UV Microbeam Analysis of Microtubule Dynamics

在细胞分裂之前，包含在染色体结构中的遗传信息被精确地复制。在细胞分裂过程中，复制的染色体被分配到两个子细胞中，因此每个子细胞随后包含完全相同种类和数量的染色体。负责执行这一关键过程的细胞器统称为有丝分裂纺锤体。纺锤体主要由一个复杂的微管电缆网络组成，这些微管电缆一端连接到单个染色体上，另一端固定在称为细胞极点的位置上。在细胞分裂的过程中，这些电缆以某种方式将染色体拉到各自的极点，其机制的细节尚不清楚。在这篇新颖且写得很好的提案中，首席研究员将设计、构建和校准紫外线微束装置。该装置能够照射并因此切割活细胞中的单个微管纤维。所描述的实验将允许研究者区分染色体运动过程中微管功能的几种当前模型。之所以会出现这种情况，是因为不同的模型对间隙产生对纤维的稳定性和动力学、染色体的运动以及辐射诱导的间隙修复的性质的影响做出了不同的预测。

Before cells divide, their genetic information, contained in structures called chromosomes, is duplicated precisely. During cell division, the duplicated chromosomes are distributed into the two daughter cells so that each daughter subsequently contains exactly the same kind and number of chromosomes. The cellular organelles responsible for carrying out this crucial process are collectively called the mitotic spindle. The spindle is composed primarily of a complex network of microtubule cables that attach to individual chromosomes at one end, and become anchored at their other end to sites called the cell poles. During the course of cell division these cables somehow pull the chromosomes to their respective poles, by a mechanism whose details are only poorly understood. In this novel and well written proposal, the principal investigator will design, construct, and calibrate an ultraviolet microbeam apparatus. This device is capable of irradiating and thereby cutting a single microtubule fiber in a living cell. The experiments described will allow the investigator to distinguish between several current models of microtubule function during chromosome movement. This is the case because the various models made different predictions with respect to the effect of gap production on the stability and dynamics of the fiber, the movement of chromosomes, and the nature of irradiation-induced gap repair.