Stowers Institute for Medical Research, Kansas City, Missouri 64110.
MD-PhD Physician Scientist Training Program, University of Kansas Medical Center, Kansas City, Kansas 66160.
Genetics. 2018 Mar;208(3):875-908. doi: 10.1534/genetics.117.300081.
A century of genetic studies of the meiotic process in females has been greatly augmented by both modern molecular biology and major advances in cytology. These approaches, and the findings they have allowed, are the subject of this review. Specifically, these efforts have revealed that meiotic pairing in females is not an extension of somatic pairing, but rather occurs by a poorly understood process during premeiotic mitoses. This process of meiotic pairing requires the function of several components of the synaptonemal complex (SC). When fully assembled, the SC also plays a critical role in maintaining homolog synapsis and in facilitating the maturation of double-strand breaks (DSBs) into mature crossover (CO) events. Considerable progress has been made in elucidating not only the structure, function, and assembly of the SC, but also the proteins that facilitate the formation and repair of DSBs into both COs and noncrossovers (NCOs). The events that control the decision to mature a DSB as either a CO or an NCO, as well as determining which of the two CO pathways (class I or class II) might be employed, are also being characterized by genetic and genomic approaches. These advances allow a reconsideration of meiotic phenomena such as interference and the centromere effect, which were previously described only by genetic studies. In delineating the mechanisms by which the oocyte controls the number and position of COs, it becomes possible to understand the role of CO position in ensuring the proper orientation of homologs on the first meiotic spindle. Studies of bivalent orientation have occurred in the context of numerous investigations into the assembly, structure, and function of the first meiotic spindle. Additionally, studies have examined the mechanisms ensuring the segregation of chromosomes that have failed to undergo crossing over.
一个世纪以来，女性减数分裂过程的遗传研究在现代分子生物学和细胞学的重大进展的推动下得到了极大的发展。这些方法及其所允许的发现是本综述的主题。具体来说，这些努力揭示了女性减数分裂的配对不是体细胞配对的延伸，而是在减数分裂前期有丝分裂中通过一个尚未完全理解的过程发生的。这种减数分裂配对的过程需要几个联会复合体（SC）组件的功能。当完全组装时，SC 还在维持同源物联会和促进双链断裂（DSB）成熟为成熟交叉（CO）事件中起着关键作用。在阐明 SC 的结构、功能和组装方面，以及促进 DSB 形成和修复为 CO 和非交叉（NCO）的蛋白质方面，已经取得了相当大的进展。控制 DSB 成熟为 CO 或 NCO 的事件，以及决定采用两种 CO 途径（I 类或 II 类）中的哪一种的事件，也正在通过遗传和基因组方法进行表征。这些进展使我们能够重新考虑减数分裂现象，如干扰和着丝粒效应，这些现象以前只能通过遗传研究来描述。在描述卵母细胞控制 CO 数量和位置的机制时，就有可能理解 CO 位置在确保同源物在第一次减数分裂纺锤体上正确定向的作用。双价取向的研究是在对第一次减数分裂纺锤体的组装、结构和功能进行的大量研究的背景下进行的。此外，还研究了确保未经历交叉的染色体分离的机制。
