Genetic control of RBE of alpha-particles for yeast cells irradiated in stationary and exponential phase of growth.
Survival curves of S. cerevisiae wild type and rad 50, 51, 52 and 54 mutants in haploid and diploid strains were measured after gamma-ray and alpha-particle irradiation in stationary and exponential phase of growth. The values of RBE of high-LET radiation, defined as the ratio of the mean lethal doses after sparsely and densely ionizing radiations, were determined. A correlation between the RBE of alpha-particles and cell repair capacity was supported for stationary phase cultures. For the first time, it was shown for all strains studied that at exponential phase of growth the RBE of alpha-particle-induced survival was decreased in comparison with that for stationary cells. For most mutant cells RBE was close to unity, i.e. cell radiosensitivity was almost identical for both sparsely and densely ionizing radiation. Possible reasons for the observed radiation responses are discussed.
Petin
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DV
Medical Radiological Research Center, Russian Academy of Medical Sciences, Obninsk, Kaluga Region.
Petin
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VG
D000512:Alpha Particles; D002453:Cell Cycle / Q000502:physiology; D002455:Cell Division; D004171:Diploidy; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays; D005800:Genes, Fungal; D005804:Genes, Lethal; D006238:Haploidy; D009154:Mutation; D011836:Radiation Tolerance / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects*