The galectin family in large yellow croaker (Larimichthys crocea): Genome-wide identification, stress-responsive regulation to Pseudomonas plecoglossicida infection and hypoxia, and functional validation of LcGal-2a.

Galectins are carbohydrate-binding proteins involved in many physiological functions, including immune response and cell migration. Although galectins have been studied in various fish species, their functional roles and expression patterns in large yellow croaker (Larimichthys crocea) remain poorly understood. In this study, 13 galectin genes (Lcgalectins) were identified using the whole genome database of large yellow croaker. Phylogenetic analyses as well as gene structure characterization of coding/non-coding regions, motif information, and gene locations revealed evolutionary conservation and highly conserved domains in galectins. Under acute hypoxia stress, multiple Lcgalectins displayed temporally and spatially dynamic expression patterns across different tissues, suggesting their potential involvement in hypoxia-response. Following Pseudomonas plecoglossicida infection, diverse Lcgalectins were significantly altered in the spleen of large yellow croaker, highlighting their potential participation in immune responses. Protein-protein interaction network analysis further revealed extensive interactions between protein family members. Among these, Lcgalectin-2a displayed significant expression changes following acute hypoxia and P. plecoglossicida infection, with protein-protein interaction analysis revealing its central network position. Based on these findings, LcGal-2a was selected for further functional study and was found to possess significant bacteriostatic properties. These results provided valuable insights into the immunological and stress-responsive roles of galectins in large yellow croaker, laying the groundwork for future studies on their molecular mechanisms and applications in aquaculture disease management.