| Project/Area Number |
12640651
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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 |
生物形態・構造
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| Research Institution | Hiroshima University |
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Principal Investigator |
MINEYUKI Yoshinobu Hiroshima Univ., Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (30219703)
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| Co-Investigator(Kenkyū-buntansha) |
KARAHARA Ichirou Toyama Univ., Fac. Science, Research Associate, 理学部, 助手 (60283058)
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| Project Period (FY) |
2000 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2001: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2000: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Keywords | preprophase band / microtubule / high pressure freezing / coated vesicles / coated pit / Allium cepa (onion) / high voltage electron microscopy / tomoography / トモグラフィー / Coated Pit / トモブラフィー |
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| Research Abstract |
The preprophase band (PPB) is an array of microtubules in plant cells that appears in G2 and disappears in prometaphase. Its function appears to be to mark the site on the plasma membrane where the cell plate will fuse at the end of cytokinesis. Little is known about how the plasma membrane becomes modified during PPB formation. To understand the mechanism of how a PPB memory site is generated, we have re-analyzed the structural changes in membrane architecture associated with PPB formation using epidermal cells of high pressure frozen onion cotyledons. Our micrographs demonstrate that the forming PPB regions contain large numbers of clathrin-coated pits and clathrin-coated vesicles.
To compare the density of coated vesicles in PPB and non-PPB regions, we have prepared serial thin sections both in the nuclear region and in the region far from the nucleus in prophase and interphase cells. The density of coated vesicles was significantly higher in the PPB regions than in the adjacent non-PPB regions. A more detailed morphological analysis of the vesicles by means of dual-axis EM tomography (7 nm 3-D resolution) shows that plasma membrane associated clathrin-coated pits and two types of vesicles, clathrin-coated and noncoated. The latter had more densely staining contents and were distributed even further away from the plasma membrane than the clathrin-coated vesicles. This suggests the involvement of endocytosis in the development of PPBs. Outside the forming PPB regions in a prophase cell and in the cortical region of an interphase cell we also saw the same structures, but they were less numerous, confirming the notion that PPB formation involves an upregulation of endocytosis in the future PPB region.
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