Molecular cloning and characterization of a galectin-1 homolog in orange-spotted grouper, Epinephelus coioides

• EcGel-1 is expressed in all tested tissues.
• EcGel-1 was up-regulated in the spleen after challenge with SGIV, poly (I:C), and LPS.
• EcGel-1 was distributed in both cytoplasm and nucleus in GS cells.
• rEcGel-1 protein can make chicken erythrocyte aggregation in the presence of β-ME.
• rEcGel-1 can combine with gram negative bacteria and gram positive bacteria.

As a member of animal lectin family, galectin has the functions of pathogen recognition, anti-bacteria and anti-virus. In the present study, a galectin-1 homolog (EcGel-1) from grouper (Epinephelus coioides) was cloned and its possible role in fish immunity was analyzed. The full length cDNA of EcGel-1 is 504 bp, including a 408 bp open reading frame (ORF) which encodes 135 amino acids with a molecular mass of 15.19 kDa. Quantitative real-time PCR analysis indicated that EcGel-1 was constitutively expressed in all analyzed tissues of healthy grouper. The expression of EcGel-1 in the spleen of grouper was differentially up-regulated challenged with Singapore grouper iridovirus (SGIV), poly (I:C), and LPS. EcGel-1 was abundantly distributed in the cytoplasm in GS cells. Recombinant EcGel-1(rEcGel-1) protein can make chicken erythrocyte aggregation, and combine with gram negative bacteria and gram positive bacteria in the presence of 2-Mercaptoethanol (β-ME). Taken together, the results showed that EcGel-1 may be an important molecule involved in pathogen recognition and pathogen elimination in the innate immunity of grouper.