Radiation induction of germline mutation at a hypervariable mouse minisatellite locus.
Paternal 60Co gamma-irradiation was tested for the induction of germline mutation at the mouse hypervariable minisatellite locus, Ms6hm. Male C3H/HeN mice were exposed to 3 Gy 60Co gamma-ray and mated with C57BL/6N females. Matings were made at 1-7, 15-21 and 71-77 days post-treatment to test spermatozoa, spermatids and spermatogonia stages. Reciprocal crosses were also made with irradiated C57BL/6N males. Southern analysis was carried out on DNA from parents and F1 mice. The paternal mutation frequencies per gamete of the Ms6hm locus were 8.3, 13, 28 and 15% for the C3H/HeN control, exposed spermatozoa, spermatids and spermatogonia stages, respectively. The paternal mutation frequencies per gamete were 7.7% for the C57BL/6N control and 13% for the C57BL/6N exposed spermatozoa stage. The increase in the paternal germline mutation frequency was statistically significant for C3H/HeN spermatids irradiation (p < 0.005). The induced mutation frequencies were of the order of 10(-1), and was too high to be accounted for by the direct action of radiation on the locus. These results suggest the presence of a previously unexpected mechanism of radiation induction of germline mutation. In addition, we demonstrate that the hypervariable minisatellite locus can serve as a sensitive monitor for genetic damages to germline cells.
Sadamoto
S
S
Department of Pathology, Hiroshima University, Japan.
Suzuki
S
S
Kamiya
K
K
Kominami
R
R
Dohi
K
K
Niwa
O
O
D000818:Animals; D004276:DNA, Satellite / Q000737:chemistry / Q000235:genetics* / Q000528:radiation effects*; D005260:Female; D014644:Genetic Variation; D006579:Heterozygote; D007135:Immunoglobulin Variable Region; D008098:Litter Size / Q000528:radiation effects; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D009154:Mutation; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics* / Q000528:radiation effects*; D013087:Spermatids / Q000502:physiology / Q000528:radiation effects; D013093:Spermatogonia / Q000502:physiology / Q000528:radiation effects; D013094:Spermatozoa / Q000502:physiology* / Q000528:radiation effects*
D004276:DNA, Satellite; D007135:Immunoglobulin Variable Region