[Increase in resistance to UV-light in E. coli bearing the Hly plasmid resistance]

Hly plasmide of wild type and its derepressive (by transmission) mutant communicated to the E. coli cells an increased resistance to the action of ultraviolet rays. Hly plasmide failed to compensate the defects associated with the excision and postreplicative DNA reparation or the reparative DNA synthesis. Hly plasmide increased the resistance to the ultraviolet light in the lon--mutant in which the ultraviolet irradiation disturbed the process of cell division. It is supposed that the resistance to the ultraviolet light connected with Hly plasmide was caused by the influence of the plasmide on some stages of cell division following the ultraviolet irradiation.