| Project/Area Number |
63440080
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
Biological pharmacy
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| Research Institution | University of Tokyo |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
KOMANO Hiroto 東京大学, 薬学部, 助手 (40170378)
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| Project Period (FY) |
1988 – 1990
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| Project Status |
Completed (Fiscal Year 1990)
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| Budget Amount *help |
¥30,200,000 (Direct Cost: ¥30,200,000)
Fiscal Year 1990: ¥5,000,000 (Direct Cost: ¥5,000,000)
Fiscal Year 1989: ¥12,100,000 (Direct Cost: ¥12,100,000)
Fiscal Year 1988: ¥13,100,000 (Direct Cost: ¥13,100,000)
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| Keywords | Sarcophaga Peregrina / Sarcophaga lectin / imaginal discs / defense molecules / dual functions / development / morphogenesis / Northern blotting / プロセッシング / プロテア-ゼ / 発生 / 胚細胞 / 成長因子 / 分化 / 昆虫 |
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| Research Abstract |
Sarcophaga lectin is a galactose-binding lectin induced in the hemolymph of Sarcophaga peregrina (flesh fly) larvae in response to body injury. This lectin is essential for the elimination of foreign substance from the following evidence. When sheep red blood cells were injected into the abdominal cavity of Sarcophaga larvae, they were lysed and disappeared from the hemolymph withtime. However. when the blood cells were injected together with antibody against Sarcophaga lectin or hapten-sugar galactose, no elimination of the blood cells was detected. Premimune serum or non-hapten sugar glucose had no effect on the lysis of the blood cells. This indicates that Sarcophaga lectin is a defense molecule and participates in the elimination of foreign of substances invading through the damaged body wall.
Northern blot analysis using cDNA for Sarcophaga lectin revealed that the gene for this lectin is expressed twice during ontogeny without any outside stimuli : First in the embryonic stage and
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then again in the pupal stage. Sarcophaga lectin synthesized at the pupal stage was shown to be necessary for the development of imaginal discs. When leg or wing discs were cultured in vitro in the presence of ecdysone, they differentiate into adult structures. When anti-Sarcophaga lectin or galactose was present in the culture medium, the differentiation stopped at the stage of apolysis, whereas preimmune serum or glucose did not interfere with the differentiation of imaginal discs. This indicates that Sarcophaga lectin is essential for the terminal differentiation of imaginal discs. Since no Sarcophaga lectin was added to the culture medium, it must be synthesized by the imaginal disc itself. Immunoblotting experiments showed that imaginal discs (both wing and leg discs) synthesize Sarcophaga lectin at the stage of apolysis. Therefor, it is clear that Sarcophaga lectin has dual functions in defense and development.
It is likely that the concept of one gene-one protein-one function is not necessarily correct. Biological system seems to be able to use the asme protein in two ways (or in multiple ways) to maintain its homeostasis, depending upon environmental conditions. Less
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