Figure 2.

GMRGal4 ERG phenotypes. Response intensity (V/log I) functions measured from ERG (plateau at end of 1-s stimuli). ERGs from flies with one copy of GMRw (A) or GMR (B) were significantly reduced in amplitude across all intensities compared with respective eye color–matched wild-type controls (mean ± SEM, n = 10–17 flies; p < 0.0001; two-tailed t tests). A, GMRw/+ (F1 of Sp/Cy;GMRw × w¹¹¹⁸ compared with w¹¹¹⁸). Data from Sp/Cy;GMRw/GMRw parent also plotted. Representative traces on right (at intensities marked by arrows in B). B, F1 of w⁺;GMR × wild-type (red-eyed) cross compared with red-eyed wild-type (w+) and GMR/GMR homozygote, n = 10–14 flies. C, In contrast, ERGs of GMR/+;IP₃R-RNAi (one copy, n = 16, or two copies, n = 19) were similar to a control GMR/+ (control RNAi; n = 10, dotted line). Flies were F1 of GMRGal4;IP₃R-RNAi/TM6 × UAS-IP₃R-RNAi or UAS-fwd-RNAi (control RNAi line chosen because it has similar eye color, but no effect on photoreceptor physiology). However, all GMR/+ genotypes were less sensitive (p < 0.0001) than the IP₃R-RNAi parent stock (n = 7). Maximum intensity (10°) equivalent to ∼10⁷ effectively absorbed photons per photoreceptor in wild-type (w¹¹¹⁸).