Friday, July 30, 2010

genome surprise!!!

Wired | The ebola virus is one of the nastiest pathogens known to man. It corrodes blood vessels and stops clotting, leaving most of its human victims bleeding to death through their pores. And guinea pigs — along with opossums, wallabies and insect-eating bats — have it in their genes.

A genomic hunt for virus genes traced sequences to Ebola and the closely related Marburg virus in no fewer than six vertebrate species. Echoes of the less-gruesome borna virus family appeared in 13 species, including humans. The genes appear to have been mixed in about 40 million years ago, and have stuck around ever since.

“Some of these sequences have been conserved,” and that’s almost certainly not a coincidence, said cell biologist Ann Marie Skalka of the Fox Chase Cancer Center. “We speculate that some of these must have provided an evolutionary advantage.”

Skalka specializes in RNA viruses, which unlike most common viruses are made from single strands of primitive genetic material, rather than DNA.

Common viruses, better known as retroviruses, insert their DNA into the genomes of infected cells. They hijack its function and, should the cell survive, leave pieces of themselves behind. Retroviral leftovers have accumulated for hundreds of millions of years in animal genomes; they account for about 8 percent of the human.

RNA viruses, however, were long thought to leave no leftovers. They float outside a cell’s chromosomes, hijacking its machinery from afar and ostensibly leaving genomes intact. But that assumption proved wrong. Fist tap Nana.