Island Assay: A High-Throughput Method to Evaluate Drosophila Locomotor Behavior

- The island assay consists of a raised white platform in a tray of soapy water, covered by a transparent box with one open side. A camera on top of the box records overhead images of the platform, and lights are placed to ensure even illumination of the area.

To load the flies on the arena, tap a vial against a flat surface to bring all the flies to the bottom. In quick succession, remove the vial plug, turn the vial over, and tap the vial's open end onto the platform to knock all the flies out at the same time. Landing on the platform triggers an escape response. Flies with typical mobility can clear the platform in a few seconds, unlike those with locomotor defects.

Subjects are confined to the box, and those that land on the soapy water quickly submerge because soap decreases water's surface tension. To assess locomotor behavior from different conditions, count the remaining flies on the platform after a set time period.

In this example protocol, we will see a setup of the island assay compatible with semi-automated image analysis.

- First, prepare a minimum of three vials per experimental condition as biological replicates. Each vial should contain approximately 15 flies of th