| Project/Area Number |
63045001
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | University-to-University Cooperative Research |
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| Research Institution | Hokkaido University |
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Principal Investigator |
YAMADA Juro Professor, Faculty of Fisheries, Hokkaido University, 水産学部, 教授 (60001575)
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| Co-Investigator(Kenkyū-buntansha) |
EBBESSON Sve アラスカ大学, 海洋学部, 教授
MATHISEN Ole A. Professor, Fisheries and Ocean Sciences, University of Alaska, 水産海洋学部, 教授
ANDO Seiichi Associate Professor, Faculty of Fisheries, Kagoshima University, 水産学部, 助教授 (80131986)
SHIMIZU Motohiro Lecturer, Faculty of Fisheries, Hokkaido University, 水産学部, 講師 (80002088)
TAKAHASHI Koretaro Associate Professor, Faculty of Fisheries, Hokkaido University, 水産学部, 助教授 (90125328)
HARA Akihiko Associate Professor, Faculty of Fisheries, Hokkaido University, 水産学部, 助教授 (40091483)
YAMAUCHI Kohei Associate Professor, Faculty of Fisheries, Hokkaido University, 水産学部, 助教授 (10109514)
HATANO Mutsuo Professor, Faculty of Fisheries, Hokkaido University, 水産学部, 教授 (80001600)
MASADA Kiyoshi Professor, Faculty of Fisheries, Hokkaido University, 水産学部, 教授 (20001589)
SATO Osamu Professor Emeritus, Faculty of Fisheries, Hokkaido University, 水産学部, 名誉教授 (70001568)
EBBESSON Sven O. E. Professor, Institute of Marine Sciences, University of Alaska
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| Project Period (FY) |
1988 – 1990
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| Keywords | Salmonids / Spawning migration / Gonadal maturation / Sex steroids / Thyroid hormone / Vitellogenin / Bone metabolism / Triglyceride synthesis |
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| Research Abstract |
Captain Masuda (Oshoro-maru), professor Hatano (Hokkaido University), Associate Professor Yamauchi (Hokkaido University), Dr. Takagi (Hokkaido University) and Professor Mathisen (University of Alaska) obtained the fish samples in the Gulf of Alaska and the mouth, the middle and spawning ground of Copper River. After coming back to Japan, their analysis were performed. The results obtained are as follows : After
1) Changes in circulating hormones during spawning migration
At the start of chum salmon spawning migration, estradiol-17beta (E_2) levels raised, followed by the increase as spawning migration progressed. Vitellogenin contents also increased during the migration. However, the concentrations decreased on the spawning ground, whereas 17alpha, 20beta-dihydroxy-4-pregnen-3-one (DHP) increased dramatically. These results suggest that E_2 and DHP are involved in vitellogenesis and oocyte maturation, respectively.
Thyroxine (T_4) and triiodothyronin (T_3) showed constant levels during sp
… More
awning migration. Interestingly, however, T_4 and T_3 were taken in the gonad at the start of the migration. These results indicate that T_4 and T_3 may be involved in the gonadal development.
2) Changes in bone metabolism
In the sockeye salmon collected from Gulf of Alaska, both formation and resorption of the bone were very active. On the surface of the bone, there were very active osteoblasts forming bone matrix and mononuclear and multinuclear resorptive cells destroying and resorbing calcified matrix. These indicate rapid bone growth during the migration in the ocean. When the fish approached to the mouth of Copper River, activities of the bone formation and resorption decreased. At the spawning ground, on the other hand, almost no osteoblast and resorptive cells existed on the bone surface and bone growth stopped completely. No sexual difference was observed on the metabolism of bone.
3) Changes in lipid synthesis
In accordance with the sexual maturation, chum salmon exhibited an obvious decrease in triglyceride synthetic activity in the liver tissue, while it was increased in the muscle tissue. This was attributed to homeostasis under extraordinary lack of lipid in the muscle tissue under the fasting condition during spawning migration without the substrate supply from the liver. The causes of the degenerative change such as the loss of lipid contents can be ultimately attributed to the progressed activation of lipid hydrolytic enzymes, since there was a remarkable increase in this activity in the liver tissue and also in the muscle tissues of male. Intactivation of lipid sysnthesis in the liver tissue is considered to give impetus to degenerative change.
Professor Sven O. E. Ebbesson (University of Alaska) visited Hokkaido University, Japan, and exchanged the informations on salmon research with this project members. We made sure of keeping the further exchange of mutual informations. Less
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