RNA-seq of hypo- and hyper-salinity stress-response transcriptome in the liver of greater amberjack (Seriola dumerili) juveniles

Salinity is an important abiotic stress that has significant effects on the physiology and metabolism of marine fish. The greater amberjack (Seriola dumerili) is a large, fast-growing species with high commercial value in global aquaculture. To describe the molecular response of the greater amberjack liver to different salinity stresses, RNA-seq analysis was performed to identify the important genes and signaling pathways activated in response to salt stress. Greater amberjack juveniles were reared under different salinity stresses (20, 30, and 40 ppt) for 30 days to evaluate their tolerance, adaptability, and molecular responses. A total of 657 (426 up-regulated and 231 down-regulated) and 65 (17 up-regulated and 48 down-regulated) differentially expressed genes (DEGs) were identified in the group at 30 vs. 20 ppt and 30 vs. 40 ppt salinity, respectively. qPCR and transcriptomic analysis showed that salinity stress affected the expression of genes involved in lipid metabolism (pld2, pla2g7, acacb, and acsl4a), vitamin metabolism (cyp24a1 and cyp2r1), ion transporters (slc4a1a, slc4a4b, rhag, and rh50), and signal transduction (itpkcb, fgf19, and fgfr4). KEGG pathway enrichment analysis showed that the DEGs were primarily involved in metabolism, ribosome biogenesis in eukaryotes, and insulin signaling pathway. The identified candidate genes involved in metabolism pathways, ion transporters, and signal transduction, provide a basis for further study of the molecular mechanisms involved in salinity adaptation and transcriptional plasticity in the livers of marine fish.