1987 Fiscal Year Final Research Report Summary
Cytoplasmic control of the cell cycle
| Project/Area Number |
61490016
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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 |
広領域
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| Research Institution | Kyoto University |
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Principal Investigator |
YONEDA Mitsuki Faculty of Science, Kyoto University, 理学部, 教授 (50017183)
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| Co-Investigator(Kenkyū-buntansha) |
MARUYAMA Yoshihiko K. Faculty of Science, Kyoto University, 理学部, 助手 (60135514)
KUBOTA Hirochi Y. Faculty of Science, Kyoto University, 理学部, 助手 (40115837)
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| Project Period (FY) |
1986 – 1987
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| Keywords | Xenopus / Calcium / Fertilization / Activation / Cell cycle / Sea urchin / Androgenesis / 付活 |
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| Research Abstract |
(1) Mechanical properties of sea-urchin eggs as an index of the cell cycle. Profile of the spherical shells flattened under two parallel plates was calculated to obtain the relation between the compressing force and the degree of flattening. Matching it with observed relation of force-deformation in sea-urchin eggs, we found Young's modulus of the egg sufrace of 10^2 dyne/cm^2, being 1/10 of an estimate made by Hiramoto.
(2) Wave of free calcium on activation of Xenopus eggs. Unfertilized eggs injected with aequorin were activated by pricking and observed with a two-dimensional photon-counting system tith an image processor. A free Ca incredse was initiated around the point of pricking, and this state of high Ca propagated as a wave, similar to the wave of change in brightness of the surface on activation, knwn as "activation wave". By correlating images of aequorin luminescence and the brightness of the surface, we found temporal coincidence between the Ca wave and the activation wave.
(3) Correlation of the Calcium wave and the ultrastructure of the cortex in fertilized Xenopus eggs. Difficulty in finding Ca wave in fertilized frog eggs due to loss of their fertility on treating them with Ca-fiee madium (to prevent egg activation during injection of aequorin) was overcome by injecting aequorin into coelomic oocytes, and by placing them into the coelom of an albino-type female. Wild-type eggs found among albino eggs from the albino mother was then fertilized by sperm. We found a Ca wave in fertilized eggs. The Ca wave coincided with the relaxation zone of the activation wave, where exocytosis of cortical granules and elongation of microvilli were taking place.
(4) Developmental timing in androgenesis. Careful observation of the development of the pairs of embryos derived from nucleate and non-nucleate fragments of single unfertilized eggs indicated that the delay is entirely dueto extension of sperm amphiaster stage.
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