EVIDENCE FOR MULTIPLE DISTINCT MAJOR HISTOCOMPATIBILITY COMPLEX CLASS I LINEAGES IN TELEOSTEAN FISH*

• Published in: International Journal of Immunogenetics
• Main Authors: Van Erp, S. H. M., Egberts, E., Stet, R. J. M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1996
• Subjects: Genetics (clinical); Genetics; Molecular Biology; General Medicine; Immunology; Bree; Atlantic salmon
• Online Access: http://dx.doi.org/10.1111/j.1744-313x.1996.tb00010.x; http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1744-313X.1996.tb00010.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1744-313X.1996.tb00010.x

SUMMARY In the context of studies on the expression of MhcCyca‐Z sequences of the common carp, PCR amplifications of exon 4 were performed on cDNA obtained from pooled thymi of 20 carp F1 individuals. Five recombinant clones ( Cyca ‐TC3, ‐TC13, ‐TC15, ‐TC17 and ‐TC18) were found to be 96% similar to the exon 4 region of Cyca‐ZA1 . Each of the five sequences was unique, and differed in a few positions in both the nucleotide and the derived amino acid sequences from any of the Cyca‐Z sequences known to date. These data suggest that multiple Z genes per locus are present in the carp, which are transcribed in the thymus. In the course of analysing the amplified Cyca‐Z sequences, serendipity yielded a clone, Cyca ‐TC16, containing a class I‐like sequence substantially different from any other carp class I sequence. The predicted amino acid sequence of Cyca ‐TC16 was most similar to the class I genes ( Lach‐U ) from the coelacanth (42–46% amino acid identity). Cyca ‐TC16 contains three conserved β2‐microglobulin contact residues, and the secondary structure was predicted by computer algorithms to be similar to that of the α3 domain of HLA‐A2 . Phylogenetic analysis shows that carp class I sequences reside in four distinct clusters: (i) Cyca‐Z, Cyca ‐TC3, ‐TC13, ‐TC15, ‐TC17 and ‐TC18 together with Caau‐Z from ginbuna crucian carp, (ii) Cyca‐U with Bree‐U (zebrafish) and Sasa ‐p30 (Atlantic salmon), (iii) Cyca ‐TC16 with Lach‐U (coelacanth), and (iv) Cyca ‐C4.