind spot in the retina where the optical nerve crosses the photosensitive layer.
In mollusks, OTOH, the outer layer of cells is the photosensitive one. The eye is more sensitive to light, has no blind spot, and allows for more data processing in the retina itself. That may be one of the reasons why octopuses are so good at camouflage, their eyes are very sensitive.
All this is one more argument for evolution and against the "intelligent design" theory.
>We're all for teaching science in the classroom.
....
No we aren't.
We're all for legal immigration.
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We're all for stopping illegal immigration.
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We're all against any form of terrorism.
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We're all for reducing the deficit.
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We're all against child pornagraphy.
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You don't speak for a lot of people. How about we all agree to not agree with you since we have our own beliefs and opinions? Mmmmkay?
...isn't necessarily a representation of the number of actual protein products that a genome produces. Part of what makes humans so complex is the number of genes that produce multiple proteins. It isn't unique to humans, but is especially prevalent.
Beadle and Tatum's original hypothesis that "One gene encodes one enzyme" no longer holds true. Mechanisms such as alternative splicing and epigenomic effects (gene activation and silencing) can cause one gene to produce many isoforms, each which may be active differently between tissue types, and each which may have entirely different functions. Our 27,000 genes are quite possibly far more complex than another species 27,000.
All I have to say is: Single Cell Swiss Army Knife + Spore = Pwnage
Oh, and if we survive after the sun envelopes the Earth, I think it's pretty likely that we'll take bacteria with us - and that we'll find bacteria already there when we get where we're going!
[javac] 100 errors
Bacteria don't have a space program. Therefore, they're fucked when the Sun expands. We're not.
;-), but most of it escapes the Solar System.
Don't bet on this.
Back in the 1960s and 70s, there were a number of papers written by astronomers about the Earth's "dust tail", equivalent to a comet's tail, and made of particles of the outer atmosphere blown off by the solar wind. This was of some significance for long exposures in the part of the sky behind the tail.
The studies showed that the Earth's dust tail is mostly gases, but also includes small dust particles, including particles the size of bacterial spores. Further study showed that the upper atmosphere does in fact have a small number of such particles, including bacterial spores. More studies showed that many bacterial spores can survive conditions in space for a rather long time.
So the Earth is spewing a tail of gases, dust and bacterial spores into interplanetary space. The solar wind blows this outward. A small amount hits the outer planets (and "dwarf planets"
This has probably been going on for 3 to 4 billion years. The Earth makes an orbit of the galaxy in about 220 million years. So we've made a dozen or more circuits of the galaxy, broadcasting bacterial spores the whole time. Calculations show that these spores by now have totally permeated the galaxy, and may have reached the Magellanic clouds, but probably not more distant galaxies.
There's a certain amount of conjecture here, of course. We don't actually know that bacterial spores are viable for the millions of years that it would take to reach other star systems. Few of them would ever encounter another planet where they could wake up and start living again. But over a few billion years, with a few billion spores per year (not much mass, really), small chances add up.
Some have suggested that this could be how life reached Earth. Google for the "panspermia" hypothesis for more information. There could well be other planets in the galaxy that are similarly broadcasting bacterial spores. Some of them could have been doing it for 12 billion years or so.
It's interesting to think about. Over billions of years, the Earth may not be as isolated as we might like to believe.
Those who do study history are doomed to stand helplessly by while everyone else repeats it.