Induction of DNA double-strand breaks by X-rays in a radiosensitive strain of the yeast Saccharomyces cerevisiae.

Sedimentation profiles for chromosomal DNA from unirradiated and X-irradiated yeast cells of wild type and rad 52 strains are presented. These profiles indicate that, whereas wild type strains rejoin DNA double-strand breaks, rad 52 strains apparently do not. These data suggest that the rad 52 mutant lacks a repair system for X-ray induced damage and are consistence with the proposal that an unrepaired chromosome break leads to reproductive cell death.