| Project/Area Number |
14360117
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General fisheries
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| Research Institution | Fisheries Research Agency, National Research Institute of Aquaculture |
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Principal Investigator |
KAMAISHI Takashi Fisheries Research Agency, National Research Institute of Aquaculture, Aquatic Animal Health Division, Senior researcher, 養殖研究所・病害防除部, 主任研究官 (80344456)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAYASU Chihaya Fisheries Research Agency, National Research Institute of Aquaculture, Aquatic Animal Health Division, Researcher, 養殖研究所・病害防除部, 研究員 (00311225)
SAKAMI Tomoko Fisheries Research Agency, National Research Institute of Aquaculture, Farming System Division, Senior researcher, 養殖研究所・生産システム部, 主任研究官 (70372034)
KURITA Jun Fisheries Research Agency, National Research Institute of Aquaculture, Aquatic Animal Health Division, Senior researcher, 養殖研究所・病害防除部, 主任研究官 (20372039)
ITO Takafumi Fisheries Research Agency, National Research Institute of Aquaculture, Aquatic Animal Health Division, Researcher, 養殖研究所・病害防除部, 研究員 (70372050)
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| Project Period (FY) |
2002 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥14,600,000 (Direct Cost: ¥14,600,000)
Fiscal Year 2004: ¥4,500,000 (Direct Cost: ¥4,500,000)
Fiscal Year 2003: ¥4,400,000 (Direct Cost: ¥4,400,000)
Fiscal Year 2002: ¥5,700,000 (Direct Cost: ¥5,700,000)
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| Keywords | Akoya oyster / experimental infection / cultivation of bacteria / PCR / monoclonal anti body / SSU rRNA / 細菌培地 / ssrRNA / 単クローナル抗体 |
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| Research Abstract |
Mass mortalities have been occurring in cultured Japanese pearl oysters, akoya oyster, Pinctada fucata martensii in western Japan. Although the involvement of some causative agents was suggested for the disease, the cause of the disease is still unidentified. The following sentences are the results in this research.
A variety of bacterial media were tried to confirm the involvement of the filtrable eubacteria in the cause of akoya oyster disease. The specific primers were made from the sequence data of the bacteria isolated from the diseased oyster. But the amplification products were detected from healthy shellfish. A clear conclusion has not been obtained about the involvement of eubacteria in akoya oyster disease.
The virus was not isolated from diseased akoya oyster (both naturally infected shellfish and experimentally infected shellfish) using some established fish cell lines, although following the published reports in which the viral pathogen could be isolated from diseased akoya
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oyster. On the other hand, the results of the experimental infection and re-infection that used the continual samples were consistent under the control conditions in the facility. It became clear the pathogen was not the virus isolated by the reported methods by established fish cell lines from diseased akoya oyster.
It aimed to analyze the bacterial phase inside the Akoya oyster by non-cultured technique, and to clarify the relation between change to a morbid state and the bacterial phase. DNA was extracted from the akoya oyster each organization and 16S-rRNA gene was amplified. They separated and compared by the denaturing gradient gel electrophoresis (DGGE). As a result, an obvious difference was not observed in the bacterial phase between a healthy shellfish, the experimental infection shellfish, and the naturally-infected shellfish. On the other hand, the genes of related species of opportunistic bacterium were detected in the diseased akoya oyster.
In this study, an experimental infection was performed by cohabitation of the diseased and healthy pearl oysters. A high mortality and characteristic disease conditions were observed in the test group. The result reconfirmed that the disease probably caused by a certain infectious agent. To clarify the tissue distribution of the causative agent in diseased pearl oysters, two experimental infections were performed by transplantation of pieces of various tissues or injection of homogenates of various tissues from pearl diseased oysters into healthy pearl oysters. The hemolymph, mantle and adductor muscle showed high infectious titers compared with that of the heart, digestive gland, and hemocytes. The mantle had the highest infectious titer. Moreover, injection of the supernatant of mantle homogenate also transmitted the disease strongly to the test pearl oysters. These results suggest that the causative agent is concentrated in the mantle.
The monoclonal antibody to the diseased akoya oyster was made, and the responsiveness was examined. The result revealed that the antibody reacted to the hemolymph of akoya oyster. The antibody was thought to be effective for the diagnosis of the disease from the result of the time course observations of the seasonal changes and the experimental infection, and was applied for the patent. Less
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