| Project/Area Number |
16580162
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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 |
General fisheries
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| Research Institution | Kumamoto Health Science University |
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Principal Investigator |
TAKAHASHI Tohru Kumamoto Health Science University, Department of Medical Technology, Faculty of Health Science, Professor, 保健科学部, 教授 (70369122)
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| Co-Investigator(Kenkyū-buntansha) |
TSUTSUMI Hiroaki Prefectural University of Kumamoto, Faculty of Environmental and Symbiotic Sciences, Professor, 環境共生学部, 教授 (50197737)
AKAIKE Norio Kumamoto Health Science University, Department of Medical Technology, Faculty of Health Science, Professor, 保健科学, 教授 (30040182)
NOMURA Yuji Hiroshima University, Department of Biomaterials Science, Graduate School of Biomedical Science, Assistant Professor, 大学院・医歯薬学総合研究科, 助手 (80218370)
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| Project Period (FY) |
2004 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2005: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2004: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Keywords | short neck clam / Ariake Bay / manganese / tidal flat / heavy metal / eco-toxicology / juvenile clam / shell formation |
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| Research Abstract |
I.Field research
Settlement, growth and survival of juvenile clams (Ruditapes philippinalum) were traced at three research areas (A : covered with sand collected from the offshore, C : uncovered area, C : medium area between A and C) in Arao Tidal Flat where Manganese concentration of sand is very high. Among the Mn collected from the sediment and interstitial water, soluble Mn was quantified, and there was significant relationship between the concentration of soluble Mn and the mortality of juvenile calms. The threshold Mn ion concentration of the interstitial water for the extinction of juvenile clam was estimated to be over 60 mg/L.
II.Narrowing down the death factor by rearing experiment.
Mn ion did not have a lethal effect for the juvenile clams even if the concentration was over 60 mg/L. However, the survival rate decreased when the sediment was added to the rearing water with Mn ion. In addition, the mortality raised when reared with top clear layer of the sediment-Mn ion mixed wat
… More
er, whilst no lethal effect when reared with organic free sand. These results suggest that the death of juvenile clams are caused by the reaction between the soluble manganese and some organic matter in the sediment.
III.Bioassay by cell culture
In order to carry out the exposure experiment about the factors narrowed down by field research or rearing experiment at any time, we tried to establish the bioassay system by cell culture. However, diversion cell culture technology of vertebrates was partly ineffective for clams. On the other hand, the collateral experiment using Xenopus hepatocyte suggested that Mn ion had some inhibiting effect on the vitellogenesis of Xenopus.
IV.Pathological study of juvenile clams.
Although detail observation was carried out under the light microscope, no obvious pathological change was detected in the sections of juvenile clams. We are continuously carrying out TEM observation. On the other hand, we prepared to review secreted peptides in juvenile clams by using MALDI-TOF MS. If any difference of peptide secretion was detected between the juvenile clams collected from Arao Tidal Flat (high Mn concentration) and Kikuchi River Moouth (low Mn concentration), corresponding secretion cell will be detected by In situ hybridization. During the above experiment, we found that shell of the high mortality group in the rearing experiment became fragile, and so on about Arao population. It is thought that trouble is caused in the process of the shell formation under the high Mn condition. We are currently carrying out the examination that applies the focus to the shell formation : shell strength, microstructure of the shell, shell formation cells in the mantle. Less
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