Analysis of Chromosome Condensation and Cohesion in Arabidopsis

拟南芥染色体凝聚和凝聚分析

• 批准号: 9982367
• 负责人: Christopher Makaroff
• 金额: --
• 依托单位: Miami University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-08-01 至 2003-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9982367&HistoricalAwards=false
• 关键词: Analysis; Chromosome; Condensation; Cohesion; Arabidopsis

As part of studies to better understand the molecular and biochemical processes that occur during meiosis, a T-DNA tagged, synaptic mutant of Arabidopsis, syn1, has been characterized. The syn1 mutation disrupts chromosome condensation and pairing prior to leptonema of meiosis I and results in fragmentation of the chromosomes. Arabidopsis SYN1 has been isolated and found to exhibit similarity to S. pombe RAD21 and RAD21-like proteins, which are required for chromosome condensation and sister chromatid cohesion during mitosis. Therefore, Arabidopsis SYN1 is a RAD21-like protein that is required for chromosome condensation and sister chromatid cohesion during meiosis. Based on similarity to SYN1, two additional Arabidopsis RAD21 homologues, SYN2 and SYN3 have recently been isolated and are being characterized. Experiments proposed here are designed to further characterize Arabidopsis SYN1, SYN2 and SYN3 and understand how they participate in chromosome condensation and sister chromatid cohesion. It has been demonstrated that syn1 plants are defective in chromosome condensation and sister-chromatid cohesion during meiosis; however it is not clear what role SYN1 plays in these processes or how the two processes are linked. Fluorescence in situ hybridization (FISH) experiments will be conducted to examine chromosome pairing and sister-chromatid cohesion during meiosis in syn1 plants. In addition, the distribution of SYN1 on chromosomes will be investigated to determine when and where it is localized and if it is involved in cohesion along the chromosome arms, the centromeres or both. Finally altered forms of SYN1 will be introduced into syn1 plants to begin to identify regions of the protein that are necessary for function . Based on their sequence, it is very likely that SYN2 and SYN3 play important roles in chromosome condensation and/or sister chromatid cohesion; however it is not clear if they function during meiosis, mitosis or both. Also, it is not clear if RAD21-like proteins function in a same way during mitosis and meiosis. These questions will be addressed through the isolation and characterization of lines defective in SYN2 and SYN3. Expression studies to examine the tissue-specificity and timing of expression of the genes as well as immunolocalization experiments to examine the distribution of the proteins on chromosomes, will be conducted. The proposed studies will yield new insights into the processes of chromosome condensation and sister chromatid cohesion and a better understanding of how these two important events are linked. Meiosis, a highly ordered series of events that results in the production of haploid gametes, is essential for eukaryotic sexual reproduction. A single round of DNA replication, followed by homologous chromosomes pairing and recombination initiates the process, which culminates in two division phases, the first a reductive division that segregates homologous chromosomes and the second in which sister chromatids are separated. The establishment of sister chromatid cohesion and chromosome condensation are central events during both meiosis, and mitosis, which ensure the proper segregation of genetic information during cellular division. While considerable progress has been made towards understanding chromosome condensation during mitosis, perhaps one of the least understood aspects of eukaryotic chromosome dynamics is the mechanism of sister-chromatid cohesion.

作为更好地了解减数分裂过程中发生的分子和生化过程的研究的一部分，已表征了拟南芥的TNNA，Syn1的突触突变体。 Syn1突变破坏了减数分裂I的嗜睡之前的染色体凝结和配对，并导致染色体破碎。拟南芥Syn1已被分离，发现与pombe rad21和rad21样蛋白具有相似性，这是染色体凝结所需的染色体和姐妹染色单体内含性所必需的。因此，拟南芥Syn1是一种RAD21样蛋白，在减数分裂过程中需要染色体凝结和姐妹染色单体内聚力所必需。基于与Syn1的相似性，最近已经分离出了另外两个拟南芥RAD21同源物，Syn2和Syn3并正在表征。此处提出的实验旨在进一步表征拟南芥Syn1，Syn2和Syn3，并了解它们如何参与染色体凝结和姐妹染色单体内聚。已经证明Syn1植物在减数分裂过程中的染色体凝结和姊妹染色剂有缺陷。但是，尚不清楚Syn1在这些过程中扮演什么角色或如何链接两个过程。将进行荧光原位杂交（FISH）实验，以检查Syn1植物减数分裂过程中减数分裂过程中染色体配对和姐妹 - 染色剂的凝聚。此外，将研究Syn1在染色体上的分布，以确定何时和何处的位置，以及它是否参与沿染色体臂，丝粒或两者兼而有之。最终，Syn1的改变形式将被引入Syn1植物，以开始识别功能所需的蛋白质区域。根据它们的序列，Syn2和Syn3很可能在染色体凝结和/或姐妹染色单体内聚会中起重要作用。但是，尚不清楚它们在减数分裂，有丝分裂或两者兼有期间是否发挥作用。同样，尚不清楚Rad21样蛋白在有丝分裂和减数分裂过程中是否以相同的方式起作用。这些问题将通过SYN2和SYN3中有缺陷的线的隔离和表征来解决。将进行表达研究，以检查基因表达的组织特异性和时机以及免疫定位实验，以检查蛋白质在染色体上的分布。提出的研究将对染色体凝结和姐妹染色质被的过程产生新的见解，并更好地理解这两个重要事件如何联系起来。减数分裂是一系列高度有序的事件，导致单倍体配子的产生，对于真核性有性繁殖至关重要。一轮DNA复制，其次是同源染色体配对和重组的启动过程，该过程达到了两个分裂阶段，第一个阶段是一个还原性分裂，将同源染色体分离，第二个分离姐妹染色体分离。在减数分裂和有丝分裂的过程中，建立姐妹染色单体的内聚力和染色体凝结是中心事件，可确保细胞分裂期间遗传信息的适当分离。尽管在有丝分裂过程中已经取得了相当大的进步，但在有丝分裂过程中，真核染色体动力学的知识最少的方面之一也许是姐妹 - 染色剂凝聚力的机制。