title: Signal joint of immunoglobulin V lambda 1-J lambda and novel joints of chimeric V pseudogenes on extrachromosomal circular DNA from chicken bursa.
abstract: We isolated extrachromosomal circular DNA from the bursa of 18-day chick embryos and cloned their BamHI fragments into a phage vector. We found examples of the signal joint fused by V lambda 1-J lambda rearrangement and the sequences homologous to V lambda 1 segments that showed: (1) clustered V pseudogene (psi V) germ-line segments containing new psi V26, (2) a head-to-tail duplication of psi V13-psi V12 region and (3) chimeric structures composed of 5'-V lambda 1 and 3'-psi V segments. Both intrachromosomal tandem duplications and extrachromosomal circles may be generated by unscheduled DNA synthesis and recombination. The chimeric structure of V lambda 1 joined with upstream psi V segments suggests the involvement of V gene replacement for somatic diversification of the immunoglobulin genes in addition to a mechanism of segmental gene conversion.
authors.affiliation: Department of Biophysics, Faculty of Science, Kyoto University, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Kondo
authors.forename: H
authors.initials: H
authors.lastname: Arakawa
authors.forename: H
authors.initials: H
authors.lastname: Kitao
authors.forename: Y
authors.initials: Y
authors.lastname: Hirota
authors.forename: H
authors.initials: H
authors.lastname: Yamagishi
mesh_terms: D000818:Animals; D001483:Base Sequence; D002060:Bursa of Fabricius / Q000276:immunology*; D002645:Chickens; D002678:Chimera; D004270:DNA, Circular / Q000737:chemistry*; D015321:Gene Rearrangement; D005803:Genes, Immunoglobulin; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D007146:Immunoglobulin lambda-Chains / Q000235:genetics*; D008969:Molecular Sequence Data; D005810:Multigene Family; D011544:Pseudogenes
chemical_list: D004270:DNA, Circular; D007135:Immunoglobulin Variable Region; D007146:Immunoglobulin lambda-Chains