Male and female mouse DNAs can be discriminated using retroviral probes

Abstract

Only two markers have been identified for the mouse Y chromosome: a gene that determines the male transplantation antigen (H-Y)¹ and sequences homologous to a satellite DNA originally isolated from a heterogametic female snake². To investigate the molecular organization of the murine Y chromosome and to understand its role in sex determination, more Y-specific sequences and genes must be identified. We have now compared restriction digests of DNAs from female and male mice using hybridization probes representing two different classes of murine retroviruses. Some viral DNA-containing fragments were present in male but not female DNAs. The male-specific fragments varied in copy number from 1 to as many as 100, and we estimate that in some Mus species, as much as 3% of the Y chromosome is composed of retrovirus-related sequences. To our knowledge this is the first report of (1) an association of retrovirus-related sequences with a mammalian Y-chromosome and (2) many copies of retrovirus-related sequences on the same chromosome.