Comparative strain and hybrid investigation of dominant lethals and reciprocal translocations induced to mouse spermatogonia.

Abstract

Dominant lethals and translocation induction were assayed in mice after 276 R spermatogonial X-irradiation. Inbred A/Jax strain matings showed a much higher foetal mortality than did the CBA strain matings both in controls and in irradiated groups. No significant irradiation induction of dominant lethals was found. No strain-by-treatment interaction in embryonic death was found for males of either strain when mated to CBA females. Neither did the dominant lethal study reveal any differences between the two types of reciprocal hybrids between the strains, mated to CBA females, albeit the irradiated F1 (A/Jax x CBA) group showed a significant increase of foetal mortality compared to its control. The frequencies of spermatocytes with translocations after spermatogonial irradiation of CBA, A/Jax, F1 (CBA x A/Jax) and F1 (A/Jax x CBA) males were 0.040, 0.044, 0.047 and 0.047 respectively. No translocations were found in the control males. The estimates of the amount of dominant lethals expected from these frequencies seem to be somewhat higher than the actual results. The variances for the means of spermatocytes with translocations were significantly higher for both types of hybrids than for both strains.