Whole-cell patch-clamp analysis of adult Drosophila photoreceptors

Adult Drosophila have a compound eye composed of approximately 750 repeating units, called ommatidia, packed together to form the retina. Each ommatidium is a precise arrangement of 19 cells: eight photoreceptors (primary sensory neurons) and 11 accessory cells. Analysis of visual physiology in Drosophila photoreceptors has been central to understanding a number of important areas of modern biology including the G-protein-coupled receptor cycle, phosphoinositide signaling, and calcium signaling. Analysis of photoreceptor performance and synaptic transmission also can be studied using Drosophila photoreceptors as a model system. Electrophysiological analysis of responses to light is a powerful tool for characterizing and understanding visual transduction in Drosophila photoreceptors. The ommatidia can be dissociated to generate healthy cells under a limited set of conditions. The basolateral plasma membrane of the photoreceptors then becomes accessible to a patch pipette and light responses can be recorded in a whole-cell configuration. This approach has principally been used to study the activity of the light-activated channels in voltage-clamped photoreceptors.