REGULATED EXPRESSION OF TESTIS ANGIOTENSIN-CONVERTING ENZYME DURING SPERMATOGENESIS IN MICE

A unique isozyme of angiotensin-converting enzyme (ACE) is produced in large amounts by developing germ cells and is referred to as testis A CE. This protein results from the transcriptional recognition of a spe rm-specific promoter during spermatogenesis. The expression within ger m cells of testis ACE mRNA was studied using in situ hybridization, ri bonuclease (RNase) protection, and Northern analysis. In parallel, tes tis ACE protein expression was measured through use of Western blot an alysis and immunohistochemistry. Although testis ACE protein is first detected in step 10 spermatids, testis ACE mRNA is first detected in a developmentally younger cell population, late pachytene spermatocytes . Thus, testis ACE mRNA is translationally arrested for a period of se veral days until late in spermiogenesis.