Dataset Information

Vasa identifies germ cells and critical stages of oogenesis in the Asian seabass.

ABSTRACT: Germ cells produce sperm and eggs for reproduction and fertility. The Asian seabass (Lates calcarifer), a protandrous marine fish, undergoes male-female sex reversal and thus offers an excellent model to study the role of germ cells in sex differentiation and sex reversal. Here we report the cloning and expression of vasa as a first germ cell marker in this organism. A 2241-bp cDNA was cloned by PCR using degenerate primers of conserved sequences and gene-specific primers. This cDNA contains a polyadenylation signal and a full open reading frame for 645 amino acid residues, which was designated as Lcvasa for the seabass vasa, as its predicted protein is homologous to Vasa proteins. The Lcvasa RNA is maternally supplied and specific to gonads in adulthood. By chromogenic and fluorescent in situ hybridization we revealed germ cell-specific Lcvasa expression in both the testis and ovary. Importantly, Lcvasa shows dynamic patterns of temporospatial expression and subcellular distribution during gametogenesis. At different stages of oogenesis, for example, Lcvasa undergoes nuclear-cytoplasmic redistribution and becomes concentrated preferentially in the Balbiani body of stage-II~III oocytes. Thus, the vasa RNA identifies both female and male germ cells in the Asian seabass, and its expression and distribution delineate critical stages of gametogenesis.

SUBMITTER: Xu H

PROVIDER: S-EPMC3927134 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Vasa identifies germ cells and critical stages of oogenesis in the Asian seabass.

Xu Hongyan H Lim Menghuat M Dwarakanath Manali M Hong Yunhan Y

International journal of biological sciences 20140206 2

Germ cells produce sperm and eggs for reproduction and fertility. The Asian seabass (Lates calcarifer), a protandrous marine fish, undergoes male-female sex reversal and thus offers an excellent model to study the role of germ cells in sex differentiation and sex reversal. Here we report the cloning and expression of vasa as a first germ cell marker in this organism. A 2241-bp cDNA was cloned by PCR using degenerate primers of conserved sequences and gene-specific primers. This cDNA contains a p ...[more]

PMID: 24550690

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Project description:BACKGROUND: The Asian seabass (Lates calcarifer) is a protandrous hermaphrodite that typically matures as a male at approximately 2-4 years of age and then changes sex in subsequent years. Although several sexual maturation stages have been described histologically for both testis and ovary, the underlying gene expression profiles remain lacking. The development of a gene expression platform is therefore necessary to improve our understanding of the gonad development of this cultured teleost species. METHODS: Thirty Asian seabass gonads were collected from farms in Singapore, examined histologically and staged according to their sex and gonadal maturation status. Partial coding sequences of 24 sex-related genes were cloned using degenerate primers and were sequenced. Additional 13 cDNA sequences were obtained through next-generation sequencing. A real-time qPCR was then performed using the microfluidic-based Fluidigm 48.48 Dynamic arrays. RESULTS: We obtained 17 ovaries and 13 testes at various stages of sexual maturation. Of the 37 genes that were tested, 32 (86%) showed sexually dimorphic expression. These genes included sex-related genes, sox9, wt1, amh, nr5a2, dmrt1 and nr0b1, which showed testis-enhanced expression similar to other vertebrate species. Known male- and female-enhanced germ cells markers, which were established from studies in other species, similarly showed testis- and ovary-enhanced expression, respectively, in the Asian seabass. Three pro-Wnt signaling genes were also upregulated in the ovary, consistent with existing studies that suggested the role of Wnt signaling in ovarian differentiation in teleosts and mammals. The expression patterns of genes involved in steroidogenesis, retinoic acid metabolism, apoptosis and NF-?B signaling were also described. We were able to classify gonads according to sex and gonadal maturation stages, based on their small-scale transcriptomic profiles, and to uncover a wide variation in expression profiles among individuals of the same sex. CONCLUSIONS: The analysis of a selected set of genes related to reproduction and in sufficient number of individuals using a qPCR array can elucidate new insights into the molecular mechanisms involved in Asian seabass gonad development. Given the conservation of gene expression patterns found in this study, these insights may also help us draw parallels with other teleosts.

Dataset Information

Vasa identifies germ cells and critical stages of oogenesis in the Asian seabass.

Publications

Vasa identifies germ cells and critical stages of oogenesis in the Asian seabass.

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