Collective dynamics of active filament complexes

TL;DR

This study explores how complex-shaped active biofilament objects interact and move collectively, revealing new dynamic behaviors like a 'moving smectic' band, advancing understanding of cellular structure formation.

Contribution

It introduces a model of active objects composed of two filaments, extending previous rod-like filament studies to complex shapes, and uncovers novel collective behaviors.

Findings

Identification of various collective dynamics depending on shape parameters.

First description of the 'moving smectic' density band.

Analysis of interactions leading to complex collective motion.

Abstract

Networks of biofilaments are essential for the formation of cellular structures that support various biological functions. For the most part, previous studies have investigated the collective dynamics of rod-like biofilaments; however, the shapes of the actual subcellular components are often more elaborate. In this study, we considered an active object composed of two active filaments, which represents the progression from rod-like biofilaments to complex-shaped biofilaments. Specifically, we numerically assessed the collective behaviors of these active objects in two dimensions and observed several types of dynamics depending on the density and the angle of the two filaments as shape parameters of the object. Among the observed collective dynamics, a moving density band that we named a `moving smectic' is introduced here for the first time. By analyzing the trajectories of individual objects and the interactions among them, this study demonstrated how interactions among active biofilaments with complex shapes could produce collective dynamics in a non-trivial manner.