DYNAMICS OF CENTROSOME-MICROTUBULE ASSOCIATION

母提案的主要目标是了解 微管动力学在体内和这种动态活动之间的关系 和重要的细胞生物学功能，包括组织 细胞质、细胞形态的产生、细胞分裂和细胞运动。的 作为母提案基础的概念框架是， 微管和它们在细胞中的周转是由细胞内 件.两类重要的组成部分是：（1）中心体作为一个 成核和锚定结构和（2）影响细胞质因子， 分别是负端和正端的动态活动。特别关注的 在父母的建议将是一个新的，最近制定的假设， 微管周转，他们称之为“负端途径”。" 在本申请中，研究人员建议探索相关问题。一 微管动力学领域的一个悖论是， 微管快速周转和正末端的缓和动态不稳定性。 实验分析和理论计算表明， 动态不稳定性不能解释的快速形成和周转 在各种细胞中常见的几十微米长的微管。 研究人员认为，这种差异是由于一个不完整的 对微管行为的理解，由于观察有限 而细胞质内部的行为仍然存在 基本上未知。要检验的具体假设是“持久的 微管形成和周转的“生长”模型。根据这一观点， 从中心体释放的微管从其负端脱落， 被在中心体成核的微管所取代， 向细胞边缘连续延伸。只有在单元格边缘附近 微管显示出称为动态不稳定性的随机随机行为。 将开发采用数字荧光显微镜的新方法， 获得细胞内部微管行为的数据。

The broad objectives of the Parent Proposal are to understand the mechanism of microtubule dynamics in vivo and the relationship between this dynamic activity and important cell biological functions including organization of the cytoplasm, the generation of cell form, cell division, and cell locomotion. The conceptual framework underlying the Parent Proposal is that the organization of microtubules and their turnover in cells result from an interplay of cellular components. Two important classes of component are: (1) the centrosome as a nucleating and anchoring structure and (2) cytoplasmic factors that effect the dynamic activity of the minus and plus ends, respectively. Of particular focus in the Parent Proposal will be a novel, recently formulated hypothesis for microtubule turnover which they call the "minus-end pathway." In this application, the investigators propose to explore a related issue. A paradox in the microtubule dynamics field is the apparent contradiction between rapid microtubule turnover and tempered dynamic instability of plus ends. Experimental analysis and theoretical calculations indicate that tempered dynamic instability can not account for the rapid formation and turnover of microtubules tens of micrometers long commonly observed in a variety of cells. The investigators suggest that this discrepancy results from an incomplete understanding of microtubule behavior resulting from observations being limited to the cell periphery while behavior in the internal cytoplasm remains essentially unknown. The specific hypothesis to be tested is the "persistent growth" model for microtubule formation and turnover. According to this view, microtubules released from the centrosome depolymerize from their minus end and are replaced by microtubules nucleated at the centrosome which grow by continuous elongation towards the cell margin. Only near the cell margin do microtubules display the random stochastic behavior termed dynamic instability. Novel methods employing digital fluorescence microscopy will be developed to obtain data on microtubule behavior in the cell interior.