Self-organized pattern formation in motor-microtubule mixtures

Area of Science:

• Biophysics
• Soft Matter Physics
• Non-equilibrium Thermodynamics

Background:

• Mixtures of molecular motors and microtubules exhibit complex self-organized patterns in nonequilibrium steady states.
• Experimental studies have observed various configurations like asters, vortices, and disordered states in quasi-two-dimensional systems.

Purpose of the Study:

• To model and understand the formation of stable self-organized patterns in molecular motor-microtubule systems.
• To investigate the influence of confinement and motor density on pattern transitions and stability.

Main Methods:

• Development of a two-dimensional vector field model for microtubule orientation.
• Inclusion of two scalar density fields for molecular motors (bound and free).
• Simulation of pattern transitions and analysis of steady-state motor distributions.

Main Results:

• Model reproduces experimental observations of aster, vortex, and disordered patterns.
• Confinement and parameter variations induce transitions between different states (aster, spiral, vortex).
• A phase map of nonequilibrium steady states is presented, detailing aster, vortex, and mixed configurations.

Conclusions:

• The model provides insights into the stability of various patterns based on motor density and confinement effects.
• Crowding effects are identified as crucial for stabilizing single aster configurations.
• Results offer implications for the design and interpretation of related biological experiments.