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Differential expression and localization of four connexins in the ovary of the ayu (Plecoglossus Altivelis)

Molecular Reproduction and Development

By:
, , , , ,
DOI: 10.1002/mrd.20562

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Abstract

The post-vitellogenic oocytes of teleost fish are generally unresponsive to maturation-inducing hormone (MIH) until a luteinizing hormone (LH) surge stimulates sensitivity via the acquisition of oocyte-maturational competence (OMC). Heterologous gap junctions (GJs) between granulosa cells and the oocyte have been previously implicated in the regulation of oocyte maturation in various vertebrate species. Although heterologous GJ are present in ovarian follicles of ayu (Plecoglossus altivelis), their role in maturation remains unclear. In the present study, we cloned and characterized complementary DNAs for GJ protein connexin (Cx), and examined the expression pattern of Cx messenger RNAs in the ayu ovary. Four Cx cDNAs with predicted molecular masses of 32.1 (Cx32.1), 34.9 (Cx34.9), 44.1 (Cx44.1), and 44.2 (Cx44.2) kDa, respectively, were cloned. Northern blot analysis revealed that the levels of Cx44.1 and Cx44.2 transcripts were similar during the vitellogenic and ovulatory stages. Cx32.1 transcripts were more abundant during the vitellogenic stage, but their levels declined thereafter. Cx34.9 transcript levels increased during the vitellogenic stage and remained high during the acquisition of OMC. In situ hybridization revealed that Cx44.1 and Cx44.2 signals were restricted to the oocyte, whereas the Cx32.1 and Cx34.9 signals were detected in both cellular fractions. Furthermore, a dye-transfer assay revealed the presence of functional GJs between the oocytes and follicle cells. These results suggest that Cx34.9 contributes to the formation of heterologous GJs between oocytes and granulosa cells. Moreover, GJs formed by Cx34.9 may function during the LH-dependent acquisition of OMC and the MIH-dependent resumption of meiosis in ayu. ?? 2007 Wiley-Liss, Inc.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Differential expression and localization of four connexins in the ovary of the ayu (Plecoglossus Altivelis)
Series title:
Molecular Reproduction and Development
DOI:
10.1002/mrd.20562
Volume
74
Issue:
9
Year Published:
2007
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
1113
Last page:
1123
Number of Pages:
11