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

TL;DR

This study investigates the superdiffusive movement of dense core vesicles in C. elegans neurons, revealing consistent superdiffusive behavior across strains and proposing a heterogeneous random walk model to explain the observed transport dynamics.

Contribution

We introduce a simple heterogeneous random walk model that captures the superdiffusive retrograde transport behavior of DCVs in C. elegans neurons.

Findings

DCVs exhibit superdiffusive movement with displacement variance proportional to t^2.

The displacement distribution fits a beta-binomial distribution.

The proposed model explains the superdiffusive retrograde transport behavior.

Abstract

Transport of dense core vesicles (DCVs) in neurons is crucial for distributing molecules like neuropeptides and growth factors. We studied the experimental trajectories of dynein-driven directed movement of DCVs in the ALA neuron C. elegans over a duration of up to 6 seconds. We analysed the DCV movement in three strains of C. elegans: 1) with normal kinesin-1 function, 2) with reduced function in kinesin light chain 2 (KLC-2), and 3) a null mutation in kinesin light chain 1 (KLC-1). We find that DCVs move superdiffusively with displacement variance $var(x) \sim t^2$ in all three strains with low reversal rates and frequent immobilization of DCVs. The distribution of DCV displacements fits a beta-binomial distribution with the mean and the variance following linear and quadratic growth patterns, respectively. We propose a simple heterogeneous random walk model to explain the observed superdiffusive retrograde transport behaviour of DCV movement. This model involves a random probability with the beta density for a DCV to resume its movement or remain in the same position.