| Bohai Bay parthenogentica Artemia is a nutrient-rich biological live bait,which is widely used in the infantile period of aquatic economic animals.With the high-quality development of aquatic economic animals,the content of unsaturated fatty acids in Artemia becomes unable to meet the developmental needs of most marine fish and shrimp species.Therefore,it is of important guiding significance to study the effects of different combinations of environmental conditions on the physiological and ecological of Artemia and the molecular mechanism of baits on the accumulation of unsaturated fatty acids in Artemia for optimizing Artemia culture conditions and promoting the development of nutrition fortification technology.Based on the regulation mechanism of unsaturated fatty acid biosynthesis and metabolism in Bohai Bay parthenogentica Artemia,the following researches was carried out: Effects of environmental conditions on the growth,body fatty acids and antioxidant indexes of the Bohai Bay parthenogentica Artemia were analyzed to optimize the culture conditions of Bohai Bay parthenogentica Artemia.The metabolome and transcriptome levels were studied to optimize the accumulation of unsaturated fatty acids in Bohai Bay parthenogentica Artemia The effects were combined with the analysis of two sets of scientific data to optimize the regulation mechanism of diets on the metabolism of unsaturated fatty acids in Bohai Bay parthenogentica Artemia.The test results are as follows:1.The combination of environment has different effects on the survival,growth,body fatty acid accumulation and antioxidant capacity of Bohai Bay parthenogentica Artemia.In the main effect test,p H has a significant effect on the survival and growth of Artemia.The type of baits has the largest effect on the fatty acid accumulation of Artemia,Salinity has a significant effect on the activity of Total Superoxide Dismutase(T-SOD)and Peroxidase(POD)of Artemia.The best breeding conditions were screened as follows: light intensity was 72 μmol /(m2 · s),salinity was 25,p H was 8.0,and the type of bait was Isochrysis galbana.The survival rate of Bohai Bay parthenogentica Artemia was the highest in this environment.The body length and weight increase significantly,the body has the most fatty acids and the highest composition;Artemia T-SOD,POD,Catalase(CAT)and other antioxidant enzymes have higher activity and lower Malondialdehyde(MDA)content.2.The culture experiment was carried out by using an optimized bait Isochrysis galbana in the early stage to study the effect of the optimized bait on the accumulation of unsaturated fatty acids in Artemia,while the Yeast group was set as the comparison group.The results showed that the contents of total fatty acids,polyunsaturated fatty acids,Eicosapentaenoic acid(EPA),Docosahexaenoic acid(DHA),and Arachidonic acid(ARA)in Isochrysis galbana(IG-group)group were significantly higher than those in the Yeast(Y-group)group.Based on metabolomics techniques such as LC-MS/MS,the metabolite differential maps of Bohai Bay parthenogentica Artemia under different baits conditions were constructed.There were 13,399 metabolites in Bohai Bay parthenogentica Artemia.5,399 up-regulated differential metabolites and 4,427 down-regulated differential metabolites were selected.Through KEGG pathway annotation and enrichment analysis,it was found that the significant fatty acid-related differential metabolites pathways were the fatty acid biosynthetic metabolic pathway and unsaturated fatty acid biosynthetic pathway.In these two metabolic pathways,α-linolenic acid(ALA),EPA,DHA,oleic acid,caprylic acid,myristic acid,stearic acid enriched in the IG-group,ARA and palmitoleic acid in Y-group Artemia,are all important metabolites for the regulation of unsaturated fatty acid metabolism in Bohai Bay parthenogentica Artemia;the above-mentioned significant differential metabolites may be potential biomarkers affecting the anabolic metabolism of unsaturated fatty acids in Bohai Bay parthenogentica Artemia.3.The Illumia high-throughput sequencing platform was used to sequence the transcriptome of Bohai Bay parthenogentica Artemia samples optimized for baits breeding.After the transcripts were spliced,a total of 248,932 Unigene sequences were obtained.The number of genes successfully annotated to the NR library was 35,009;The Swiss Prot library had 23,768 entries;The PFAM library had 16,382 entries;11,445 entries were successfully annotated in the GO library;and 10,641 entries were successfully annotated in the KO database.At the gene expression level,there are 401 down-regulated genes and 148 up-regulated genes,a total of 9 are enriched to the pathways related to lipid metabolism,of which only one is related to the fatty acid pathways,which is the ARA metabolic pathway in the Y-group.The differential genes CD224/GGT1-5 are highly expressed on this pathway,and the gene-expressing transporters γ-glutamyl transpeptidase,glutathione hydrolase,and leukotriene-C4 synthase are highly synthesized.There were no significant changes in differential genes in unsaturated fatty acid-related pathways in the IG-group Artemia.Therefore,the CD224/GGT1-5 gene may be a regulatory gene for the biosynthesis of unsaturated fatty acids in the Y-group Artemia in this omics perspective.4.The combined analysis of transcriptomics and metabolomics screened a total of 46 metabolic pathways that participated in the two groups.There are two pathways related to unsaturated fatty acids,which are the ARA metabolic pathway and unsaturated fatty acid biosynthetic pathway.In the two pathways,the CD224/GGT1-5 gene and des C gene of Y-group Artemia are positively correlated with ARA,that is,the CD224/GGT1-5 gene is on the ARA metabolic pathway,which promotes the ARA metabolism in Y-group Artemia and accelerates the conversion of ARA to lipids,reducing the synthesis and accumulation of unsaturated fatty acids and other substances in Y-group Artemia;The des C gene in Y-group promotes ARA accumulation in Artemia in the unsaturated fatty acid biosynthesis pathway,and inhibits the biosynthesis of ALA,EPA,DHA,and oleic acid in Artemia.Compared with the Y-group,the normal expression of the des C gene and the CD224/GGT1-5 gene in the IG-group promoted the biosynthesis of unsaturated fatty acids such as ALA,EPA,DHA,and oleic acid in Artemia,which reduced ARA metabolism and accumulation,and promoted the metabolism and absorption of Artemia lipids in the IG-group. |
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