MUTAGENIC EFFECT OF DIMETHYLNITROSOUREA I N MALE-MICE - INDUCTION OF DOMINANT LETHAL MUTATIONS AND CHROMOSOME-ABERRATIONS IN GERM-CELLS - GENOTYPE INFLUENCE ON THE CLASTOGENIC EFFECT IN BONE-MARROW CELLS

The ability of dimethylnitrosourea (DMNU) to induce dominant lethal mu tations in germ cells and chromosome aberrations in bone marrow cells of male CBAB6F1 mice was studied. At a mutagen dose of 200 mg/kg, mort ality was 19% in the second week after treatment (being 5% in the cont rol) and the frequency of bone marrow cells containing chromosome aber rations was 19.6% 24 h after treatment. DMNU induces dominant lethals in postmeiotic cells and in spermatogonia; the effects in spermatozoid s and spermatogonia are equal. Chromosome aberrations in spermatocytes induced by DMNU are not realized as dominant lethals. The sensitivity of mouse strains to the clustogenic effect of DMNU ranged in an order similar to that observed in experiments with thioTEPA. The most sensi tive was the TPS strain (29.2 +/- 4.6% of cells with chromosome aberra tions), the most resistant-the CBA/Lac strain (9.5 +/- 2.9%). DMNU exh ibited a relatively poor clustogenic activity; the effect in bone marr ow cells was higher than that in male germ cells.