Brangwynne Clifford P, Koenderink Gijsje H, Mackintosh Frederick C, Weitz David A
School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
Phys Rev Lett. 2008 Mar 21;100(11):118104. doi: 10.1103/PhysRevLett.100.118104.
Biological activity gives rise to nonequilibrium fluctuations in the cytoplasm of cells; however, there are few methods to directly measure these fluctuations. Using a reconstituted actin cytoskeleton, we show that the bending dynamics of embedded microtubules can be used to probe local stress fluctuations. We add myosin motors that drive the network out of equilibrium, resulting in an increased amplitude and modified time dependence of microtubule bending fluctuations. We show that this behavior results from steplike forces on the order of 10 pN driven by collective motor dynamics.
生物活性会在细胞质中引发非平衡涨落；然而，直接测量这些涨落的方法却很少。利用重构的肌动蛋白细胞骨架，我们发现嵌入其中的微管的弯曲动力学可用于探测局部应力涨落。我们添加了驱动网络偏离平衡状态的肌球蛋白马达，导致微管弯曲涨落的幅度增加且时间依赖性发生改变。我们表明，这种行为是由集体马达动力学驱动的约10皮牛量级的阶梯状力所导致的。
