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Expression and localization of aquaporin 1b during oocyte development in the Japanese eel (Anguilla japonica).

Kagawa H, Kishi T, Gen K, Kazeto Y, Tosaka R, Matsubara H, Matsubara T, Sawaguchi S - Reprod. Biol. Endocrinol. (2011)

Bottom Line: Light microscopic immunocytochemical analysis of ovary revealed that the Japanese eel AQP1b was expressed in the cytoplasm around the yolk globules which were located in the peripheral region of oocytes during the primary yolk globule stage; thereafter, the immunoreactivity was observed throughout the cytoplasm of oocyte as vitellogenesis progressed.The immunoreactivity became localized around the large membrane-limited yolk masses which were formed by the fusion of yolk globules during the oocyte maturation phase.These results together indicate that AQP1b, which is synthesized in the oocyte during the process of oocyte growth, is essential for mediating water uptake into eel oocytes.

View Article: PubMed Central - HTML - PubMed

Affiliation: Faculty of Agriculture, University of Miyazaki, Miyazaki 889-2192, Japan. kagawa@cc.miyazaki-u.ac.jp

ABSTRACT
To elucidate the molecular mechanisms underling hydration during oocyte maturation, we characterized the structure of Japanese eel (Anguilla japonica) novel-water selective aquaporin 1 (AQP1b) that thought to be involved in oocyte hydration. The aqp1b cDNA encodes a 263 amino acid protein that includes the six potential transmembrane domains and two Asn-Pro-Ala motifs. Reverse transcription-polymerase chain reaction showed transcription of Japanese eel aqp1b in ovary and testis but not in the other tissues. In situ hybridization studies with the eel aqp1b cRNA probe revealed intense eel aqp1b signal in the oocytes at the perinucleolus stage and the signals became faint during the process of oocyte development. Light microscopic immunocytochemical analysis of ovary revealed that the Japanese eel AQP1b was expressed in the cytoplasm around the yolk globules which were located in the peripheral region of oocytes during the primary yolk globule stage; thereafter, the immunoreactivity was observed throughout the cytoplasm of oocyte as vitellogenesis progressed. The immunoreactivity became localized around the large membrane-limited yolk masses which were formed by the fusion of yolk globules during the oocyte maturation phase. These results together indicate that AQP1b, which is synthesized in the oocyte during the process of oocyte growth, is essential for mediating water uptake into eel oocytes.

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Localization of aqpb1 gene transcripts in Japanese eel oocytes by in situ hybridization. Oocyte at the perinucleolus stage (A, B, C), the oil droplet stage (D), the primary yolk globule stage (E), and the secondary yolk globule stage (F). Arrows indicate intense AQP1b signals observed in oocytes.
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Figure 4: Localization of aqpb1 gene transcripts in Japanese eel oocytes by in situ hybridization. Oocyte at the perinucleolus stage (A, B, C), the oil droplet stage (D), the primary yolk globule stage (E), and the secondary yolk globule stage (F). Arrows indicate intense AQP1b signals observed in oocytes.

Mentions: In situ hybridization was carried out to characterize the cellular expression of eel aqp1b in the oocytes at various developmental stages. Although an aqp1b signals could not be observed at oocytes at the perinucleolus stage (Figure 4A), the intense signal was first found in larger oocytes at the same stage (Figure 4B). Relatively intense signals were localized to regions within the cytoplasm (Figure 4B) and later they became distributed throughout the cytoplasm (Figure 4C). Similar intense signals were found in the oocyte at the oil droplet stages (Figure 4D). Thereafter, the expression of eel aqp1b signals became weak in association with oocyte growth from the primary yolk (Figure 4E) to the secondary yolk globule stage (Figure 4F) and sometimes became absent.


Expression and localization of aquaporin 1b during oocyte development in the Japanese eel (Anguilla japonica).

Kagawa H, Kishi T, Gen K, Kazeto Y, Tosaka R, Matsubara H, Matsubara T, Sawaguchi S - Reprod. Biol. Endocrinol. (2011)

Localization of aqpb1 gene transcripts in Japanese eel oocytes by in situ hybridization. Oocyte at the perinucleolus stage (A, B, C), the oil droplet stage (D), the primary yolk globule stage (E), and the secondary yolk globule stage (F). Arrows indicate intense AQP1b signals observed in oocytes.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3117773&req=5

Figure 4: Localization of aqpb1 gene transcripts in Japanese eel oocytes by in situ hybridization. Oocyte at the perinucleolus stage (A, B, C), the oil droplet stage (D), the primary yolk globule stage (E), and the secondary yolk globule stage (F). Arrows indicate intense AQP1b signals observed in oocytes.
Mentions: In situ hybridization was carried out to characterize the cellular expression of eel aqp1b in the oocytes at various developmental stages. Although an aqp1b signals could not be observed at oocytes at the perinucleolus stage (Figure 4A), the intense signal was first found in larger oocytes at the same stage (Figure 4B). Relatively intense signals were localized to regions within the cytoplasm (Figure 4B) and later they became distributed throughout the cytoplasm (Figure 4C). Similar intense signals were found in the oocyte at the oil droplet stages (Figure 4D). Thereafter, the expression of eel aqp1b signals became weak in association with oocyte growth from the primary yolk (Figure 4E) to the secondary yolk globule stage (Figure 4F) and sometimes became absent.

Bottom Line: Light microscopic immunocytochemical analysis of ovary revealed that the Japanese eel AQP1b was expressed in the cytoplasm around the yolk globules which were located in the peripheral region of oocytes during the primary yolk globule stage; thereafter, the immunoreactivity was observed throughout the cytoplasm of oocyte as vitellogenesis progressed.The immunoreactivity became localized around the large membrane-limited yolk masses which were formed by the fusion of yolk globules during the oocyte maturation phase.These results together indicate that AQP1b, which is synthesized in the oocyte during the process of oocyte growth, is essential for mediating water uptake into eel oocytes.

View Article: PubMed Central - HTML - PubMed

Affiliation: Faculty of Agriculture, University of Miyazaki, Miyazaki 889-2192, Japan. kagawa@cc.miyazaki-u.ac.jp

ABSTRACT
To elucidate the molecular mechanisms underling hydration during oocyte maturation, we characterized the structure of Japanese eel (Anguilla japonica) novel-water selective aquaporin 1 (AQP1b) that thought to be involved in oocyte hydration. The aqp1b cDNA encodes a 263 amino acid protein that includes the six potential transmembrane domains and two Asn-Pro-Ala motifs. Reverse transcription-polymerase chain reaction showed transcription of Japanese eel aqp1b in ovary and testis but not in the other tissues. In situ hybridization studies with the eel aqp1b cRNA probe revealed intense eel aqp1b signal in the oocytes at the perinucleolus stage and the signals became faint during the process of oocyte development. Light microscopic immunocytochemical analysis of ovary revealed that the Japanese eel AQP1b was expressed in the cytoplasm around the yolk globules which were located in the peripheral region of oocytes during the primary yolk globule stage; thereafter, the immunoreactivity was observed throughout the cytoplasm of oocyte as vitellogenesis progressed. The immunoreactivity became localized around the large membrane-limited yolk masses which were formed by the fusion of yolk globules during the oocyte maturation phase. These results together indicate that AQP1b, which is synthesized in the oocyte during the process of oocyte growth, is essential for mediating water uptake into eel oocytes.

Show MeSH
Related in: MedlinePlus