Figure 2

Writhing behavior induced by UVC(M) requires generation of endogenous ROS. (A) Ubiquitous expression of antioxidant enzymes in transgenic larvae suppresses the behavioral response induced by medium intensity UVC(M). Superoxide dismutase(hSod1) had no effect on the response(n = 5, 14, 11, 10, 8, 6, 6 and 6, respectively). ***p < 0.0001, one-way ANOVA with Tukey’s post comparison test, daGAL4/UAS vs UAS/+ . (B) Tissue-specific expression of catalase enzyme to degrade endogenous H₂O₂ efficiently suppressed UVC(M)-induced writhing behavior only when expressed in or near the epidermis (NP6202, GawB 227 and BG487 GAL4 lines)(n = 10, 8, 7, 8, 8, 6, 8, 6, 7, 9 and 7, respectively). ***p < 0.0001, one-way ANOVA with Tukey’s post comparison test, GAL4/Cat vs GAL4/+ . (C) Transient ubiquitous expression of catalase in tubPGAL80ts/UAS-Cat; daGAL4/+ larvae is sufficient to suppress UVC(M)-induced writhing behavior(n = 6 for all). ***p < 0.0001, one-way ANOVA with Tukey’s post comparison test, noHS vs HS. (D) Neuron-specific expression of antioxidant enzymes in mdIV neurons using ppk1GAL4 driver caused moderate suppression of writhing behavior in response to UVC(M). (n = 6, 4, 14, 5, 9, 4 and 6 respectively) (E) Writhing responses to UVC(H) could not be overcome by ubiquitous(daGAL4) or mdIV neuron-specific(ppk1GAL4) expression of antioxidants. (F) Overexpression of antioxidant enzymes had no effect on thermal nociceptive rolling response(n = 8, 6, 6 and 7, respectively). *p < 0.05, ***p < 0.001 from student t-test. For thermal nociception assays, data are presented as percentage of the total with each N value representing one individual larva tested. Data are presented as mean±SEM. For UVR-induced writhing behavior, each N value represents results from one experimental trial using 5 larvae exposed to UVR and visually scoring the percentage responding.