Brown University researchers have discovered that Candida albicans, a human fungal pathogen that causes thrush and other diseases, pursues same-sex mating in addition to conventional opposite-sex mating.
Scientists have observed this same-sex mode of reproduction in other fungi, but this is the first time they have identified it in Candida albicans, the most common human fungal pathogen.
Details are highlighted in the August 2009 edition of the journal Nature.
"This discovery really surprised us," said Richard Bennett, assistant professor of biology in the Department Molecular Microbiology and Immunology at Brown. "Candida albicans has two mating types - a and alpha - and it was assumed that mating could only occur between these two cell types. We now know that a mechanism exists for same-sex mating, and thus sex could be more prevalent in this species than previously recognized."
Bennett is the paper's senior author, and graduate student Kevin Alby is first author. Research assistant Dana Schaefer also contributed.
Bennett said his lab learned the mechanisms of sexual reproduction for Candida albicans are both more varied and interesting than previously thought. Researchers also showed that the mechanism by which same-sex mating is driven involves high levels of mating pheromones.
Bennett sees his lab's findings as suggesting that sex can take place within a unisexual population - populations once thought to be completely asexual because they have only one of the two sexes. This can increase the opportunities for sex in natural populations of Candida cells.
The findings have broader implications for how sex occurs in related species that only have one sex.