| Project/Area Number |
04454027
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
動物発生・生理学
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
YAMANA Kiyotaka Kyushu Univ., Facul. Sci., Prof., 理学部, 教授 (20037162)
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| Co-Investigator(Kenkyū-buntansha) |
YUGE Masahiro Fukuoka Women's Univ., Facul. Domes. Sci. Lecturer, 家政学部, 講師 (80220523)
NOMURA Kazuya Kyushu Univ., Facul. Sci., Assoc. Prof., 理学部, 助教授 (30150395)
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| Project Period (FY) |
1992 – 1993
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| Project Status |
Completed (Fiscal Year 1993)
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| Budget Amount *help |
¥5,600,000 (Direct Cost: ¥5,600,000)
Fiscal Year 1993: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1992: ¥4,800,000 (Direct Cost: ¥4,800,000)
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| Keywords | Dorsoventral axis / Body axis / Xenopus laevis / Early development / Determinant |
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| Research Abstract |
Prior to the beginning of development, the dorsoventral axis is specified in a newly laid egg of Xenopus laevis. The specification of this axis enables transformation of radial symmetry into bilateral symmetry, an event which is a prerequisite for subsequent body formation. Recently, we have shown that the cytoplasm taken from dorsal cells of an early embryo has also the activity to induce the dorsoventral axis when injected into ventral cells of a recipient. The purpoase of the present investigation is to identify the molecule responsible for the axis-inducing activity and to analyze the mechanism by which the axis is specified.
First, we homogenized dorsal cells of early embryos and obtained a soluble fraction, and showed that the fraction retained the axis-inducing activity. Then, to purify an active cytoplasmic material, we fractionated a soluble fraction of eggs and early embryos into several fractions according to the molecular size of proteins contained. It has been shown that Fr
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action 3 is the most active in inducing the dorsoventral axis. Proteinase K treatment, but not RNase A treatment, lowered the activity below a 50% level.
Second, we studied the timing of appearance and the distribution of the axis-inducing activity by assaying a number of cytoplasmic samples of different regions of eggs and embryos at different stages. The obtained results have revealed that the activity is present around the vegetal pole in an egg before cortial rotation. After rotation, the activity is now located at the future dorsal equatorial region of an embrho, and the movement of activity to the dorsal region depends on cortical rotation. When cortical rotation is stopped by UV irradiation the activity remains around the vegetal pole. Such irradiated eggs later developed into embryos that lacked the dorsoventral axis. Furthermore, cutting an irradiated embryo along the first cleavage plane rescures the axis probably by causing the movement of activity during wound healing. It is therefore concluded that cortical rotation is in some way involved in the movement of activity to the equatorial region and is in some way involved in the movement of activity to the equatorial region and this movement is indispensable for the specication of the dorsoventral axis. Less
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