Long-term activity drives dendritic branch elaboration of a C. elegans sensory neuron

Abstract

Neuronal activity often leads to alterations in gene expression and cellular architecture. The nematode Caenorhabditis elegans, owing to its compact translucent nervous system, is a powerful system in which to study conserved aspects of the development and plasticity of neuronal morphology. Here we focus on one sensory neuron in the worm, termed URX, which senses oxygen and signals tonically proportional to environmental oxygen. Previous studies have reported that URX has variable branched endings at its dendritic sensory tip. By controlling oxygen levels and analyzing mutants, we found that these branched endings grow over time as a consequence of neuronal activity. Furthermore, we observed that the branches contain microtubules, but do not appear to harbor the guanylyl cyclase GCY-35, a central component of the oxygen sensory transduction pathway. Interestingly, we found that although URX dendritic tips grow branches in response to long-term activity, the degree of branch elaboration does not correlate with oxygen sensitivity at the cellular or the behavioral level. Given the strengths of C. elegans as a model organism, URX may serve as a potent system for uncovering genes and mechanisms involved in activity-dependent morphological changes in neurons.