I’ve rarely seen a critique this strong in the reviewed scientific literature. It’s about Wolfe-Simon et al.’s paper in Science suggesting that a bacterium could incorporate arsenic instead of phosphorus in DNA and biomolecules. Simon Silver and and Le T. Phung take strong issue with this in a piece in the “current controversies” section of FEMS Microbiology Letters, “Novel expansion of living chemistry or just a serious mistake?” Simon and Phung suggest that although arsenic could have been taken up by the bacteria when they were grown in vitro, there is no evidence that it was sequestered in DNA or other places save perhaps in vesicles, where the desperate bacterium was trying to remove it.
Note, this is not post-publication peer review on a blog, but a critique in the published literature. And it’s strong from the outset. Take a look at this abstract:
The recent online report in Science (Wolfe-Simon et al., 2010; http://www.sciencexpress.org) that a newly isolated bacterial strain can apparently replace phosphate with arsenate in cellular constituents such as DNA and RNA either (1) wonderfully expands our imaginations as to how living cells might function (as the authors and the sponsoring government agency, the USA NASA, claim) or (2) is just the newest example of how scientist-authors can walk off the plank in their imaginations when interpreting their results, how peer reviewers (if there were any) simply missed their responsibilities and how a press release from the publisher of Science can result in irresponsible publicity in the New York Times and on television. We suggest the latter alternative is the case, and that this report should have been stopped at each of several stages.
Some of the meat:
The questionable conclusion of the paper appears as an established fact in the abstract (first paragraph of the report): ‘arsenate in macromolecules that normally contain phosphate, most notably nucleic acids and proteins.’ There are no data to support this claim, which is repeated. . . . There is no reason to conclude (as the authors have in their penultimate sentence) that they have found life ‘substituting As for P’.
And the conclusion, which tries to exculpate two authors from participating in the paper’s hype (and, I believe, lay the blame for that hype at the door of Wolfe-Simon):
One caveat: we consider two of the senior-scientist authors, R.S. Oremland and J.F. Stolz, to be microbiologists who have contributed in major ways to the understanding of the environmental microbiology of arsenic in recent years (including three reports published in Science in the last 10 years and several in FEMS journals). These caused no antihype flak. We hope our long-term relationships can survive this entirely negative and uncompromising analysis of their new report, which would have been much better handled before publication (Obama style over a bottle of beer), rather than with the excessive Internet hype that the authors initiated and the controversy that developed on newspaper and journal pages. However, this is only a current example of a report, where basically no one who can form a detailed technical opinion believes the conclusions (except the authors), based on the data shown. It is a sad story, reminiscent of the quip: déjà vu – all over again!
Silver, S. and L. T. Phung. 2011. Novel expansion of living chemistry or just a serious mistake? FEMS Microbiol. Lett 315:79-80.