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Arsenic-based life finding fails follow-up

Tests see no evidence that microbe uses element in cellular machinery

The controversial claim that one microbe can use arsenic in its cellular machinery is mired in scientific quicksand after scientists attempting to duplicate the finding have come up empty-handed. Though the microbe in question clearly thrives in the presence of the usually toxic substance, there is no evidence that the bacterium requires arsenic to live or incorporates the element in its DNA, researchers report in a paper posted February 1 at arXiv.org.

The original study began when researchers led by Felisa Wolfe-Simon, a NASA astrobiology research fellow, cultured a microbe now known as GFAJ-1 from eastern California’s Mono Lake. The lake has an unusual aquatic chemistry rich in carbonates, phosphorus, arsenic and sulfur. Wolfe-Simon and her colleagues starved GFAJ-1 of phosphate, a combination of phosphorus and oxygen that’s an essential building block of life, and force-fed the critter arsenate, an almost identical arrangement of arsenic and oxygen.

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