The use of bioluminescent Caenorhabditis elegans as multicellular eukaryotic biosensors

Whole cell biosensors offer a powerful approach to environmental monitoring and toxicity testing, as they measure bioavailability of toxins and biological effects rather than total concentrations obtained by traditional analytical techniques. C. elegans is an excellent candidate for a biosensor that represents multicellular eukaryotes. We have constructed a strain of bioluminescent C. elegans with the firefly luciferase luc gene under the control of let-858 constitutive promoter. The transgenic nematodes luminesce after addition of the luciferin substrate and the amount of light emitted reflects the levels of intracellular ATP, providing a rapid, real-time indication of metabolic status. Conditions that affect their metabolism can be detected by a change in luminescence. Light reduction was observed in response to representative environmental insults such as increasing temperature, or concentrations of copper, lead and 3,5-DCP. This was due to a combination of increased mortality coupled with a decreased metabolic activity in the surviving animals. The luminescence assays are carried out in vivo and are rapid, sensitive and an easily quantifiable method for assessing toxicity. The assays lend themselves well to rapid screening and we are currently adapting them to a 96 well microplate format. Other potential applications of the technology developed here include development and screening of novel nematocide drugs and as a tool to study ageing.