Scientists say NASA's 'new arsenic form of life' was untrue

Jul 09, 2012 by Kerry Sheridan
File photo of the Mono Lake in Lee Vining, California. Two scientific papers appear to have disproved a controversial claim made by NASA-funded scientists in 2010 that a new form of bacterial life in the lake had been discovered that could thrive on arsenic.

Two new scientific papers have disproved a controversial claim made by NASA-funded scientists in 2010 that a new form of bacterial life had been discovered that could thrive on arsenic.

"Contrary to an original report, the new research clearly shows that the bacterium, GFAJ-1, cannot substitute arsenic for phosphorus to survive," said a statement by the US journal Science, a prestigious, peer-reviewed magazine.

Science published Sunday the much-hyped initial study in December 2010, with lead researcher Felisa Wolfe-Simon, then a fellow in NASA's astrobiology program, announcing that a new form of life had been scooped from a California lake.

The bacterium in arsenic-rich Mono Lake was said to redefine the building blocks of life, surviving and growing by swapping phosphorus for arsenic in its DNA and cell membranes.

Biologists consider these six elements as necessary for life: carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur.

Arsenic is similar to phosphorus but is typically poisonous to living organisms.

The original study needed to be confirmed in order to be considered a true discovery, and two separate teams found that indeed, the bacterium needed some phosphate to survive, and could not fully substitute arsenic to live.

NASA has conducted numerous probes at eastern California's Mono Lake, an unusually salty body of water with high arsenic and mineral levels, as it is likely to reflect conditions under which early life evolved on Earth, or perhaps Mars.

While Wolfe-Simon and colleagues acknowledged that there were very low levels of phosphate within their study samples, they concluded that this was a level of contamination that was insufficient to permit GFAJ to grow.

Two separate Science articles "now reveal that, in fact, her medium did contain enough phosphate contamination to support GFAJ-1's growth," said a statement by the magazine issued late Sunday.

One paper was written by Marshall Louis Reaves and colleagues at Princeton University, Rosemary Redfield at the University of British Columbia, and Leonid Kruglyak of the Howard Hughes Medical Institute.

Graphic on the basic elements of life. Researchers have refuted claims of a NASA-funded study that said a new form of bacterial life had been discovered that could thrive on arsenic.Text slug: Science-US-space-astrobiology-biology130 x 144 mm

It found that the bacterium was not really replacing phosphorus with arsenic throughout its DNA but "may sometimes assimilate arsenate into some small molecules in place of phosphate."

Co-author Redfield, a Canadian microbiologist, was among the first outspoken critics of the initial study.

"I don't know whether the authors are just bad scientists or whether they're unscrupulously pushing NASA's 'There's life in outer space!' agenda," wrote Redfield in a blog that ignited the web furor shortly after the paper was first published.

The other paper to refute the findings was written by Tobias Erb and colleagues at the Institute of Microbiology, ETH Zurich, and found that the bacterium, while able to live in a high-arsenic environment, still needed phosphorus to survive and grow.

Rather than being a new form of life that thrives on arsenic, Science's statement summed up the latest studies by describing the bacterium as "a well-adapted extremophile that lives in a high-arsenic environment."

It "is likely adept at scavenging phosphate under harsh conditions, which would help to explain why it can grow even when arsenic is present within the cells," said the journal's statement.

"The scientific process is a naturally self-correcting one, as scientists attempt to replicate published results," it added.

The journal did not retract the original study but said it was "pleased to publish additional information on GFAJ-1."

Wolfe-Simon said in a statement sent to AFP that the data in the new papers "are consistent with our original paper" and that she and colleagues expect to publish new information in the next few months.

"A great thing about science is that the ability to do rigorous tests with controls provides an increasingly accurate knowledge of life and the universe that is extremely useful," she said.

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antialias_physorg
5 / 5 (6) Jul 09, 2012
Why cant they just take a DNA sample of GFAJ-1 and put it under an atomic force microscope? Should be possible to distinguish arsenic from phosphorous, shouldnt it?
Instead of doing all these indirect tests.

Even if it just scavenges phosphorous and uses arsenic as a replacement in some minor molecules that would be a first indication that life-supporting stuff can be made of different atomps than CHONPS.
docmordin
5 / 5 (5) Jul 09, 2012
Why cant they just take a DNA sample of GFAJ-1 and put it under an atomic force microscope?


I have no clue; granted, in the paper (M. L. Reaves, et al., "Absence of detectable srsenate in DNA from arsenate-grown GFAJ-1 cells", Science, 2012) mentioned in the article, mass spectrometry was used to verify that only trace amounts of free arsenate existed and that arsenate was not covalently bound.

(As an aside, I do know that back when the original article from Wolfe-Simon was published, it was virtually impossible to get GFAJ-1 bacterial strains (I tried through one of my colleagues at Yale), short of going to Mono Lake, gathering my own samples, etc. I also remember Rosemary Redfield having the same problem, which is why she initially published just a very short technical comment (R. J. Redfield, "Comment on 'A Bacterium that can grow by using arsenic instead of phosphorus'", Science, 332: 1149, 2011).)
antialias_physorg
5 / 5 (2) Jul 09, 2012
Well, maybe some good will come of it. Now that the subject is controversely being debatd in scientific circles there's bound to be someone who is going to try and get a direct measurement.
infiniteMadness
1 / 5 (5) Jul 09, 2012
no matter what; this has to be somewhat embarrasing to NASA and smells like they're more focused on getting proof for their funding, then actually making valid discoveries...

Thank you, critical scientists!
TopherTO
5 / 5 (1) Jul 09, 2012
Media's insatiable appetite for sensational headlines often remove the doubts and conditions a scientist will include in their findings (re: neutrinos breaking the speed of light).
antialias_physorg
5 / 5 (6) Jul 09, 2012
Media's insatiable appetite for sensational headlines often remove the doubts and conditions a scientist will include in their findings

You are aware that this was submitted to a peer reviewed journal BEFORE the media got a hold of it (and accepted)? Scientists don't give a toss about what the mass media report on or not (or how).

If you like you can compare the mass media commenting on science to an obese fan commenting on the performance of his favorite athlete.
The opinion of someone who isn't on a par (or at least close to it) is completely irrelevant.
ubavontuba
2.2 / 5 (5) Jul 09, 2012
You are aware that this was submitted to a peer reviewed journal BEFORE the media got a hold of it (and accepted)? Scientists don't give a toss about what the mass media report on or not (or how).

If you like you can compare the mass media commenting on science to an obese fan commenting on the performance of his favorite athlete.
The opinion of someone who isn't on a par (or at least close to it) is completely irrelevant.
I think most everyone seeks approval. And sports stars really do care about what their fans think. Fan support (or not) can indeed affect the level of an athlete's play, as fans can inspire the athlete to play more vigorously (or not).

Or put more bluntly, public perceptions and attitudes affect personal perceptions and attitudes.
Temple
5 / 5 (3) Jul 09, 2012
And now we will witness the sad, yet inevitable, spectacle of science being undermined by those who have much to gain by spreading fear, uncertainty, and doubt.

No amount of overwhelmingly measured, reviewed, and supported results will be able to stand up to the masterful manipulation that can be done while citing this single study in which a single small group of biologists has been quickly reviewed and refuted by the scientific community at large.

The ultimate irony is that the circumstances surrounding this arsenic life is a perfect example of why science works so well. Even when the entire biological community would *love* it to be true, they still work hard to refute it.

That's the essence of Science: attack every notion from every possible angle, trying to tear it down. The longer an idea has been standing, the bigger the reward for toppling it. And those that are left undefeated we call Science.
Torbjorn_Larsson_OM
1 / 5 (1) Jul 09, 2012
I think the science is pretty clear.

I don't think much of the original work. It originated by Paul Davies et al taking an interest in astrobiology, and it was sloppy work.

Davies is a Templeton-funded deist, and his ideas of "a shadow biosphere" is not very biologically likely. The universal common ancestor of all observed cellular and viral life is the best observed fact of all of science, with ~ 10^2000 against multiple ancestors by way of the common genetic code.

I assume his interest in trying to observe alternate biochemistries derives from the idea that it makes life elsewhere more possible and by that roundabout human analogs more special. 'Therefore gods exist.'

But both of these are common biological hypotheses (evolving populations is easy, evolving traits is very constrained - see the uniqueness of the Elephantidae trunk. They certainly has no connection with Davies stated ultimate interests in understanding nature
Torbjorn_Larsson_OM
3 / 5 (2) Jul 09, 2012
Personal peeves and nitpicks:

The original claim wasn't "disproved", but soon revealed as unacceptable on grounds of sloppiness and now rejectable on grounds of being erroneous.

And it was embraced as a discovery as it should, but its extraordinary claim warranted extraordinary evidence. Unfortunately, if not most claims go unchecked besides peer review for reasons of science politics. (Too little to gain in repetition.) Turns out there wasn't even ordinary evidence that held up to examination.

@ antalias:

The degree of proposed substitution was low, ~ 1 in 10 000 atoms as I remember it. (The nucleotides would be used against loss towards repair, with most DNA preserved and most RNA recycled.)

It should be hard to distinguish atoms in a large molecule by size alone (an AFM would trace outline) anyway, even if the DNA backbone happens to face outwards making it theoretically possible I guess.
Torbjorn_Larsson_OM
2.5 / 5 (2) Jul 09, 2012
Speaking of Davies as deist, where is his fellow creationists with absolutely no training in science but so eager a desire to shit all over it that they visit here most every day? (Including the day when their fundamentalist text proclaim a rest, making them sanctimonious hypocrites to boot.) Their absence may be testing my otherwise untestable conspirationist idea... =D
antialias_physorg
3.7 / 5 (3) Jul 09, 2012
I think most everyone seeks approval

You seek approval from, your peers. If a child says that you're great at maths because you can add 2 and 2 then that doesn't mean you're great at maths - and if you feel that you're mathematical skills are somehow great because of a child telling you so, then you're just deluding yourself.

Fans can give athletes a push - but their opinion about the technique of the athlete is so uninformed that its worthless. With sports uninformed laymen can at least know the basics (you have a drivers license - so you at least know what driving is like. Even though that's still far from racing)
Now think of science: you may be able to train up to be a good driver in a year. But to be a good scientist - that takes a decade or more.

So, no: the public opinion doesn't matter one bit to a scientist. He's couldn't care less. I've never met one who did.

ubavontuba
2 / 5 (3) Jul 09, 2012
So, no: the public opinion doesn't matter one bit to a scientist. He's couldn't care less. I've never met one who did.
Then I guess you've never had the occasion to meet Stephen Hawking, Brian Greene, or Neil deGrasse Tyson?

All of these scientists have been all over the media espousing science to lay people. Can you really say they don't then care about lay opinions? Hardly.

Sure, not ALL scientists are of a like bent. And of those that are, few are so media savvy. But public opinion matters to most people.

The fact is, people are social animals and (generally speaking) people inherently seek public approval.

This is so fundamentally true, that to feel otherwise is classified within neurological/social detachment disorders (Aspergers, for instance).

So although you may feel you're above caring what the media says about you, I'm confident that if the media dog-piled on you, you'd feel the heat (unless you have one or more of the above mentioned conditions).
Nerdyguy
1 / 5 (1) Jul 10, 2012
You are aware that this was submitted to a peer reviewed journal BEFORE the media got a hold of it (and accepted)? Scientists don't give a toss about what the mass media report on or not (or how).


Truly entertaining stuff. I had a hearty laugh. Sometimes there are those among us who, for a variety of reasons, are incapable of understanding human nature as well as they might understand...oh, let's say...physics. The reality, of course, is that even many of the most scholarly among us actually have (and sometimes exercise) what is known as a personality. And most human personalities include copious amounts of vanity. Ever met a media whore in a science/technical circle?
antialias_physorg
5 / 5 (1) Jul 10, 2012
And most human personalities include copious amounts of vanity.

You cannot publish in a peer reviewed journal/conference if you've published before. So vanity or not - scientists publish papers first. Then, if the media finds it interesting, may come some interviews.

But seriously: the vanity crowd among scientists (in the hard sciences) is thin to non-existent (I've never met one...and I've met hundreds of scientists in my career).
You and your work lives by cooperation. Anyone who values looks over substance wouldn't last long (and would most certainly have chosen another career path, anyhow)