Thymine Dimers and Inhibition of DNA Synthesis by Ultraviolet Irradiation of Cells

Abstract

Measurements of the inhibition of DNA synthesis in bacteria and the formation of thymine dimers by ultraviolet irradiation of the cells indicate that one thymine dimer per 350-IA strand of DNA acts as a block to further synthesis. In a sensitive strain of Escherichia coli the blocks are permanent. In a resistant strain the blocks are only temporary but recovery of synthesis is not the result of splitting dimers.