Abstract
Simple SummaryThe gill tanscriptomes of greater amberjack (Seriola dumerili) reared under different salinity stress were analyzed. The regulatory networks of salinity-related pathways were explored through Kyoto Encyclopedia of Gene and Genome (KEGG) pathway enrichment and bioinformatics analyses. This will be of great value in understanding the molecular basis of salinity adaptation in greater amberjack.Salinity significantly affects physiological and metabolic activities, breeding, development, survival, and growth of marine fish. The greater amberjack (Seriola dumerili) is a fast-growing species that has immensely contributed to global aquaculture diversification. However, the tolerance, adaptation, and molecular responses of greater amberjack to salinity are unclear. This study reared greater amberjack juveniles under different salinity stresses (40, 30, 20, and 10 ppt) for 30 days to assess their tolerance, adaptation, and molecular responses to salinity. RNA sequencing analysis of gill tissue was used to identify genes and biological processes involved in greater amberjack response to salinity stress at 40, 30, and 20 ppt. Eighteen differentially expressed genes (DEGs) (nine upregulated and nine downregulated) were identified in the 40 vs. 30 ppt group. Moreover, 417 DEGs (205 up-regulated and 212 down-regulated) were identified in the 20 vs. 30 ppt group. qPCR and transcriptomic analysis indicated that salinity stress affected the expression of genes involved in steroid biosynthesis (ebp, sqle, lss, dhcr7, dhcr24, and cyp51a1), lipid metabolism (msmo1, nsdhl, ogdh, and edar), ion transporters (slc25a48, slc37a4, slc44a4, and apq4), and immune response (wnt4 and tlr5). Furthermore, KEGG pathway enrichment analysis showed that the DEGs were enriched in steroid biosynthesis, lipids metabolism, cytokine–cytokine receptor interaction, tryptophan metabolism, and insulin signaling pathway. Therefore, this study provides insights into the molecular mechanisms of marine fish adaptation to salinity.
Highlights
Marine environmental factors, such as salinity, low O2 concentration, temperature, and pH value, influence the physiological and biological status of marine animals [1]
The HiSeq X Ten platform was used for RNA sequencing of gill samples at 20, 30, and 40 ppt
Salinity alterations can lead to various physiological reactions to maintain homeostasis, Salinity alterations can lead to various physiological reactions to maintain homeostaincluding osmotic regulation, ion transports, and respiratory metabolism [55]
Summary
Marine environmental factors, such as salinity, low O2 concentration, temperature, and pH value, influence the physiological and biological status of marine animals [1]. Environmental stresses activate the sympathetic nervous system [2], the release of adrenaline and noradrenaline [3], and the hypothalamic–pituitary–interrenal axis in fish [4], causing the release of the steroid glucocorticoid hormones and other hormones for adaptation [5]. Salinity enhances optimum fish growth, it can influence growth rate, immunity, antioxidant capacity, and lipid metabolism in fish [6,7]. Salinity stress induces more active energy metabolism, including lipid metabolism and glycogen metabolism [8]. Salt stress environments trigger various metabolic changes in fish, enhancing fish adaptation to salinity [9,10]. Osmolality and water balance are energy-demanding processes maintained through osmoregulatory mechanisms, and they often alter survival, growth, and other physiological processes [11,12,13]
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