Chemotaxis Assay for Nematode Attraction

Chemotaxis plates were prepared similarly to the magnetotaxis plates, with a strong odorant replacing the neodymium magnets. To attract the worms, 1 µl of 0.5% aqueous diacetyl solution (Acros Organics #107650050; T - taxis) was added to one circle and 1 µl of ddH₂O to the other circle (C - control). The excess M9 buffer was carefully removed with a small piece of filter paper to allow the worms to crawl on the agar surface. The plates were placed in styrofoam boxes to ensure a constant temperature and darkness and left for 30 min until counting. After allowing the animals to migrate for 30 min, the paralyzed worms were counted manually by a blinded experimenter as in the magnetotaxis assays.