Comparative Studies On The Digestive System And Digestive Enzymes Of Wild And Cultivated Hucho Taimen

Hucho taimen(Pallas) is rare cold water fish in Heilongjiang River.It's delicious and nutrient and has high economic value.In order to provide reference for artificial propagation, digestive physiology and the preparation of the compound feed,the morphology and histology of digestive system also the distribution and expression of digestive enzyme in Hucho taimen of wild and cultivated types were comparative researched.The main results are as following:The morphology and histology of the digestive system of wild and cultivated Hucho taimen were studied using dissection and microscope method.The digestive tract is composed of buccal-pharynx cavity,esophagus,stomach,pyloric caeca and intestine.The digestive gland is liver.The character of morphology and histology of the digestive system of the two types is consistent with their flesh-food habit.Hucho taimen has very developed tines;the esophagus is short and thick;the stomach expands bulgy and there are plentiful of gastric gland in the mucosa of both fundic stomach and pyloric stomach;pyloric caeca it's also developed which also has clear brush border;the intestine has two portion:the carnial intestine and the caudal intestine,the intestine length and the body length ratio is under 1.There's definite difference in their morphology,but no distinct difference in histology.Compared with the wild type,the capacity and flexibility of each organ are not so good in cultivated type which also has a lot of lipin around organs in digestive tract.The PAGE was used to analyse the species and relative content of the main digestive enzymes(esterase,amylase and protease) in each organ(esophagus,stomach,liver,pyloric caeca,intestine) in the two types.The results showed that:the expression of digestive enzymes is in accord with flesh-food habit.Esterase and protease are abundance of species and have high relative content whereas the amylase is not.The expression of digestive enzymes in digestive system of two types is relative to pH and tissue-specific.The expression of esterase and amylase are active in liver,for protein,is active in stomach.The expressions of enzymes are not the same in different pH condition.The digestive enzymes(esterase,amylase,protease) in two types have certain differences which is relative to the living condition,the way of taking foods and the food ingredients.