Recovery of deoxyribonucleic acid synthesis in ultraviolet-light-exposed bacteria

Abstract

Studies of the effects of chloramphenicol on induced mutation and on nucleic acid synthesis in synchronized cultures of Esoherichia coli exposed to ultraviolet light demonstrated that a relation exists between the amount of postirradiation RNA which has been synthesized at the time of chloramphenicol addition and the relative rate of DNA synthesis in the presence of chloramphenicol. These studies were extended to log phase cultures of E. coli strain B/r, and experimental results are described which suggest that the recovery of cellular capacity for DNA synthesis (involving the synthesis of RNA and protein) is related to the institution of a rate limiting component of the postirradiation DNA synthetic systsm. The results further show that the presence of chloramphenicol after ultraviolet exposure does not limit the amount of DNA formed as is the case with unirradiated cells. (auth)