Stage and Tissue Specific Expression of Four TCR Subunits in Olive Flounder (Paralichthys olivaceus)

TCR subunits are members of membrane-bound receptors which allow the fast and efficient elimination of the specific fish pathogens have regulated function in adaptive immunity. Sequence structure of TCR subunits have been reported for various teleosts, but the information of each TCR subunit functional characterization through expression analysis in fish was unknown. In this study, we examined the gene expression of TCR subunits in the early developmental stages and observed transcript levels in various tissues from healthy adult olive flounder by RT-PCR. The mRNA expression of alpha subunit was already detected in the previous hatching step. But the transcripts of another TCR subunit were not observed during embryo development and increased after hatching and maintained until metamorphosis at the same level. It was found that all TCR subunits mRNAs are commonly expressed in the immune-related organ such as spleen, kidney and gill, also weak expressed in fin and eye. TCR alpha and beta subunit were expressed in brain, whereas gamma and delta were not expressed same tissue. The sequence alignment analysis shows that there are more than 80% sequence homology between TCR subunits. Because it has a high similarity of amino acid sequence to expect similar in function, but expression analysis show that will have may functional diversity due to different time and place of expression.