Valsalva Yellow Catfish Digestive System Development

Pelteobagrus vachelli is one kind offish with imporment economical value in the YangZi River. In order to probe into the development law of the digestive system, three experiments were designed. In fisrt experiment, the development of digestive system was investigated histologically; In second experiment two, ontogentic development of digestive enzymes in Pelteobagrus vachelli larvae was investigated using biochemistry. In third experiment, growth, the variety of digestive enzymes activities in Pelteobagrus vachelli juvenile was investigated.The results extracted from the experiments list as follows:1. The development of digestive system in Pelteobagrus vachelli larvaeThe development of digestive system in Pelteobagrus vachell larvae was investigated using histological. The results of experiment as follows: Two major periods of differentiation could be distinguished. During the first period, within three days of hatching and prior to exogenous feeding, the digestive tract exhibited extensive differentiation from a straight tube to a looped alimentary canal with clearly distinguishable oesophagus, stomach and gut. The second period corresponded to the formation of the gastric glands around 20-26 days post-hatch. The pancreas is a diffuse gland, distributing on the border of the liver, some pancreatic tissuse even extend into the liver.2. Ontogentic development of digestive enzymes in Pelteobagrus vachelli larvaeGrowth, the activities of some digestive enzymes was studied in Pelteobagrus vachelli larvae during the first month of life. Samples were taken at l,2,3,4,6,8,10,12,15,18,22,26,30DAH. In order to monitor growth, a pool of 20 larvae was sampled in triplicate.For enzyme deteminations, at each sampling time pooled sample of 100 larvae untile 22 DAH, of 80 larvae until 30 DAH, were collectde in triplicate. Whole larvae body homogenaes were used for enzymatic determination in larvae younger than 18 days afer hatching. Older larvae were dissected in order to obtain the abdomen segment. The homogenate centrifuged at 4000 r/min. The supernatant was subsequently used for analyses of enzyme activity and protein content. The results of experiment as follows: In ldays, the activities of protease, amylase and lipase had detected. The activities of pepsin had detected in 22 days. The activities of digestive enzymea exhibited a pattern characteristic of deoeloping animals: From ldays to 4 days, the strong increase in protease activities to the maximum, then, the protease specific activities progressively decreased with age. In 10 days, the specific activities were minimum point. From 10 days to 30 days, the protease activities were progressively increased with age. From ldays to 4days, the strong increase in amylase activities to the maximum, then sharp decreased to very low levels in 10 days. From lOdays to the 18days, the amylase specific...