Characterization of immunoglobulin loci in the gigantic genome of Ambystoma mexicanum .

The immunoglobulin share the same general genome architecture as most studied tetrapods. Consistent with its large genome, Ig are larger; however, local size restrictions indicate evolutionary constraints likely to be imposed by high transcriptional demand of certain Ig genes, as well as the V(D)J recombination over very long genomic distance ranges. The has undergone an extensive process of Ig gene loss which partially explains a reduced potential repertoire diversity that may contribute to its impaired antibody response.