Chemotactic Behavior of Caenorhabditis elegans in Different Chemical Gradients

Abstract

The nematode Caenorhabditis elegans (C. elegans) has been extensively used as a model organism for studying various behavioral aspects in small organisms. Chemotaxis has, by far, been one of the most important studies to help us understand the fundamental search and avoid behavior of C. elegans. A typical chemotaxis assay involves the use of anesthetics to paralyze the worms near the center of a chemoattractant gradient that enables us to keep track of the number of worms approaching the chemical species. In this work, we investigate the behavior of C. elegans in absence of any anesthetic during chemotaxis. The slope of the gradient was controlled by varying the salt concentration at the peak location. Our results indicate that both slope of the gradient and the absolute concentration have a significant impact on the chemotaxis behavior of C. elegans. In all the experiments C. elegans circled the peak several times before leaving the gradient. However, for steeper gradients, the diameter of the circular path was smaller compared to that for flatter gradients. As the concentration of the salt at peak location was increased, the nematodes accumulated farther away from the center showing a strong preference to a specific local concentration. Interestingly, the absolute value of the concentration at those locations was in excellent agreement with the concentration of the corresponding ions found to be generated during the metabolic growth of bacteria.

Keywords: C. elegans, locomotion, chemotaxis, surface stiffness, optimal salt concentration, memory

Cite this Article: Lipika Parida, Venkat Padmanabhan. Chemotactic Behavior of Caenorhabditis elegans in Different Chemical Gradients. International Journal of Animal Biotechnology and Applications. 2019; 5(1 & 2): 25–37p.