COMPARATIVE STUDIES OF MICRO-ULTRASTRUCTURE AND FATTY ACID COMPOSITION OF NORMAL AND ALBINO HEPATOPANCREAS OF CHINESE MITTEN CRAB ERIOCHEIR SINENSIS

In recent years,Eriocheir sinensis with white hepatopancreas was frequently observed in the cultivation process,and the white hepatopancreas was called hepatopancreas albinism,but the albino hepatopancreas was mainly observed in male crabs.The study was investigated to determine the factors and causes resulting in that phenomenon during the Eriocheir sinensis cultivation process.The animals used in this experiment were collected from the different cultivation locations in the Yangcheng Lake.They were quickly sacrificed after being taken to the laboratory,and then hepatopancreas were dissected from the experimental crabs.The lipid classes,fatty acid composition and micro-ultrastructure of the crabs with albino hepatopancreas were determined,compared with those crabs with normal hepatopancreas.According to the results,significant difference was found at hepatosomatic index and total content of lipid.The lipid classes of two kinds crabs were almost the same,the contents of neutral lipid were 86.45% in normal hepatopancreas and 89.30% in albino,and the main component was triacylglyceride.The content of C18:1 was 28.00% and 37.75%,respectively,higher than any other kind of fatty acid in neutral lipid.The contents of C15∶0,C16∶1,C20∶1 and EPA of normal crabs were higher than albino crabs,but the contents of C16∶0 and C18∶1 were opposite.The fatty acid composition of polar lipid in the hepatopancreas of two kinds of crabs was similar to that of the neutral lipid.The content of C18∶1 was the highest and the content of albino crabs was significant higher than normal ones(p0.01).In normal crabs,epithelial cell wall of hepatic tubule was comprised of monolayer cells.B cell and R cell arranged in the order.The microvilli and enteric coat at the top of cells showed complete structure.The lumen of hepatic tubule contained some inclusion.In contrast,the cells of epithelial cell wall of hepatic tubule arranged in disorder in the albino crabs.The microvilli and its mucosal disappeared.Cavity appeared irregularly in hepatic tubule,and cells separating from lumen walls were observed.It is estimated that the color of hepatopancreas has tight connection with differences of lipid content.The hepatopancreas of normal crabs have low content of water but high content of lipid,therefore,it contained more lipid-soluble vitamins and coloring matters than albino ones,which leads to yellow color.However,the result of albinol ones was opposite.The accumulation of lipid-soluble vitamins and coloring matters were prevented,which leads to white color.According to some surveys,fatty acid composition and micro-ultrastructure of albino hepatopancreas cells has tight relationship to the lack of EFA.