Nuclear DNA Synthesis in Yeast and the Effect of Irradiation

Summary

The synthesis of DNA can be measured in yeast by following the uptake of 5-bromodeoxy-uridine-5′-triphosphate in a mutant that utilizes deoxythymidine-5′-monophosphate; approximately 60 per cent of the DNA is synthesized semi-conservatively before replication stops. Neither ultraviolet light (U.V.), nor ionizing radiation stimulates repair-type synthesis. Based on the ability to detect small amounts of synthesis, it appears that fewer than ten bases are synthesized per pyrimidine dimer removed.