By ELIZABETH PENNISI - AAAS - SCIENCE INSIDER
Added: Sat, 04 Feb 2012 17:16:19 UTC
The debate over whether a bacterium can incorporate arsenic into its DNA just flared up again, with the posting yesterday of a paper refuting the idea on ArXiv, an electronic preprint archive primarily used by astronomers, mathematicians, and physicists. The controversy began in December 2010, when NASA astrobiology fellow Felisa Wolfe-Simon and colleagues described online in Science a microbe called GFAJ-1, which grew, albeit slowly, in the presence of arsenic, leading the authors to conclude the bacterium had taken up the toxic element and incorporated it into its cellular components. The report, amplified by a NASA press conference, quickly lit up the blogosphere and Twitter and led to the unprecedented publication of eight critical technical comments alongside the print version of the paper.
Wolfe-Simon and her colleagues agreed to make samples of GFAJ-1 available and now one vocal critic, Rosemary Redfield, a microbiologist at the University of British Columbia, Vancouver, in Canada, has grown the bacterium in the presence of arsenic and found no evidence of its uptake in the microbe's genetic material. "The data they have supports the conclusion there is no arsenic in the DNA," comments Michael Bartlett, a chemist at the University of Georgia, Athens, who is an expert in mass spectrometry of DNA, RNA, and related molecules.
Redfield, who chronicled every twist and turn of her experiments on her blog, and is back on the authors," she says. "They are going to have to provide some better data than they did in their paper."