News24

Scientists refute 'new life' claim

2012-07-09 12:40

Washington - Two scientific papers published on Sunday 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 the much-hyped initial study in December 2010, with lead researcher Felisa Wolfe-Simon, then a fellow in Nasa's astrobiology programme, 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 sulphur.

Contamination

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 on 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.

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".

Critics

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 furore 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 and two of her co-authors did not immediately respond to requests for comment.

Comments
  • CaptainGaza - 2012-07-09 12:52

    Gotta love the scientific-method.

  • PikesNo1 - 2012-07-09 13:03

    Don't trust the outcomes of government funded research programmes. #lifedidnotevolve

      CaptainGaza - 2012-07-09 13:10

      As apposed to privately funded programmes or are you championing religiously funded programmes?

      eddy.deepfield - 2012-07-09 13:56

      Rather trust the scientific-method than a prescience Bible. Science changes accordingly the Bible remains backward and obsolete.

      arne.verhoef - 2012-07-09 15:09

      #youreanidiot

      Peter - 2012-07-09 15:44

      The bible (KJV) is not against science only against lies.....

      zaatheist - 2012-07-09 16:08

      PikesNo1 Oh dear. A brainwashed, brain addled, unthinking clot posting in the science and technology section. Piker, you are way, way out of your depth so please go back to reading fairy tales.

  • duanne.dames - 2012-07-09 13:57

    There just seems no end to this kind of thing, there really needs to be a rethinking of journal published peer review papers. Almost immediately Wolfe-Simon's data was questioned. And strangely enough its the really out-there discoveries that get a pass. Could this be to push up the sales? The Martian meteorite ALH84001, Korean Doctor Hwang Woo-suk and now this. Come on guys, your making the stupid people look good . .

  • GodBeliever - 2012-07-09 14:18

    And scientists are supposed to be trusted.....

      mike.mcc.71 - 2012-07-09 14:31

      Yes, it is afterall scientists that are refuting the claim.

      michael.a.devilliers - 2012-07-09 14:43

      Wow, a study regarding potassium-arsenic consuming bacteria was flawed - science is wrong. Get a life.

      arthur.hugh - 2012-07-09 14:48

      Believer - over a pedo priest, yup any day.

      merven.halo - 2012-07-09 15:15

      Yes, because science and its findings is open for debate, unlike religion.

      poloyatonkim - 2012-07-09 15:19

      Yes, just like you trust your doctor not your God.

      eddy.deepfield - 2012-07-09 15:28

      @GodBeliever - Believers are in denial so much that they are forced to selectively deny science only in those rare areas where it disconfirms something found in their holy books, written by, now get this everyone, ancient superstitious pre-scientific people!

      enlightened.bowman - 2012-07-09 18:02

      well yes, dude. They just admitted they were wrong. Didn't they? What is wrog with you people? The Turin shroud has been proven through carbon dating to be fake but the church still makes a fuss of it and went absolutely berserk when they found out that someone had nipped a few fibres. Why? because of the historic value of the shroud ar because they knew carbon dating would disprove the claim. And Pleeeease, pleeease, I beg, don't come back and tell me carbon dating doesn't work. Should the church be trusted?

      gawie.vandermerwe.7 - 2012-07-09 18:50

      A quote from the article: "The scientific process is a naturally self-correcting one, as scientists attempt to replicate published results,"

  • enlightened.bowman - 2012-07-09 17:55

    Why doesn't the religious community come out in hordes to show appreciation for the fact that sciebnce is meticulous and perfectly willing to refute all that they can not prove and confirm? I think they are worried we ask the same of them!

  • enlightened.bowman - 2012-07-09 17:56

    Pikes No 1. That is a contradiction in terms.

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