CHARACTERIZATION AND IMMUNE RESPONSES OF SELECTED THREE TUMOR NECROSIS FACTOR RECEPTOR-ASSOCIATED FACTORS (TRAFs) FROM BLACK ROCKFISH Sebastes schlegelii AGAINST IMMUNE STIMULI

Tumor necrosis factor (TNF) is a multifunctional cytokine that plays important roles in cell survival, proliferation, differentiation and death. They are the prototypic members of the TNF ligand family which is mainly crucial in the regulation of inflammatory processes. Additionally, Black rockfish is a highly valued aqua crop mainly in the Asian-Pacific region because of its characteristic features including tolerance to low-water temperature, high survival rate and the fast growth. However, due to the massive culturing systems, the prevalence of infectious diseases was found to be drastically increased over the time. In this study we have characterized and studied the expression of three TRAFs including TRAF 2, 3 and 4 from black rockfish. In silico characterization was conducted using bioinformatics tools. Phylogenetic analysis was conducted to determine the evolution of these three genes. The expression analysis of three TRAF transcripts was conducted by performing quantitative real time PCR (qPCR). The results of pairwise alignments revealed that RfTRAF 2 shared 93% of the highest identity with Larimichthys crocea where RfTRAF 3 and RfTRAF 4 shared their highest identities with Lates calcarifer with 97% and 95% respectively. Interestingly, all three rockfish TRAF members were cladded with fish counterparts. According to the spatial distribution blood tissue shows the highest expressional level in all three genes and followed by gill tissue. In addition, post-bacterial infection kinetic expressions of all transcripts were examined in blood tissue. All three TRAF transcripts showed their highest upregulations at 12 h post infection against Streptococus iniae. Additionally the highest upregulation of RfTRAF 2 against poly I:C was observed at the 24 h post infection where RfTRAF 3 and RfTRAF 4 were obtained their intense expression at 12 h post infection. Collectively, the importance of these TRAF members in immune related functions was elucidated through the immune challenged results.