TRANSGENIC MICE DEMONSTRATE A TESTIS-SPECIFIC PROMOTER FOR LACTATE-DEHYDROGENASE, LDHC

The mammalian genome encodes a family of lactate dehydrogenase (LDH) i sozymes. Two of these, ldha and ldhb, are expressed ubiquitously. The ldhc gene is active only in the germinal epithelium during spermatogen esis. In our analysis of ldhc gene regulation, we found that a 60-base pair promoter sequence was sufficient for testis-specific expression in an in vitro transcription assay. To confirm these findings, a genom ic fragment containing 100 base pairs overlapping the transcription st art site was isolated and linked to the Escherichia coil lacZ gene. We report that this genomic fragment drives testis-specific expression i n transgenic mice. We conclude that transcription of the transgene and possibly of the endogenous ldhc gene is restricted to leptotene/pachy tene primary spermatocytes.