SACCHAROMYCES CEREVISIAE MUTANT WHICH MAY SHOW CYTOPLASMIC SENSITIVITY TO ULTRAVIOLET LIGHT

MUTAGENIC agents such as ionizing radiation, ultraviolet light and various chemicals induce lesions in DNA many of which are subject to repair by the so-called dark-repair systems1-3. In yeast, as in other microorganisms, mutants have been isolated which are more sensitive to ultraviolet light than normal, wild-type, strains4-7. It is anticipated that such mutants will be defective in some component of the dark-repair system. They might therefore be useful in a study of processes of dark-repair of damaged DNA. It is to be expected that this class of mutants will show greater resistance to ultraviolet light in the homozygous diploid state than in the haploid state, because inactivation of a diploid nucleus may require lesions in both sets of genetic material. Certain highly sensitive mutants have been shown to exhibit this expected increased resistance in the diploid state5,7. © 1969 Nature Publishing Group.