Autosomal Translocations Causing Male Sterility and Viable Aneuploidy in the Mouse

Abstract

In previous experiments on the induction of trans locations in the mouse tests were usually confined to the sons of treated animals. In the present experiment daughters of irradiated males were studied, with a view to finding the frequency of X-linked translocations and of autosomal aberrations causing male sterility. The treated males were given 600 rad X-rays to the hind part of the body and offspring were obtained in the pre-sterile period. Forty-six of the 168 daughters studied were semi-sterile, and, of these, 26 carried translocations causing semisterility in both sexes, 5 carried translocations causing semi-sterility in females and full sterility in males and 5 had translocations giving some semi-sterile and some sterile males. All the translocations were autosomal. The translocations causing male sterility were studied more fully. All gave chain quadrivalents and some univalents at male meiosis, and 3 out of 4 showed recognisably abnormal chromosomes at mitosis. An unexpected finding in 2 of the translocations was the occurrence of live adult mice with 41 to 39 chromosomes. The extra or absent chromosome was thought to be one of the translocation products. Two of the aneuploid types were associated with mild pheno-typic abnormality, and in all cases the males were sterile and the females had reduced fertility. This is the first report autosomal translocations causing male sterility and of inherited autosomal aneuploidy in the mouse.