# A simple yet reliable assay for chemotaxis in C. elegans

## TL;DR

This paper introduces a new method to study how C. elegans worms move in response to smells without using harmful chemicals or physical restraints.

## Contribution

The study presents a novel, reliable chemotaxis assay for C. elegans that avoids immobilization and accounts for environmental gradients.

## Key findings

- Unfed worms consistently move toward butanone and benzaldehyde.
- Worms move away from the odorant nonanone.
- The assay controls for locomotion defects and unknown gradients.

## Abstract

Animals can move towards or away from an odorant. Here we develop an assay for the nematode
C. elegans
that avoids use of chemical or physical immobilization when measuring response to odorants. We use opposing orientations of rectangular arenas to control for unknown gradients outside the arena and introduce a measure of dispersal to control for locomotion defects and unknown gradients within the arena, enabling the analysis of responses to a variety of chemicals. Using this setup, we found that unfed worms show reproducible movement towards the odorants butanone and benzaldehyde, and away from the odorant nonanone.