[ETA Dec. 8, 2010: The 'arsenic bacterium' story noted has been corrected in my Dec. 8, 2010 posting. The conclusions first reported do not seem to be supported by the evidence in the article.] There’s a podcast over at The Guardian science blogs that features last week’s story from NASA (US National Aeronautics and Space Administration) about a bacterium, living deep in a California Lake, that uses arsenic instead of phosphorus in its molecular makeup. From the Dec. 2, 2010 article by Alok Jha for The Guardian newspaper,
A bacterium discovered in a Californian lake appears to be able to use arsenic in its molecular make-up instead of phosphorus – even incorporating the toxic chemical into its DNA. That’s significant because it goes against the general rule that all terrestrial life depends on six elements: oxygen, hydrogen, carbon, nitrogen, sulphur and phosphorus. These are needed to build DNA, proteins and fats and are some of the biological signatures of life that scientists look for on other planets. [emphases mine]
Christened GFAJ-1, the microbe lends weight to the notion held by some astrobiologists that there might be “weird” forms of life on Earth, as yet undiscovered, that use elements other than the basic six in their metabolism. Among those who have speculated is Prof Paul Davies, a cosmologist at Arizona State University and an author on the latest research.
“This organism has dual capability – it can grow with either phosphorus or arsenic,” said Davies. “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. However, GFAJ-1 may be a pointer to even weirder organisms. The holy grail would be a microbe that contained no phosphorus at all.”
As the pundits note, this changes some fundamental ideas we have about life on this planet and elsewhere.
Getting back to the podcast, the hosts also cover stories about the neanderthals and the [UK] Natural History Museum’s new approach to telling the story of evolution using a ‘kid-proof iPad’.