Sunday, February 05, 2012

What news from the ‘arsenic life’ front?

Mono Lake, CA, photo by NASA
This story has already become sort of a case study. In December 2010, NASA held a press conference about its astrobiology research program and the discovery of a bacterium from Mono Lake (CA) allegedly capable of substituting phosphorus by arsenic in its DNA. The research was published in ScienceExpress and attracted a lot of attention from the media - mostly as a consequence of the ‘hype’ factor brought by NASA, which went as far as saying that “The definition of life has just expanded”. All life on Earth shares the same DNA, whose backbone is made of sugar and phosphate. If any organism could replace phosphate by arsenate, that indeed would be very surprising and exciting.

Very rapidly, skeptic commentaries from other researchers appeared on the internet, notably on blogs. This is not so surprising, since after all the scientific claim was extraordinary - and so was the announcement of the discovery itself, quite astray compared to the scientific usage. The authors of the arsenic life paper did little to solve the controversy, since they rapidly refused to comment on criticisms that were not published in a scientific journal. 

It took Science six more months until the final paper was published, together with half a dozen comments from other scientists. The validity of the authors’ results - that is, that arsenic replaced phosphorus in the DNA -  is uncertain, to say the least.  

But one of the most interesting part of the story was the attempt by Rosie Redfield of the University of British Columbia (she was one of the first vocal critics of the arsenic paper) to repeat the experiment and perform additional tests to verify whether arsenic was truly replacing phosphorus. Her progress could be followed on her blog, which turned into a fascinating exercise of open reviewing. And apparently she found evidence against the arsenic paper's claim...

What I find of specific interest in this story is:
  • When and how a paper should be discussed? The authors' insistence that they should only discuss peer-reviewed commentaries is disappointing. Why not debating it publicly? See for instance the coverage of the arsenic life by Carl Zimmer, a very insightful discussion.
  • The way science is communicated to the public. In this case, we see how the desire to construct an 'event' (the NASA press conference about a new life form) and to embargo the results has backfired. "Never oversell your findings" might be a moral of this story.
It will be interesting to see how all this will end up. In any case, such debate makes an excellent job of enlivening the life science community!

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