Effect of fasting on protein metabolism in muscle tissue of Larimichthys crocea revealed by transcriptome and proteome

The large yellow croaker(Larimichthys crocea)is an important mariculture fish in China.Farmed large yellow croaker undergo periods of fasting to adapt to the environment or to improve meat quality.To better understand the physiological responses of their muscle tissues to fasting stresses,we analyzed the transcriptomes and proteome s of both normally-fed and fasting fish groups and identified 7578 differentially expressed genes(DEGs)and 297 differentially expressed proteins(DEPs)among them.Gene ontology and KEGG analysis showed that the enriched biological pathways were mainly involved in various synthetic and catabolic pathways,especially the protein metabolism.Based on the omics data,nine DEGs related to muscle composition(CAN3,MYL3,and TNNC2),growth(MSTN and MYF5),autophagy(TSC2 and ULK1),and the ubiquitin proteasome pathway(PRS6 B and UCHL3)were examined using qPCR.In response to fasting stress,MYL3 and TNNC2 were significantly downregulated,while genes associated with autophagy and the ubiquitin proteasome pathway were significantly upregulated.In re sponse to fasting stres s,MYL3,TNNC2,and MYF5 positively correlated with muscle growth were significantly downregulated,while inhibiting growth MSTN and genes associated with autophagy and the ubiquitin proteasome pathways were significantly upregulated.These results clarify the effects of fasting on metabolic changes in their muscle components and growth at the molecular level.