PROVIDENCE, R.I. [Brown University] From a biological point of view, the world's most exotic sex lives may be the ones lived by fungi. As a kingdom, they are full of surprises, and a new one reported in the journal Nature seems sure to titillate the intellects of those who study the evolution of mating and ploidy, the complement of chromosomes in each cell.
Fungal fecundity is a seemingly anything goes world. Individual yeasts reserve the option of either sexual or asexual reproduction. Biologists remain puzzled about why, but different species predominantly maintain cells containing one (haploidy), two (diploidy), or three or more (polyploidy) versions of their chromosomes. Contrast that with the humdrum reproduction of animals who are locked into an unwavering program of sex and two versions of chromosomes in most cell types, except eggs, sperm and some others. Scientists look to yeasts to study the true variety of reproduction in the natural world.
"Fungi, in terms of sexual reproduction, are on the outer limits with what they can do, when they do it, and how they do it," said study corresponding author Richard Bennett, associate professor in Brown University's Department of Molecular Microbiology and Immunology. "There is a lot of super interesting biology in studying fungal sex. They keep surprising us."
In a study Bennett's lab published online in October in the journal Eukaryotic Cell, for example, a team led by undergraduate Riyad Seervai found that when Candida tropicalis mates, it turns diploid cells into tetraploid cells. But then it uses a mechanism other than meiosis to reduce the chromosome complement back to that of a diploid. This work was highlighted in print earlier this month.
In the new study in Nature, Bennett's team, including lead authors Christine Scaduto and Raquel Kim Sherwood (now at Yale), focused on the infectious species Candida
|Contact: David Orenstein|