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NASA's 'Arsenic Microbe' Science Under Fire

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."

15 of 152 comments (clear)

  1. Papers and Questions by eldavojohn · · Score: 4, Interesting
    I managed to find a (probably illegal) copy of this paper at pdfcast and also the supplemental figures. 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?

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    My work here is dung.
    1. Re:Papers and Questions by __aagctu1952 · · Score: 4, Informative

      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?

      From Rosie Redfield's critique:

      Could 400 atoms of arsenate per genome be due to carryover of the arsenate in the phenol-chloroform supernatant rather than to covalent incorporation of As in DNA? The Methods describes a standard ethanol precipitation with no washing (and no column purification which would have included washing), so I think some arsenate could easily have been carried over with the DNA, especially if it is not very soluble in 70% ethanol. Would this arsenate have left the DNA during the gel purification? Maybe not - the methods don't say that the DNA was purified away from the agarose gel matrix before being analyzed. This step is certainly standard, but if it was omitted then any contaminating arsenic might have been carried over into the elemental analysis.

    2. Re:Papers and Questions by eldavojohn · · Score: 4, Insightful
      From your own quote:

      Would this arsenate have left the DNA during the gel purification? Maybe not - the methods don't say that the DNA was purified away from the agarose gel matrix before being analyzed. This step is certainly standard, but if it was omitted then any contaminating arsenic might have been carried over into the elemental analysis.

      Seriously? Her criticisms rely on the assumption that they skipped a 'standard step' and didn't delve into it in their paper? Who's being the presumptuous one now?

      I think it's pretty common for field to omit standard procedure in their papers lest they become too long and verbose. Hopefully NASA and the team get a chance to respond to these comments although it's looking like a landslide right now.

      You know that there are going to be a ton of researchers that are going to want to reproduce these tests so it's only a matter of time.

      I did enjoy that blog post though:

      The authors never calculated whether the amount of growth they saw in the arsenate-only medium (2-3 x 10^7 cfu/ml) could be supported by the phosphate in this medium (or maybe they did but they didn't like the result).

      At times that blog reads more like politics than science. Yeah, it's an extraordinary claim, I guess we should just get used to this sort of reaction whenever something game changing is claimed.

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      My work here is dung.
  2. They said they used radioactive tracers... by Rooked_One · · Score: 4, Interesting

    ... which are very distinguishable down to the DNA level - if of course of you have that kind of microscope - which NASA does...

  3. Re:NASA is becoming sad... by arkane1234 · · Score: 4, Insightful

    That tends to happen when we live in a time when warfare in multiple countries is worth more than expanding the knowledge.
    I mean, at least WW2 produced SOMETHING that altered science... the atomic era. What do we have... Remote-control planes? better guns?
    On top of it, mothballing existing projects... ugh
    Why does it seem like we're in high school and the asshat "cool" kids have taken office?

    --
    -- This space for lease, low setup fee, inquire within!
  4. Not true. Europa FTW. by tetrahedrassface · · Score: 4, Insightful

    The paper made it through peer review. It was published by Nature, and while the peer review process and closed nature of Nature Publishing may not be perfect the paper was in fact reviewed. However NASA is in go-mode, and they desperately want to find life out there. Maybe when they really get serious about finding life they will send a probe down to Europa and sniff around. No telling what they will find.

    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. We still don't know about dark matter very well, or even it exists, we still don't know so many things about almost everything! Text books continue to be updated every year, and the current consensus on big things like String Theory, or whatever are laid down to us as authoritative law, yet rescinded just as quickly when we learn something new. This reminds me of the global warming debate a little bit.

    Scientists sure like to argue a lot. :)

    1. Re:Not true. Europa FTW. by Sockatume · · Score: 4, Interesting

      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.

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      No kidding!!! What do you say at this point?
  5. Re:Of course it's under fire by __aagctu1952 · · Score: 5, Insightful

    If a scientist other than themselves didn't make the discovery, it's obvious the other guy's methods are flawed!

    Scientists can be such whiny, arrogant assholes...whatever happened to science being done for science, rather than recognition?

    You do realize that criticizing research is a crucial part of the scientific method, right? Letting claims go unchallenged is the domain of religion, not science.
    People are ripping apart this paper because it makes grand claims based on a potentially flawed methodology. If the results can be replicated with those flaws fixed, then the NASA team's research recieves further validation. If not, hey, I guess they jumped the gun. Either way, you have to identify the potential flaws, which is what people are doing here.

    Also, to once again quote Rosie Redfield:

    There's a difference between controls done to genuinely test your hypothesis and those done when you just want to show that your hypothesis is true.

  6. This is how science works by edremy · · Score: 4, Insightful
    I'm teaching a course in the scientific method and controversial theories this semester, and this is such a perfect example of how science is *supposed* to work. This isn't cold fusion- the original paper passed peer review and was published in Science, not exactly a bottom-feeder journal. NASA is making the organism itself available to anyone who wants it- run your own tests and see if the science stands up.

    If it does- awesome. Really neat microbiology

    If it doesn't- well an awful lot of published papers turn out to wrong. Acknowledge the mistake and move on.

    I see comments about how peer review failed. I'm not a microbiologist so I can't judge if there were any really obvious errors, but peer review isn't supposed to verify claims in papers- it's a sanity check to make sure that nothing blatantly wrong gets through. Given that Science is the 2nd highest impact journal out there I'm sure they have competent peer reviewers available. Is it possible they screwed up? Sure, but it's not a catastrophe: we're seeing science self-correct in exactly the way it's supposed to.

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    "Seven Deadly Sins? I thought it was a to-do list!"
  7. Re:The Scientific (Publication) Process by emt377 · · Score: 5, Informative

    Wait, wait, wait. The whole point of publication is to open up your results so that other scientists can poke holes in it and the science can be redone and improved upon. Isn't it kind of a bogus statement say something like "this paper shouldn't have been published"? And with outrage, no less. Could the science really have been that bad and still be approved for publication to begin with? It must have been subject to at least a bit of peer review prior to its release. How come no one was outraged about the guy who reinvented integration (http://science.slashdot.org/story/10/12/06/0416250/Medical-Researcher-Rediscovers-Integration)?!

    The paper spurs justified criticism of methodology; that's perfectly reasonable. What ruffles people's feathers is using the resources of NASA to peddle their results in highly hyped press conferences. The lesson here is that if you're going to do that your research better be airtight. And that would include correlating the research by others using different methods. What they have in no way correlates with the presentation, which makes them look like used car salesmen.

  8. Re:NASA is becoming sad... by Sockatume · · Score: 5, Insightful

    They've assembled a space telescope, landed several autonomous rovers on Mars that have exceeded their mission profile tenfold, have a squadron of probes out in the gas giants, another heading for Pluto, a next-generation space telescope the size of a bus is currently under construction. NASA's got a lot of problems but the selectivity of your examples is comical, and your argument bewildering. It's not like the rocket guys go on holiday when the astrobiologists decide to start working on something.

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    No kidding!!! What do you say at this point?
  9. Re:Yes, but we expect BETTER of our betters by the+phantom · · Score: 4, Insightful

    Except that your depiction of the debate is incorrect. In reality, it looks more like this:

    Wolfe-Simon et al.: We have made an extraordinary claim!
    Redfield et al.: Your methods appear to be flawed.

    And that is as far as we have gotten. In other words, the process is working.

  10. Re:Of course it's under fire by the+gnat · · Score: 4, Interesting

    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.

  11. Re:Of course it's under fire by jpmorgan · · Score: 4, Insightful

    Peer review isn't done in blog posts.

  12. Re:NASA is becoming sad... by gad_zuki! · · Score: 4, Insightful

    I hate how cynical and ignorant mods mod people like you up.

    First off, you are engaging in the fallacy of idealizing the past, a particular popular fallacy on slashdot. I find the more recent NASA accomplishments a lot more impressive than just lobbing meatbags onto the nearest satellite. Robotic rovers on mars, stardust mission, all manner of flybys and good space science, planetary probe hubble and webb in 2014, etc, Heck, we just had a god damn comet flyby last month.

    You want expensive moon missions? Convince your fellow voters to trim 100+ billion off our bloated military budget and to put into NASA. NASA gets a paltry 17 billion annually. We spend almost that much of corn subsidies. Your defense budget is 700 billion.

    Dont blame NASA because your democracy is broken and prefers to invest its money on war, defense, subsidies, and science last. Its amazing what NASA is doing with such small amounts of money.