From The New York Times:
A new kind of machine for decoding DNA may help bring costs so low that it would be feasible to decode an individual’s DNA for medical reasons. The machine, developed by 454 Life Sciences of Branford, Conn., was used to resequence the genome of a small bacterium in four hours, its scientists report in an article published online today by the journal Nature. In 1995, when the same bacterium was first sequenced, by Claire M. Fraser, it required 24,000 separate operations spread over four to six months, she said in an e-mail message. The machine uses the chemistry of fireflies to generate a flash of light each time a unit of DNA is correctly analyzed. The flashes from more than a million DNA-containing wells, arrayed on a credit-card-sized plate, are monitored by a light-detecting chip, of the kind used in telescopes to detect the faintest light from distant stars. Then, they are sent to a computer that reconstructs the sequence of the genome.