Studying Membrane Protein Trafficking in Drosophila Photoreceptor Cells

Take a dark-adapted, anesthetized, transgenic, white-eyed fly.

The fly expresses eGFP-tagged TRPL ion channels in the photoreceptors of the eye.

In darkness, TRPL localizes to the membranes of the rhabdomeres— the microvilli of the photoreceptors. 

Using compressed air, push the fly headfirst into a pipette tip.

Trim the tip and push the fly backward.

Trim it again and push the fly forward until only its head protrudes.

Immobilize the tip in modeling clay adhered to a slide and place it on a fluorescence microscope stage, with the eye facing the microscope objective radially. 

Add a drop of water to the objective, then lower it until it touches the eye.

Capture images of the photoreceptors.

Measure the fluorescence intensities in the rhabdomeres, cell body, and background.

Illuminate the fly with orange light to induce TRPL translocation to the cell body.

Repeat the imaging and fluorescence measurements.

Compare the images to observe reduced rhabdomeral fluorescence post-illumination, indicating TRPL translocation to the cell body.