The Schizosaccharomyces pombe rad51 + and dmc1 + genes code for homologues of the Escherichia coli recombination protein RecA. Deletion of rad51 + causes slow growth, retardation of cell division and a decrease in viability. rad51Δ cells have a defect in mating-type switching. The DNA modification at the mating-type locus required for mating-type switching contributes to slow growth in the rad51 mutant. Cell mating is reduced in crosses homozygous for rad51Δ. Ectopic expression of the dmc1 + gene allowed us to demonstrate that the reduction in meiotic recombination in dmc1 mutants is not caused by a disturbance of rad24 expression from the dmc1-rad24 bicistronic RNA. We describe the functional defects of terminally epitope-tagged Dmc1 and Rad51 and discuss it in terms of protein interaction. Presumptive Rad51 and Dmc1 foci were detected on spreads of meiotic chromati
