Characterisation of immunoglobulin light chain cDNAs of the Atlantic salmon, Salmo salar L.; evidence for three IgL isotypes

• Published in: Developmental and comparative immunology Vol. 26; no. 7; pp. 635 - 647
• Main Authors: Solem, Stein Tore, Jørgensen, Trond Ø
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 01.09.2002
• Subjects: Amino Acid Sequence; Animals; Atlantic salmon; Base Sequence; Blotting, Southern; CDR; DNA, Complementary; IgL; Immunoglobulin Constant Regions - classification; Immunoglobulin Constant Regions - genetics; Immunoglobulin Isotypes - genetics; Immunoglobulin Light Chains - classification; Immunoglobulin Light Chains - genetics; Immunoglobulin Variable Region - classification; Immunoglobulin Variable Region - genetics; Isotypes; Molecular Sequence Data; Organisation; Phylogeny; Salmo salar - genetics; Salmo salar - immunology; Sequence Homology, Amino Acid; Transcription; Transcription, Genetic; CDR; Atlantic salmon; Isotypes; Organisation; Transcription; IgL
• ISSN: 0145-305X; 1879-0089
• DOI: 10.1016/S0145-305X(02)00012-5

By screening a cDNA library and analysis of DNA produced by a combined 3′RACE/5′-anchored PCR, we have isolated three isotypes of IgL in the Atlantic salmon. Two of the isotypes were homologous to rainbow trout IgL1 and L2 sequences, while the third represents a previously uncharacterised salmonid IgL. The novel type 3 CL region is homologous to spotted wolffish c1 and yellowtail sequences, while the VL region is more similar to channel catfish F class than to any other fish VL sequences. Southern analysis indicates that the gene segments of all three isotypes are organised in multiple clusters. In addition, the VL gene segments of type 3 are arranged in opposite orientation relative to the JL and CL segments, while gene segments in type 2 clusters are all in the same orientation. Although transcripts of type 1 and 3 were readily found in the spleen and head kidney, only minute amounts of type 2 transcripts were seen. The majority of type 3 messages were truncated, suggesting that spliced and full-length transcripts of this isotype probably are present at a low level compared to type 1 transcripts. The uniqueness of the type 3 VLJL sequences suggests that this isotype offers additional diversity to the antigen-binding site of Atlantic salmon immunoglobulins.