BIOPHYSICAL STUDIES OF CYTOSKELETAL FUNCTION

这项研究正在开发和应用生物物理分析方法来 细胞骨架功能。项目使用三种不同的相互 互补的方法。一种测试，认识到一种 细胞骨架的主要功能是维持或改变 细胞形状，使用一种新的方法测量细胞 变形性。这提供了一个量化的物理指标 细胞骨架的状态，以所需的力来衡量 微缩进附着在固体上的细胞裸露表面 底物。这一测量的生物物理分析使用 连续介质力学理论和模型试验包括 项目的一部分。它的目标是提取量化的 细胞黏度和弹性模数的估算。 同时，变形性对形状的依赖关系， 细胞的生理状态和细胞骨架结构以及 细胞骨架参与生理功能，如 AS的封顶和分泌物将以经验为特征。 该项目的第二部分将这项工作带到分子 通过确定活细胞中蛋白质的功能来达到水平 调节聚合程度和相互作用 微丝。明胶蛋白和α-肌动蛋白等蛋白质， 已经在体外得到了很好的表征，将被引入 进入细胞质。一种可操作的细胞骨架分析方法 状态，包括形态、细胞粘弹性和 细胞内运输将测量调制的效果 细胞骨架上的蛋白质。 该项目的第三部分扩展了荧光关联 光谱学和荧光光漂白恢复 细胞骨架聚合反应。前者将被用来 测量聚合度分布；后者， 测定细胞内聚合反应动力学。这些 方法将提供更多用户不容易获得的信息 传统的技术。

This research is developing and applying biophysical assays for cytoskeletal function. The project uses three different mutually complementary approaches. One assay, recognizing that a principal function of the cytoskeleton is to maintain or change cell shape, uses a new method for measuring cellular deformability. This provides a quantitative index of the physical state of the cytoskeleton, measured in terms of the force needed slightly to indent the exposed surface of a cell adherent to a solid substratum. Biophysical analysis of this measurement using continuum mechanical theory and model experiments comprises one portion of the project. Its goal is to extract quantitative estimates for cellular viscosities and elasticity moduli. Concurrently, the dependence of deformability on the shape, physiological state and cytoskeletal structure of a cell and the participation of the cytoskeleton in physiological functions such as capping and secretion will be characterized empirically. A second portion of the project carries this work to the molecular level by determining the function in living cells of proteins which modulate the extent of polymerization and interactions in microfilaments. Proteins such as gelsolin and alpha-actinin, which have been well characterized in vitro, will be introduced into the cytoplasm of cells. An operational assay of cytoskeletal state which includes morphology, cellular viscoelasticity, and intracellular transport will gauge the effects of the modulating proteins on the cytoskeleton. A third portion of the project extends Fluorescence Correlation Spectroscopy and Fluorescence Photobleaching Recovery to cytoskeletal polymerization reactions. The former will be used to measure the distribution of degrees of polymerization; the latter, to measure polymerization reaction kinetics in cells. These methods will provide information not readily available by more conventional techniques.