title: Initiation of V(D)J recombination in zebrafish (Danio rerio) ovaries.
abstract: The assembly of mammalian antigen receptor genes is a lymphoid-specific process. However, rearranged immunoglobulin genes can also be recovered from non-lymphoid tissues of cartilaginous fish. This event, known as germline rearrangement, has been speculated to arise from recombination-activating gene (RAG)-mediated recombination in germ cells. In this report, we demonstrate that zebrafish (Danio rerio) oocytes expressing high levels of RAG-RNA can readily initiate recombination cleavage at immunoglobulin gene loci, providing direct evidence for an ongoing process of attempted germline rearrangement in zebrafish ovaries. This attempted rearrangement is largely unproductive, yielding no accumulation of germline-joined immunoglobulin genes in zebrafish, which is consistent with their general absence in this species. Our data, therefore, substantiate the speculation that RAG might have been derived from a transposase, invading germ cells of ancient species, and later become a dedicated recombinase only expressed in developing lymphocytes.
authors.affiliation: Center of Developmental Biology and Genetics, College of Life Sciences, Peking University, Beijing 100871, PR China.
authors.forename: Hanbing
authors.initials: H
authors.lastname: Zhong
authors.forename: Zhi
authors.initials: Z
authors.lastname: Li
authors.forename: Shuo
authors.initials: S
authors.lastname: Lin
authors.forename: Yung
authors.initials: Y
authors.lastname: Chang
mesh_terms: D000818:Animals; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000235:genetics*; D005260:Female; D015870:Gene Expression; D015321:Gene Rearrangement; D005803:Genes, Immunoglobulin / Q000235:genetics*; D018398:Homeodomain Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D010053:Ovary / Q000737:chemistry / Q000276:immunology*; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D011995:Recombination, Genetic; D015027:Zebrafish / Q000235:genetics / Q000276:immunology*
chemical_list: D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D012333:RNA, Messenger; C064655:V(D)J recombination activating protein 2; C064658:RAG-1 protein