| Similar to that of the other oviparous animals, the process of the early development of fish is a process of decomposing and using the nutrients in the yolk and forming tissues and organs of the new organism. The nutrients in the yolk is mainly composed of proteins, lipids and carbohydrates. Lipid as one of the major nutrient composition in the yolk, on the one hand, lipid could provide energy and essential fatty acids for early development of fish. On the other hand, lipid as the biomembrane organize of constitute the part. On the basis of existing studies,including embryo development, growth characteristics of larvae and lipid nutrition during embryo periods of Puan silver crucian carp(Carassius auratus gibelio), the early development, the activity and the m RNA expression level of key lipid metabolic enzyme, and the effects of gulcose, vitamin C on them during early development of Puan silver crucian carp were explored by the method of enzymology and the methods of real-time PCR. Meanwhile, the characteristic of histological changes of the digestive system during early development of Puan silver crucian carp was studied by the histological method. The relationship among the activity of lipid metabolic enzyme, the level mRNA expression of lipid metabolic enzyme and the development of digestive system were studied. This thesis aimed at understanding the lipid metabolism during the early development.The study results and conclutions were as follows:1. In the water temperature of(24±0.5) centigrade, glucose solutions and vitamin C solutions at different concentrations were added into the hatching water, the treatments lasted until the yolk sac disappeared completely. The concentrations of glucose were 0 g/L, 5 g/L, 10 g/L, 15 g/L and 20 g/L. The concentrations of vitamin C were 0 mg/L, 20 mg/L, 25 mg/L, 30 mg/L and 35 mg/L. We recorded the incubationtime, the hatching rate and survival rate of larvae, the results showed that:①When the concentration of glucose below 15 g/L, the membrane time of larvae were decreasing, the hatching ratio, survival rate, weight and full-length were increasing with the increase of glucose. While the concentration of glucose solution was higher than that of 15 g/L, which showed inhibitory effect on the early development of Puan silve Crucian Carp.②When the concentration of vitamin C below 30 mg/L, the membrane time of larvae were decreasing, the hatching ratio, survival rate, weight and full-length were increasing with the increase of vitamin C. When the concentration of vitamin C solution was higher than that of 30 mg/L, which showed inhibitory effect on the early development of Puan silve Crucian Carp.③15 g/L glucose solutions and 30 mg/L vitamin C solutions could promote the early development of Puan silve Crucian Carp.2. The activities of acetyl-CoA carboxylase, fatty acid synthase, lipoprotein lipase, hepatic lipase and carnitine palmitoyltransferases characteristics and effects of15g/L glucose solutions, 30 mg/L vitamin C solutions on them during early development of Puan silve Crucian Carp, The results showed that:①The activities of acetyl-CoA carboxylase, fatty acid synthase, lipoprotein lipase, hepatic lipase and carnitine palmitoyltransferases have existed in mature eggs.This five kinds of enzymes activites during early development were higher than that of mature eggs, they showed increasing trend during early development, and the activity of enzymes showed a marked increase in point in gastrula stage.②Appropriate glucose solution(15 g/L), vitamin C solution( 30 mg/L) could promote the activities of acetyl-CoA carboxylase, fatty acid synthase, lipoprotein lipase, hepatic lipase and carnitine palmitoyltransferases during early development of Puan silve Crucian Carp.3. The real-time PCR technology was used to exam the mRNA expression level of acetyl-CoA carboxylase α, fatty acid synthase, lipoprotein lipase and hepatic lipase genes and effects of 15 g/L glucose solution, 30 mg/L vitamin C solution on the expression of the above genes during early development of Puan silve Crucian Carp.The results showed that:①The genes of acetyl-CoA carboxylase α, fatty acid synthase, lipoprotein lipase and hepatic lipase have already started to express in mature eggs, this four kinds of genes showed increasing trend with the early development, and the mRNA expression level of this four kinds of genes showed a marked increase in point in gastrula stage.②Appropriate glucose solution(15 g/L) and vitamin C solution( 30 mg/L) could induce the genes mRNA expression level of acetyl-CoA carboxylase α, fatty acid synthase, lipoprotein lipase and hepatic lipase during early development of Puan silve Crucian Carp.4. The digestive system and its associated glands was examined by the method of morphology and histology during yolk-sac larvae development of Puan silve Crucian Carp, and the relationship among the activity of acetyl-CoA carboxylase, fatty acid synthase, lipoprotein lipase and hepatic lipase, the level mRNA expression of acetyl-CoA carboxylase α, fatty acid synthase, lipoprotein lipase and hepatic lipase and the development of digestive system were studied. The results showed that:①The structure and function constantly growing and improving with the growth of larvae.The endogenous stage, during 1-2 days after hatching, the yolk sac was bigger. At the beginning of the digestive system has not yet fully developed, and depend on absorbing the yolk nutritents from yolk sac which under abdomen to maintain life and organ development. In 2 days after hatching, the digestive duct in the larvae is formed but no food is intaken when the catfish is in endotrophic. The mixotrophic stage, 3-4 days after hatching, the yolk is absorbed fairly well, while the digestive tract was differentiated into oesophagus, intestine and liver. From fifth day,the yolk disappears gradually, and the fish was into exdoerophic stage. Then these digestive associated glands became mature gradually with the development.②The activities of acetyl-CoA carboxylase, fatty acid synthase, lipoprotein lipase, hepatic lipase and carnitine palmitoyltransferases was directly correlated to the development of the digestive system.③The genes m RNA expression level of acetyl-CoA carboxylase α, fatty acid synthase, lipoprotein lipase and hepatic lipase and the activities of correspondingenzymes showed same variation trend, which indicated that the variation trend of genes mRNA expression level could measure the digestive system development during early development of Puan silve Crucian Carp. |
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