Comprehensive analysis of metabolomics and transcriptomics provides insights into growth difference of juvenile Eriocheir sinensis during the molting cycle

Considerable differences in weight gain rates (WGRs) after molting is a puzzling phenomenon exhibited by individuals of the Chinese mitten crab Eriocheir sinensis even under the same environmental conditions. However, the mechanisms underlying the control of growth difference during the molting cycle have not been illustrated. In the present study, juvenile E. sinensis individuals were cultured in the same environment during one molting cycle. After molting, the E. sinensis individuals were classified into the high- and low-WGR groups on the basis of WGRs. Hemolymph samples were collected at the intermolt (InM), premolt (PrM) and postmolt (PoM) stages of the molting cycle for metabolomic and transcriptomic analyses. Differential metabolites (DMs) and differentially expressed genes (DEGs) at the InM, PrM, and PoM stages were identified and mapped to Kyoto Encyclopedia of Genes and Genomes pathways. Integrated metabolomic and transcriptomic analyses revealed significantly varied metabolic pathways between different WGR groups at the three molting stages. These pathways involved amino acid metabolism, nucleotide metabolism, and energy metabolism. Results showed that the high-WGR group exhibited more active cellular protein biosynthesis, a robust neuroendocrine system, and higher antioxidant and detoxifying capabilities than the low-WGR group, which may promote weight gain during the molting cycle. This study provided novel insights into the molecular and metabolic mechanisms in controlling the growth of E. sinensis during the molting cycle, and afforded the theoretical basis for further aquaculture and selective breeding practices of crustacean species.