title: Origin and evolution of the vertebrate leukocyte receptors: the lesson from tunicates.
abstract: Two selected receptor genes of the immunoglobulin superfamily (IgSF), one CTX/JAM family member, and one poliovirus receptor-like nectin that have features of adhesion molecules can be expressed by Ciona hemocytes, the effectors of immunity. They can also be expressed in the nervous system (CTX/JAM) and in the ovary (nectin). The genes encoding these receptors are located among one set of genes, spread over Ciona chromosomes 4 and 10, and containing other IgSF members homologous to those encoded by genes present in a tetrad of human (1, 3 + X, 11, 21 + 19q) or bird chromosomes (1, 4, 24, 31) that include the leukocyte receptor complex. It is proposed that this tetrad is due to the two rounds of duplication that affected a single prevertebrate ancestral region containing a primordial leukocyte receptor complex involved in immunity and other developmental regulatory functions.
authors.affiliation: Laboratory of Animal Physiology and Evolution, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples, Italy. ivana.zucchetti@szn.it
authors.forename: Ivana
authors.initials: I
authors.lastname: Zucchetti
authors.forename: Rosaria
authors.initials: R
authors.lastname: De Santis
authors.forename: Simona
authors.initials: S
authors.lastname: Grusea
authors.forename: Pierre
authors.initials: P
authors.lastname: Pontarotti
authors.forename: Louis
authors.initials: L
authors.lastname: Du Pasquier
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015815:Cell Adhesion Molecules / Q000235:genetics; D002645:Chickens / Q000235:genetics; D002874:Chromosome Mapping; D002938:Ciona intestinalis / Q000196:embryology / Q000235:genetics / Q000254:growth & development; D019143:Evolution, Molecular; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006434:Hemocytes / Q000378:metabolism; D015395:Histocompatibility Antigens Class I / Q000235:genetics; D017403:In Situ Hybridization; D062726:Junctional Adhesion Molecules; D007962:Leukocytes / Q000276:immunology / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D000075983:Nectins; D010802:Phylogeny; D011971:Receptors, Immunologic / Q000145:classification / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D026801:Synteny; D014561:Urochordata / Q000196:embryology / Q000235:genetics / Q000254:growth & development; D014714:Vertebrates / Q000145:classification / Q000235:genetics* / Q000276:immunology
chemical_list: D015815:Cell Adhesion Molecules; D015395:Histocompatibility Antigens Class I; D062726:Junctional Adhesion Molecules; D000075983:Nectins; D011971:Receptors, Immunologic