ATHENS, Ga. -- Some viruses are easy. They run their infective course, do little damage and then look for another host. Medical researchers have found ways to treat the effects of such viruses by eliminating symptoms or hurrying them on their way. Other viruses are killers.
Especially difficult has been a class called retroviruses, which includes HIV, the cause of AIDS. These viruses are the quick-change artists of the microbial world and outrun both the immune system and medicines designed to fight them. And important in understanding retroviruses are retrotransposons -- pieces of DNA closely related to retroviruses.
Now, researchers at the University of Georgia have uncovered intriguing new clues about the evolution of retrotransposons in a genome -- evidence that could serve as a model system for understanding why retroviral elements evolve so quickly.
"This is the first study to show that transposons exchange genetic information," said Dr. John McDonald, head of the genetics department. "Our study indicates that invading retroviruses may pick up genetic information from other retroelements already present in the genome and thereby evolve at a faster rate."
The study, with Dr. King Jordan, a recent graduate in genetics at UGA, was just published in the July issue of the Journal of Molecular Evolution.
Until the 1970s, scientists thought transposons were simply pieces of "selfish" DNA that roamed around in the cellular world. It soon became clear, however, that retroelements are pervasive. Researchers then understood that retroelements must have a crucial role in the functioning of plants and animals if they had been conserved over thousands of millennia.
Jordan and McDonald chose to study the evolution of yeast retroelements because the genetic sequence of the Saccharomyces cervisiae genome was the first to be completed.