title: Expression of IgM, IgD, and IgY in a reptile, Anolis carolinensis.
abstract: The reptiles are the last major group of jawed vertebrates in which the organization of the IGH locus and its encoded Ig H chain isotypes have not been well characterized. In this study, we show that the green anole lizard (Anolis carolinensis) expresses three Ig H chain isotypes (IgM, IgD, and IgY) but no IgA. The presence of the delta gene in the lizard demonstrates an evolutionary continuity of IgD from fishes to mammals. Although the germline delta gene contains 11 C(H) exons, only the first 4 are used in the expressed IgD membrane-bound form. The mu chain lacks the cysteine in C(H)1 that forms a disulfide bond between H and L chains, suggesting that (as in IgM of some amphibians) the H and L polypeptide chains are not covalently associated. Although conventional IgM transcripts (four C(H) domains) encoding both secreted and membrane-bound forms were detected, alternatively spliced transcripts encoding a short membrane-bound form were also observed and shown to lack the first two C(H) domains (VDJ-C(H)3-C(H)4-transmembrane region). Similar to duck IgY, lizard IgY H chain (upsilon) transcripts encoding both full-length and truncated (IgYDeltaFc) forms (with two C(H) domains) were observed. The absence of an IgA-encoding gene in the lizard IGH locus suggests a complex evolutionary history for IgA in the saurian lineage leading to modern birds, lizards, and their relatives.
authors.affiliation: State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, Peoples Republic of China.
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Wei
authors.forename: Qian
authors.initials: Q
authors.lastname: Wu
authors.forename: Liming
authors.initials: L
authors.lastname: Ren
authors.forename: Xiaoxiang
authors.initials: X
authors.lastname: Hu
authors.forename: Ying
authors.initials: Y
authors.lastname: Guo
authors.forename: Gregory W
authors.initials: GW
authors.lastname: Warr
authors.forename: Lennart
authors.initials: L
authors.lastname: Hammarström
authors.forename: Ning
authors.initials: N
authors.lastname: Li
authors.forename: Yaofeng
authors.initials: Y
authors.lastname: Zhao
mesh_terms: D000818:Animals; D019143:Evolution, Molecular; D007072:Immunoglobulin D; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D007132:Immunoglobulin Isotypes / Q000032:analysis / Q000737:chemistry / Q000235:genetics*; D007075:Immunoglobulin M; D007136:Immunoglobulins; D007155:Immunologic Factors; D010802:Phylogeny; D012326:RNA Splicing; D012333:RNA, Messenger / Q000032:analysis; D012104:Reptiles / Q000235:genetics* / Q000276:immunology
chemical_list: C016512:IgY; D007072:Immunoglobulin D; D007143:Immunoglobulin Heavy Chains; D007132:Immunoglobulin Isotypes; D007075:Immunoglobulin M; D007136:Immunoglobulins; D007155:Immunologic Factors; D012333:RNA, Messenger