The Repair of Double-Strand Breaks in the Nuclear DNA of Saccharomyces Cerevisiae and Its Genetic Control

Mol Gen Genet. 1976 Jan 16;143(2):119-29. doi: 10.1007/BF00266917.

Abstract

With the use of neutral sucrose sedimentation techniques, the size of unirradiated nuclear DNA and the repair of double-strand breaks induced in it by ionizing radiation have been determined in both wild-type and homozygous rad52 diploids of the yeast Saccharomyces cerevisiae. The number average molecular weight of unirradiated DNA in these experiments is 3.0 X 10(8)+/-0.3 Daltons. Double-strand breaks are induced with a frequency of 0.58 X 10(-10) per Daltonkrad in the range of 25 to 100 krad. Since repair at low doses is observed in wild-type but not homozygous rad52 strains, the corresponding rad52 gene product is concluded to have a role in the repair process. Cycloheximide was also observed to inhibit repair to a limited extent indicating a requirement for protein synthesis. Based on the sensitivity of various mutants and the induction frequency of double-strand breaks, it is concluded that there are 1 to 2 double-strand breaks per lethal event in diploid cells incapable of repairing these breaks.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Centrifugation, Density Gradient
  • Cobalt Radioisotopes
  • DNA / analysis*
  • DNA Repair*
  • Diploidy
  • Gamma Rays
  • Homozygote
  • Molecular Weight
  • Mutation
  • Radiation Genetics*
  • Recombination, Genetic
  • Saccharomyces cerevisiae / radiation effects*

Substances

  • Cobalt Radioisotopes
  • DNA