马达驱动的平流与拥挤竞争驱动细胞骨架复合物中的时空异质运输
Motor-driven advection competes with crowding to drive spatiotemporally heterogeneous transport in cytoskeleton composites
摘要：
细胞骨架--生物聚合物、分子马达和相关结合蛋白的复合网络--是活性物质的典型例子。粒子通过细胞骨架的运输可以从异常和不均匀的亚扩散到超扩散和平流。然而，概括和理解这些特性-普遍存在于细胞骨架和其他失衡的软物质系统-仍然具有挑战性。在这里，我们结合光片显微镜与微分动态显微镜和单粒子跟踪阐明异常和平流运输肌动球蛋白微管复合物。我们发现，粒子表现出多模式的运输，从显着的次扩散过渡到超扩散在可调的交叉时间尺度。令人惊讶的是，虽然较高的肌动球蛋白含量提高超扩散，它也显着增加了在短时间尺度的亚扩散的程度，并普遍减慢运输。相应的位移分布显示出非高斯性、不对称性和非零模式的独特组合，表明定向平流与笼状扩散和跳跃相结合。在更大的时空尺度上，粒子发生超扩散，通常随着肌动球蛋白含量的增加而增加，与正常的相反，但更快，没有肌动球蛋白的扩散。我们的具体结果揭示了重要的新的光之间的相互作用的非平衡过程，拥挤和异质性活跃的细胞骨架系统。更一般地说，我们的方法是广泛适用于活性物质系统，阐明跨尺度的运输和动力学。
英文摘要：
The cytoskeleton -- a composite network of biopolymers, molecular motors, and associated binding proteins -- is a paradigmatic example of active matter. Particle transport through the cytoskeleton can range from anomalous and heterogeneous subdiffusion to superdiffusion and advection. Yet, recapitulating and understanding these properties -- ubiquitous to the cytoskeleton and other out-of-equilibrium soft matter systems -- remains challenging. Here, we combine light sheet microscopy with differential dynamic microscopy and single-particle tracking to elucidate anomalous and advective transport in actomyosin-microtubule composites. We show that particles exhibit multi-mode transport that transitions from pronounced subdiffusion to superdiffusion at tunable crossover timescales. Surprisingly, while higher actomyosin content enhances superdiffusivity, it also markedly increases the degree of subdiffusion at short timescales and generally slows transport. Corresponding displacement distributions display unique combinations of non-Gaussianity, asymmetry, and non-zero modes, indicative of directed advection coupled with caged diffusion and hopping. At larger spatiotemporal scales, particles undergo superdiffusion which generally increases with actomyosin content, in contrast to normal, yet faster, diffusion without actomyosin. Our specific results shed important new light on the interplay between non-equilibrium processes, crowding and heterogeneity in active cytoskeletal systems. More generally, our approach is broadly applicable to active matter systems to elucidate transport and dynamics across scales.
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