Yeast can undergo sexual reproduction despite missing sex genes

They examined and defined the structure and functions of the mating-type genes in yeast, which helped them learn that forms of Candida yeast undergo meiosis but generate offspring of several types. About two-thirds have the classic 50:50 division of chromosomes from the split parent cell, but a third of them have an extra chromosome or even double copies of all chromosomes. "What we found is that the sexual cycle has a new way to create genetic diversity, and it provides a unique vantage point from which we can explore the mechanisms of sexual reproduction. This provides a new way to study sexual reproduction and how chromosomal abnormalities arise," Reedy said. Heitman said that Candida''s meiosis without meiotic genes might be what gives rise to the progeny with unusual numbers of chromosomes. "Or maybe the genes were lost for a reason, to provide a route to genetic diversity. Or maybe these differing types of progeny are the unfortunate consequence of undergoing meiosis without the machinery that species normally have when they reproduce sexually," Heitman said. The researchers point out that humans, too, have their share of oddly paired chromosomes. "Experts estimate that about 10 to 30 percent of human eggs or fusion products may be aneuploid, with chromosomes from mother and father not paired exactly one to one, but the great majority of those fusions of sperm and egg don''t make it to the implantation and pregnancy stage. That''s why it is important to find models like this, so that we may shed light on related human conditions," Reedy said. The findings have been reported in two research papers, published in Nature and Current Biology. (ANI) <<---Back