EFFECTS OF UV-LIGHT POST-TREATMENTS ON SURVIVAL CHARACTERISTICS OF 21-UV-SENSITIVE MUTANTS OF SACCHAROMYCES-CEREVISIAE

The effects of dark-holding and photoreactivating-light treatment after UV exposure has been determined in a range of 21 complementing UV-sensitive mutants of the yeast Saccharomyces cerevisiae. The results indicate that the various strains may be classified into 4 groups on the basis of the effects of dark holding, and dark holding followed by photoreactivation. The characteristics of these groups are: Group 1: survival increases during dark holding, dark holding followed by photoreactivation has no further effect; Group 2: survival increases during dark holding, dark holding followed by photoreactivation produces a further increase in survival; Group 3: survival decreases during dark holding, dark holding followed by photoreactivation has no further effect; Group 4: survival decreases during dark holding, dark holding followed by photoreactivation produces an increase in survival. These characteristics are discussed in the light of current views on excision-repair models. © 1969.