| Project/Area Number |
12660255
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied animal science
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| Research Institution | Kobe University |
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Principal Investigator |
MIYANO Takashi Faculty of Agriculture, Department of Animal Scientce, Professor, 農学部, 教授 (80200195)
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| Project Period (FY) |
2000 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2002: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2001: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2000: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | oocyte / maturation / MAP kinase / Cdc2 kinase / growth |
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| Research Abstract |
Meiotic maturation of mammalian oocytes is under the control of cell cycle molecules Cdc2 kinase and MAP kinase. In the present study, I investigated the relationship between the ability to activate Cdc2 kinase and MAP kinase and the acquisition of meiotic competence during oocyte growth. In vitro growth culture of incompetent growing oocytes was also conducted to induce their maturation.
1) Growing and fully grown pig oocytes were collected from antral follicles of various diameters (0.5-6.0 mm) and cultured in vitro. Fully grown oocytes (120-125 μm) which have full competence to mature to metaphase II had the ability to activate both Cdc2 and MAP kinase. In contrast, growing oocytes which have limited competence to resume meiosis had no such ability. Cyclin B1 molecules did accumulate, however, with phosphorylated inactive forms of p34^<cdc2> appearing in the cultured oocytes. Growing oocytes of 110 μm in diameter resumed meiosis but arrested at metaphase I. The oocytes were capable o
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f activating Cdc2 kinase, although they did not appear to have established a MAP kinase-activating pathway. These results suggest that pig oocytes acquire the ability to activate Cdc2 kinase and then establish the MEK-MAP-kinase pathway for full meiotic competence during the final growth phase.
2) Active forms of MAP kinase (pMAPK) was localized around condensed chromosomes at metaphase I. During the progression of anaphase I and telophase I pMAPK was detected at the mid-zone of the elongated spindle. The inhibition of MAP kinase activity during the meiosis I/meiosis II transition suppressed chromosome separation, first polar body emission and formation of the metaphase II spindle. These results suggest that the spindle-associated pMAPK plays an important role in the events occurring during the meiosis I/meiosis II transition.
3) Growing pig and bovine oocytes from early antral follicles grew efficiently in hypoxanthine-supplemented medium and some of them acquired the meiotic competence after 8-16 days of culture. Inhibitors of PP1/PP2A induced a rapid activation of MAP kinase in growing oocytes. Some of the treated oocytes matured to metaphase II. Less
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