title: The immunoglobulin heavy-chain locus in zebrafish: identification and expression of a previously unknown isotype, immunoglobulin Z.
abstract: The only immunoglobulin heavy-chain classes known so far in teleosts have been mu and delta. We identify here a previously unknown class, immunoglobulin zeta, expressed in zebrafish and other teleosts. In the zebrafish heavy-chain locus, variable (V) gene segments lie upstream of two tandem diversity, joining and constant (DJC) clusters, resembling the mouse T cell receptor alpha (Tcra) and delta (Tcrd) locus. V genes rearrange to (DJC)(zeta) or to (DJC)(mu) without evidence of switch rearrangement. The zebrafish immunoglobulin zeta gene (ighz) and mouse Tcrd, which are proximal to the V gene array, are expressed earlier in development. In adults, ighz was expressed only in kidney and thymus, which are primary lymphoid organs in teleosts. This additional class adds complexity to the immunoglobulin repertoire and raises questions concerning the evolution of immunoglobulins and the regulation of the differential expression of ighz and ighm.
authors.affiliation: Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA.
authors.forename: Nadia
authors.initials: N
authors.lastname: Danilova
authors.forename: Jeroen
authors.initials: J
authors.lastname: Bussmann
authors.forename: Kerstin
authors.initials: K
authors.lastname: Jekosch
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Steiner
mesh_terms: D000818:Animals; D001483:Base Sequence; D005399:Fishes / Q000235:genetics; D015321:Gene Rearrangement; D005803:Genes, Immunoglobulin; D007143:Immunoglobulin Heavy Chains / Q000235:genetics* / Q000378:metabolism; D007132:Immunoglobulin Isotypes / Q000235:genetics / Q000378:metabolism; D007138:Immunoglobulin delta-Chains / Q000235:genetics; D007148:Immunoglobulin mu-Chains / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D015027:Zebrafish / Q000235:genetics* / Q000276:immunology*; D029961:Zebrafish Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D007143:Immunoglobulin Heavy Chains; D007132:Immunoglobulin Isotypes; D007138:Immunoglobulin delta-Chains; D007148:Immunoglobulin mu-Chains; D029961:Zebrafish Proteins; C498004:immunoglobulin zeta, zebrafish