Ancient DNA defense still protects

Gorovsky

A new discovery by Martin Gorovsky, Rush Rhees Professor of Biology, and his postdoctoral colleague Kazufumi Mochizuki reveals that an ancient DNA defense mechanism still offers protection for modern-day organisms.

The mechanism, a complex correction system, ensures that any foreign genetic material that has been inserted into a cell's DNA is neutralized before being passed on to the next generation. The research, which was published in the September 20 issue of Cell, is reviewed in the recent issues of Science and Journal of Cell Biology.

Researchers discovered the mechanism while looking at a single-celled organism called Tetrahymena, which contains two nuclei, the area of a cell where DNA is usually stored. The members of the University team wanted to learn how the cell transfers its genetic code from one of its nuclei to one in its offspring, so they monitored each step as the cell inspected its DNA and passed it to the next generation.

Gorovsky and Mochizuki, who are already planning to look deeper into the way the cell's defense mechanism works, believe that in evolutionarily ancient times, cells had to fight against a variety of assaults just as they must today. To survive, cells evolved a correction system that recognized the invading DNA and either eliminated or silenced it.

"This is exciting research that provides new understanding of how cells control the activity of their genes," says Joseph Gall, a cell biologist at the Carnegie Institution in Baltimore. "This work shows once again that basic research on a seemingly obscure topic--how a minute pond organism reproduces--can throw light on important medical issues such as viral infection."

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