Induction of specific-locus mutations in female mice by 1-ethyl-1-nitrosourea and procarbazine.

Using the specific-locus method, the ability of 1-ethyl-1-nitrosourea (ENU) and procarbazine hydrochloride (procarbazine) to induce gene mutations in mouse oocytes was tested and confirmed. The sensitive stage for the induction of mutations in oocytes with 160 mg/kg of ENU is 2-4 weeks post treatment. The induced mutation frequency in this mating interval was 5.1 X 10(-7) mutations/locus/gamete/mg/kg. The induction of mutations by procarbazine occurred 8-33 weeks after treatment. The induced mutation frequency in this mating interval for the 400 mg/kg group was 0.4 X 10(-7) mutations/locus/gamete/mg/kg. One third of the induced mutations was lethal in homozygous condition in both experiments. ENU and procarbazine have a lower mutational response in oocytes than in stem-cell spermatogonia.