Studies On The Digestive System And Digestive Enzymes Of Four Species In Sliuriformes

Silurus asotus(Linnaeus), Silurus soldatovi Nikolsky et Soin, Pelteobagrus fulviridraco (Richardson) and Pseudobagrus ussuriensis(Dybowski) are nutrient and high economical species. At present, great progress had been made in the fields of reproductive biology. The morphology, histology and digestive enzymes of the digestive system in four species were studied in order to provide reference for the preparation of the compound feed.The histology of the digestive system of four species was studied using light microscopes. The digestive system of four species consists of digestive tract and digestive gland. The digestive tract is composed of the buccal-pharynx cavity, the esophagus, the stomach and intestine. There are tines in the upper jaw and lower jaw. The esophagus is short and it can be found a lot of goblet cells in the mucosa. The stomach expands as U shape. There are plentiful of gastric gland in the mucosa of both cardiac stomach and fundic stomach but few goblet cells. The intestine length and the body length ratio is under 1. From foregut to hindgut the number of goblet cells increases unceasingly. Digestive gland contains liver and pancreas. The pancreas of S. asotus and S. soldatovi is unifoliate while P. fulviridraco and P. ussuriensis's are unmacroscopic. The character of morphology and histology of the digestive system of the four specie was consistent with their flesh-food habit.The PAGE was used to analyse the patterns and activities of protease, amylase and esterase from the digestive system in four species. The results are as following: (1) It was shown that the expression of protease and esterase appeared more patterns than amylase. There were 8 bands of protease in S. soldatovi, that was the most patterns comparing with three other species. The esterase expressed most patterns in P. fulvidraco, also, 8 bands. (2) The expression of digestive enzymes had tissue-specific. The protease of S. asotus and P. fulvidraco appeared strongest activities in stomach while of S. soldatovi and P. ussuriensis in foregut. All the four species studied appeared strongest activities in liver. The esterase in P. ussuriensis appeared strongest activities in stomach while the others in liver. (3) Among four species, the sequence of protease activities from high to low is: S. soldatovi＞S. asotus＞P.fulviridraco＞P.ussuriensis, that of amylase is: P. ussuriensis＞P. fulviridraco＞S.soldatovi＞S.asotus, and that of esterase is: S. soldatovi＞S.asotus＞P.ussuriensis＞P. fulviridraco.