Arsenic based genome

The accumulation of small heritable changes within populations over time.

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Arsenic based genome

#1  Postby iMMz » May 29, 2011 4:39 pm

So I came across this article months ago:

http://gizmodo.com/5704158/nasa-finds-new-life

Then today I read this:

http://www.washingtonpost.com/national/ ... story.html


So the TL;DR...

We have found bacteria that uses arsenic in its genome as opposed to the elements we are familiar with. If this is true it would change all the laws of life as we currently have written because according to thermodynamics having an arsenic backbone would not be feasible at all, it would just spontaneously combust everytime the rogue molecule was formed by chance (which is leading other to believe there is another piece of the puzzle. NASA is obvi pumped because they say it opens a whole new door for extraterrestrial life, and rightly so. Not everyone is satisfied though, three major critiques (which I will just copy/paste from the 2nd article)

1.One of Wolfe-Simon’s loudest critics, who accused her in December of sloppy lab work, is zoologist Rosie Redfield of the University of British Columbia. In the batch of eight critiques released Friday morning, Redfield flatly states that Wolfe-Simon’s dishes of bacteria were contaminated and that the scientist failed to properly purify the bacteria’s DNA .

2. Another critique, from Steve Benner at the Foundation for Applied Molecular Evolution, points out that the arsenic compounds supposedly employed by the bizarre bacteria would fall apart in DNA — not hold together as required.

3. A third attack highlights other microbes that can live on tiny amounts of phosphorus, and argues that Wolfe-Simon’s bacteria were probably doing the same.


So keep your eyes open. If there are updates in the matter I will post them here.
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Re: Arsenic based genome

#2  Postby Rumraket » May 30, 2011 6:22 pm

Yeah it seems the safest bet is to assume the claims are false until properly shown otherwise.
http://scienceblogs.com/pharyngula/2011/05/further_panning_of_the_arsenic.php

PZ Myers wrote:Science magazine has published the formal criticisms of the claim to have found extremophiles that substituted arsenic for phosphorus in their chemistry. It's a thorough drubbing, and the most disappointing part is that Wolfe-Simon's rebuttal simply insists that they were right, and doesn't even acknowledge that many valid criticisms of the study were made. That's not how you do it. Instead, she should answer the complaints by saying that they will do the experiments in a way that specifically addresses the perceived shortcomings of the study; she and her lab have their credibility invested in this research now, and the answer to the barrage is not to batten down the hatches and do nothing, but to do more experiments to show that the critics are wrong.

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Re: Arsenic based genome

#3  Postby iMMz » May 30, 2011 7:28 pm

I don't know why she is being THIS defensive about it. The least she should do is acknowledge that she MIGHT be wrong because if time proves all this to be false nobody will ever take her seriously again.
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Re: Arsenic based genome

#4  Postby DavidMcC » Jul 10, 2012 1:07 pm

An end to this at last?:
http://www.nature.com/news/arsenic-loving-bacterium-needs-phosphorus-after-all-1.10971
After 18 months of controversy, the official verdict is in: an arsenic-tolerant bacterium found in California’s Mono Lake cannot live without phosphorus.
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Re: Arsenic based genome

#5  Postby Godless Infidel » Jul 10, 2012 4:29 pm

I was listening to Rosie Redfield present this story on Sunday. Her Papers were officialy published during the talk.
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Re: Arsenic based genome

#6  Postby DavidMcC » Jul 11, 2012 10:16 am

It would still be good to know how exactly the little bit of phosphorus is used. Is it in the bases or some amino acids, or both?
I suspect it's mainly the bases, because the shape of DNA gets distorted when large As atoms replace P, but proteins would simply fold differently. A distorted helix probably couldn't replicate or allow gene expression, because the enzymes involved might not work properly. That's only a suspicion, I don't know for sure.
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Re: Arsenic based genome

#7  Postby Microfarad » Jul 13, 2012 4:59 pm

DavidMcC wrote:An end to this at last?:
http://www.nature.com/news/arsenic-loving-bacterium-needs-phosphorus-after-all-1.10971
After 18 months of controversy, the official verdict is in: an arsenic-tolerant bacterium found in California’s Mono Lake cannot live without phosphorus.

Just an high tolerance. Pity.
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