PerspectiveMolecular Biology

Putting the breaks on meiosis

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Science  20 Nov 2015:
Vol. 350, Issue 6263, pp. 913
DOI: 10.1126/science.aad5404

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Summary

Sexual reproduction involves the production of haploid gametes from diploid cells through a series of genome divisions, called meiosis. Accurate meiotic chromosome segregation requires homologous recombination, initiated by programmed DNA double-strand breaks (DSBs). DSBs are focused at sites, called hotspots, where recombination preferentially occurs (1). Because DSB repair by recombination involves copying information from an unbroken chromosome, one prevailing view is that, over time, DSB hotspots should be replaced by “cold” sequence variants that reduce DSBs at the same site (2). Consistent with this paradigm, hotspot patterns in mice and primates display high divergence between species and even individuals (3). This view is now challenged by two research articles in this issue, by Lam and Keeney (page 932) and Singhal et al. (page 928), that characterize recombination hotspot patterns in species of budding yeast (4) and birds (5), respectively. Both papers document remarkable hotspot pattern stability over evolutionary time, suggesting that the picture in mammals may be the exception rather than the rule.