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Curr Biol. 2017 Jan 9;27(1):96-102. doi: 10.1016/j.cub.2016.10.055. Epub 2016 Dec 15.

Bloom Syndrome Helicase Promotes Meiotic Crossover Patterning and Homolog Disjunction.

Author information

1
Curriculum in Genetics and Molecular Biology, 120 Mason Farm Road, University of North Carolina, Chapel Hill, NC 27599-7264, USA.
2
Department of Biology, Winthrop University, 701 Oakland Avenue, Rock Hill, SC 29733, USA.
3
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.
4
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.

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.

KEYWORDS:

Drosophila; bloom syndrome helicase; centromere effect; crossover assurance; crossover interference; crossover patterning; meiosis; meiotic recombination; nondisjunction

PMID:
27989672
PMCID:
PMC5225052
DOI:
10.1016/j.cub.2016.10.055
[Indexed for MEDLINE]
Free PMC Article

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