Liquid holding recovery kinetics in wild-type and radiosensitive mutants of the yeast Saccharomyces exposed to low- and high-LET radiations.
Three wild-type diploid yeast strains Saccharomyces ellipsoideus and Saccharomyces cerevisiae and five radiosensitive mutants of S. cerevisiae in the diploid state were irradiated with gamma-rays from 60Co and alpha-particles from 239Pu in the stationary phase of growth. Survival curves and the kinetics of the liquid holding recovery were measured. It was shown that the irreversible component was enhanced for the densely ionizing radiation in comparison to the low-LET radiation while the probability of the recovery was identical for both the low- and high-LET radiations for all the strains investigated. It means that the recovery process itself is not damaged after densely ionizing radiation and the enhanced RBE of the high-LET radiation may be caused by the increased yield of the irreversible damage. A parent diploid strain and all its radiosensitive mutants showed the same probability for recovery from radiation damage. Thus, the mechanism of the enhanced radiosensitivity of the mutant cells might not be related to the damage of the repair systems themselves but with the production of some kind of radiation damage from which cells are incapable to recover.
Petin
Vladislav G
VG
Biophysical Laboratory, Medical Radiological Research Center, 249036 Obninsk, Kaluga Region, Russia.
Kim
Jin Kyu
JK
D000251:Adenosine Triphosphatases; D000512:Alpha Particles; D064447:Checkpoint Kinase 2; D004260:DNA Repair / Q000528:radiation effects*; D045643:DNA Repair Enzymes; D004268:DNA-Binding Proteins / Q000235:genetics; D005720:Gamma Rays; D009154:Mutation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000528:radiation effects*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D013997:Time Factors
D004268:DNA-Binding Proteins; C063607:RAD18 protein, S cerevisiae; C087191:RAD55 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D064447:Checkpoint Kinase 2; D017346:Protein Serine-Threonine Kinases; D000251:Adenosine Triphosphatases; C071451:RAD57 protein, S cerevisiae; D045643:DNA Repair Enzymes