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

Xu H, Lim M, Dwarakanath M, Hong Y - Int. J. Biol. Sci. (2014)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543.

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.

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RT-PCR analysis of vasa expression in seabass. (A) Adult tissues. (B) Embryos. Stages given above lanes are hours post fertilization (hpf). β-actin serves as a normalization factor.
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Figure 4: RT-PCR analysis of vasa expression in seabass. (A) Adult tissues. (B) Embryos. Stages given above lanes are hours post fertilization (hpf). β-actin serves as a normalization factor.

Mentions: In many organisms including zebrafish, medaka and gibel carp, vasa RNA is supplied maternally and zygotic expression is restricted to germ cells. In the seabass, adult expression of vasa RNA was examined by RT-PCR to be high in the ovary and testis, but absent in any somatic organs examined, such as the eye, gill, heart, kidney, spleen, intestine and liver (FIG. 4A). Therefore, vasa RNA expression is restricted to the gonads. During embryogenesis, the vasa transcript is high in early stages, while persists at a reduced and detectable level in late stages till 30 hpf (FIG. 4B). Since the onset of zygotic transcription in fish occurs after midblastula transition, the vasa transcript is maternally inherited in seabass.


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

Xu H, Lim M, Dwarakanath M, Hong Y - Int. J. Biol. Sci. (2014)

RT-PCR analysis of vasa expression in seabass. (A) Adult tissues. (B) Embryos. Stages given above lanes are hours post fertilization (hpf). β-actin serves as a normalization factor.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3927134&req=5

Figure 4: RT-PCR analysis of vasa expression in seabass. (A) Adult tissues. (B) Embryos. Stages given above lanes are hours post fertilization (hpf). β-actin serves as a normalization factor.
Mentions: In many organisms including zebrafish, medaka and gibel carp, vasa RNA is supplied maternally and zygotic expression is restricted to germ cells. In the seabass, adult expression of vasa RNA was examined by RT-PCR to be high in the ovary and testis, but absent in any somatic organs examined, such as the eye, gill, heart, kidney, spleen, intestine and liver (FIG. 4A). Therefore, vasa RNA expression is restricted to the gonads. During embryogenesis, the vasa transcript is high in early stages, while persists at a reduced and detectable level in late stages till 30 hpf (FIG. 4B). Since the onset of zygotic transcription in fish occurs after midblastula transition, the vasa transcript is maternally inherited in seabass.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543.

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.

Show MeSH
Related in: MedlinePlus