An upstream region of the rat spermatogenesis-specific heat-shock-like Hst70 gene confers testis-specific expression in transgenic mice.

In order to study the temporal and spatial regulation of a rat testis-specific heat-shock-like hst70 gene, an 0.8-kb fragment of its upstream DNA was fused to the lacZ gene and microinjected into one-cell murine embryos. Independent tgHST1 and tgHST2 transgenic mice strains were established, containing about 5-7 and 40-60 transgene copies/haploid genome, respectively. Enzyme assays in various tissues showed that transgene-encoded beta-galactosidase accumulates exclusively in testes of transgenic animals and cannot be detected until 16-17 days after birth. In-situ assays revealed that the enzyme accumulates mainly in pachytene primary spermatocytes. Our data complement previous studies on the endogenous rat hst70 and suggest that its 0.8-kb upstream region contains sufficient information to function as an active spermatogenesis-specific promoter.