Figure 5.

Impairing the targeting of G_qα to the signaling membrane by mutations is a specific effect. The average peak amplitude of the LIC of various mutants is plotted against the relative orange light intensity in a paradigm identical to that in Figure 4. A–C, The insets are sample responses to the highest light intensity of the presented R-log-I curves. The null trpl (trpl³⁰²) mutant (A), the hypomorph Arr2 (arr2³) mutant (B), and a mutant rhodopsin having Rh1 without the phosphorylation sites at the C terminus (Rh1^Δ356; C) had no significant effects on long-term adaptation. D, There is no significant reduction in the photopigment level between light-raised and dark-raised WT flies. The photopigment level was measured by eliciting the M-potential, which is a linear electrical manifestation of the photopigment level in the fly eye. Flies <2 d old were illuminated with maximal intensity blue (BG28; Schott broad-band blue filter) for 20 s and after 10 s in the dark a maximal intensity white flash (arrow; stroboscopic photographic flash lamp of 70 Joules) elicited the M-potential (left traces). The histogram compares the average amplitude of the M-potential in dark-raised (left column) and light-raised (right column) flies. No significant difference between the averaged M-potential amplitudes under the two adaptation conditions was observed (t test, p > 0.05).