Meiotic Gene Conversion: A Signal of the Basic Recombination Event in Yeast

Gene conversion, a phenomenon described more than 50 years ago, may be defined as a departure from the meiotic segregation ratio expected for a heterozygous genetic marker which is not ascribable to conventional genetic mechanisms such as polyploidy, suppressors, or multiple gene control. This phenomenon is most readily studied in organisms in which all the products of individual meioses are preserved as a biological unit. These organisms include the ascomycetes, certain basidiomycetes, and lower plants. However, the bulk of the data concerning aberrant segregations derive from studies on the ascomycetes Neurospora, Sordaria, Ascobolus, and Saccharomyces. Much of the earlier work on recombination in these organisms has recently been reviewed by Catcheside (1977). The present report describes our recent experiments on gene conversion in the yeast Saccharomyces.