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NASA Science

NASA's 'Arsenic Microbe' Science Under Fire 152

Posted by CmdrTaco
from the arsenic-is-yummy dept.
radioweather writes "The cryptic press release NASA made last week that set the blogosphere afire with conjecture, which announced: 'NASA will hold a news conference at 2 p.m. EST on Thursday, Dec. 2, to discuss an astrobiology finding that will impact the search for evidence of extraterrestrial life.' may be a case of 'go fever' science pushed too quickly by press release. A scathing article in Slate.com lists some very prominent microbiologists who say the NASA-backed study is seriously flawed and that the finding may be based on something as simple as poor sample washing to remove phosphate contamination. One of the scientists, Shelley Copley of the University of Colorado said 'This paper should not have been published,' while another, John Roth of UC-Davis says: 'I suspect that NASA may be so desperate for a positive story that they didn't look for any serious advice from DNA or even microbiology people,' The experience reminded some of another press conference NASA held in 1996. Scientists unveiled a meteorite from Mars in which they said there were microscopic fossils. A number of critics condemned the report (also published in Science) for making claims it couldn't back up."
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NASA's 'Arsenic Microbe' Science Under Fire

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  • Papers and Questions (Score:5, Interesting)

    by eldavojohn (898314) * <eldavojohn@nOspAM.gmail.com> on Wednesday December 08, 2010 @09:55AM (#34485702) Journal
    I managed to find a (probably illegal) copy of this paper at pdfcast [pdfcast.org] and also the supplemental figures [sciencemag.org]. I must emphasize that I have absolutely no experience in professional biology let alone microbiology let alone geobiology. So the bulk of the refutation in the blog posting seems to focus on some procedures that the team took while the paper contains several different correlations supporting the hypothesis that arsenic is a major component in the microbe's DNA. So, for example:

    Initially, we measured traces of As by ICP-MS analysis of extracted nucleic acid and protein/metabolite fractions from +As/-P grown cells (11) (table S1). We then used high-resolution secondary ion mass spectrometry (NanoSIMS) to positively identify As in extracted, gel purified genomic DNA (Fig. 2A). These data showed that DNA from +As/-P cells had elevated As and low P relative to DNA from the -As/+P cells.

    So my question is basically what does it matter what they grew or washed the bacteria with when, in one of the many investigations, they found that gel purified genomic DNA had elevated levels of arsenic in them? Unless I'm misunderstanding what 'gel purified genomic DNA' means, I would assume that there's still several pieces of data in these experiments that point toward an organism that uses arsenic in place of phosphorous -- even if only somehow partially. Would this sort of spectrometry reveal any arsenic at all in my gel purified genomic DNA?

  • by Rooked_One (591287) on Wednesday December 08, 2010 @09:57AM (#34485706) Journal
    ... which are very distinguishable down to the DNA level - if of course of you have that kind of microscope - which NASA does...
  • by Sockatume (732728) on Wednesday December 08, 2010 @10:12AM (#34485838)

    Also, arguments in the scientific community are nothing new, and a lot controversy occurs because somebodies research infringes on someone else's predetermined view of things.

    It's telling in this case that many of the sceptical responses are coming from the researchers who pioneered arsenic-based biochemistry.

  • by vlm (69642) on Wednesday December 08, 2010 @11:10AM (#34486806)

    then redo the experiment to see whether they can reproduce the result.

    See:

    So the bulk of the refutation in the blog posting seems to focus on some procedures

    "I keep doing the wrong thing, and getting the wrong result, WTF?"

    Very much like the tired old meme that won't die of aluminum found in the brains of Alzheimers patients. Every time they sliced specimens in an aluminum microtome, they detected aluminum in the specimens.

  • by the gnat (153162) on Wednesday December 08, 2010 @11:34AM (#34487270)

    As in any other profession, some percentage of scientists are the kind of whiny, arrogant assholes that would attempt to embarrass their colleagues in a mass-market publication rather than put the critique where it belongs: The letters section of Science.

    First of all, the article in Slate was written by a science journalist (Carl Zimmer), not a professional research scientist. (Not to bash Zimmer, I think he's a good writer, but he has no personal motivation to sling mud here.)

    Secondly, if you'll think way back to. . . last week, there was a breathless NASA announcement of an imminent press conference about a game-changing discovery, which received widespread coverage in mass-market publications. We call this "science by press release". At least they actually had a paper, unlike the cold fusion debacle, but they're still guilty of shameless self-promotion.

    Lastly, most of the real debate is happening on blogs, and probably a lot of internal email chatter that we aren't aware of. I don't see anything wrong with this, for quite a few reasons. One is that it's simply an electronic, real-time version of what used to happen only at conferences and faculty meetings; people say far more savage things about each other offline. We could wait around for formal responses to get published, but there's a great deal of scientific value in this real-time analysis and dissection of flaws. I'm learning a lot, and I think we'll arrive at a conclusive answer much faster than if we had to read through several months of stilted exchanges in Science.

    The editors of major journals are often reluctant to air controversies about the papers they publish. There was a case several years ago where several scientists wrote a letter to a journal pointing out possible evidence of fabricated data in a paper; the journal made them water down the letter, and allowed the author of the original article to get away with a half-assed, evasive reply. What the editors should have done instead was demand raw data and a reasonable explanation, and thoroughly investigated the paper, but they seemed content to let the matter slide. So, what we ended up with was mob justice, and the accused scientist's reputation was quickly destroyed on mailing lists and at meetings. It turned out that he was a serial fabricator, and he may face federal charges for defrauding the NIH.

    That's a much more serious example than this one - there's no evidence that the NASA researchers did anything unethical, but there are some serious holes in the paper, and in general the evidence does not meet the standards one would hope for one of the pre-eminent scientific journals. I really hope that there's some truth in their claims, because it would be a fascinating organism to study, but the paper shouldn't have made it past peer review in this state.

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