MINNEAPOLIS / ST. PAUL (July 20, 2011) University of Minnesota Medical School and College of Biological Sciences researchers have made a key discovery showing that male sex must be maintained throughout life.
The research team, led by Drs. David Zarkower and Vivian Bardwell of the U of M Department of Genetics, Cell Biology and Development, found that removing an important male development gene, called Dmrt1, causes male cells in mouse testis to become female cells.
The findings are published online today in Nature.
In mammals, sex chromosomes (XX in female, XY in male) determine the future sex of the animal during embryonic development by establishing whether the gonads will become testes or ovaries.
"Scientists have long assumed that once the sex determination decision is made in the embryo, it's final," Zarkower said. "We have now discovered that when Dmrt1 is lost in mouse testes even in adults many male cells become female cells and the testes show signs of becoming more like ovaries."
Previous research has shown that removing a gene, called Foxl2, in ovaries caused female cells to become male cells and the ovaries to become more like testes. According to Zarkower, the latest U of M research determines that the gonads of both sexes must actively maintain the original sex determination decision throughout the remainder of life.
For the genetic research community this new understanding is a breakthrough. The findings provide new insight into how to turn one cell type into another, a process known as reprogramming, and also show that throughout life, cells in the testis must be actively prevented from transforming into female cells normally found in the ovary.
"This work shows that sex determination in mammals can be surprisingly prone to change, and must be actively maintained throughout an organism's lifetime," said Dr. Susan Haynes, who oversees developmental biology grants at the N
|Contact: Kelly O'Connor|
University of Minnesota