title: Distribution of interstitial telomere-like repeats and their adjacent sequences in a dioecious plant, Silene latifolia.
abstract: The dioecious plant Silene latifolia has large, heteromorphic X and Y sex chromosomes that are thought to be derived from rearrangements of autosomes. To reveal the origin of the sex chromosomes in S. latifolia, we isolated and characterized telomere-homologous sequences from intra-chromosomal regions (interstitial telomere-like repeats; ITRs) and ITR-adjacent sequences (IASs). Nine genomic DNA fragments with degenerate 84- to 175-bp ITRs were isolated from a genomic library and total genome of male plants. Comparing the nucleotide sequences, the IASs of the nine ITRs were classified into seven elements (IAS-a, IAS-b, IAS-c, IAS-d, IAS-e, IAS-f, and IAS-g) by sequence similarity. The ITRs were grouped into two classes (class-I and -II ITRs) according to the classification of IASs. The class-I ITRs were sub-grouped into three subclasses (subclasses-IA, -IB, and -IC ITRs) based on the arrangement of IAS elements. By contrast, the class-II ITR was located between two different IASs (IAS-f and IAS-g). Genomic Southern analyses showed that both the male and female genomes contained six (IAS-f) to 153 (IAS-d) copies of each IAS per haploid genome. Fluorescence in situ hybridization analyses showed that one IAS element, IAS-d, was distributed in the interstitial and proximal regions of the sex chromosomes of S. latifolia. The distribution of IAS-d is important evidence for past telomere-mediated chromosome rearrangements during the evolution of the sex chromosomes of S. latifolia.
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwanoha 5-1-5, Kashiwa, Chiba 277-8562, Japan. kk17507@mail.ecc.u-tokyo.ac.jp
authors.forename: Wakana
authors.initials: W
authors.lastname: Uchida
authors.forename: Sachihiro
authors.initials: S
authors.lastname: Matsunaga
authors.forename: Ryuji
authors.initials: R
authors.lastname: Sugiyama
authors.forename: Fukashi
authors.initials: F
authors.lastname: Shibata
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kazama
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Miyazawa
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hizume
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Kawano
mesh_terms: D001483:Base Sequence; D017404:In Situ Hybridization, Fluorescence; D008969:Molecular Sequence Data; D012091:Repetitive Sequences, Nucleic Acid; D017422:Sequence Analysis, DNA; D012730:Sex Chromosomes / Q000235:genetics; D029751:Silene / Q000235:genetics*; D016615:Telomere / Q000235:genetics*