Region-specific activators of meiotic recombination in Schizosaccharomyces pombe.

Schizosaccharomyces pombe rec mutants were previously isolated on the basis of their deficiency in meiotic recombination at the ade6 locus. We surveyed their meiotic recombination deficiencies at and between other loci. In rec10 mutants recombinant frequencies in the approximately 2-Mb region surrounding the ade6 locus were reduced 10- to 100-fold, but recombinant frequencies at or between nine other unlinked loci were reduced < 3-fold. The rec10 mutations are recessive and are on chromosome I; the ade6 region is on chromosome III. These results indicate that the rec10 gene product is required for activation of meiotic recombination in the approximately 2-Mb region surrounding ade6 but not in the other regions surveyed. Similar ade6 regional specificities were observed for rec8 and rec11. We infer that there are multiple activators of meiotic recombination, each specific for a limited set of loci, and we discuss how these regional activators may work.