DNA Damage Response Laboratory, Cancer Research UK, London Research Institute, Clare Hall, Blanche Lane, South Mimms EN6 3LD, UK.
J Cell Sci. 2011 Feb 15;124(Pt 4):501-13. doi: 10.1242/jcs.074427.
Meiotic crossovers are essential for ensuring correct chromosome segregation as well as for creating new combinations of alleles for natural selection to take place. During meiosis, excess meiotic double-strand breaks (DSBs) are generated; a subset of these breaks are repaired to form crossovers, whereas the remainder are repaired as non-crossovers. What determines where meiotic DSBs are created and whether a crossover or non-crossover will be formed at any particular DSB remains largely unclear. Nevertheless, several recent papers have revealed important insights into the factors that control the decision between crossover and non-crossover formation in meiosis, including DNA elements that determine the positioning of meiotic DSBs, and the generation and processing of recombination intermediates. In this review, we focus on the factors that influence DSB positioning, the proteins required for the formation of recombination intermediates and how the processing of these structures generates either a crossover or non-crossover in various organisms. A discussion of crossover interference, assurance and homeostasis, which influence crossing over on a chromosome-wide and genome-wide scale - in addition to current models for the generation of interference - is also included. This Commentary aims to highlight recent advances in our understanding of the factors that promote or prevent meiotic crossing over.
减数分裂交叉是确保正确染色体分离以及为自然选择创造新的等位基因组合所必需的。在减数分裂过程中，会产生过多的减数分裂双链断裂（DSB）；这些断裂的一部分被修复形成交叉，而其余部分则被修复为非交叉。是什么决定了减数分裂 DSB 的产生位置，以及在任何特定的 DSB 处形成交叉还是非交叉，在很大程度上仍不清楚。然而，最近的几篇论文揭示了控制减数分裂中交叉与非交叉形成之间决策的重要因素，包括决定减数分裂 DSB 位置的 DNA 元件，以及重组中间体的产生和处理。在这篇综述中，我们重点介绍了影响 DSB 定位的因素、形成重组中间体所需的蛋白质，以及这些结构的处理如何在各种生物体中产生交叉或非交叉。还讨论了交叉干扰、保证和动态平衡，它们除了当前的干扰产生模型外，还影响着染色体和基因组范围内的交叉频率。这篇评论旨在强调我们对促进或阻止减数分裂交叉的因素的理解的最新进展。
