Mapping Meiotic Single-Strand DNA Reveals A New Landscape Of DNA Double-Strand Breaks In Saccharomyces Cerevisiae

Main Category: Biology / Biochemistry
Article Date: 10 Dec 2007 - 17:00 PDT

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During meiosis, the two copies of each chromosome present in the full (diploid) genome come together and then separate, forming haploid gametes (sperm and eggs, in animals). Recombination, which swaps DNA between chromosomes, is critical for chromosome pairing and separation, and also promotes genetic diversity in the next generation, providing the feedstock for evolution. DNA double-strand breaks (DSBs), which are formed by the conserved Spo11 nuclease, initiate meiotic recombination.

DSB mapping is thus an alternative to standard genetic analysis for determining where meiotic recombination occurs. DSBs have been most extensively mapped in budding yeast mutants that fail to remove Spo11 from break ends, blocking further recombination steps. Paradoxically, those studies indicated that DSBs are absent from large regions where recombination was known to occur.

This week in the open-access journal PLoS Biology, Cyril Buhler, Valerie Borde, and Michael Lichten show how they have developed a new DSB mapping method that purifies and analyzes the single-strand DNA formed at breaks after Spo11 removal. This new map shows that DSBs (and by inference, recombination) actually occur frequently throughout almost all of the budding yeast genome, in a distribution consistent with recombination's roles in chromosome pairing and in generating genetic diversity. This new mapping method will be useful for studying meiotic recombination and DNA damage repair in other organisms.

Citation: Buhler C, Borde V, Lichten M (2007) Mapping meiotic single-strand DNA reveals a new landscape of DNA double-strand breaks in Saccharomyces cerevisiae.
PLoS Biol 5(12): e324. doi:10.1371/journal.pbio.0050324
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