Large-scale regulation of meiotic chromosome dynamics

在有性生殖过程中，染色体分离将一条染色体放置在母本或父本的染色体上， 复制，在每个配子中。精确的减数分裂染色体分离要求亲本染色体 通过杂交的形成相互作用并交换遗传信息。调节不当 染色体相互作用可导致核型重排和染色体错误分离， 从而导致不育和先天性出生缺陷。事实上，交叉形成是严格管制的， 局部和染色体范围的尺度。这里提出的研究解决了调节机制 染色体的相互作用，通过使用线虫和芽殖酵母，并通过开发新的实验 适合研究大规模调控的染色体过程的方法。 该建议探讨了染色体组织和动力学的两个方面。第一部分论述了 联会复合体是一个保守的界面，在双亲染色体之间组装， 调节交叉点的分布。这项工作建立在最近的理解，即联会线 复合物，尽管其有序的外观时，通过电子显微镜观察，是一个液体样的隔室。 通过应用遗传学方法、进化分析、单分子跟踪和尖端显微镜， 该研究旨在了解联会复合体的超微结构和液体性质如何允许 它组装到亲本染色体上，并大规模地调节交叉。具体来说，如何 蛋白质-蛋白质相互作用和联会复合体蛋白中保守的卷曲螺旋结构域产生 一个有序的三维结构，但仍然具有液体性质，如恒定的亚基交换？ 而且，是什么样的分子机制来调节液晶联会复合体加载到 减数分裂染色体，将它们从头到尾排列起来？ 第二部分论述了在染色体组化过程中亲本染色体和姐妹染色单体的组织结构。 有性生殖这些大的染色质束形成不同的细胞学实体， 进行精确的信息交换--这是成功传递一代基因组的必要步骤 到下一个。在实验室中开发的一种仅标记两个相同姐妹染色单体之一的方法将允许 姐妹篇之间的区别。这一点很重要，因为跨界车的形成- 在父母染色体之间交换信息-包括有规律地避免姐妹染色体 染色单体该实验室还在开发一种新的方法来获得单分子，高分辨率的描述 染色体构象和动力学的研究， DNA分子。将这种方法应用于有性生殖过程中的染色体-当染色体 被组织成一系列染色质环-将揭示对齐父母的机制， 染色体，保持它们的登记册，并允许它们准确地交换信息。

Chromosome segregation during sexual reproduction places one chromosome, either the maternal or paternal copy, in each gamete. Accurate meiotic chromosome segregation requires that the parental chromosomes interact with one another and exchange genetic information through the formation of crossovers. Mis-regulated chromosomal interactions could lead to karyotype rearrangement and chromosomal mis-segregation, and consequently to infertility and congenital birth defects. Indeed, crossover formation is tightly regulated on both local and chromosome-wide scales. The research proposed here addresses the mechanisms regulating chromosomal interactions by using nematodes and budding yeast, and by developing new experimental approaches suited to study chromosomal processes that are regulated on large scales. This proposal probes two aspects of chromosome organization and dynamics. The first part addresses the role of the synaptonemal complex, a conserved interface that assembles between the parental chromosomes and regulates the distribution of crossovers. This work builds on the recent understanding that the synaptonemal complex, despite its ordered appearance when visualized by electron microscopy, is a liquid-like compartment. By applying genetic approaches, evolutionary analysis, single-molecule tracking and cutting-edge microscopy, the research aims to understand how the ultrastructure and liquid properties of the synaptonemal complex allow it to assemble onto the parental chromosomes and regulate crossovers on a large scale. Specifically, how do protein-protein interactions and the conserved coiled-coil domains in synaptonemal complex proteins generate an ordered, 3-dimensional structure that nonetheless has liquid properties such as constant subunit exchange? And, what is the molecular mechanism that regulates loading of a liquid-crystalline synaptonemal complex onto meiotic chromosomes, aligning all of them from end to end? The second part addresses the organization of the parental chromosomes and the sister chromatids during sexual reproduction. These large bundles of chromatin form distinct cytological entities that can nonetheless undergo precise exchange of information – a necessary step to successfully pass genomes from one generation to the next. An approach developed in the lab to label only one of the two identical sister chromatids will allow probing of the differentiation of the sisters from one another. This is important, since formation of crossovers – which exchange information between the parental chromosomes – involves regulated avoidance the sister chromatid. The lab is also developing a novel approach to obtain a single-molecule, high-resolution description of chromosome conformation and dynamics by utilizing an emerging technology to sequence very long molecules of DNA. Applying this approach to chromosomes during sexual reproduction – when chromosomes are organized as an array of chromatin loops – will shed light on the mechanisms that align the parental chromosomes, keeping them in register and allowing them to accurately exchange information.