Worm Breeder's Gazette 16(3): 15 (June 1, 2000)

These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.

A Feeding Assay

Robert J. Allan, Don Jones, E. Peter M. Candido

Department of Molecular Biology and Biochemistry, University of British Columbia, Vancouver, BC, Canada

We are interested in how the feeding behaviour of C. elegans changes when stressors are encountered in the environment. Previously1, this was assessed by observing decreases in the optical density of a suspension of worms and bacteria as the latter were consumed. Acting on a suggestion from the Adamson lab in the Department of Zoology at the University of BC, a protocol for directly observing feeding was developed. Such an assay should be able to distinguish between a mere slowing down of feeding and actual cessation.

Briefly, worms are washed, suspended in buffer (K or M9) and placed in the wells of a tissue culture plate. The suspected toxicants are added and then the worms are fed a small quantity of fluorescent latex beads2. The spheres come in a variety of sizes. A diameter of 1 µm was chosen to be comparable in size to bacteria and the worms consume these readily. After incubation the beads can be easily seen by both light and fluorescent microscopy and are particularly striking in the latter. A spectrum of colours, both fluorescent and not, is available. Ingestion of the beads does not adversely affect the health of the worms (a difficulty encountered when using other particles, such as acrylic paint) and the passage of the beads through the entire intestinal tract can be followed. This could make the assay useful, not only for examining feeding, but also for studies of the gut and of defecation.

1 Jones D, Candido EPM (1999) Feeding is inhibited by sublethal concentrations of toxicants and by heat stress in the nematode Caenorhabditis elegans: Relationship to the cellular stress response. Journal of Experimental Zoology 284: 147-157.

2 Fluoresbrite Microspheres from Polysciences, Inc. <http://www.polysciences.com/>