Detecting origins of subdiffusion: P-variation test for confined systems

Area of Science:

• Statistical Physics
• Biophysics
• Computational Biology

Background:

• Single molecule subdiffusion is crucial for understanding cellular processes.
• Distinguishing between diffusion mechanisms (e.g., continuous-time random walk vs. fractional Brownian motion) in confined biological systems is challenging.
• Existing methods may not be suitable for complex environments with binding potentials and reflecting boundaries.

Purpose of the Study:

• To develop and validate a method for distinguishing between different subdiffusion mechanisms in confined systems.
• To apply this method to experimental data of mRNA molecule motion within E. coli.
• To determine the predominant diffusion mechanism governing mRNA transport in bacteria.

Main Methods:

• Adaptation of the p-variation method for analyzing subdiffusion in confined spaces.
• Development of a statistical test to differentiate between heavy-tailed continuous-time random walk and fractional Brownian motion.
• Application of the test to experimental single-molecule tracking data of mRNA molecules in E. coli.

Main Results:

• The p-variation method is effective for analyzing subdiffusion in confined biological systems.
• The proposed test successfully distinguishes between different random walk models.
• Analysis of mRNA motion in E. coli indicates a higher likelihood of fractional Brownian motion.

Conclusions:

• Fractional Brownian motion is a more probable mechanism for mRNA molecule transport within E. coli compared to heavy-tailed continuous-time random walk.
• The p-variation method provides a powerful tool for elucidating molecular transport mechanisms in cellular environments.
• This research offers insights into the biophysical processes governing gene expression regulation in bacteria.