8-Methoxypsoralen plus 365 nm light effects and repair in yeast.
Haploid wild-type and mutant cells of Saccharomyces carrying one of the single genes rad2-20 or rad9-4 and the double mutant rad2-20rad9-4 were tested for their response to a treatment with 8-methoxypsoralen plus 365 nm light using immediate and delayed plating techniques. The mutant defective in the excision of ultraviolet-induced pyrimidine dimers (rad2-20) as well as that presumably deficient in a recombinational repair system (rad9-4) are more sensitive than wild type cells. The double mutant (rad2-20rad9-4) demonstrates a higher sensitivity than each of the single mutants, indicating that at least two pathways are involved in the repair of the 8-methoxypsoralen plus 365 nm induced damages. In all cases survival curves have shoulders. The survival of wild type and rad9-4 cells is increased after dark holding whereas it remains constant for the rad2-20 mutant and for the double mutant. These results show that the induced damages are reparable. Respiratory deficient mutant (p-) were compared to the corresponding respiratory competent cells. It is shown that the respiratory function is required for the expression of the excision repair activity. The 8-methoxypsoralen plus 365 nm ligh treatment appears to be less effective than ultraviolet irradiation (254 nm) in the induction of the cytoplasmic 'petite' mutation at the same survival levels.
D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D004260:DNA Repair / Q000187:drug effects / Q000528:radiation effects*; D005838:Genotype; D006238:Haploidy; D008730:Methoxsalen / Q000494:pharmacology*; D009154:Mutation; D011830:Radiation Effects; D011995:Recombination, Genetic; D012440:Saccharomyces / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D013045:Species Specificity; D013997:Time Factors; D014466:Ultraviolet Rays
D008730:Methoxsalen