Zfy is transcribed in the normal mouse epididymis and in the XXSxr (“sex reversed”) testis

Abstract

The presence of the mutation Sex reversed (Sxr), a copy of a Y-chromosomal segment that gets transferred to an X chromosome, causes the resulting XXSxr mice to develop as apparent males. However, several features of male sexual development are abnormal in these animals. The testes are small and aspermatogenic, and the epididymides lack the initial segment. Testes and epididymides show abnormalities of extracellular matrix. In this study we examined transcription of the conserved Y chromosomal gene Zfy, which has an X-chromosomal homologue (Zfx). Northern blotting showed Zfy to be expressed in the testes of XXSxr animals, except for those that carry the coat-marker gene Tabby (Ta), despite the lack of germ cells in XXSxr mice. Reverse transcription polymerase chain reaction (RT-PCR) studies detected Zfy in mRNA in testes even when Ta was present. RT-PCR also demonstrated Zfy transcription in epididymides of normal males, though not in XXSxr mice. Previous authors reported an absence of Zfy transcription in XXSxr testes; Zfy transcription in normal testes has been ascribed to germ cells. Our observation indicates that this idea requires re-evaluation. The occurrence of Zfy transcription in the normal epididymis is similarly a novel finding that may help explain those aspects of epididymal development that occur in the absence of androgen.