Multiscale Microtubule Dynamics in Active Nematics

TL;DR

This paper investigates the dynamics of microtubules in active nematics, revealing how isolated bundle extension speeds compare to dense systems, highlighting the complexity of multi-filament interactions.

Contribution

It provides quantitative measurements of microtubule sliding speeds in both isolated and dense active nematics, aiding the development of multiscale models.

Findings

Isolated microtubule pairs extend at speeds comparable to motor stepping.

Dense active nematics show slower, widely distributed sliding speeds.

Filaments exhibit both contractile and extensile motions in dense systems.

Abstract

In microtubule-based active nematics, motor-driven extensile motion of microtubule bundles powers chaotic large-scale dynamics. We quantify the interfilament sliding motion both in isolated bundles and in a dense active nematic. The extension speed of an isolated microtubule pair is comparable to the molecular motor stepping speed. In contrast, the net extension in dense 2D active nematics is significantly slower; the interfilament sliding speeds are widely distributed about the average and the filaments exhibit both contractile and extensile relative motion. These measurements highlight the challenge of connecting the extension rate of isolated bundles to the multi-motor and multi-filament interactions present in a dense 2D active nematic. They also provide quantitative data that is essential for building multiscale models.