Immunoelectron microscopic study of the opsin distribution in the photoreceptor cells of Drosophila melanogaster.

Distribution of opsin in the compound eye of Drosophila melanogaster was examined by post-embedding immunoelectron microscopy using a monoclonal antibody against the Drosophila Rh1 opsin and gold-conjugated secondary antibody. Numerous gold particles were observed on the rhabdomeric microvilli of R1-R6 retinular cells. In the retinular cell body, gold particles were distributed in rough endoplasmic reticulum, subrhabdomeric cisternae (SRC), multivesicular bodies, and secondary lysosomes. In the rdgA mutant, whose SRC are absent, density of gold particles on the rhabdomeric microvilli was about 20% of normal. These results suggest the involvement of SRC in opsin transport.