DISSOCIATION OF PHOTORECEPTORS FROM WHOLE HEADS OF THE FRUIT-FLY, DROSOPHILA-MELANOGASTER

Photoreceptor cells that were mostly free of extracellular material an d suitable for most electrophysiological study procedures were dissoci ated from whole heads of the fruit fly, Drosophila melanogaster, by a simple ''smash'' technique employing gentle chopping by a razor blade through Parafilm sheets. A variety of commonly available proteolytic a nd glycolytic digestion enzymes were tested as additions to the basic dissociation procedure described. With the aid of Nomarski interferenc e contrast optics, periodic acid-Schiff staining, and fluorescent labe ling and microscopy methods, it was determined that proteolytic enzyma tic digestion does little to enhance the dissociation procedure, and i nstead, often damages the cells that one is attempting to recover. Une xpectedly, certain glycolytic enzymes, when added to the basic procedu re, appear to enhance the recovery of intact viable Drosophila photore ceptors that are stripped of most extracellular material. Based on the se results, a hypothesis concerning the biochemical nature of the extr acellular matrix of the Drosophila retina is proposed. Drosophila phot oreceptors are an interesting model system for the study of invertebra te phototransduction and photoreceptor cell biology because of their m any well-characterized mutant strains. The technique described here sh ould produce clean viable photoreceptors or ommatidia that respond to light, and that are suitable for patch clamping or cell culture.