Anti-Human IgHM monoclonal antibody, clone DI3

The only immunoglobulin heavy-chain classes known so far in teleosts have been mu and delta. We identify here a previously unknown class, immunoglobulin zeta, expressed in zebrafish and other teleosts. In the zebrafish heavy-chain locus, variable (V) gene segments lie upstream of two tandem diversity, joining and constant (DJC) clusters, resembling the mouse T cell receptor alpha (Tcra) and delta (Tcrd) locus. V genes rearrange to (DJC)(zeta) or to (DJC)(mu) without evidence of switch rearrangement. The zebrafish immunoglobulin zeta gene (ighz) and mouse Tcrd, which are proximal to the V gene array, are expressed earlier in development. In adults, ighz was expressed only in kidney and thymus, which are primary lymphoid organs in teleosts. This additional class adds complexity to the immunoglobulin repertoire and raises questions concerning the evolution of immunoglobulins and the regulation of the differential expression of ighz and ighm.

Fish culture in ponds with heated water offers better fish growth compared to farms in natural sea water temperature, but the increase in temperature favors the development of bacteria and fish disease. In this study, in European sea bass (Dicentrarchus labrax) specimens reared in ponds with heated water from a power plant showing symptoms of a vibriosis-like disease we aimed to characterize the bacterial community as well as some serum metabolic and immune parameters. Bacteriological analysis revealed an important contamination with fecal coliforms, Pseudomonas aeruginosa, Vibrio alginolyticus, yeasts and molds whilst fish tissues from both healthy and diseased specimens were positive for total aerobic flora and several potential pathogenic bacteria such as V. alginolyticus, Aeromonas hydrophila, Pasteurella multocida, P. aeruginosa, Proteus vulgaris and P. mirabilis. Additionally, Grimontia hollisae was only present in diseased fish tissues. Serum metabolic parameters such as aspartate aminotransferase, bile acids, creatine kinase, uric acid, glucose, globulin and potassium were generally increased in diseased fish though only the levels of phosphorous reached a significant level compared to the healthy specimens. Regarding fish innate immunity, our results showed no statistical differences between healthy and diseased fish on peroxidase, protease or antiprotease activity while the bactericidal activity against V. anguillarum was significantly decreased in diseased fish. Lastly, the gene expression of il1b, c3, dic and mpx was down-regulated in the blood of diseased fish while ighm was up-regulated. (C) 2018 PVJ. All rights reserved