Correlation Between Glycolipid Metabolism And Autophagy In Larval And Juvenile Yellow Catfish (Pelteobagrus Fulvidraco) And Juvenile Zebrafish(Danio Rerio)

The high mortality during the larval and juvenile stage in the process of fish ontogeny is one of the important factors affecting the production of aquaculture.This process involves the transformation from endogenous feeding to exogenous feeding.Therefore,the high mortality during the larval and juvenile stage may be closely related to the changes of nutritional metabolism in this process.Autophagy is a process of selfdegradation in cells,which is closely related to glucose and lipid metabolism.Therefore,this experiment took the larval and juvenile yellow catfish(Pelteobagrus fulvidraco)and beclin1 heterozygous zebrafish(Danio rerio)and its comparison in juvenile as experimental materials to explore the correlation between glycolipid metabolism and autophagy in the early larvae and juvenile stage of fish,in order to provide a new idea for understanding and reducing the mortality of fish during the larval and juvenile stage in aquaculture.In this experiment,the development of digestive system(stomach,intestine and liver),the changes of glycolipid content,the expression of genes related to glycolipid metabolism and autophagy of yellow catfish during the larval and juvenile stage and wild-type and beclin1 heterozygous zebrafish in juvenile were detected to explore the correlation between glycolipid metabolism and autophagy in the early larvae and juvenile stage of fish.The main results are as follows:1.In this experiment,HE staining of main digestive organs of yellow catfish during the larval and juvenile stage showed that the development of stomach and intestine was normal.The digestive gland liver developed normally in the 3-4 dph mixed feeding,while after entering the exogenous feeding,the whole liver tissue structure was loose and hepatocytes degenerated,liver development impaired.ORO and PAS staining showed that the glycogen and lipid content of fish body continued to decline during the transformation from endogenous to mixed and exogenous feeding: the yolk sac of 2dph fry was rich in fat and the liver contained a large amount of glycogen,while the fat and glycogen signal were almost invisible in 5-6dph fry.2.In this experiment,the m RNA expression of glycolipid metabolism related genes were detected by q RT-PCR,including glyconeogenesis related genes gys1,pck2 and g6 pca.1,glycolysis related genes gck,hk1 and pklr,lipogenesis related genes srebf1,acaca and cd36,lipolysis related genes cpt1 aa and acox3 showed a continuous downward trend,indicating that the level of glycolipid metabolism in fish continued to decline during this period,and the m RNA expression of autophagy related genes beclin1,atg7 and atg12 showed a continuous downward trend during this period.3.The results of HE and ORO staining of liver of wild-type and beclin1 heterozygous zebrafish showed that,similar to the wild-type zebrafish,the liver of beclin1 heterozygous zebrafish developed well from surface,but a large number of fat vacuoles appeared in most of its hepatocytes.The overall fat content was higher than that of the wild-type zebrafish,and the fat content in the intestinal tract was richer than that of the wild-type zebrafish,but there was no significant difference in the fat content in the stomach between the two.4.In the expression of glucose and lipid metabolism and autophagy related genes of beclin1 heterozygous zebrafish,compared with wild-type zebrafish,glucose metabolism related genes pck1,gys1,g6 pca.1,hk1 and pklr,lipid metabolism related genes srebf1,acox3 and cpt1 aa were down regulated,while the expression of gck was significantly up-regulated,which may be related to the abnormal development of liver.The expression of acaca and cd36 related to lipogenesis showed individual differences.At the same time,the expression of beclin1 and atg12 decreased significantly,which means the level of autophagy decreased as a whole.In conclusion,we think that the decrease of autophagy level may lead to the decrease of glucose and lipid metabolism level to a certain extent in the early larvae and juvenile stage of fish,which may be related to the high mortality during the larval and juvenile stage in the process of fish ontogeny.This result enriches the signal pathways and mechanisms related to the energy metabolism of fish in theory,and provides a new idea for understanding and reducing the high mortality of fish during the larval and juvenile stage in aquaculture.It is of great significance to improve the aquaculture yield of yellow catfish and other economic fish and accelerate the healthy development of aquaculture industry in China.