Followup on “arsenic life”

Alchemical symbol for arsenic. Image via Wikipedia.

Some time ago, I blogged about the claim made by NASA researchers that they had found a bacterium that incorporated arsenic into DNA.  In the comments on that post, I had some updates about other researchers being very dubious of the claims.

Now Rosie Redfield, in her blog RRResearch, is keeping an open lab notebook of her attempts to replicate the original work with proper controls.  So far, she has been unable to get results anything like what Felisa Wolfe-Simon claimed, but she has more experiments to do before she can dismiss Wolfe-Simon’s claim.

So far, Redfield has been able to grow GFAJ-1 (the bacterium of interest) in low phosphate media, but not in the complete absence of phosphate, and adding small amounts of arsenate kills the bacteria.  This is the normal behavior for bacteria, and so is not surprising, but it is completely different from what Wolfe-Simon reported.  Of course, failure to grow a bacterium can come from any of several causes, so Wolfe-Simon’s claims are not definitively debunked, but things are not looking good for the arsenic-life hypothesis.

It is interesting that Redfield is keeping a more or less open lab notebook (I’m sure she has more details recorded than are in her blog).  I like to do that also (as with the Banana Slug Genomics project), but many of my projects are collaborations and my collaborators prefer to keep data secret until publication (which often takes many years).

Related articles

• Open research casts doubt on arsenic life (nature.com)
• RRResearch: Phosphate levels and DNA controls for GFAJ-1 (rrresearch.fieldofscience.com)
• Replication of arsenic life experiment not successful so far (physorg.com)
• First evidence refuting Wolfe-Simon et al.’s results (rrresearch.fieldofscience.com)
• Concerns Aired About Arsenic-Containing Bacteria (news.sciencemag.org)

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