Cloning and sequence analysis of two isotypic IgM heavy chain genes from Atlantic salmon, Salmo salar L

• Published in: European Journal of Immunology
• Main Authors: Hordvik, Ivar, Voie, Ann Mari, Glette, Johan, Male, Rune, Endresen, Curt
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1992
• Subjects: Atlantic salmon; Salmo salar
• Online Access: http://dx.doi.org/10.1002/eji.1830221130; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Feji.1830221130; https://onlinelibrary.wiley.com/doi/pdf/10.1002/eji.1830221130

Abstract A leukocyte cDNA library from Atlantic salmon, based on oligo‐dT priming, was constructed in λ‐gt10. Immunoglobulin heavy chain (IgH) cDNA were isolated from the library using a specific probe generated by polymerase chain reaction (PCR) between two conserved areas within the variable region (second and fourth frame region). Two cDNA clones encoding the entire constant region of membrane‐bound IgH, and one cDNA encoding the entire constant region of secretory IgH were sequenced, revealing messages from two isotypic IgM genes. Both genes were shown to be present in haploid embryos and have been isolated from a genomic library, the exons and deduced amino acid sequences of which are presented here (salmon C H A and C H B). The splicing of transcripts encoding the membrane‐bound IgH excises the whole fourth exon as in other teleosts. The nucleotide and amino acid identity between salmon C H A and C H B are 98.2 %, and 96.2%, respectively. Two subfractions of IgM from Atlantic salmon separated by ion chromatography can be explained by a net exchange of basic residues in salmon C H B compared to C H A. The finding of two closely related salmon C H genes is in accordance with the quasi‐tetraploid state of the Atlantic salmon genome.