Sry promoters from domesticus (Tirano) and C57BL/6 mice function similarlyin embryos and adult animals

Introduction of the Y chromosome from a Mus musculus domesticus (Tirano) su bspecies into the Mus musculus musculus C57BL/6 (B6) inbred strain backgrou nd results in sex reversal in XY offspring. It has been hypothesized that t he domesticus testis-determining Y (Tdy) locus is misregulated in B6 genome , thereby impairing sex determination in B6.Y-Dom animals. The identificati on of a gene in the sex-determining region on the Y chromosome (Sry) as the Tdy has provided a means to experimentally examine this hypothesis. We hav e generated several lines of B6 transgenic mice harboring a green fluoresce nt protein gene directed by a Sry promoter from the domesticus (Tirano) Y c hromosome. Detailed analysis of the transgene expression was conducted in b oth fetal and adult tissues of the transgenic mice. The domesticus Sry prom oter was capable of directing the expression of the green fluorescent prote in gene in a pattern similar, if not :identical, to that of the endogenous B6 Sry gene. These observations suggest that the domesticus Sry promoter is not involved in the postulated misregulation of the domesticus (Tirano) Sr y gene in the B6 genomic background. These results are discussed with refer ence to a second hypothesis invoking incompatible protein interaction(s) as a mechanism of aberrant sex determination in B6.Y-Dom animals. J. Exp. Zoo l. 290:632-641, 2001. (C) 2001 Wiley-Liss, Inc.