Effects Of Dietary N-3/n-6 HUFA On The Growth,Body Composition,Transcriptome Expression And Fat Metabolism Related Genes Of Juvenile Rockfish(Sebastes Schlegeli)

This article take the juvenile Sebastes schlegeli[mean initial weight(36.30±0.03)g] as the research object.To explore the effects of dietary n-3/n-6 HUFA on the growth,body composition,transcriptome expression and fat metabolism related genes of juvenile Sebastes schlegeli.The specific research results are as follows:In order to study the effects of dietary n-3/n-6HUFA(A1:14.28,A2:9.26,A3:5.66,A4:3.06,A5:2.02,A6:1.50)on the growth,body composition and fatty acid composition of whole fish,muscle,liver andabdominal fat in juvenile Sebastes schlegeli.Six kinds of diet were formulated to feed six groups for 65 days.Each diet was randomly fed to triplicate groups of 30 fish per cage.The results show that: 1)Dietary n-3/n-6 HUFA had no significant impact on the survival rate(SR)of the Sebastes schlegeli(P>0.05).With the decreasing of dietary n-3/n-6 HUFA,the weight gain rate(WGR)and specific growth rate(SGR)showed a trend of first increased and then decreased,and the weight gain rate of D2 and D3 groups was significantly higher than that of other groups(P<0.05).2)The crude fat in the whole fish and muscle showed a trend of first rising and then falling,reaching the maximum value in group D2 and D3(P<0.05).The crude fat in the liver first decreased and then increased,and the D2 group was significantly lower than the other groups(P<0.05).3)The fatty acid composition of fish is closely related to fatty acid composition of dietary.The fatty acid composition of fish body was negatively correlated with the feed C20:5n-3 and C20:4n-6.Under this experimental conditions,the appropriate proportion of dietary n-3/n-6HUFA(5.66-9.26)can significantly improve the growth of experimental fish,modified the fatty acid composition of fish body and tissue,The square regression analysis based on weight gain rate and feed coefficient,and the appropriate proportion of n-3/n-6 HUFA in the feed of juvenile Sebastes schlegeli is 8.93 and 8.70,respectively.In order to explore the effect of dietary n-3/n-6 HUFA on the transcriptome of juvenile Sebastes schlegeli,three groups(14.28,5.66,1.50)of molecular samples in experiment 1 were used for transcriptome analysis.A total of 65146 unigenes were assembled,with an average length of 1064.05 bp.By comparing the function annotations of the six major databases,a total of 27920 articles were annotated.The unigene numbers of the six major database annotations are: 25815(Nr),23132(Swiss Prot),20603(Pfam),12488(COG),8377(GO),and 18449(KEGG).The data results are well assembled,and subsequent transcriptome analysis can be obtained: 1)There are 500 differentially expressed genes,and 25 metabolic metabolisms are screened out 2)GO enrichment analysis of the differentially expressed genes is performed to obtain 100 enrichment volumes From this,20 related genes were screened.Involved in fecal synthesis,fecal decomposition,transcription factors,apolipoproteins,transporters,binding proteins and other categories.3)KEGG pathway enrichment analysis was performed on the differentially expressed genes,and there were 211 pathways,and the significance was screened out.There are 17 differential set pathways,of which 6 are related to lipid metabolism: PPAR signaling pathway,bile acid biosynthesis,small amount digestion and absorption,metabolic biosynthesis,steroid hormone synthesis,and steroid biosynthesis.The highest degree of enrichment.In this experiment,the transcriptome analysis was used to reveal the differences in the transcriptome of juvenile Sebastes schlegeli under different ratios of n-3 / n-6 HUFA,and to dig out the key genes and regulatory pathways.It is important to study the fat metabolism mechanism of juvenile Sebastes schlegeli meaning of reference.The study of the effects of dietary n-3/n-6HUFA on the serum biochemical and metabolism genes in juvenile Sebastes schlegeli.The results show that: 1)With the decreasing of n-3/n-6 HUFA,Albumin(ALB),High-density lipoprotein cholesterol(HDL-C)and Total cholesterol(TCHO)increased first and then decreased,while Triglycerides(TG)has the opposite trend with Low density lipoprotein cholesterol(LDLC),and ALB,HDL-C and TCHO in D2 and D3 groups are significantly higher than those in other groups(P<0.05).Both TG and LDL-C reached the minimum in D3 group,and D6 group was significantly larger than each group(P<0.05).2)With the decreasing of n-3/n-6 HUFA,the expression of genes related to liver fat synthesis and decomposition are significantly affected.The Fatty acid synthetase(FAS)and Acetyl-Co A carboxylase(ACC)genes showed a trend of first decreased and then increased,and both had minimum values in the D3 group.The relative expression levels of Malic enzyme(ME)and Sterol regulatory element binding protein 1(SREBP 1)genes generally showed a downward trend,with a minimum in group D6.The four fat oxidation genes all showed an upward trend and then a downward trend,all of which had a maximum in the D2 group.In the Peroxisome proliferator-activated receptor ?(PPAR?),the group of D2 was significantly higher than each group(P<0.05),and D6 group was significantly lower than each group(P<0.05);In the Carnitine palmitoyl transferase 1(CPT1),the group of D2-D4 was significantly higher than the D6 and D1 groups(P<0.05).In summary,with the decreasing of n-3/n-6 HUFA,the expression levels of genes related to fat synthesis and decomposition are changing,and the homeostasis of fish liver is the result of the combined action of two metabolic pathways.