NMR-based Metabonomics Study On The Metabolic Respones Of Grouper(Epinephelus Coioides) Intestine To Different Level Of Dietary Taurine And Lipid

With the growing scale of aquaculture around the world,the price of fish meal which is the main source of protein in feeds has been rising sharply and is now in short supply.Therefore,using plant protein raw materials(almost no taurine)to make the feeds instead of fish meal has been a trend in aquaculture.The proper addition of taurine and fat in plant protein feeds can not only promote the growth and quality of fish,but also reduce the cost of feeds.However,the effects of dietary taurine and fat on the metabolism of fish are not fully understood.Grouper(Epinephelus coioides)is the first-class edible fish with low-fat and high-protein,riching in nutrients.Their meat is tender and white,resemble chicken.Thus,grouper are known as "The chicken in the sea" and are regarded as a kind of valuable marine fish.Moreover,resulting from their rich nutrition and high economic values,grouper have become an important economic species of aquaculture in Hainan,Guangdong,Fujian,Guangxi and Zhejiang.And with the increasing demand for fresh seafood,the scale of aquaculture of grouper has been expanding.In this thesis,grouper was used to study the impact that feeds with different levels of taurine and fat have on the metabolism of intestine tissue of fish to reveal the rule of metabolism of taurine and fat that closely related with the growth of grouper,construct the metabolic network under the influence of taurine and fat and clarify the biological mechanism of taurine regulation on fish growth on the basis of 1H NMR-based metabolomics approaches.The main research works include:First,to investigate the metabolomic variations in intestine tissue of grouper in different feeding periods and different feeds under the intervention of taurine.The grouper was fed with one of the four kinds of diets containing equal nitrogen and 0.0,0.5,1.0 and 1.5%supplemental taurine respectively for 84 days.The NMR technology was exploited to obtain the fingerprints of intestine tissue in different periods as well as different taurine levels and the multivariate pattern recognition technique was used to obtain differential metabolites.Results showed that a total of 25 kinds of metabolites such as glucose and amino acid were found to change significantly in intestine of fish while fed with different taurine-added diets,and a markedly altered phenomenon happened in 1.0%taurine-added diet.These metabolite changes basically involved in various kinds of metabolic pathways including biosynthesis of biological substances,protein digestion and absorption,lipid metabolism and lipolysis,carbohydrate metabolism,digestion and absorption,and ATP-binding cassette transporters(ABC transporters).And all these metabolic changes reflected the important effect that taurine had on the metabolism and physiological state of fish body while promoting growth and development of fish.Second,based on above,further study the effects of taurine on the metabolic changes of intestine tissue of grouper under high fat diet feeding conditions,and explore the regulatory effect of taurine on fat under the condition of high fat diets.The NMR based metabolomics was used to analyze the differential metabolites of intestine tissue in different fat and taurine levels.The experiment adapted the method of 2×4 double factors to prepare the feeds with 2 fat levels(10%and 15%)and 4 taurine levels(0.0%,0.5%,1.0%and 1.5%)being set.And the grouper were fed with these eight kinds of feeds for 56 days.It was found that the regulation of taurine was not obvious when the fat content was 15%,and the metabolic status under the four taurine levels expressed the similar trends.However,when the content of fat in the feed was 10%,the taurine showed a better regulation ability and the metabolism of grouper was changed greatly after adding taurine.The volume of changes was the most obvious when the content of taurine was 0.5%.Overall,the results showed that taurine had promoted the lipase activity of grouper in high fat feed and the digestion and absorption of liposoluble material.Thus,the protein efficiency of fish was improved while fed in high fat.