Regions of the genome that determine the sexual identity of the infectious fungus Cryptococcus neoformans bear striking similarities to the human Y chromosome -- the sex chromosome associated with male characteristics -- the team found. The researchers reported their findings in the December 2004 issue of the Public Library of Science Biology (now available online).

The result suggests that, despite their differences, similar evolutionary processes shaped the chromosomal sex-determining regions in both groups, said HHMI investigator Joseph Heitman, M.D., director of Duke's Center for Microbial Pathogenesis. The fungus might therefore serve as a useful model system for the study of sex chromosome evolution and the genetic changes that can lead to infertility, he said.

"The revolution in genome sciences has rapidly accelerated our ability to elucidate the process by which sex chromosomes evolved," Heitman said. "While mechanisms of sex determination are extremely diverse, our study highlights remarkable similarities among them in widely divergent groups."

The findings might also provide new insight into the process whereby the infectious fungus spurs disease, because evidence suggests a close tie between the genes involved in sexual identity and virulence, Heitman added. The work was supported by the National Institute of Allergy and Infectious Diseases.

Sexual identity is governed by sex chromosomes in plants and animals. In humans and other mammals, males have one X and one Y chromosome, while females have a pair of X's.

In fungi, sexual identity is determined by so-called "mating type loci," genes located in a contiguous region of the genome, but which ty
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Contact: Kendall Morgan
kendall.morgan@duke.edu
919-660-1306
Duke University Medical Center
10-Nov-2004