title: Multiple IgH Isotypes Including IgD, Subclasses of IgM, and IgY Are Expressed in the Common Ancestors of Modern Birds.
abstract: Although evolutionarily just as ancient as IgM, it has been thought for many years that IgD is not present in birds. Based on the recently sequenced genomes of 48 bird species as well as high-throughput transcriptome sequencing of immune-related tissues, we demonstrate in this work that the ostrich (Struthio camelus) possesses a functional δ gene that encodes a membrane-bound IgD H chain with seven CH domains. Furthermore, δ sequences were clearly identified in many other bird species, demonstrating that the δ gene is widely distributed among birds and is only absent in certain bird species. We also show that the ostrich possesses two μ genes (μ1, μ2) and two υ genes (υ1, υ2), in addition to the δ and α genes. Phylogenetic analyses suggest that subclass diversification of both the μ and υ genes occurred during the early stages of bird evolution, after their divergence from nonavian reptiles. Although the positions of the two υ genes are unknown, physical mapping showed that the remaining genes are organized in the order μ1-δ-α-μ2, with the α gene being inverted relative to the others. Together with previous studies, our data suggest that birds and nonavian reptile species most likely shared a common ancestral IgH gene locus containing a δ gene and an inverted α gene. The δ gene was then evolutionarily lost in selected birds, whereas the α gene lost in selected nonavian reptiles. The data obtained in this study provide significant insights into the understanding of IgH gene evolution in tetrapods.
authors.affiliation: State Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing 100193, People's Republic of China;
authors.forename: Binyue
authors.initials: B
authors.lastname: Han
authors.affiliation: BGI-Shenzhen, Shenzhen 518083, People's Republic of China; College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, People's Republic of China;
authors.forename: Hui
authors.identifier: 0000-0003-4718-7864
authors.initials: H
authors.lastname: Yuan
authors.affiliation: State Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing 100193, People's Republic of China;
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.affiliation: BGI-Shenzhen, Shenzhen 518083, People's Republic of China;
authors.forename: Bo
authors.initials: B
authors.lastname: Li
authors.affiliation: State Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing 100193, People's Republic of China;
authors.forename: Li
authors.identifier: 0000-0002-6904-631X
authors.initials: L
authors.lastname: Ma
authors.affiliation: State Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing 100193, People's Republic of China;
authors.forename: Shuyang
authors.initials: S
authors.lastname: Yu
authors.affiliation: School of Life Science, Henan University, Kaifeng 475004, People's Republic of China;
authors.forename: Tian
authors.initials: T
authors.lastname: Huang
authors.affiliation: Key Laboratory of Animal Reproduction and Germplasm Enhancement in Universities of Shandong, Qingdao Agricultural University, Qingdao 266109, People's Republic of China; and.
authors.forename: Yan
authors.identifier: 0000-0002-6386-4389
authors.initials: Y
authors.lastname: Li
authors.affiliation: BGI-Shenzhen, Shenzhen 518083, People's Republic of China;
authors.forename: Dongming
authors.initials: D
authors.lastname: Fang
authors.affiliation: BGI-Shenzhen, Shenzhen 518083, People's Republic of China;
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Chen
authors.affiliation: BGI-Shenzhen, Shenzhen 518083, People's Republic of China;
authors.forename: Yongsi
authors.initials: Y
authors.lastname: Wang
authors.affiliation: BGI-Shenzhen, Shenzhen 518083, People's Republic of China;
authors.forename: Si
authors.initials: S
authors.lastname: Qiu
authors.affiliation: State Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing 100193, People's Republic of China;
authors.forename: Ying
authors.initials: Y
authors.lastname: Guo
authors.affiliation: State Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing 100193, People's Republic of China;
authors.forename: Jing
authors.initials: J
authors.lastname: Fei
authors.affiliation: State Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing 100193, People's Republic of China;
authors.forename: Liming
authors.initials: L
authors.lastname: Ren
authors.affiliation: Division of Clinical Immunology, Department of Laboratory Medicine, Karolinska University Hospital Huddinge, SE-141 86, Stockholm, Sweden.
authors.forename: Qiang
authors.identifier: 0000-0003-1990-8804
authors.initials: Q
authors.lastname: Pan-Hammarström
authors.affiliation: Division of Clinical Immunology, Department of Laboratory Medicine, Karolinska University Hospital Huddinge, SE-141 86, Stockholm, Sweden.
authors.forename: Lennart
authors.initials: L
authors.lastname: Hammarström
authors.affiliation: BGI-Shenzhen, Shenzhen 518083, People's Republic of China;
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.affiliation: BGI-Shenzhen, Shenzhen 518083, People's Republic of China;
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.affiliation: BGI-Shenzhen, Shenzhen 518083, People's Republic of China;
authors.forename: Yong
authors.initials: Y
authors.lastname: Hou
authors.affiliation: Key Laboratory of Animal Reproduction and Germplasm Enhancement in Universities of Shandong, Qingdao Agricultural University, Qingdao 266109, People's Republic of China; and yaofengzhao@cau.edu.cn xuxun@genomics.cn qjpan@126.com.
authors.forename: Qingjie
authors.initials: Q
authors.lastname: Pan
authors.affiliation: BGI-Shenzhen, Shenzhen 518083, People's Republic of China; yaofengzhao@cau.edu.cn xuxun@genomics.cn qjpan@126.com.
authors.forename: Xun
authors.initials: X
authors.lastname: Xu
authors.affiliation: State Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing 100193, People's Republic of China; yaofengzhao@cau.edu.cn xuxun@genomics.cn qjpan@126.com.
authors.forename: Yaofeng
authors.identifier: 0000-0003-4499-8610
authors.initials: Y
authors.lastname: Zhao
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001717:Birds / Q000235:genetics / Q000276:immunology; D019143:Evolution, Molecular; D020869:Gene Expression Profiling; D005803:Genes, Immunoglobulin; D059014:High-Throughput Nucleotide Sequencing; D007072:Immunoglobulin D / Q000235:genetics* / Q000276:immunology; D007075:Immunoglobulin M / Q000145:classification / Q000235:genetics*; D007138:Immunoglobulin delta-Chains / Q000235:genetics; D007136:Immunoglobulins / Q000145:classification / Q000235:genetics*; D010802:Phylogeny; D012104:Reptiles / Q000235:genetics / Q000276:immunology; D016415:Sequence Alignment; D020310:Struthioniformes / Q000235:genetics / Q000276:immunology*
chemical_list: C016512:IgY; D007072:Immunoglobulin D; D007075:Immunoglobulin M; D007138:Immunoglobulin delta-Chains; D007136:Immunoglobulins