ARTICLE NO. RC988530 The Dazh Gene Is Expressed in Male and Female Embryonic Gonads before Germ Cell Sex Differentiation

leted in Azoospermia); the only transcription unit re-The autosomal homologs of the human Y-chromo- ported in this region [2]. Autosomal genes homologous somal DAZ gene (DAZH and Dazh in human and to the Y-chromosomal DAZ gene have been shown to mouse, respectively) are strong candidate for be present in many vertebrates [3] and were character-Azoospermia factor and encode a testis speci®c ized in human [4, 5, 6, 7], mice [3, 8] and DrosophilaRNA-binding proteins. We studied the expression [9] in which they appear to be expressed exclusively inpattern of the mouse Dazh during embryonic devel-germ-cells [3, 9, 10, 11]. It has been postulated thatopment by using Northern-blotting of developing go-the human DAZ gene on the Y-chromosome arose fromnads. In the mouse, we have detected 3.5kb and 4.5kb the autosomal ancestor DAZH (DAZ homolog, knowntranscripts in male and female embryonic gonads at also as DAZLA) mapped recently to human chromo-12.5 dpc (days post coitum). During this period, the some 3 via a series of structural transformations [4].only germ cells present in the gonad are primordial As gauged by DAZ/DAZH protein sequences and ex-germ cells. Dazh transcripts were not detected in pression patterns, the newly emergent Y gene clustersembryonic gonads of mice that lack germ cells be-retained key functional characteristics of its autosomalcause of mutation in W gene, suggesting that expres-ancestor [4]. Northern-blotting [3] and In-situ hybrid-sion is limited to germ-cells. In females, oogonia en-ter meiosis at 13.5-14.5 dpc: at this time Dazh tran- ization [10] demonstrate that both, the human DAZ