Fig. 1. Time-course of G_q translocation from the rhabdomere to the cell body. (A) 1-µm-thick retinal cross-sections of wild-type flies that were dark-raised (0 minutes) or light exposed for 5 minutes or 60 minutes. Sections were stained with anti-G_q antibodies. In dark-raised flies, G_q displays complete rhabdomeric localization. Dark-raised flies exhibited G_q immunoreactivity that was non-uniform across any one rhabdomere, displaying areas of higher concentration that appear to be randomly localized. By contrast, after 5 minutes of illumination, G_q was progressively concentrated towards the base of the rhabdomere (arrowheads). After 60 minutes, we often observed localization of G_q at the plasma membrane of the cell body. (B) A 1-µm-thick retinal cross-section of a single wild-type Drosophila ommatidium stained with phalloidin conjugated to rhodamine. The rhabdomere and cell body of a single photoreceptor cell are indicated by the letters R and C, respectively. For further clarification, the cell body is outlined. (C) Quantitation of G_q in the rhabdomeres from cross-sections of dark-raised wild-type flies, exposed to light for 5 minutes, 10 minutes, 20 minutes or 60 minutes. Images used were taken at the same exposure time as dark-raised samples. Values are expressed as a percentage of G_q signal measured in the rhabdomeres of dark-raised flies, in which G_q protein is exclusively localized to the rhabdomeres. After 5 minutes of illumination at 50.7x10³ lumens meter^-2, 54.4±0.63% of G_q translocates out of the rhabdomere; no additional G_q appears to be translocated out of the rhabdomere with longer light exposures. SEMs are indicated.