Comparative analysis of spontaneous mitotic recombination in [cir0] and [cir+] strains of the yeast Saccharomyces cerevisiae.

The influence of the 2 microns plasmid on homologous recombination in the right arm of chromosome XV of the yeast Saccharomyces cerevisiae has been examined. No differences between spontaneous mitotic recombination rates in [cir0] and [cir+] derivatives of two yeast diploid tester strains were detected. In the course of analysis an unusually high coincident conversion frequency at ADE2, HIS3, and two RFLP loci adjacent to ADE2, was observed. The character of coincident homozygotization of linked markers argues for a "break-and-replicate" mechanism underlying the coincident conversion events.