Evidence for DNA double-strand breaks as the critical lesions in yeast cells irradiated with sparsely or densely ionizing radiation under oxic or anoxic conditions

Evidence is presented that DNA double-strand breaks are the critical lesions leading to yeast cells death. First, the RBE and OER values found for the induction of double-strand breaks under different irradiation conditions are similar to the corresponding RBE and OER values obtained for killing of the rad 52 mutant which is deficient in double-strand break repair. Second, one to two double-strand breaks per cell per lethal event were measured irrespective of the ionization density of the radiation applied and irrespective of oxic or anoxic conditions