Studies on Changes in Toughness of the Body Wall from Sea Cucumber

Research Project

Project/Area Number	61560227
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	Fisheries chemistry
Research Institution	The University of Tokyo
Principal Investigator	WATABE Shugo Instructor; Faculty of Agric., Univ. of Tokyo., 農学部, 助手 (40111489)
Project Period (FY)	1986 – 1987
Project Status	Completed (Fiscal Year 1987)
Budget Amount *help	¥2,100,000 (Direct Cost: ¥2,100,000) Fiscal Year 1987: ¥800,000 (Direct Cost: ¥800,000) Fiscal Year 1986: ¥1,300,000 (Direct Cost: ¥1,300,000)
Keywords	Sea Cucumber / Body Wall / Acidic Glycosaminoglycan / Chondroitin Sulfate / コンドロイチン硫酸 / コラーゲン / 微細構造 / 貫入強度
Research Abstract	Holothurian body wall rapidly changes its mechanical properties. However, the mechanisms involved are not fully understood. The present study deals with the cation-dependent changes in toughness of holothurian body wall in association with acidic glycosaminoglycan(AGAG). 1. The toughness of the body wall from a sea cucumber Stichopus japonicus was 0.6 to 1.4kg in the absence of salt and decreased markedly by monovalent cations, until it reached zero at 0.3M NaCl or 0.4M KCl. The toughness tended to decrease by CaCl_2 and MgCl_2, though the extent was much smaller. 2. The specific viscosity (<eta>sp) of holothurian AGAG decreased from 0.7 in the absence of salt to 0.47, 0.51, 0.49, and 0.57 in 0.1M NaCl, KCl, CaCl2, and MgCl_2, respectively. Increase of salt concentration resulted in a successive decrease of <eta>sp with monovalent cations, whereas <eta>sp rather increased with divalent cations. 3. Chemical analyses showed that sea cucumber AGAG contained 19% glucuronic acid, 33% N-acetyl galactosamine and 30% SO^<4->, suggesting that it was a kind of chondroitin sulfate. 4. Electron micrographs of the thin sections stained with lead citrate showed many collagen fibrils. By ruthenium red staining of the desalted body wall, AGAG was found to be distributed between collagen fibers and in their peripheral portions. When the body wall was treated with NaCl, there occurred some coagulation of thin fibrils as observed by ruthenium red staining. 5. It was suggested from these observations that AGAG plays an important role in toughness changes of the body wall of sea cucumber.