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Arsenic-Based Life

December 2, 2010 Leave a comment Go to comments

I can’t remember the last time I had a science post, but there was a pretty cool announcement today in the realm of astrobiology, and I can’t resist mentioning it.

One might describe astrobiology as the inter-disciplinary study of how life begins, or could begin, on Earth or elsewhere in the universe. One challenge to studying this is that we haven’t found life anywhere else in the universe. That makes it a little difficult to study life elsewhere. But what we can do instead is study life in harsh conditions on Earth, such as at deep sea hydrothermal vents. Faculty at my university study such things. I even know some of these faculty. And a few years back, my administrative duties included overseeing our Astrobiology Program, not that that made me especially knowledgeable about the field. But I did come to develop some appreciation for it. I always remember the remark of a visiting astrobiologist that this field is really going to explode when life is found elsewhere in the universe.

Meantime, we have to settle for life here. That’s the context for the news announced today. The NYT’s Dennis Overbye explains in his story in tomorrow’s paper:

Scientists said Thursday that they had trained a bacterium to eat and grow on a diet of arsenic, in place of phosphorus — one of six elements considered essential for life — opening up the possibility that organisms could exist elsewhere in the universe or even here on Earth using biochemical powers we have not yet dared to dream about.*

The bacterium, scraped from the bottom of Mono Lake in California and grown for months in a lab mixture containing arsenic, gradually swapped out atoms of phosphorus in its little body for atoms of arsenic.

Scientists said the results, if confirmed, would expand the notion of what life could be and where it could be. “There is basic mystery, when you look at life,” said Dimitar Sasselov, an astronomer at the Harvard-Smithsonian Center for Astrophysics and director of an institute on the origins of life there, who was not involved in the work. “Nature only uses a restrictive set of molecules and chemical reactions out of many thousands available. This is our first glimmer that maybe there are other options.”

Felisa Wolfe-Simon, a NASA astrobiology fellow at the United States Geological Survey in Menlo Park, Calif., who led the experiment, said, “This is a microbe that has solved the problem of how to live in a different way.”

This story is not about Mono Lake or arsenic, she said, but about “cracking open the door and finding that what we think are fixed constants of life are not.”

Dr. Wolfe-Simon and her colleagues publish their findings Friday in Science.

I find this pretty exciting.

*Responding to the notion of powers we have not yet dared to dream about, the New Yorker’s Amy Davidson asked, “Is this where we have to choose between X-ray vision and flying?”

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