title: Novel sequencing strategy for repetitive DNA in a Drosophila BAC clone reveals that the centromeric region of the Y chromosome evolved from a telomere.
abstract: The centromeric and telomeric heterochromatin of eukaryotic chromosomes is mainly composed of middle-repetitive elements, such as transposable elements and tandemly repeated DNA sequences. Because of this repetitive nature, Whole Genome Shotgun Projects have failed in sequencing these regions. We describe a novel kind of transposon-based approach for sequencing highly repetitive DNA sequences in BAC clones. The key to this strategy relies on physical mapping the precise position of the transposon insertion, which enables the correct assembly of the repeated DNA. We have applied this strategy to a clone from the centromeric region of the Y chromosome of Drosophila melanogaster. The analysis of the complete sequence of this clone has allowed us to prove that this centromeric region evolved from a telomere, possibly after a pericentric inversion of an ancestral telocentric chromosome. Our results confirm that the use of transposon-mediated sequencing, including positional mapping information, improves current finishing strategies. The strategy we describe could be a universal approach to resolving the heterochromatic regions of eukaryotic genomes.
authors.affiliation: Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Madrid, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Méndez-Lago
authors.forename: Jadwiga
authors.initials: J
authors.lastname: Wild
authors.forename: Siobhan L
authors.initials: SL
authors.lastname: Whitehead
authors.forename: Alan
authors.initials: A
authors.lastname: Tracey
authors.forename: Beatriz
authors.initials: B
authors.lastname: de Pablos
authors.forename: Jane
authors.initials: J
authors.lastname: Rogers
authors.forename: Waclaw
authors.initials: W
authors.lastname: Szybalski
authors.forename: Alfredo
authors.initials: A
authors.lastname: Villasante
mesh_terms: D000818:Animals; D002503:Centromere / Q000737:chemistry*; D022202:Chromosomes, Artificial, Bacterial; D003001:Cloning, Molecular; D004247:DNA / Q000737:chemistry; D004251:DNA Transposable Elements; D004331:Drosophila melanogaster / Q000235:genetics*; D019143:Evolution, Molecular; D012091:Repetitive Sequences, Nucleic Acid; D017422:Sequence Analysis, DNA / Q000379:methods*; D016615:Telomere / Q000737:chemistry*; D014998:Y Chromosome / Q000737:chemistry*
chemical_list: D004251:DNA Transposable Elements; D004247:DNA