| Project/Area Number |
13306004
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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 |
植物保護
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| Research Institution | The University of Tokyo |
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Principal Investigator |
NAMBA Shigetou The University of Tokyo, Graduate School of Frontier Sciences, Professor, 大学院・新領域創成科学研究科, 教授 (50189221)
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| Co-Investigator(Kenkyū-buntansha) |
ISHIKAWA Yukio The University of Tokyo, Graduate School of Frontier Sciences, Associate Professor, 大学院・農学生命科学研究科, 助教授 (60125987)
SATO Mamoru National Institute of Agrobiological Sciences, Research Leader, 主席研究管理官
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| Project Period (FY) |
2001 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥37,700,000 (Direct Cost: ¥29,000,000、Indirect Cost: ¥8,700,000)
Fiscal Year 2003: ¥14,040,000 (Direct Cost: ¥10,800,000、Indirect Cost: ¥3,240,000)
Fiscal Year 2002: ¥11,830,000 (Direct Cost: ¥9,100,000、Indirect Cost: ¥2,730,000)
Fiscal Year 2001: ¥11,830,000 (Direct Cost: ¥9,100,000、Indirect Cost: ¥2,730,000)
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| Keywords | small circular DNA / complete genomic analysis / host factor for insect transmissibility / ATP synthase / leafhopper / host switching / ヨコバイ / ミュータント / 昆虫非伝搬性変異株 / 特異抗体 / 遺伝子発現 |
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| Research Abstract |
In this year, we determined the complete genomic sequence of the plant-pathogenic bacterium Candidatus Phytoplasma asteris. Comparison of the genome of P.asteris with those of other parasitic and symbiotic bacteria reveals features that are unique to this intracellular parasite, which has adapted to a nutrient-rich environment. The genome of P.asteris encodes genes for basic functions, such as DNA replication, transcription, and translation. In contrast, genes responsible for amino acid and fatty acid biosynthesis, the TCA cycle, and oxidative phosphorylation are absent. This may be because phytoplasmas can depend on their host cells for supplies of many biological substances, as is the case with mycoplasmas. Surprisingly, the P.asteris genome encodes proteins for even fewer metabolic functions than do those of mycoplasmas. For example, the genes for the pentose phosphate cycle and ATP synthase have not been found. R.prowazekii has also lost the genes for the pentose phosphate cycle ; however, this organism has retained genes for the TCA cycle, electron transfer system, and ATP synthase. The complete P.asteris genome suggests that the set of known metabolic pathways of phytoplasmas is even smaller than that of mycoplasmas, representing the most minimal genome among living organisms. Instead, P.asteris possesses genes for transporter proteins involved in the uptake of substances from the surrounding host cell cytoplasm. This may be the result of reductive evolution, as a consequence of life as an intracellular parasite in a nutrient-rich environment Phytoplasmas are unique bacteria that contain a new minimal gene set, and this finding should help to elucidate the host determination mechanisms of phytoplasmas.
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