Elucidating the Molecular Basis of Thermal Stress Response in Juvenile Turbot (Scophthalmus maximus) via an Integrative Transcriptome–Metabolome Approach

Temperature has always been an important environmental factor, and changes in water temperature are closely related to the entire life process of fish. Investigating the impact of thermal stress on fish physiology is critical for optimizing aquaculture. This study employed transcriptomic and metabolomic approaches to investigate temperature-induced variations in the gene expression and metabolic profiles of turbot. The results showed that thermal stress could induce abnormal genes transcription, and functional annotation demonstrated predominant associations of these genes with key pathways including PI3K-Akt signaling, PPAR regulation, steroid biosynthesis, fatty acid metabolism, and FoxO signaling cascade. Metabolomic analysis revealed that amino acid metabolism was dysregulated, such as valine, leucine, and isoleucine. Joint analysis revealed significant positive associations between CDH1, Col9a1, and ECT2 genes and leucine/isoleucine metabolism. The expression levels of Plch2 and Col9a1 genes exhibited significant regulatory effects on valine metabolism. Moreover, the gene cluster comprising DNAJB6, Gcnt1 and trim71 was significantly involved in the metabolic regulation of galactonic acid. Collectively, these findings demonstrate that thermal stress induces significant alterations in gene expression, metabolic profiles, and signaling pathways in turbot, offering new perspectives for thermal stress mitigation strategies.