Heterogeneous model for superdiffusive movement of dense core vesicles in C. elegans

Area of Science:

• Neuroscience
• Cell Biology
• Biophysics

Background:

• Intracellular transport of dense core vesicles (DCVs) is essential for neuronal function, involving the distribution of neuropeptides and growth factors.
• Dynein-mediated retrograde transport of DCVs is a critical process that has been investigated in model organisms.

Purpose of the Study:

• To analyze the superdiffusive movement of DCVs in C. elegans ALA neurons under different kinesin functional states.
• To develop and validate a mathematical model explaining the observed DCV transport dynamics.

Main Methods:

• Experimental tracking of DCV trajectories in Caenorhabditis elegans (C. elegans) ALA neurons over 6 seconds.
• Analysis of DCV movement in wild-type, kinesin light chain 2 (KLC-2) reduced function, and kinesin light chain 1 (KLC-1) null mutant strains.
• Statistical analysis of displacement distributions and first passage times, fitting to beta-binomial and beta-negative binomial distributions.

Main Results:

• DCVs displayed superdiffusive movement across all tested C. elegans strains, with low reversal rates and frequent immobilization.
• DCV displacement distributions were accurately described by a beta-binomial distribution.
• The proposed heterogeneous random walk model successfully explained the superdiffusive retrograde transport and predicted first passage time distributions.

Conclusions:

• The study elucidates the complex superdiffusive nature of DCV transport in neurons.
• A novel random walk model provides a mechanistic explanation for DCV movement patterns, incorporating probabilistic transitions between movement and immobilization.
• Experimental validation confirms the model's predictive power for DCV transport dynamics.