A series of products were amplified using a PCR strategy based on short minimally degenerate primers and R. eglanteria (clearnose skate) spleen cDNA as template. These products were used as probes to select corresponding cDNAs from a spleen cDNA library. The cDNA sequences exhibit significant identity with prototypic α, β, γ, and δ T cell antigen receptor (TCR) genes. Characterization of cDNAs reveals extensive variable region diversity, putative diversity segments, and varying degrees of junctional diversification. This demonstrates expression of both α/β and γ/δ TCR genes at an early level of vertebrate phylogeny and indicates that the three major known classes of rearranging antigen receptors were present in the common ancestor of the present-day jawed vertebrates.
Rast, J. P., Anderson, M. K., Strong, S. J., Luer, C., Litman, R. T., & Litman, G. W. (1997). α, β, γ, and δ t cell antigen receptor genes arose early in vertebrate phylogeny. Immunity, 6(1), 1–11. https://doi.org/10.1016/S1074-7613(00)80237-X