Discrete Growth Mechanism Of Large Yellow Croaker (Larimichthys Crocea) Based On Transcriptomics,Intestinal Microflora And Metabonomics

Large yellow croaker(Larimichthys crocea)is a kind of economic fish with high aquaculture value in China’s marine fishery,and its growth benefit is one of the criteria to evaluate its economic value.Growth efficiency is one of the standards to measure its economic value.However,the same parent’s offspring of large yellow croaker had different growth rates under the same culture environment,which affected its growth efficiency.In order to provide a reference for improving the growth efficiency of cultured large yellow croaker,it is necessary to study the molecular mechanism and the intestinal microflora in order to find out the causes of the non-synchronous growth rate of large yellow croaker.Therefore,in this study,different sizes of large yellow croaker in the same cage were studied as follows:1.Transcriptome analysis of liver tissue in large yellow croaker with different growth rates.Based on the high-throughput RNA-Seq,the liver tissues of large yellow croaker was performed to explore the physiological mechanisms that influence its growth rate.The results showed that 382 genes were differentially expressed in the two groups,compared with the slow-growing fish,the fast-growing fish had 145 up-regulated genes and 237 down-regulated genes.GO and KEGG enrichment analysis showed that DEGs was mainly involved in signal transduction pathway(such as MAPK signaling pathway)and biochemical metabolic pathway(such as Carbon metabolism,Fatty acid metabolism,Glyoxylate and dicarboxylate metabolism and Glutathione metabolism).The results of RT-PCR shows that IGF-1,fgf19,idh1 and me1 were up-regulated in fast-growing fish,while fgf1,fgfr1 and gadd45 b,g were down-regulated.It was also found that idh1,Pgd,cat and Myc were related to immunity and stress response and have an important effect on the growth rate of large yellow croaker.2.Analysis of microbiome and metabolome to reveal the differences in large yellow croaker with different growth rates.In the present study,large yellow croaker with different sizes from the same parents were selected to reveal the differences in composition,community assembly,ecological network and metabolites of intestinal microbiota.The results showed that the composition of intestinal microbiota were not significantly different between the two groups,and Firmicutes and Proteobacteria were the predominant phyla in large yellow croaker,and there was no significant difference in the abundance and diversity of intestinal microbiota between the two groups.The assemblies of intestinal microbial communities in the large yellow croaker were dominated by stochastic processes no matter at fast-growing or slow-growing individuals.A further network analysis revealed that the property and structure of network in fast-growing individual were significantly different from those in slow-growing individual,and the network in fast-growing individual was more stable.In addition,the composition of metabolites in fast-growing individual was different from that in slow-growing individual.Metabolites belonging to short chain fatty acids,amino acids and bile acids obviously upregulated in the fast-growing individual.Based on the findings of this study,we gain a comprehensive understanding of the intestinal microbiota of large yellow croaker with different sizes.