Effect of thymine deprivation on the restoration of DNA synthesis in ultraviolet-irradiated Escherichia coli B/r Hcr+.

The influence of a prior period of thymine and amino acid deprivation on the restoration of DNA synthesis and on the fraction of cells surviving after u.v. irradiation and subsequent incubation with chloramphenicol in Escherichia coli B/r Hcr+ has been studied. Thymine and amino acid deprivation stimulated post-irradiation DNA synthesis and increased the fraction of surviving cells if, in the period between deprivation and u.v. irradiation, protein synthesis occurred. It is concluded that proteins induced by thymine starvation participated in the repair of u.v.-irradiated cells.