| Project/Area Number |
15208001
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Breeding science
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| Research Institution | The University of Tokyo |
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Principal Investigator |
TSUTSUMI Nobuhiro The University of Tokyo, Graduate School of Agricultural and Life Sciences, Professor (00202185)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAZONO Mikio The University of Tokyo, Graduate School of Agricultural and Life Sciences, Associate Professor (70282697)
KADOWAKI Koichi The University of Tokyo, Team Leader (60355724)
SAKAMOTO Wataru Okayama University, Institute of Plant Science and Resources, Professor (20222002)
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| Project Period (FY) |
2003 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥52,260,000 (Direct Cost: ¥40,200,000、Indirect Cost: ¥12,060,000)
Fiscal Year 2005: ¥11,180,000 (Direct Cost: ¥8,600,000、Indirect Cost: ¥2,580,000)
Fiscal Year 2004: ¥11,310,000 (Direct Cost: ¥8,700,000、Indirect Cost: ¥2,610,000)
Fiscal Year 2003: ¥29,770,000 (Direct Cost: ¥22,900,000、Indirect Cost: ¥6,870,000)
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| Keywords | DRP3 / mitochondrial fusion / mitochondrial fission / Kaede / ミトコンドリア分裂因子 / DRP3a / DRP3b / アンチマイシン耐性 / ミトコンドリア形質転換 / AtFis1a / ダイナミン |
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| Research Abstract |
The Arabidopsis genome has two similar dynamin-like proteins, DRP3a and DRP3b (76.7% identity). DRP3a is reported to be localized in chloroplasts [Kang et al. (1998) Plant Mol. Biol. 38 : 437], while DRP3b functions in mitochondrial division [Arimura and Tsutsumi (2002) Proc. Natl. Acad. Sci. USA 99 : 5727]. Using GFP fusion proteins, we observed both DRP3a and DRP3b in portions of mitochondria but not in chloroplasts. Furthermore, cells transformed with DRP3a and DRP3b with a defective GTPase domain had normal chloroplasts but elongated mitochondria. These results imply that both DRP3b and DRP3a are involved in the division of plant mitochondria.
The balance between mitochondrial fusion and fission influences the reticular shape of mitochondria in yeasts. Little is known about whether mitochondria fusion occurs in plants. Plant mitochondria are usually more numerous and more grain-shaped than animal mitochondria. blast searches of the nuclear and mitochondrial genome sequences of Arabidopsis thaliana did not find any obvious homologue of mitochondrial fusion genes found in animals and yeasts. To determine whether mitochondrial fusion actually occurs in plants, we labeled mitochondria in onion epidermal cells with a mitochondria-targeted, photoconvertible fluorescent protein Kaede and then altered the fluorescence of some of the mitochondria within a cell from green to red. Frequent and transient fusion of red and green mitochondria was demonstrated by the appearance of yellow mitochondria that subsequently redivided. We also show that mitochondrial fission occasionally occurs without an equal distribution of the nucleoid (DNA-protein complex in mitochondria), resulting in the coexistence of mitochondria containing various amounts of DNA within a single cell. The heterogeneity of DNA contents in mitochondria may be overcome by the frequent and transient fusion of mitochondria.
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