CAREER: Molecular and physical mechanisms of chromosome condensation

DNA编码了所有生命形式和功能的蓝图，必须根据其所在细胞的性质，将其盘绕、捆绑和压缩成不同的包装。了解DNA如何在空间和时间上改变形状是发现基因如何被调节和代代相传的下一个重大障碍。本研究项目所包含的工作旨在创新技术，揭示活的、分裂的细胞中DNA随时间的三维动态。由于细胞分裂对疾病的预测、诊断和治疗，提高粮食作物的产量和抗逆性，以及保护生态生物多样性的关键性质，本项目的成果将服务和丰富社会。这些更广泛的目标将通过培养多个层次的学生（本科生，研究生，博士）作为一个团队工作，创造性地使用尖端的光学显微镜和数据分析来实现。最后，通过公众会议和展览（包括永久性和巡回），外展计划将向公众教授光学显微镜在DNA和细胞分裂研究中的历史和影响。染色体（单链DNA）在进入有丝分裂时通过一种未知的机制压缩了几个数量级。100年的研究最终形成了一个模型，其中这种压实是通过染色质（核体DNA）组织成有规则间隔的环来实现的。然而，早在50年前就有证据表明，有丝分裂的染色体不会采用“静态”的规则构象。提出的工作利用秀丽隐杆线虫早期胚胎作为模型细胞类型，以发现控制有丝分裂染色体凝聚的基本生物物理特性。该研究项目将采用一种新发明的光片模式，其中发育中的活胚胎中的染色体以高时空分辨率成像（通过使用高数值孔径（1.4或更大）的物镜）。该项目的完成将定义亚分辨率染色质动力学在凝聚过程中如何变化，负责这些变化的分子，以及这些动力学是如何通过发育调节的。这里生成的动态单细胞数据与静态的基于种群的基因组生物信息学数据的相关性将被合成，以提供染色体如何保持其形状并快速转换的基本理解，以满足其细胞功能的需求。

DNA encodes the blueprint for all of life's forms and functions and must be coiled, bundled and compacted into different packages, depending on the nature of the cell where it resides. Understanding how DNA changes shape in space and time is the next great hurdle in discovering how genes are regulated and passed down through generations. The work encompassed in this research program is aimed at innovating technologies to reveal the three-dimensional dynamics of DNA over time in living, dividing cells. Results from this project will serve and enrich society due to the critical nature of cell division to predicting, diagnosing and treating diseases, improving food crop yield and hardiness, and conserving ecological biodiversity. These broader goals will be realized by training students at multiple levels (undergraduate, graduate, Ph.D.) to work as a team and creatively employ cutting edge light microscopy and data analysis. Finally, through public meetings and displays (both permanent and travelling), the outreach program will teach the general public the history and impact of light microscopy on the study of DNA and cell division.Chromosomes (single DNA strands) compact several orders of magnitude upon entry into mitosis via a yet unknown mechanism. One hundred years of research has culminated in a model wherein this compaction is achieved by the organization of chromatin (nucleosomal DNA) into regularly spaced loops. Evidence from as long as 50 years ago, however, concluded that mitotic chromosomes do not adopt a "static" regular conformation. The proposed work utilizes the C. elegans early embryo as a model cell type to discover the basic biophysical properties governing mitotic chromosome condensation. The research project will employ a newly invented light sheet modality, wherein chromosomes in living developing embryos are imaged with high temporal and spatial resolution (by using high numerical aperture (1.4 or greater) objective lenses). Fulfillment of this project will define how subresolution chromatin dynamics change during condensation, the molecules responsible for these changes, and how these dynamics are modulated through development. Correlation of dynamic, single-cell data generated here with static, population-based genomic bio-informatics data will be synthesized to provide fundamental understanding of how chromosomes maintain their shape, and quickly transform, to meet the demands of their cellular functions.