title: Bloom Syndrome Helicase Promotes Meiotic Crossover Patterning and Homolog Disjunction.
abstract: In most sexually reproducing organisms, crossover formation between homologous chromosomes is necessary for proper chromosome disjunction during meiosis I. During meiotic recombination, a subset of programmed DNA double-strand breaks (DSBs) are repaired as crossovers, with the remainder becoming noncrossovers [1]. Whether a repair intermediate is designated to become a crossover is a highly regulated decision that integrates several crossover patterning processes, both along chromosome arms (interference and the centromere effect) and between chromosomes (crossover assurance) [2]. Because the mechanisms that generate crossover patterning have remained elusive for over a century, it has been difficult to assess the relationship between crossover patterning and meiotic chromosome behavior. We show here that meiotic crossover patterning is lost in Drosophila melanogaster mutants that lack the Bloom syndrome helicase. In the absence of interference and the centromere effect, crossovers are distributed more uniformly along chromosomes. Crossovers even occur on the small chromosome 4, which normally never has meiotic crossovers [3]. Regulated distribution of crossovers between chromosome pairs is also lost, resulting in an elevated frequency of homologs that do not receive a crossover, which in turn leads to elevated nondisjunction.
authors.affiliation: Curriculum in Genetics and Molecular Biology, 120 Mason Farm Road, University of North Carolina, Chapel Hill, NC 27599-7264, USA.
authors.forename: Talia
authors.initials: T
authors.lastname: Hatkevich
authors.affiliation: Department of Biology, Winthrop University, 701 Oakland Avenue, Rock Hill, SC 29733, USA.
authors.forename: Kathryn P
authors.initials: KP
authors.lastname: Kohl
authors.affiliation: Department of Biology, University of North Carolina, 120 South Road, Chapel Hill, NC 27599-3280, USA; Integrative Program in Biological and Genome Sciences, 250 Bell Tower Drive, University of North Carolina, Chapel Hill, NC 27599-7100, USA.
authors.forename: Susan
authors.initials: S
authors.lastname: McMahan
authors.affiliation: Curriculum in Genetics and Molecular Biology, 120 Mason Farm Road, University of North Carolina, Chapel Hill, NC 27599-7264, USA.
authors.forename: Michaelyn A
authors.initials: MA
authors.lastname: Hartmann
authors.affiliation: Department of Biology, Winthrop University, 701 Oakland Avenue, Rock Hill, SC 29733, USA.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Williams
authors.affiliation: Curriculum in Genetics and Molecular Biology, 120 Mason Farm Road, University of North Carolina, Chapel Hill, NC 27599-7264, USA; Department of Biology, University of North Carolina, 120 South Road, Chapel Hill, NC 27599-3280, USA; Integrative Program in Biological and Genome Sciences, 250 Bell Tower Drive, University of North Carolina, Chapel Hill, NC 27599-7100, USA. Electronic address: sekelsky@unc.edu.
authors.forename: Jeff
authors.initials: J
authors.lastname: Sekelsky
mesh_terms: D000818:Animals; D004265:DNA Helicases / Q000378:metabolism*; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology* / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D005260:Female; D059765:Homologous Recombination; D008297:Male; D008540:Meiosis; D009630:Nondisjunction, Genetic
chemical_list: D029721:Drosophila Proteins; D004265:DNA Helicases; C470639:blm protein, Drosophila
keywords: Drosophila; bloom syndrome helicase; centromere effect; crossover assurance; crossover interference; crossover patterning; meiosis; meiotic recombination; nondisjunction