Storify Feed Feedburner Facebook Twitter Flickr Youtube

ROS Lboard

Scientists say NASA’s ‘new form of life’ was untrue

July 9, 2012

WASHINGTON: Two scientific papers published 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 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.

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

-AFP


Comments

Readers are required to have a valid Facebook account to comment on this story. We welcome your opinions to allow a healthy debate. We want our readers to be responsible while commenting and to consider how their views could be received by others. Please be polite and do not use swear words or crude or sexual language or defamatory words. FMT also holds the right to remove comments that violate the letter or spirit of the general commenting rules.

The views expressed in the contents are those of our users and do not necessarily reflect the views of FMT.

Comments