The Influence of Oxygen on the Survival and Yield of DNA Double-strand Breaks in Irradiated Yeast Cells

Summary

Survival and induction of DNA double-strand breaks were studied in cells of Saccharomyces cerevisiae irradiated under oxic or anoxic conditions with 30 MeV electrons. A linear relationship between DNA double-strand breakage and dose was found in both cases. The o.e.r.-value for colony forming ability was found to be 1·9 ± 0·2, whereas the o.e.r.-value for DNA double-strand breakage was 3·0 ± 0·1. These results are not inconsistent with the idea that DNA double-strand breaks are involved in killing of yeast cells. The frequency of induction of DNA double-strand breaks was found to be 0·74 × 10⁻¹¹ double-strand breaks per g/mol per Gy when cells were irradiated under oxygen and 0·24 × 10⁻¹¹ double-strand breaks per g/mol per Gy under nitrogen.