title: Limited diversity of the immunoglobulin heavy chain variable domain of the emerald rockcod Trematomus bernacchii.
abstract: To investigate the diversity of the immunoglobulin heavy chain variable domain of the cold adapted teleost Trematomus bernacchii, 45 cDNA clones, containing complete or partial sequences of rearranged VH/D/JH segments, were analysed. Clones were isolated from a spleen library constructed by 5' RACE or from an expression library previously constructed and immunoscreened with rabbit anti- T. bernacchii Ig heavy chain antibodies. VH sequences shared, on average, 79.9% nucleotide identity and defined only two gene families referred to as Trbe VH I and Trbe VH II, the latter comprising 89% of the VH sequences analysed in this study. A Southern blot analysis, performed with family specific probes, revealed that there are at least 25 genomic VH genes. A phylogenetic tree showed that Trbe VH I clustered with VH genes belonging to group D and Trbe VH II with those of group C. Four putative distinct D segments were found to contribute to the diversity of CDR3, which showed a high glycine content. The Shannon analysis revealed that FRs are very highly conserved. Of CDRs, CDR2 exhibits a mean entropy value higher than CDR1, contributing to variability in a significant manner. Moreover, eight distinct JH segments were identified. These findings provide several clues suggesting a limited diversity of the VH genes in the Antarctic teleost T. bernacchii.
authors.affiliation: Institute of Protein Biochemistry, CNR, Via Marconi, 12, 80125, Naples, Italy. coscia@dafne.ibpe.na.cnr.it
authors.forename: Maria Rosaria
authors.initials: MR
authors.lastname: Coscia
authors.forename: Umberto
authors.initials: U
authors.lastname: Oreste
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003080:Cold Temperature; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D015723:Gene Library; D014644:Genetic Variation; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D010473:Perciformes / Q000235:genetics*; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity
chemical_list: D018076:DNA, Complementary; D007143:Immunoglobulin Heavy Chains; D007135:Immunoglobulin Variable Region