| Project/Area Number |
09640804
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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 |
動物生理・代謝
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| Research Institution | TOKYO INSTITUTE OF TECHNOLOGY |
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Principal Investigator |
MOTOKAWA Tatsuo Tokyo Institute of Technology, Faculty of Bioscience and Biotechnology, Professor, 生命理工学部, 教授 (80092352)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 1998: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1997: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | echinoderms / connective tissue / catch connective tissue / contractility / nerve / neurotransmitters / crinoids / ウミシダ / 筋収縮 |
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| Research Abstract |
The structure and basic contractile properties of crinoid ligaments were studied. The materials were cirri and arms of the stalked crinoid Metacrinus rotundus and the comatulids Comanthus pinguis and Tropiometra afra
CIRRUS : The electronmicroscopic observation revealed that there are no muscle cells in cirral ligaments. Immunohistochemical staining with gamma-amino butylic acid (GABA) antibody showed immunoreactive cells : the cell bodies lies in the coelotherial plexus and their branches penetrate into the ligaments.
The isolated cirrus was bent a little to generate a counter force and that deformation was held constant. The counter force decreased when GABA was applied, that is, the ligament became soft. In some preparations the ligament generated active contractile forces. Acetylcholine and nicotinic agonists softened the ligament and muscarinic agonists softened at first and later evoked active contraction. The results show that the ligament is catch connective tissue and it also shows active contraction although they contain no muscles.
ARM : The aboral arm ligament, which contains no muscles, was isolated and the isotonic contraction and the stiffness change were measured simultaneously. The results show that artificial seawater with 100 mM potassium ions and the cholinergic drugs acetylcholine, methacholine, and nicotine can evoke contractions of the ligaments. Contraction differed in two ways from that of muscles : 1. The ligaments stayed contracted for over one hour after the drugs had been washed out. 2. The ligaments softened when they contracted and stayed soft after contraction. Some ligaments showed softening without contraction indicating that contraction is not necessarily correlated with softening. In conclusion, contraction and stiffness change are two different phenomena occurring independently in the same connective tissue. The contractile mechanism is different from that of muscles.
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