Drosophila Y-maze Assay: A Method to Assess Olfactory Responses in Flies

- A Y-maze consists of a Y-shaped connector with three fly vials connected to it by straight or tapered tubes. Flies move through the maze toward the side with the stimulus that they prefer. To start the experiment, place a tissue paper with the solution containing the volatile chemicals into each vial. Then, connect them to the tapered tubes. The tapered tubes limit the ability of the flies to return to the center of the maze and slows the diffusion of the volatile chemicals.

Next, chill starved flies to slow them down. Do not use chemical anesthesia, as this may affect the outcome of the assay. Quickly connect the vial with the chilled flies to the final side of the maze. Leave the flies to explore the maze. To reduce any preference caused by bright light, carry out this step under far-red light, which flies do not see. Finally, count the flies on each side of the maze. Their location in the maze indicates their preference toward that volatile chemical scent.

In the example protocol, we will see a setup of the Y-maze assay with wild type Drosophila.

- Before conducting the assay the following morning, at the end of the day, transfer cohorts of 10 to 20 experimental lines to glass