title: Linear dose--response relationships after prolonged expression times in V-79 Chinese hamster cells.
abstract: The expression time for induced mutants resistant to 6-thioguanine, in V-79 Chinese hamster cells, was determined by respreading the cells in the selective medium, at various times after treatment. The length of the expression time for mutants induced by X-rays, ethyl methane sulphonate and ultraviolet irradiation was dose dependent. For the highest dose used this was 7 to 8 days, beyond which there was no further changes in mutant frequency. The dose-response relationship of these agents does not appear to deviate from linearity; this permits the calculation of mutation rate per unit dose. For X-rays this value was 1.35 - 10(-7) per rad per locus, for ethyl methane sulphonate, 2.2 - 10(-2) per mole per locus and for ultraviolet irradiation, 6.3 - 10(-6) per erg per mm2 per locus. The effectiveness of the 3 different mutagens for the induction of mutations was compared by calculating the increase in mutant frequency per unit of decrease in survival (Do). These increments in frequency were: 5.6 - 10(-5) for X-rays, 69.5 - 10(-5) for ethyl methane sulphonate and 16.1 - 10(-5) for ultraviolet irradiation.
mesh_terms: D002460:Cell Line; D002470:Cell Survival; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D005020:Ethyl Methanesulfonate / Q000494:pharmacology*; D008698:Mesylates / Q000494:pharmacology*; D009153:Mutagens; D009154:Mutation; D011831:Radiation Genetics; D014466:Ultraviolet Rays; D014965:X-Rays
chemical_list: D008698:Mesylates; D009153:Mutagens; D005020:Ethyl Methanesulfonate