Sharon Bickel, assistant professor of biological sciences at Dartmouth, and her colleagues reported in the March 18 issue of Current Biology that fruit flies are an excellent model organism to study how age affects meiosis, the specialized cell division that gives rise to the egg and the sperm. In humans, the incidence of births of children with Down syndrome increases with the age of the mother, according to the National Down Syndrome Society.

"Age-related meiotic defects are hard to study in humans, because it's difficult to examine how this process deteriorates in females over a span of twenty years," said Bickel. "So we wanted to find out if we could utilize Drosophila as a model system to measure a similar phenomenon. Because flies are easy to grow in the lab, it's possible to look at thousands of flies and determine how frequently mistakes during meiosis are occurring."

Bickel's team specifically measured Drosophila meiotic nondisjunction, the term used to describe faulty cell division that can result in eggs that contain too many or too few chromosomes. During female meiosis in humans, nondisjunction can give rise to eggs with an extra copy of chromosome 21 and this accounts for 95 percent of all Down syndrome cases, according to the National Down Syndrome Society.

To determine whether or not meiotic errors increased in older eggs of fruit flies, the researchers devised a strategy with Drosophila to mimic the aging process that human eggs normally undergo. In humans, each female is born with all the eggs that will develop during her lifetime. As a woman ages, so do her eggs. Drosophila females, however, constantly produce and lay ne
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Contact: Sue Knapp
sue.knapp@dartmouth.edu
603-646-3661
Dartmouth College
2-May-2003