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Title: A comparative study of genetic change in eukaryotes : the role of DNA repair enzymes in the genetic consequences of mutagen damaged Saccharomyces cerevisiae cells
Author: Ali, A.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1982
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A number of yeast Saccharomyces cerevisiae strains, having a particular rad mutation and auxotrophic markers, derived from the strain D7 (Zimmermann et al., 1975), were constructed to evaluate the role of RAD loci in the genetic consequences of ethyl methanesulfonate (EMS), nitrous acid (HN02), Ultraviolet-light (UV) and X-ray damaged cells. The relative sensitivity of the various rad mutants, as compared with RAD, to induced lethality, mutagenesis and recombination, was based upon the slopes of regression lines. The dose-response survival data indicated that RAD 9 and recombination had the most vital role in enhancing the viability of mutagen damaged cells. Cross sensitivity between X-ray and EMS; UV and HN02 was variable. Haploid cultures exhibited enhanced sensitivity to induced lethality than their respective diploids except rad 51-1 and rad 54-1 where both phases were either equally sensitive (HN02) or diploids were more sensitive (UV) than respective haploids. The mutagenic and recombinogenic efficiency of the 4 agents, irrespective of the rad background, was in the order EMS > HNO > UV > X-ray. The ilv 1 and trp 5 mutations, although both of the bale substitution type, with trp 5 being suppressible, were differentially inducible and the extent of difference was minimum with X-ray. Ade 2-40 mutation was not inducible with acridine orange as well. The mutation induction data indicated that EMS induced mutagenesis was largely independent of DNA repair enzymes, for the other three agents independent or partially independent sets of gene functions were required for mutagenesis at different sites or with different agents. The RAD 54-1 gene function plays a central role in enhancing the viability of mutagen damaged cells and for the normal induction of mutagenesis and recombination. The dose-response analysis of the data produced indicates that there may be no safe level for the exposure to EMS, HNO2, UV and X-ray.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available