Properties of Gene Conversion of Deletions in Saccharomyces cerevisiae
Studies of large numbers of unselected asci in Saccharomyces cerevisiae have shown that gene conversion for heterozygous sites occurs frequently (Fogel and Mortimer, 1969; Hurst et al., 1972). The conversion event is identified by 3+: 1 m or 3m: 1+ ratios instead of the expected 2+: 2m. A number of empirical generalizations have emerged from the conversion studies of Fogel, Hurst, and Mortimer. They are (1) parity — conversions of the type 3+: 1m are equal to the type 3m: 1+; (2) fidelity — new alleles are not produced by gene conversion; (3) coconversion — when two sites within a gene are heterozygous, the alleles convert together as well as separately; (4) absence of marker effects — the conversion frequency for a given heterozygous site is constant, unrelated to its position in the map, and not influenced by other alleles within the gene; and (5) conversion-associated recombination — the frequency of reciprocal recombination for genes bracketing a site at which gene conversion has occurred is about 50%.
KeywordsGene Conversion Conversion Frequency Conversion Event Conversion Type Heterozygous Site
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