Genome-wide characterization and seasonal modulation of Hsp60 expression in juvenile Hilsa Shad across distinct upstream habitats.

Heat shock protein 60 acts as a molecular chaperone that assists in proper protein folding under stress conditions. However, its genomic features and temperature-responsive behavior have not yet been studied in Hilsa Shad. In this study, we employed both computational and experimental approaches to investigate the genomic, proteomic, and expression dynamics of Hsp60 in this ecologically and economically important anadromous species. We identified three distinct gene copies which showed high sequence similarity compared to the Hsp60 gene of the well-studied three-spined stickleback. The physico-chemical properties, gene structure, functional domains and motifs, and sequence alignment were analyzed to characterize the paralogs. The phylogenetic analysis and structural modeling further confirmed their close evolutionary relationship and high structural similarity. However, Hilsa juvenile experience winter in the Meghna river in February and autumn in the Surma river in September due to their upstream migration. Notably, all three Hsp60 gene paralogs were significantly upregulated in the gill and liver during the warmer autumn season. While the level of relative expression was moderate in muscle and modest in kidney. This finding suggests a strong role for these genes in the thermal stress response of Hilsa Shad in the Surma river. In addition to, it demonstrates the role of Hsp60 in maintaining homeostasis in juvenile Hilsa Shad under fluctuating environmental conditions. It also aligns with the established role of heat shock proteins in thermal biology, where Hsp60 facilitates cellular protection and adaptation of juvenile Hilsa Shad to changing thermal regimes.