| Project/Area Number |
18570121
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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 |
Functional biochemistry
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| Research Institution | The University of Tokyo |
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Principal Investigator |
MORIOKA Mizue The University of Tokyo, Graduate School of Science,, Assistant Professor (20272461)
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| Co-Investigator(Kenkyū-buntansha) |
SASAKI Tetsuhiko Tamagawa University, Research Institute, Associate Professor (60235257)
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| Project Period (FY) |
2006 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥4,020,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥420,000)
Fiscal Year 2007: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2006: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | Symbiosis / Aphid / Buchnera / Lysosome / CPVL / 細胞内共生 / 鞭毛フック基部(HBB) / タンパク質輸送 / 膜輸送系 |
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| Research Abstract |
Endosymbiotic system in the aphid is maintained through a mutualistic association between the host and a symbiotic bacterium, Buchnera, which is harbored in particular host cell called bacteriocyte. In the present study, we demonstrated the dynamics of Buchnera-aphid symbiosis, and following results were obtained.
1) Buchnera density in bacteriocytes fluctuated according to the life cycle of the host in an age- and morph-dependent manner. Buchnera density decreased drastically just around the final ecdysis in the winged morph alatae, when the indirect flight muscles develop, whereas it decreased at the early larviposition stage in the wingless morph apterae.
2) Proteomic analysis of the bacteriocyte p roteins just after the final ecdysis revealed the enhanced expression of carboxypeptidase-vitellogenic like (CPVL), in the alatae bacteriocytes compared to the apterae bacteriocytes. Immunoblotting analysis using anti-CPVL antiserum revealed that Aphid-CPVL is activated in the alatae bacteriocytes accompanying with the processing, and functions as a lysosomal enzyme to degrade the Buchnera.
3) Histochemical analysis using LysoTracker indicated that the lysosomal system is drastically activated in the alatae bacteriocytes just after the final ecdysis. Further, electron microscope observations revealed many degrading Buchnera that contained irregularly spaced electron-dense areas and were enclosed by a distended symbiosome membrane in the alatae bacteriocytes.
These findings suggest that the host lysosomal system is involved in age-and morph-dependent regulation of Buchnera density in the aphid symbiotic system and the degraded Buchnera may be supplied as nutrients to the host. We considered that the result obtained in the present study would contribute in elucidating the molecular mechanism underlying the maintenance of endosymbiotic system in aphid.
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