New Life Form Discovered By NASA

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Arsenic-munching germ redefines 'life as we know it'

WASHINGTON (Reuters) – A strange, salty lake in California has yielded an equally strange bacterium that thrives on arsenic and redefines life as we know it, researchers reported on Thursday.
The bacteria do not merely eat arsenic -- they incorporate the toxic element directly into their DNA, the researchers said.

The finding shows just how little scientists know about the variety of life forms on Earth, and may greatly expand where they should be looking for life on other planets and moons, the NASA-funded team said.

"We have cracked open the door to what is possible for life elsewhere in the universe," Felisa Wolfe-Simon of the NASA Astrobiology Institute and U.S. Geological Survey, who led the study, told a news conference.
The study, published in the journal Science, demonstrates that one of the most notorious poisons on Earth can also be the very stuff of life for some creatures.

Wolfe-Simon and colleagues found the strain of Halomonadaceae in California's Mono Lake, formed in a volcanic region and very dense in minerals, including arsenic.




The lake is teeming with life, but not fish. It also contains the bacteria"Life is mostly composed of the elements carbon,
hydrogen, nitrogen, oxygen, sulfur and phosphorus," the researchers write in Science.

These six elements make up the nucleic acids -- the A, C, T and G of DNA -- as well as proteins and lipids. But there is no reason in theory why other elements should not be used. It is just that science never found anything alive that used them.
The researchers grew microbes from the lake in water loaded with arsenic, and only containing a little bit of phosphorus.
SCIENTISTS AMAZED
The GFAJ-1 strain of the Halomonadaceae grew when arsenic was in the water and when phosphorus was in the water, but not when both were taken away. And it grew even with "double whammy" of arsenic.

"It grew and it thrived and that was amazing. Nothing should have grown," Wolfe-Simon told a news conference.
"We know that some microbes can 'breathe' arsenic, but what we've found is a microbe doing something new -- building parts of itself out of arsenic."

Paul Davies of NASA and Arizona State said the bacterium is not a new life form.
"It can grow with either phosphorous or arsenic. That makes it very peculiar, though it falls short of being some form of truly 'alien' life belonging to a different tree of life with a separate origin," he said.

But it does suggest that astrobiologists looking for life on other planets do not need to look only for planets with the same balance of elements as Earth has.

"Our findings are a reminder that life-as-we-know-it could be much more flexible than we generally assume or can imagine," said Wolfe-Simon.
"If something here on Earth can do something so unexpected, what else can life do that we haven't seen yet? Now is the time to find out."

James Elser, an expert on phosphorus at Arizona State University, said such bacteria may be useful for generating new biofuels that do not requite phosphate fertilizers, treating wastewater or cleaning up toxic waste sites.
news.yahoo.com/s/nm/20101202/sc_nm/us_arsenic_bacteria;_ylt=Avt0QMdGizGs9eoUJ_rckSsPLBIF;_ylu=X3oDMTJnMjdmcWN0BGFzc2V0A25tLzIwMTAxMjAyL3VzX2Fyc2VuaWNfYmFjdGVyaWEEcG9zAzQEc2VjA3luX21vc3RfcG9wdWxhcgRzbGsDYXJzZW5pYy1tdW5j

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UPDATE.
Arsenic-Based Life Claim Gets Another Blow

One of the most vocal critics of a 2010 claim that a bizarre bacterium might be able to use toxic arsenic as a building block of life has now made public new research refuting that claim.
The manuscript, which is not yet peer-reviewed, appears on the site arxiv.org. This site is normally used by physicists to post pre-published papers and receive constructive criticism, but microbiologist Rosie Redfield of the University of British Columbia decided to extend that use to biology, in an effort to promote open science. She has also submitted the paper to the journal Science for publication.
"This very clearly says you can make research available and still have it submitted and considered for peer review and published, just as if you'd kept it secret," Redfield told LiveScience.
Redfield set to work on the research after a group of scientists reported in December 2010 that they had discovered bacteria in desolate Mono Lake, Calif., that could munch on arsenic to survive in the absence of phosphorus, an element long established as a critical building block of life. The bacteria, dubbed GFAJ-1, even seemed to be replacing phosphorous with arsenic in their DNA, the researchers reported in the journal Science. [Stunning Images of Mono Lake]
Extraordinary findings
This claim was surprising, because phosphorus is one of the six key ingredients of life on Earth, along with carbon, hydrogen, nitrogen, oxygen and sulfur. If an organism on Earth were found to survive without one of these building blocks, it could mean that life on other planets (as well as our own) is more adaptable than expected.
But the finding soon spurred a lively debate, with outside researchers criticizing the paper's methods. "The basics, growing the bacteria and purifying the DNA, had a lot of contamination problems," Redfield said.
Among those problems was the fact that the medium the researchers used to grow the bacteria they collected from Mono Lake had trace amounts of phosphorus. (The researchers countered that the contamination would not have been enough to sustain the bacteria.)
"That made the results very suspect," Redfield said.
So Redfield decided to test the two main claims in the paper: First, that the bacteria used arsenic to grow when there wasn't much phosphorus around and, second, that the bacteria were incorporating arsenic into their DNA.
Testing the first claim, Redfield grew GFAJ-1 in different media. She found that the bacteria grew just fine in very low concentrations of phosphorus, equal to the trace levels of contaminants in the original researchers' medium.
In the DNA
Next, Redfield and her colleagues took the bacteria grown in arsenic-rich media and extracted and purified their DNA — a more complete purification than in the original study, Redfield said. (A more purified sample means it is less likely to have outside contamination.)
"The results showed that there is no detectable arsenic in the DNA," she said.
That "detectable" qualification may be a sticking point in considering this new study a definitive refutation of the original, according to Steve Brenner, a biochemist at the Foundation for Applied Molecular Evolution in Gainesville, Fla. The best and most sensitive way to detect the arsenic in DNA would be to use radioactive arsenic in the medium. That way, if this arsenic showed up in the DNA, it would essentially flash "I'm here!" like a big neon sign.
"Your problem now is having chosen to go in and isolate the DNA without the most sensitive analytical tools at your disposal; you're not going to get to the point where you can absolutely rule out any binding arsenic," Brenner told LiveScience, referring to arsenic's supposed placement holding together the DNA backbone.
Nonetheless, he said, Redfield's first result — that the bacteria wouldn't grow in arsenic alone — suggests there is little need to go looking for the arsenic in the DNA, as there seems to be no evidence that GFAJ-1 can grow on arsenic alone. (It doesn't help that researchers need a government permit to work with radioactive arsenic, Brenner added. Few researchers have such a permit, he said, and he knew of no one testing out the original results with this method.)
Brenner said that nothing can ever be completely proven or disproven in science, but that he would have to "stretch" to come up with ways in which the original arsenic findings hold up.
The first author of the original paper, Felisa Wolfe-Simon, did not respond to a LiveScience request for comment. Ronald Oremland, a research hydrologist at the U.S. Geological Survey and the senior researcher on the first arsenic life paper, declined to respond to the new research.
"It is not appropriate for me to offer commentary upon an un-reviewed manuscript submitted to a journal," Oremland wrote in an email to LiveScience. "My comments would undermine the scientific review process. When (if) the manuscript has passed anonymous peer-review (and in this case the editors at Science) and is published in the journal, that would be the appropriate time for my comments, should I be willing to express them."
news.yahoo.com/arsenic-based-life-claim-gets-another-blow-214006119.html

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Scientists say NASA's 'new form of life' was untrue
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.
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.
news.yahoo.com/scientists-nasas-form-life-untrue-015324767.html