Molecular characterization and expression analysis of galectins in Japanese pufferfish (Takifugu rubripes) in response to Vibrio harveyi infection.

Galectins are a family of proteins with conserved carbohydrate recognition domains (CRDs) that bind to specific glycans, including the glycans on the surface of pathogens, and therefore play a role in cytokine secretion, cell activation, migration, adhesion and apoptosis. Currently, galectins have been extensively studied in mammalian species but rarely studied in teleost fish species. In this study, a total of 12 galectin genes were characterized to understand the molecular mechanisms of galectin function in Japanese pufferfish (Takifugu rubripes). Phylogenetic analyses and syntenic analyses confirmed their correct annotation and suggested the strongest relationships to tetraodon. Furthermore, expression analyses were conducted in healthy tissues of Japanese pufferfish and after infection with Vibrio harveyi in the intestine, liver and spleen. The results showed that galectin genes were widely expressed in all examined tissues; however, most of the galectin genes were highly expressed in mucosal tissues (skin, gill and intestine). Moreover, majority of the galectin genes were significantly regulated after V. harveyi infection in the intestine, liver and spleen, suggesting that galectins were involved in the immune response to V. harveyi infection in Japanese pufferfish. This study established the foundation for future studies of galectin gene functions.