Molecular cloning and expression analysis of two distinct F-type lectins from the rock bream, Oplegnathus fasciatus

Several lectin families characterized by distinct signature sequence motifs and structural folds, such as C-type, peptidoglycan recognition protein, ficolin, pentraxins, and most recently galectins, have been implicated in immune surveillance. In this study, two distinct F-type lectins RbFTL-1 and RbFTL-2, from the rock bream (Oplegnathus fasciatus), were identified and their expression was analyzed. The full-length cDNA of RbFTL-1 was composed of 1204 bp with a 945-bp open reading frame (ORF) that encoded a 314 amino-acid protein, while that of RbFTL-2 consisted of 1614 bp with a 951-bp ORF encoding a 316 amino-acid protein. RbFTL-1 and RbFTL-2 mRNAs were predominately expressed in the head-kidney and in the liver, respectively. Levels of the RbFTL-1 mRNA transcript increased up to 5.0- and 2.8-fold in the head-kidney and trunk-kidney compared to the muscle, respectively, while those of the RbFTL-2 mRNA transcript increased up to 12.0-fold in liver. The expression of RbFTL-1 and RbFTL-2 were differentially up-regulated in rock bream challenged with Edwardsiella tarda, Streptococcus iniae, and RSIV, with significant increases at 1 and 3h post-challenge compared to the controls.