Molecular characterization of HSP70, HSP90a, expression responses and biochemical changes in yellowfin seabream Acanthopagrus latus (Houttuyn 1782) under temperature stress.

This study investigates the molecular characteristics and expression profiles of heat shock proteins (HSP70, HSP90a, and HSP90a1) and biochemical changes in yellowfin seabream (Acanthopagrus latus) under acute temperature stress. The full-length cDNA sequences of these HSPs were cloned and analyzed, revealing open reading frames encoding 639, 730, and 724 amino acids, respectively, each containing conserved motifs indicative of their roles in the stress response. Tissue-specific expression analysis showed that AlHSP70 was predominantly expressed in the kidney, while AlHSP90a and AlHSP90a1 exhibited highest expression levels in the heart of healthy adult males. Under acute temperature stress, quantitative real-time PCR (qPCR) demonstrated that hepatic expression levels of these genes in juvenile fish initially increased, followed by a decrease and stabilization over time. Concurrently, activities of antioxidant enzymes-total superoxide dismutase (T-SOD) and catalase (CAT)-and the metabolic enzyme lactate dehydrogenase (LDH) in the liver showed a similar pattern of initial elevation followed by decline. These findings suggest that HSPs play a critical role in the physiological response to temperature-induced stress, contributing to protection against oxidative damage in A. latus. This study provides fundamental insights into the molecular mechanisms underlying thermal stress acclimation in this species.