Monday, March 28, 2011

Biology's 'dark matter' hints at fourth domain of life

Jonathan Eisen at the University of California, Davis, Genome Center has identified gene sequences hidden within these samples that are so unusual they seem to have come from organisms that are only distantly related to cellular life as we know it. So distantly related, in fact, that they may belong to an organism that sits in an entirely new domain.  Most species on the planet look like tiny single cells, and to work out where they fit on the tree of life biologists need to be able to grow them in the lab. Colonies like this give them enough DNA to run their genetic analyses. The problem is, the vast majority of these species – 99 per cent of them is a reasonable bet – refuse to be cultured in this way. "They really are the dark matter of the biological universe," says Eisen.   link

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