Meiotic chromosome synapsis and recombination in yeast.

描述(由申请人提供)：本申请涉及酵母减数分裂过程中同源染色体之间的相互作用。(I)DSB-独立配对。我们将使用FISH来探索与R-和G-带的相对丰度有关的非DSB同源配对，与姐妹染色单体凝聚力的关系以及染色质结构蛋白的参与。我们将使用“捕获染色体构象”(3C)方法来确定配对接触的位置。我们将进行一项试点实验，以探索一种可能的配对缺陷突变的新方法。(2)重组的启动：DSB过渡。我们将通过3C方法和遗传学研究来研究前DSB重组体是否与其潜在的染色体轴存在物理联系。我们还将使用3C方法来识别DSB/伴侣的新互动，并探索同源/姐妹歧视。我们将进一步探索限制DSB数量的因素，这些DSB可以出现在任何给定的减数分裂核中的单个基因座上。(3)重组后期阶段。我们将进一步探索影响交叉控制转换的突变体的减数分裂，并注意温度的重要影响。我们将继续分析野生型和精选突变体的花束阶段。我们将继续分析Mlh3在减数分裂重组中的作用。我们将研究可能影响单端入侵转化为粗线期中期双Holliday连接的突变的表型。我们还将继续研究减数分裂过程中发生的双Holliday连接的拓扑异构体(S)。(4)减数分裂的染色体结构和机制。我们将进一步探索我们最近的研究揭示的染色质/轴/姐妹的相互作用。我们将使用3C方法来研究中期前期染色体的物理性质。我们将研究体内联会复合体扭曲的动力学。我们将开始开发分离、分析和物理操作粗线期染色体的方法。

DESCRIPTION (provided by applicant): This application addresses the interactions between homologous chromosomes during meiosis in yeast. (I) DSB-independent pairing. We will use FISH to probe DSB-independent homolog pairing with respect to relative abundance in R- and G-bands, relationship to sister chromatid cohesion and involvement of chromatin structure proteins. We will use "Capturing Chromosome Conformation" (3C) methodology to identify sites of pairing contacts. We will carry out a pilot experiment to investigate a possible new assay for pairing-defective mutants. (II) Initiation of recombination: the DSB transition. We will investigate whether pre-DSB recombinosomes are physically associated with their underlying chromosome axes by 3C methodology and genetic studies. We will also use 3C methodology to identify nascent DSB/partner interactions and to explore homolog/sister discrimination. We will further explore constraints governing the number of DSBs that can occur at a single locus in any give meiotic nucleus. (III) Later stages of recombination. We will further explore meiosis in mutants that affect the crossover control transition, with attention to important effects of temperature. We will continue analysis of the bouquet stage in wild type and selected mutants. We will continue analysis of the role of Mlh3 for meiotic recombination. We will examine the phenotypes of mutations suspected to affect conversion of single-end invasions to double Holliday junctions at mid-pachytene. And we will continue to investigate which topological isomer(s) of double Holliday junctions occur during meiosis. (IV) Meiotic chromosome structure and mechanics. We will further explore chromatin/axis/sister interplay revealed by our recent studies. We will use 3C methodology to investigate physical properties of mid-prophase chromosomes. We will examine the dynamics of synaptonemal complex twisting in vivo. We will begin to develop methods for isolating, analyzing and physically manipulating pachytene chromosomes in vitro.