In June, biologists at the J. Craig Venter Institute announced that they had successfully transplanted the genome of one species of bacteria into another bacterial species. “This was the ultimate in identity theft,” says Venter, a biologist well known for his private-sector contribution to the sequencing of the human genome. “The chromosome [genome] that we put in took over the cell completely, and any characteristics of the original species were lost.”
The transplant team took several steps to be sure the transfer was complete. First, they added two genes to the donor species’ chromosome: one that made the cells resistant to the antibiotic tetracycline and one that made them turn blue. By dosing all the post-transplant bacteria with tetracycline and looking for blue colonies, the scientists could identify which cells had the donor DNA. Next, they tested all the blue, tetracycline-resistant bacteria for any traces of the recipient species’ genome. When they found none, they knew the bacteria must contain only the donor species’ genome. Finally, they found that all the proteins manufactured by the new bacteria were characteristic of the donor species.
This is a critical advance in Venter’s quest—which he has been pursuing for a decade—to create a fully synthetic life-form. Now, he says, it could be just a matter of months before a living cell stocked with a synthetic genome becomes a reality.
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