1996 Fiscal Year Final Research Report Summary
Mechanisms for the regulation of phenoloxidase activity during the process of insect metamorphosis
| Project/Area Number |
07660114
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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 |
応用微生物学・応用生物化学
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| Research Institution | Saga University |
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Principal Investigator |
TSUKAMOTO Takuji Saga University Department of Applied Biological Sciences, 農学部, 教授 (70136597)
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| Project Period (FY) |
1995 – 1996
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| Keywords | phenoloxidase / prophenoloxidase / latent phenoloxidase / phenoloxidase inhibitor / insect metamorphosis / housefly / gadfly / fluctuation in enzyme activity |
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| Research Abstract |
The purpose of this investigation was to establish a molecular and cellular understanding of the mechanisms involved in the regulation of phenoloxidase activity during metamorphosis of the housefly, Musca domestica L.
Initially, the possible fluctuation of phenoloxidase activity during metamorphosis of the housefly was re-investigated in terms of activity and reactivity toward antibody raised against purified phenoloxidase. It was found that the haemolymph phenoloxidases existed as proenzymes, prophenoloxidases, that could be activated by an endogenous activator, throughout the process of housefly metamorphosis. However, it should be noted that in housefly prepupae, phenoloxidase existed as latent phenoloxidase which was much more stable than prophenoloxidase under the action of endogenous activator. Prophenoloxidases were purified from both larvae and pupae of the housefly. Comparative studies on purified larval and pupal prophenoloxidase of the housefly revealed that both prophenoloxidases had identical molecular masses of 145,000 which was lower than those of both latent phenoloxidase (178,000) and phenoloxidase (320,000). Further, the mechanism of the activation of prophenoloxidase appeared to involve an association/dissociation system.
In addition to the above studies, the complete amino acid sequence of housefly phenoloxidase inhibitor (POI) was established. A homology search revealed no sequence similarity to other known peptides. Housefly POI could also competitively inhibit phenoloxidase isolated from insects other than the housefly (gadfly, Pteticus tenebrifa) with high affinity.
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