title: Molecular and cytological characterization of repetitive DNA sequences from the centromeric heterochromatin of Sciara coprophila.
abstract: Sciara coprophila (Diptera, Nematocera) constitutes a classic model to analyze unusual chromosome behavior such as the somatic elimination of paternal X chromosomes, the elimination of the whole paternal, plus non-disjunction of the maternal X chromosome at male meiosis. The molecular organization of the heterochromatin in S. coprophila is mostly unknown except for the ribosomal DNA located in the X chromosome pericentromeric heterochromatin. The characterization of the centromeric regions, thus, is an essential and required step for the establishment of S. coprophila as a model system to study fundamental mechanisms of chromosome segregation. To accomplish such a study, heterochromatic sections of the X chromosome centromeric region from salivary glands polytene chromosomes were microdissected and microcloned. Here, we report the identification and characterization of two tandem repeated DNA sequences from the pericentromeric region of the X chromosome, a pericentromeric RTE element and an AT-rich centromeric satellite. These sequences will be important tools for the cloning of S. coprophila centromeric heterochromatin using libraries of large genomic clones.
authors.affiliation: Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), Universidad Autónoma de Madrid, Nicolás Cabrera, Spain.
authors.forename: M Carmen
authors.initials: MC
authors.lastname: Escribá
authors.forename: Patricia G
authors.initials: PG
authors.lastname: Greciano
authors.forename: María
authors.initials: M
authors.lastname: Méndez-Lago
authors.forename: Beatriz
authors.initials: B
authors.lastname: de Pablos
authors.forename: Vladimir A
authors.initials: VA
authors.lastname: Trifonov
authors.forename: Malcolm A
authors.initials: MA
authors.lastname: Ferguson-Smith
authors.forename: Clara
authors.initials: C
authors.lastname: Goday
authors.forename: Alfredo
authors.initials: A
authors.lastname: Villasante
mesh_terms: D000818:Animals; D002503:Centromere / Q000737:chemistry* / Q000235:genetics; D002874:Chromosome Mapping; D004247:DNA / Q000737:chemistry* / Q000235:genetics; D004175:Diptera / Q000235:genetics*; D006570:Heterochromatin / Q000737:chemistry* / Q000235:genetics; D017404:In Situ Hybridization, Fluorescence; D007814:Larva / Q000235:genetics*; D008297:Male; D008540:Meiosis / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D059007:Polytene Chromosomes / Q000737:chemistry* / Q000235:genetics; D012469:Salivary Glands / Q000737:chemistry / Q000166:cytology; D020080:Tandem Repeat Sequences / Q000235:genetics*; D016707:Tissue Fixation; D014960:X Chromosome / Q000737:chemistry* / Q000235:genetics
chemical_list: D006570:Heterochromatin; D004247:DNA