The first identification of a malectin gene (CfMal) in scallop Chlamys farreri: sequence features and expression profiles

Malectin is a newly discovered lectin of the endoplasmic reticulum (ER) that might be involved in innate immunity. Information about the roles of malectin in innate immunity is scarce. In the present study, a novel malectin gene (designated as CfMal) from the Zhikong scallop Chlamys farreri was identified and characterized. Sequence features, tissue distribution, and temporal expression profiles were investigated to infer the potential functions of CfMal in innate immunity. The complete cDNA sequence of CfMal comprised 1,111 bp and contained an open reading frame of 909 bp, which encoded 302 amino acid residues. A malectin domain and a transmembrane region were identified in the predicted protein sequence. CfMal mRNA transcripts were detectable in hemocytes, muscle, mantle, gill, hepatopancreas, and gonads. CfMal expression was highest in hemocytes. Stimulation with Vibrio splendidus increased CfMal expression in hemocytes, gill, and hepatopancreas. The mRNA transcripts of CfMal and three related genes, including binding immunoglobulin protein, heat shock protein 90 kDa beta member 1 protein and ER degradation enhancing alpha-mannosidase like protein 1, increased in scallop hemocytes during an artificial ER-stress. Our results indicate that CfMal might not only be involved in ER-stress, but may also play a role in innate immunity of scallops.