title: Genes "waiting" for recruitment by the adaptive immune system: the insights from amphioxus.
abstract: In seeking evidence of the existence of adaptive immune system (AIS) in ancient chordate, cDNA clones of six libraries from a protochordate, the Chinese amphioxus, were sequenced. Although the key molecules such as TCR, MHC, Ig, and RAG in AIS have not been identified from our database, we demonstrated in this study the extensive molecular evidence for the presence of genes homologous to many genes that are involved in AIS directly or indirectly, including some of which may represent the putative precursors of vertebrate AIS-related genes. The comparative analyses of these genes in different model organisms revealed the different fates of these genes during evolution. Their gene expression pattern suggested that the primitive digestive system is the pivotal place of the origin and evolution of the AIS. Our studies support the general statement that AIS appears after the jawless/jawed vertebrate split. However our study further reveals the fact that AIS is in its twilight in amphioxus and the evolution of the molecules in amphioxus are waiting for recruitment by the emergence of AIS.
authors.affiliation: Department of Biochemistry, Guangzhou Center for Bioinformatics, College of Life Sciences, Sun Yat-Sen University, Guangzhou, People's Republic of China.
authors.forename: Cuiling
authors.initials: C
authors.lastname: Yu
authors.forename: Meiling
authors.initials: M
authors.lastname: Dong
authors.forename: Xiaokun
authors.initials: X
authors.lastname: Wu
authors.forename: Shengguo
authors.initials: S
authors.lastname: Li
authors.forename: Shengfeng
authors.initials: S
authors.lastname: Huang
authors.forename: Jing
authors.initials: J
authors.lastname: Su
authors.forename: Jianwen
authors.initials: J
authors.lastname: Wei
authors.forename: Yang
authors.initials: Y
authors.lastname: Shen
authors.forename: Chunyan
authors.initials: C
authors.lastname: Mou
authors.forename: Xiaojin
authors.initials: X
authors.lastname: Xie
authors.forename: Jianghai
authors.initials: J
authors.lastname: Lin
authors.forename: Shaochun
authors.initials: S
authors.lastname: Yuan
authors.forename: Xuesong
authors.initials: X
authors.lastname: Yu
authors.forename: Yanhong
authors.initials: Y
authors.lastname: Yu
authors.forename: Jingchun
authors.initials: J
authors.lastname: Du
authors.forename: Shicui
authors.initials: S
authors.lastname: Zhang
authors.forename: Xuanxian
authors.initials: X
authors.lastname: Peng
authors.forename: Mengqing
authors.initials: M
authors.lastname: Xiang
authors.forename: Anlong
authors.initials: A
authors.lastname: Xu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017951:Antigen Presentation / Q000235:genetics; D002816:Chordata, Nonvertebrate / Q000235:genetics* / Q000276:immunology*; D018076:DNA, Complementary / Q000235:genetics; D019143:Evolution, Molecular; D020224:Expressed Sequence Tags; D015723:Gene Library; D005803:Genes, Immunoglobulin; D008969:Molecular Sequence Data; D010802:Phylogeny; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity
chemical_list: D018076:DNA, Complementary; D011506:Proteins