The Expression Of Zebrafish Vasa Gene And Gcl Gene During Oogenesis

As a creature of sexual reproduction, zebrafish (Danio rerio) successful development requires both the male and female gametes, which originate from the primordial germ cells (PGCs). Many studies shows that the origin of germ cells is governed by a tightly controlled series of gene expression events, knowledge about the expression and function of these genes is highly important to improve our understanding of factors involved in the germ cell gensis. vasa and gcl gene are involved in germ cell genesis, and are required for the germ cell formation.The vasa gene encodes an ATP-dependent RNA helicase of the DEAD-box family. The vasa gene expression pattern during oogenesis of zebrafish was examined using in situ hybridization and fluorescent quantitative RT-PCR. During zebrafish oogensis, vasa mRNA is expressed strongly and uniformly distributed in the cytoplasm in stage â…¡ oocytes, followed by a distribution among vacuome in stage â…¢. Later in stage â…£ and â…¤, vasa mRNA is enriched at the cortex and finally localized at the cortex. The fluorescent quantitative RT-PCR shows that the quantity of vasa mRNA decreases from stage â…¡ to stage â…¢, but remains relatively invariable from stage â…¢ to stage â…¤.The zebrafish homologue of gel gene has been identified. RT-PCR revealed stronger expression in the ovary and weaker expression in testis, liver and muscle tissue, the high levels of transcripts in the ovary suggest a unique function for zebrafish oogenesis. In situ hybridization analysis revealed highly expression of the gcl gene in the oocytes of different stages: Strong gcl mRNA signals are evident and diffuse in the cytoplasm in stage â…¡ and vasa mRNA signals are visible aroundvacuome in stage III. In the following stage IV, gel mRNA is enriched at the cortex and finally is localized on one of the polar in stage V. The zebrafish Gel shows 31, 73, 71, and 85% similarity to Drosophila, mouse, human and medaka Gel protein respectively. The secondary structures were predicted using the program RNAdraw and DNAstar.The expression and subcellular localization of vasa and gel mRNA in oogytes of different stages suggest vasa and gel gene may play an important role during oogenesis, and the mechanism of mRNA localization was discussed.