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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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vasa RNA expression in the whole mount adult ovary by chromogenic ISH. An antisense vasa riboprobe (purple) was used for ISH. Different stages of oocytes (I~IV) and oogonia (og) are seen. The hybridization signal is strong in oogonia (inset) and stage-I~III oocyte.
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Figure 7: vasa RNA expression in the whole mount adult ovary by chromogenic ISH. An antisense vasa riboprobe (purple) was used for ISH. Different stages of oocytes (I~IV) and oogonia (og) are seen. The hybridization signal is strong in oogonia (inset) and stage-I~III oocyte.

Mentions: In the seabass, the adult ovary is composed of somatic follicle cells, a small number of oogonia and numerous oocytes at various stages of development. Chromogenic ISH with an antisense vasa riboprobe revealed that vasa expression in the adult ovary was limited to female germ cells but absent in somatic cells on whole mount samples, where stage-III oocytes and certain oogonia displayed the strongest signal, whereas stage-IV oocytes exhibited weak signal (FIG. 7). On ovarian sections, the strongest signal was present in stage-II~III oocytes and certain oogonia (Supplementary Material: FIG. S2A). A closer inspection revealed three types of oogonia exhibiting a strong, moderate and weak signal, which are called type I (og1), II (og2) and III oogonia (og3), respectively (FIG. S2A). Distinction of three types of oogonia became more evident at higher magnification (FIG. S2B). These results suggest that Lcvasa expression in the ovary is specific to germ cells.


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)

vasa RNA expression in the whole mount adult ovary by chromogenic ISH. An antisense vasa riboprobe (purple) was used for ISH. Different stages of oocytes (I~IV) and oogonia (og) are seen. The hybridization signal is strong in oogonia (inset) and stage-I~III oocyte.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 7: vasa RNA expression in the whole mount adult ovary by chromogenic ISH. An antisense vasa riboprobe (purple) was used for ISH. Different stages of oocytes (I~IV) and oogonia (og) are seen. The hybridization signal is strong in oogonia (inset) and stage-I~III oocyte.
Mentions: In the seabass, the adult ovary is composed of somatic follicle cells, a small number of oogonia and numerous oocytes at various stages of development. Chromogenic ISH with an antisense vasa riboprobe revealed that vasa expression in the adult ovary was limited to female germ cells but absent in somatic cells on whole mount samples, where stage-III oocytes and certain oogonia displayed the strongest signal, whereas stage-IV oocytes exhibited weak signal (FIG. 7). On ovarian sections, the strongest signal was present in stage-II~III oocytes and certain oogonia (Supplementary Material: FIG. S2A). A closer inspection revealed three types of oogonia exhibiting a strong, moderate and weak signal, which are called type I (og1), II (og2) and III oogonia (og3), respectively (FIG. S2A). Distinction of three types of oogonia became more evident at higher magnification (FIG. S2B). These results suggest that Lcvasa expression in the ovary is specific to germ cells.

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