Advertisement

Something's amiss with aliens and arsenic

First, NASA hinted at a finding tied to extraterrestrial life. But it was just the discovery of arsenic-eating bacteria in Mono Lake. Then came the skeptical scientists.

December 22, 2010|By Karen Kaplan and Eryn Brown, Los Angeles Times

The stage was set by a coy news release from NASA that hinted at a discovery tied to the search for extraterrestrial life. The blogosphere went wild: Had bacteria been found on one of Saturn's moons, or life of some sort on Mars?


FOR THE RECORD:
Mono Lake bacteria: A Dec. 23 article in Section A about a bacteria from Mono Lake that may be able to survive on the toxic element arsenic quoted Harry Collins, who studies the sociology of scientific knowledge at the University of Cardiff, and said that the university is in England. It is in Wales, another part of Britain. —

Instead, it was revealed this month in the journal Science that a strange bacterium lurking in the mud of California's Mono Lake had an uncanny ability to live off the poisonous chemical arsenic and even build it into its DNA.

News reports were dewy-eyed with wonderment over the study, which challenged conventional notions of what life on Earth — or elsewhere — could look like. Then, in short measure, came the scientific trash talk.

"Flim-flam." "Naive." "Fraudulent."

An embarrassing PR gaffe? Mediocre science that got undue attention because the buildup was too sexy to resist? A case of the peer-review process gone horribly wrong?

All played a role. But mostly, the wrangling is just a turbo-charged version of the kind of debate researchers have engaged in for centuries.

"The mythology of science is that you look down the microscope and you know what's what," said Harry Collins, who studies the sociology of scientific knowledge at the University of Cardiff in England. "But it's a matter of scientists slowly coming to a consensus, and it often takes a very, very long time to reach."

It started with a far-fetched question: Could an organism survive without phosphorus, one of the six elements considered essential to all living things?

Felisa Wolfe-Simon, a young biochemist, suspected it was possible that some creatures could — if they replaced the phosphorus with arsenic, a close chemical relative that is usually toxic. (She declined requests to discuss the controversy.)

"I thought it was crazy," said Ronald Oremland, who studies how microbes metabolize toxic elements for the U.S. Geological Survey in Menlo Park, Calif. But he agreed to help test her hypothesis.

Their research team collected bacteria from arsenic-rich Mono Lake. When they brought the bugs back to the lab, they grew some of them in a broth with only trace amounts of phosphorus and increasingly higher concentrations of arsenic. Tests strongly suggested that the bacteria not only survived, but had incorporated the arsenic into their DNA and other cellular machinery, where it appeared to be standing in for phosphorus.

"We couldn't believe it, but it worked," Oremland said last week at a geophysics conference in San Francisco.

The organisms could survive under conditions long assumed to be incompatible with life. And if it was true in this case, then other such creatures might exist on this planet — or in worlds beyond.

That prospect tickled NASA, which studies the origins of life and searches for evidence of it elsewhere in the universe. The space agency's astrobiology program funded Wolfe-Simon's long-shot inquiry.

But perhaps it went overboard in teasing the results.

"I believe in the field of astrobiology … but I think this was overhyped," said Rocco Mancinelli, a member of the NASA Astrobiology Institute based in Mountain View, Calif. "NASA should have known better."

Editors at Science did a cursory review of NASA's news release, but with work piling up before Thanksgiving, they didn't give it a thorough read, said spokeswoman Ginger Pinholster. "In hindsight, I surely wish that we had," she said.

Dwayne Brown, the NASA public affairs officer who wrote the release, defended it as a "factual statement." "Clearly 'extraterrestrial' is a buzzword, but there was no intent to hype anything," he said.

It didn't take long for skeptical scientists to dig into the report to see if all the hoopla was justified.

"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," Rosie Redfield, a professor of cell and developmental biology at the University of British Columbia in Vancouver, wrote in her blog "RRResearch."

University of Colorado microbiologist Norman Pace, who helped pioneer the study of unusual organisms and co-wrote a 2007 report commissioned by NASA on the potential for extraterrestrial life, called the study borderline fraudulent.

"It should not have been published," he said in an interview.

One of Pace's primary objections is that the bacteria weren't completely deprived of phosphorus. The broth contained more phosphorus than some parts of the ocean that are known to support life.

He and other critics added that if the microbes had incorporated arsenic into their DNA, those molecules should have been too unstable to stick together when researchers washed them with water.

Advertisement
Los Angeles Times Articles
|
|
|