Effect of the Y chromosome on testis weight in mice

We investigated the effect of the Y chromosome on testis weight in (B6.Cg-A(y) × Y-consomic mouse strain) F(1) male mice. We obtained the following results: (1) Mice with the Mus musculus domesticus-type Y chromosome had significantly heavier testis than those with the M. m. musculus-type Y chromosome. (2) Variations in Usp9y and the number of CAG repeats in Sry were significantly associated with testes weight. The A(y) allele was correlated with a reduced testis weight, and the extent of this reduction was significantly associated with a CAG repeat number polymorphism in Sry. These results suggest that Y chromosome genes not only influence testis weight but also modify the effect of the A(y) allele in mediating this phenomenon.