Luminescent Caenorhabditis elegans: a novel eukaryotic biosensor

Biosensors produce a measurable response when exposed to an environmental signal. The intensity of their response is often correlated to that of the signal, enabling its detection and quantification. Bioluminescent microbial biosensors have been developed and applied to detect xenobiotics in a wide variety of situations. However, since eukaryotic and prokaryotic cells very likely differ in their sensitivity to xenobiotics, we decided to investigate the use of C. elegans as a biosensor. We transformed C. elegans with the luc gene, from the firefly Photinus pyralis , under the control of the let-858 promoter and obtained an integrated line. The luc gene encodes an enzyme, firefly luciferase, which catalyses the oxidation of luciferin in a reaction that consumes ATP and produces light. The light emitted by cells expressing luc is thus a measure of their ATP levels and therefore of their metabolic status. Exposure to toxic compounds will disrupt the general metabolism of the cells and this can be measured as a decrease in bioluminescence. Exposure of luc expressing C. elegans to various concentrations of copper resulted in decreased light output. There was good correlation between the decrease in light and the copper concentration. This demonstrates the use of luminescent C. elegans as a novel and rapid biosensor. Experiments are currently underway to test the effects of several other toxicants on C. elegans bioluminescence. In addition to its usefulness as a biosensor, bioluminescent C. elegans provide us with a very convenient tool for studying the regulation of C. elegans metabolism in vivo .