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Discussion in 'Current Events' started by obeygiant, Dec 2, 2010.
Cue x-files music.
Heard about this on the radio yesterday
Hope it is truly interesting and not just a huge letdown
I just hope this isn't a funding plea. I hate to see NASA's budget get cut, but I would really hate to see them pull a stunt to try to prove their worth.
Oh, and they found little brown men on Uranus.
i think it will be the discovery that [terrestrial] bacteria can thrive in an arsenic-rich environment.
it's important because it shows that life can evolve-coexist in environments that we thought incompatible with it, therefore increasing the possibility to find life somewhere, or that it could have evolved in something biochemically very different from what we are,
nothing to do with the actual discovery of extra-terrtrial life. just of other possibilities for extra-terrestiral life.
Makes me wish I had the NASA channel on U-Verse. Sadly, it's in a higher package tier than we have.
Perhaps they found liquid water on an extrasolar planet.
Insert the Burger King/"Where Is Your God Now?" picture here.
For those who haven't bothered to click on the links honeytoast has provided, here's the scoop:
A bacterium in a California lake has been discovered that has a DNA composition different from everything else on Earth. Before today's discovery, DNA was known to be composed of six elements: carbon, hydrogen, oxygen, nitrogen, sulfur and phosphorus. This bacterium's DNA has arsenic instead of phosphorus.
What this does is confirm the possibility of life composed of elements other than what we previously deemed necessary for life, and thus throw the possibility of that life existing in previously-inhospitable environments wide open.
Long story short, "It's life, Jim, but not as we know it."
Nice euphemism, but a shower will solve that problem.
I, for one, welcome our new arsenic-eating overlords.
this is actually more exciting than i thought.
i just read the science paper and it's really cool.
when grown under strict AS+/P- conditions, the bacteria incorporate arsenic anywhere the phosporous is usually found.
so DNA, RNA, lipids, proteins. even ATP uses As (ATAs?). Arsenate is very unstable and is arsenic is toxic through various mechanism. An Arsenic atom is also more than twice as big as a phosphate atom.
the bacteria have found a way to be able to accommodate arsenic in every enzymatic reaction where normally phosphate is involved, and to bypass the toxicity.
very cool stuff
So, not "carbon-based unit"s.
Why the hell did I go into English?
Granted, I'm studying SF, so I get to talk about science a bit, but it's discoveries like this that make me think I'm wasting my time.
I feel sorry for high school students of the future. The mnemonic device "CHNO(P/A)S doesn't have the same ring to it.
i've seen that lake before in california, it's in the upper sierra nevada... really high..
looks something out of mars or yellowstone national park!
Alien life found in california..... gotta be steve jobs, Apple is a alien plan to control & brainwash the world Several members on here, who shan't be named, are his evil sidekicks ... it's like Mars Attacks.
Hahah I Jest, bit disappointing really, could at least announce life found on another planet.
The whole "astrobiology" angle was a little misleading since they found the new life form here on earth. Otherwise the implications are enormous.
also it would be interesting to see if the actual bacteria in the wild can do that so efficiently or if it is in part due to the in vitro evolution that was applied during the experiment to amplify the bacteria to study them.
but it is also true that this re-defines to some extent what 'life' is and what conditions amenable to life could be, expabding those tremendously.
in addition, if Arsenic can substitute Phosphorous, you got to wonder whether the classic Sci-fi darling of Silicon-based lifeforms (instead of Carbon-based) is inded occurring somewhere. Or maybe Selenium/Sulphur substituting Sulphur/Oxygen.
I tend to agree with Richard Dawkins here. They haven't actually shown that the bacteria are substituting arsenic into their DNA, they just assume it. They should have tested the assumption before making the press release.
I heard the scientist who made the discovery talking on NPR's Science Friday. http://www.sciencefriday.com/program/archives/201012033 for the clip.
Having done work on phosphorus in plants, I am really intrigued. Something to remember is that when you introduce the bacteria into a P- environment, they will carry a small amount of Phosphorus with them. So there wouldn't be a complete lack of Phosphorus, but a severe dilution would occur over a couple generations. How the phosphorus and arsenic interact in the same system would be fascinating.
although artifacts and mistakes are always possible in science, i tend to disagree here.
the mass spec analysis does show incorporation of arsenic in purified fractions that are consistent with its being used in place of phosphorous.
besides, the fact that the bacteria grow on As+/P- media but not on As-/P- shows that their continued growth is due to the usage of Arsenicum and not to contaminant phosphorous in the media or to phosphorous that might have been carried along from before within the cells, otherwise the As-/P- media would sustain growth equally well or better.
I might agree with you in principle, but how do you propose that any bacterium evolve the ability to change the materials in their DNA? With most Evolution, gradual change would do the trick, but yet a gradual substitution here would render the DNA useless and unable to replicate.
My hypothesis: It evolved some type of vacuole pouch that can help it cope with arsenic.
it is still unclear what the vacuoles do, but clearly have something to do to the neutralization of the toxic aspects of arsenic and/or to the stabilization of arsenate.
my take is that the real problem with arsenic is that of stability: arsenate has to accommodate the much larger As atom instead of the P atom, so all the O are more unstably coupled and are easily lost through hydrolysis.
the bacteria have evolved a way to stabilize the arsenate. once that is done, the arsenic can be used in place of phosphorous productively (even though not efficiently as P itself).
from an evolutionary perspective, you'd have had multiple stages (possibly still hanging around in mono lake) where the bacteria is just resistant to Arsenic, without using it for its metabolism, so the vacuoles might be involved in that.
the arsenic level is high but not to the point that it prevents life in the lake, which is not 'dead' (although water diversion to feed LA almost killed it by halving the water and doubling the salinity)
Also consider that mono lake is and extreme environment also for other reasons, in particular the high salt concentrations and very alkaline conditions, so it's possible that water exclusion due to the high-salt adapted metabolism is involved in the Arsenic resistance/incorporation
Further news. http://www.slate.com/id/2276919/
i suppose some of the critics are experts of the field, so I imagine some of these critiques are legit.
i thought that the 'contaminant' argument went out of the window because the bacteria would not grow on media in which the salt was added, but not the arsenic, whereas it grew on media containing only arsenate, only phosphate or both.
if they are growing on contaminants from the salts, they should also grow on the As-/P- media. I should re-read the paper.
in any case this is a very easy experiment to reproduce (or fail to reproduce), so we should find out very soon whether the claims are true or not.
it wouldn't be the first time that high-profile research turns out to be false, mistaken or even completely made up.
but the beauty of science is that if it is, it's going to come out, sooner than later. and the more relevant the claims, the quicker they are put to test.
I would be very disappointed, however, if this was the case.
You must be some kind of biologist or something? You seem very knowledgable.
sort of, although microbiology is not my specialty. My research is more in the cell biology/cancer biology area, but with a lot of chemistry/pharmacology in it.