Molecular and cytological characterization of repetitive DNA sequences from the centromeric heterochromatin of Sciara coprophila

11 páginas, 8 figuras -- PAGS nros. 387-397Sciara 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 clonesThis work was supported by grants BFU2008-02947-C02-02/BMC to C.G. and BFU2008-02947-C02-01/BMC to A.V. from the Ministerio de Ciencia e Innovación, an institutional grant from the Fundación Ramón Areces to the Centro de Biología Molecular “Severo Ochoa” and a grant supporting the Cambridge Resource Centre from the Wellcome Trust to M.A.FS; M.C.Escribá was supported by the FPI fellowship BES-2006-12492 from the Ministerio de Ciencia e InnovaciónPeer reviewe