Vasa mRNA expression pattern in different gonadal development stage of zebrafish

Since first reported in Drosophila, Vasa gene had been widely accepted as a good molecular marker of primordial germ cells in various species. So far the reserch had largely focused on early embyo development. The expression of Vasa gene in gonad differentiation stage and mature stage was rarely known. In this paper, we employed RT-PCR analysis and found that Vasa gene mRNA first increased and then decreased during gonad development. Real-time RT PCR analysis showed that the expression level of Vasa gene in ovary was similar or a little higher than that in testis. mRNA in situ hybridization showed that Vasa gene was specially detected in zebrafish PGCs, spermatogonia, and primary spermatocyte in immaturate and mature testis. In mature ovary, vasa mainly expressed in vitellogenic granules of Ⅲ，Ⅳ，Ⅴphase oocytes. This study would facilitate us to identify germ stem cells in gonadal tissues and to deeply understand cellular mechanisms of sex differentiation and sex reversal.