Why A Large Scale Mode Can Be Essential For Understanding Intracellular Actin Waves

肌动蛋白基推进中的细丝附着动力学;

Filament attachment dynamics in actin-based propulsion

理论和实验已经证实，F-肌动蛋白丝强烈地附着在细胞内寄生虫（如李斯特菌）上，它们用“彗星尾巴”推进。我们认为这些意见的推进的影响。通过计算各种附着体模型的运动，并与实验结果进行比较，我们证明了附着体必须是滑动的而不是铰接的。通过对ActA涂层球体的建模实验，我们得出了关于F-肌动蛋白和它们的表面之间的相互作用的结论，这些结论也可能适用于生命系统。

变形细胞迁移过程中牵引力的分布及与形态变化相关的细胞内标志物

Distribution of Traction Forces and Intracellular Markers Associated with Shape Changes During Amoeboid Cell Migration

在迁移过程中，变形虫细胞执行准周期性重复事件的周期（运动周期）。单元长度和与衬底交换的应变能以平均频率f随时间振荡，在平均频率f之上施加较小的随机波动。细胞形状的相当大一部分变化是由于周期性重复事件引起的，这一事实使得能够使用条件统计方法来分析涉及细胞运动性的生化过程网络。利用这种循环性质，我们应用主成分分析（PCa）和相平均统计来分析形状变化的主导模式及其与分子马达的活性和定位的关联。我们分析了延时测量的细胞形状，牵引力和荧光从绿色荧光蛋白（GfP）报告的f-肌动蛋白在Dictyosteoblastoma细胞进行引导趋化迁移。以野生型细胞（WT）为参照，通过研究肌球蛋白II重链缺失突变细胞（mhcA-）和肌球蛋白II必需轻链缺失细胞（mlcE-），我们研究了肌球蛋白II的收缩和肌动蛋白交联功能。

Spontaneous transitions between amoeboid and keratocyte-like modes of migration

The motility of adherent eukaryotic cells is driven by the dynamics of the actin cytoskeleton. Despite the common force-generating actin machinery, different cell types often show diverse modes of locomotion that differ in their shape dynamics, speed, and persistence of motion. Recently, experiments in Dictyostelium discoideum have revealed that different motility modes can be induced in this model organism, depending on genetic modifications, developmental conditions, and synthetic changes of intracellular signaling. Here, we report experimental evidence that in a mutated D. discoideum cell l…

Excitable solitons: Annihilation, crossover, and nucleation of pulses in mass-conserving activator-inhibitor media

Excitable pulses are among the most widespread dynamical patterns that occur in many different systems, ranging from biological cells to chemical reactions and ecological populations. Traditionally, the mutual annihilation of two colliding pulses is regarded as their prototypical signature. Here we show that colliding excitable pulses may exhibit soliton-like crossover and pulse nucleation if the system obeys a mass conservation constraint. In contrast to previous observations in systems without mass conservation, these alternative collision scenarios are robustly observed over a wide range of…

Stick-Slip model for actin-driven cell protrusions, cell polarisation and crawling

Cell crawling requires the generation of intracellular forces by the cytoskeleton and their transmission to an extracellular substrate through specific adhesion molecules. Crawling cells show many features of excitable systems, such as spontaneous symmetry breaking and crawling in the absence of external cues, and periodic and propagating waves of activity. Mechanical instabilities in the active cytoskeleton network and feedback loops in the biochemical network of activators and repressors of cytoskeleton dynamics have been invoked to explain these dynamical features. Here, we show that the in…