There are 3 H chain and 3 L chain isotypes in the cartilaginous fish, all encoded by genes in
the so-called cluster (VDDJ, VJ) organization. The H chain isotypes IgM and IgNAR, are
readily detected at the protein level in most species. The third is readily identified at the
protein level in skates (IgR) but only via immunoprecipitation or at the transcript level in
sharks (IgW). High levels of diversity in CDR3 and up to 200 germline genes have been
detected for IgM depending upon the species examined. IgNAR displays very high levels of …