Yeast can undergo sexual reproduction despite missing sex genes

Researchers at the Duke University Medical Center have found that an emerging form of the pathogenic yeast Candida can complete a full sexual cycle in a test tube, even though it is missing the genes for reproduction. The researchers say that the yeast may also do so while infecting people. "Sex contributes to the Candida yeast species'' evolutionary success. I think the fact that it has a complete sex cycle is likely to play a role in the evolution of drug resistance in this emerging pathogenic yeast species," said Dr. Joseph Heitman, director of the Center for Microbial Pathogenesis in the Duke Department of Molecular Genetics and Microbiology. Yeast infections are notoriously hard to treat. Humans are susceptible to three types of yeast infection: in the mouth and throat, vaginal infection, and a sometimes fatal systemic infection of bloodstream and organs, such as the kidney. Heitman's team have identified eight Candida species that have a sexual cycle, but lack many of the genes related to reproduction found in other species. "The unrecognized sex cycle could mean we need to develop new treatments to combat what is really happening in humans infected by yeast," said co-author Dr. Jennifer Reedy. The researchers then conducted another study to determine how could the yeast sexually produce spores when they lack so many genes responsible for meiosis, the process of sexual cell division that reduces chromosomes to half their number in the progeny. Next--->>