Active gels, heavy tails, and the cytoskeleton

Area of Science:

• Cell biology
• Soft matter physics
• Biophysics

Background:

• The eukaryotic cytoskeleton acts as an active material, with molecular motors driving embedded objects.
• Observed anomalous diffusion in cells shows non-Gaussian displacement distributions with heavy tails, often attributed to 'cytoquakes'.

Purpose of the Study:

• To investigate if a simple continuum active gel model can explain the heavy power-law tails in cytoskeletal displacements.
• To explore the influence of geometry and dimensionality on these displacement patterns.

Main Methods:

• Utilizing simulations and analytical theory.
• Modeling the cytoskeleton as a continuum active gel driven by fluctuating force dipoles.

Main Results:

• The active gel model naturally generates heavy power-law tails in cytoskeletal displacements.
• The power-law exponent demonstrates dependence on the geometry and dimensionality of force dipole distribution.
• Qualitatively different results were observed for 3D cytoskeletons versus quasi-2D cortices.

Conclusions:

• A simple active gel model driven by fluctuating force dipoles can explain heavy power-law tails in cytoskeletal displacements.
• The model provides a framework for understanding anomalous diffusion in active cellular environments.
• Potential applications exist for both biological systems and synthetic active gels.