Multiple-particle tracking measurements of heterogeneities in solutions of actin filaments and actin bundles
Multiple-particle tracking measurements of heterogeneities in solutions of actin filaments and actin bundles
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DOI：
10.1016/s0006-3495(00)76363-6
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发表时间：
2000-08-01
影响因子：
3.4
通讯作者：
Wirtz, D
中科院分区：
文献类型：
--
作者：
Apgar, J;Tseng, Y;Wirtz, D
肌动蛋白细胞骨架的中心功能之一是为细胞形态的建立和维持提供所需的机械支持。肌动蛋白丝组装体的机械性质是可用的聚合物浓度和指导更高级结构形成的肌动蛋白调节蛋白两者的结果。通过荧光显微镜监测分散良好的微球的位移，我们探测的F-肌动蛋白凝胶和网络在体外的空间异质性的程度。我们比较的时间依赖性的均方位移（MSD）的聚苯乙烯微球嵌入在低浓度和高浓度的F-肌动蛋白的解决方案，在存在和不存在的F-肌动蛋白捆绑蛋白肌成束蛋白的分布。2.6 μ M F-肌动蛋白溶液的MSD分布是对称的，其标准偏差类似于具有类似零剪切粘度的甘油的均匀溶液的标准偏差。然而，增加肌动蛋白浓度使MSD分布广泛和不对称，肌成束蛋白增强的效果。MSD分布的形状的定量变化定性地与由增加的细丝浓度和肌动蛋白束的存在产生的F-肌动蛋白溶液中的大的异质性的存在相关，如通过共聚焦显微镜检测到的。多粒子跟踪提供了一种新的定量方法来表征溶液中生物聚合物的组织。
One of the central functions of actin cytoskeleton is to provide the mechanical support required for the establishment and maintenance of cell morphology. The mechanical properties of actin filament assemblies are a consequence of both the available polymer concentration and the actin regulatory proteins that direct the formation of higher order structures. By monitoring the displacement of well-dispersed microspheres via fluorescence microscopy, we probe the degree of spatial heterogeneity of F-actin gels and networks in vitro. We compare the distribution of the time-dependent mean-square displacement (MSD) of polystyrene microspheres imbedded in low- and high-concentration F-actin solutions, in the presence and absence of the F-actin-bundling protein fascin. The MSD distribution of a 2.6-mu M F-actin solution is symmetric and its standard deviation is similar to that of a homogeneous solution of glycerol of similar zero-shear viscosity. However, increasing actin concentration renders the MSD distribution wide and asymmetric, an effect enhanced by fascin. Quantitative changes in the shape of the MSD distribution correlate qualitatively with the presence of large heterogeneities in F-actin solutions produced by increased filament concentration and the presence of actin bundles, as detected by confocal microscopy. Multiple-particle tracking offers a new, quantitative method to characterize the organization of biopolymers in solution.