Intermittent subdiffusion of short nuclear actin rods due to interactions with chromatin

Area of Science:

• Cell Biology
• Biophysics
• Soft Matter Physics

Background:

• The nucleoplasm, the cell nucleus's interior, is a complex, crowded environment.
• Chromatin, DNA polymers decorated with proteins, fills the nucleoplasm, influencing its properties.
• Non-equilibrium processes like DNA repair contribute to anomalous transport phenomena.

Purpose of the Study:

• To investigate transport phenomena within the nucleoplasm.
• To characterize the diffusive motion of particles in the nuclear environment.
• To understand how chromatin affects intracellular transport.

Main Methods:

• Single-particle tracking of nuclear actin rods.
• Analysis of particle trajectories to determine diffusion characteristics.
• Application of osmotic stress to probe the nucleoplasm's response.

Main Results:

• Nuclear actin rods display intermittent, antipersistent subdiffusion.
• Motion exhibits characteristics of fractional Brownian motion.
• Diffusive motion is heterogeneous, with particles switching between mobilities, likely due to chromatin interactions.
• Osmotic stress alters actin rod motion, with hyperosmotic stress stalling movement and hypo-osmotic conditions inducing reptation-like motion.

Conclusions:

• Nucleoplasmic transport is heterogeneous and anomalous, not simple diffusion.
• Transient associations with chromatin significantly impact particle mobility.
• Understanding these transport dynamics is crucial for nucleoplasmic organization and nuclear mechanobiology.