Effects Of Long Chain-Polyunsaturated Fatty Acids On Expression Of Lipid Metabolism And Reproduction Related Genes In Cynoglossus Semilaevis

This study investigated the transcriptomic analysis of potential"lncRNA-mRNA" interactions in liver of the marine teleost Cynoglossus semilaevis fed diets with different DHA/EPA ratios and the effects of different dietary levels of ARA on the expression of reproductive genes in immature female Cynoglossus semilaevis.The results are summarized as follows:1、Transcriptomic analysis of potential "lncRNA-mRNA" interactions in liver of the marine teleost Cynoglossus semilaevis fed diets with different DHA/EPA ratiosLong non-coding RNAs（lncRNA）have emerged as important regulators of lipidmetabolism and have been shown to play multifaceted roles in controlling transcriptional gene regulation,but very little relevant information has been available in fish,especially in non-model fish species.With a feeding trial on a typical marine teleost tongue sole C.semilaevis followed by transcriptomic analysis,the present study investigated the possible involvement of lncRNA in hepatic mRNA expression in response to different levels of dietary DHA and EPA,which are two most important fatty acids for marine fish.An 80-day feeding trial was conducted in a flow-through seawater system,and in this trial three experimental diets differing basically in DHA/EPA ratio,i.e.,0.61（D/E-0.61）,1.46（D/E-1.46）,and 2.75（D/E-2.75）,were randomly assigned to 9 tanks of experimental fish.A total of 124.04 G high quality genome-wide clean data about coding and noncoding transcripts was obtained in the analysis of hepatic transcriptome.Compared to diet D/E-0.61,D/E-1.46 up-regulated expression of 178 lncRNAs and 2629 mRNAs,and down-regulated that of 47 lncRNAs and 3059 mRNAs,while D/E-2.75 resulted in much less change in gene expression.The co-expression and co-localization analysis of differentially expressed（DE）lncRNA and mRNA among dietary groups were then conducted.The co-expressed DE lncRNA and mRNA were primarily enriched in GO terms such as Metabolic process,Intracellular organelle,Catalytic activity,and Oxidoreductase activity,as well as in KEGG pathways such as Ribosome and Oxidative phosphorylation.Overlap of co-expression and co-localization analysis,i.e.,lncRNA-mRNA matches"XR₅23541.1-solute carrier family 16,member 5（slc16a5）" and“LNC₀00285-bromodomain adjacent to zinc finger domain 2A（baz2a）",were observed in all inter-group comparisons,indicating that they might crucially mediate the effects of dietary DHA and EPA on hepatic gene expression in tongue sole.In conclusion,this was the first time in marine teleost to investigate the possible lncRNA-mRNA interactions in response to dietary fatty acids.The results provided novel knowledge of lncRNAs in non-model marine teleost,and will serve as important resources for future studies that further investigate the roles of lncRNAs in lipid metabolism of marine teleost.2、The effects of different dietary levels of ARA on reproductive genes in immature female Cynoglossus semilaevis.Three isonitrogenous and isolipidic experimental diets were formulated to contain different ARA levels:the control diet without ARA supplementation（C）and two diets with low（ARA-L）or high ARA（ARA-H）supplementation.An 70-day feeding trial was conducted in a flow-through seawater system,and in this trial three experimental diets differing basically in ARA levels were randomly assigned to 9 tanks of experimental fish.Results showed that ARA-H increased the contents of vitellogenin,gonadotropin releasing hormone,testosterone,estradiol in the serum of female Cynoglossus semilaevis.There was no significant difference in mRNA expression in estrogen receptor-αand estrogen receptor-β in immature female liver among dietary treatments.ARA-H reduced the mRNA expression of gonadotrophin releasing hormone,follicle-stimulating hormone and SCGN,increased the mRNA expression of Pro-MCH2A.ARA-L increased the mRNA expression of PI3Kcα.There was no significant difference in mRNA expression of hormone releasing hormone releasing hormone receptor,LH,PKCα,PKCβ,MAPK1,ATF3,c-Fos,c-Jun,CREB2,CREB31,ARRB1,ARRB2,AKT1,PI3Kcβ,PI3Kr1,SCG5,IER2,HSD17β8,CH25H between the treatment groups（P>0.05）in the brain.In conclusion,the addition of a certain amount of ARA in the diet can affect the expression of reproductive genes in immature female tongue sole to some extent.