Late in 2010, scientists participating in a NASA news conference dropped a bombshell: they had found evidence that bacteria in California's Mono Lake were metabolizing arsenic and using it in their life processes. This was huge news, since arsenic is toxic for carbon based life. If some forms of life evolved a way to process it, this would open up a whole new field of biochemistry! However, almost immediately, the work came under attack. Biochemists accused the original team of not performing the research carefully (to put it delicately). Rosie Redfield, a microbiologist at the University of British Columbia in Vancouver, was particularly critical. She decided, in fact, to try to verify the original work, and set out to do so openly, writing up her progress on her blog. And now, according to an article on Scientific American, she can confidently provide a "clear refutation" of the arsenic uptake in the organisms:

Their most striking claim was that arsenic had been incorporated into the backbone of DNA, and what we can say is that there is no arsenic in the DNA at all.

That's a pretty clear statement! The original team, lead by Felisa Wolfe-Simon, has responded, saying they need to see a fully peer-reviewed paper before making up their minds. I'll note that emotions have run fairly high throughout this saga. Dr. Wolfe-Simon got a lot of attention, positive and negative, and the negative was pretty charged. I'm not surprised by the reactions of either side of this issue. In the interest of full disclosure, when the press conference was aired, I wrote a pretty straight interpretation of it. As I wrote in a followup post, I am not a microbiologist, and I trust NASA at some level. This event shook that trust quite a bit, and I am now far less likely to take a claim at face value, even when it comes from a source like NASA. Science is a balance of trust versus skepticism, even at the best of times. An extra layer is added when the media become involved; that impartiality which is always precarious can be sorely tested by the chance at media exposure. That includes my desire to write about something particularly cool, of course, as well as the more fundamental results obtained from the scientific research itself. I'm glad this news has come out, and I'll be curious to see what happens next. Dr. Redfield will need to submit her team's work to the peer review process. Assuming it survives, I have little doubt we'll be hearing from Wolfe-Simon again as well. In the Scientific American article, Dr. Redfield is quoted as saying, "We've done our part. This is a clean demonstration [that the original positive findings were incorrect], and I see no point in spending any more time on this." That may be true for her and her team's work, though I have a suspicion more work will have to be done either by her or other teams to categorically rule out the arsenic. But either way, what I can be certain of is that we are not done hearing about this story just yet.

Tip o' the phosphorus backbone to Jeffrey Sullivan on Google+.

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