Studies on the induction of translocations in mouse spermatogonia: II. The effect of dose-rate

Abstract

The effect of dose-rate on the induction of reciprocal translocations in mouse A type spematogonia by 600 RX- and γ-irradiation was studied by scoring multivalent configurations in descendant spermatocytes. With X-irradiation over a range of dose-rates from 0.8 to 913 R/min there was no significant change in the frequency of affected spermatocytes, which averaged 12.8%. With γ-irradiation, however, there was a steady increase in frequency from 1.4% at 0.02 R/min to 12.1% at 86 R/min, the points fitting a straight line on a semi-log plot. At 0.08 R/min the X-ray yield was twice that for γ-rays. Possible reasons for these differences are discussed. Frequencies of 0, 1, 2 translocations per spermatocyte did not fit a Poisson distribution since there were less then expected in the 1-class, but more in higher classes. This was probably a consequence of differential radiosensitivity of the irradiated spermatogonia, although preferential clonal proliferation may also be involved.