Locomotory Rate Assay, C. elegans

Small plates.

Age synchronize animals.

Fresh OP50.

Kimwipes.

Timer.

Video equipment, if needed.

Assay plates were prepared by spreading the E. coli strain OP50-1 in a ring on NGM agar (Brenner 1974) in 5 cm petri plates.

Assay plates were always freshly spread with bacteria, incubated overnight at 37°C, and allowed to cool to room temperature before use.

Plates for measuring locomotory rate in the absence of bacteria were also incubated at 37°C. Only synchronized young adult hermaphrodites (16 h after the late L4 larval stage) were tested.

In all cases, plates were coded so that the experimenter was blind to the genotype.

For well-fed animals, locomotory rate was measured by removing 5 animals from plates with ample bacteria, washing the animals twice in S basal buffer (Brenner 1974), and transferring them to an assay plate in a drop of buffer using a capillary pipette.

The drop of buffer used to transfer the animals was absorbed with a Kimwipe.

Five minutes after transfer, the number of body bends in 20 s intervals was sequentially counted for each of the 5 animals on the assay plate and then repeated the same thing for next set of animals in a different assay plate.

Sawin E. R., Ranganathan R. & Horvitz H. R. C. elegans locomotory rate is modulated by the environment through a dopaminergic pathway and by experience through a serotonergic pathway. Cell press 26: 619-631 (2000).

Brenner S. The genetics of Caenorhabtiditis elegans. Genetics 77: 71-94 (1974).