A comparison of enzyme activity mutation frequencies in germ cells of mice(Mus musculus) and golden hamsters (Mesocricetus auratus) after exposure to 2+2 Gy gamma-irradiation

The radiation-induced germ cell mutation rate has been investigated in two species of mammals. Mice and golden hamsters of both sexes were exposed to 2+2 Gy gamma-irradiation with a 24 h fractionation interval and mated to un treated partners. In mice, specific locus mutations were examined as positi ve controls and the obtained mutation rates (per locus and gamete x 10(-5)) were 51,4, 10,1, 13.6 and 17.4 for irradiated post-spermatogonia, spermato gonia and 1-7 and >7 days post-treatment oocytes, respectively. Offspring o f mice and golden hamsters were screened for activity alterations of 10 ery throcyte enzymes coded by at least 14 loci, The observed mutation rates per locus per gamete x10(-5) for treated post-spermatogonial stages, spermatog onia and oocytes 1-7 and >7 days post-treatment were 6,5, 1,5, 8.8 and 7,0, respectively, for mice and 16,7, 0, 7.6 and 0, respectively, for golden ha msters, There is a significant difference for mutation rates in mouse oocyt es 1-7 days post-treatment compared with the control. No differences in the frequencies of mutations in the various germ cell stages could be observed between mice and golden hamsters, A critical assumption for the extrapolat ion of experimental mutagenesis studies to humans is that no species effect s exist in sensitivity to mutation induction by irradiation. Our results do not contradict this assumption.