Meiotic double-strand breaks in Schizosaccharomyces pombe

Meiotic DNA double-strand breaks (DSBs) are associated with recombination h ot spots in the yeast Saccharomyces cerevisiae and are believed to initiate the process of recombination, Until now. meiosis-induced breaks have not b een shown to occur regularly in other organisms. Here we show, by pulsed-fi eld gel electrophoresis of DNA, that meiotic DSBs occur transiently in all three chromosomes of the fission yeast Schizo-saccharomyces pombe. In a rep air defective mutant, carrying a mutation in the Rec A homolog gene rhp51, meiotic DSBs accumulate. In contrast to expectation from the genetic map of S. pombe however, many chromosomal DNA molecules remain unbroken during me iosis.