Research Paper Volume 15, Issue 2 pp 396—420

Figure 3. Activation of visual neurons is necessary and sufficient to mediate the dark lifespan extension. (A, B) Flies carrying two copies of the GMR:hid transgene, which lack light perception, failed to exhibit an extended lifespan in constant darkness (A) males (LD n = 213, DD n = 223; P = 0.288) and (B) females (LD n = 222, DD n = 217; P = 0.006). The next 4 panels were conducted in an environment meant to mimic light perception in a standard 24-hour day. Flies carrying a copy of a temperature sensitive cation channel (UAS-TrpA1) were used to obtain neuronal activation when at 29°C, and the Gal4 lines were used as background controls. Flies were aged in constant darkness with temperature oscillating 12 hr: 12 hr, 18°C: 29°C. (C, D) When aged in constant darkness, activation of GMR-expressing neurons had no effect in male flies (C) (GMR-Gal4 x w¹¹¹⁸ n = 200, GMR-Gal4 x UAS-TrpA1 n = 198; P = 0.388) but was sufficient to shorten lifespan in females (D) (GMR-Gal4 x w¹¹¹⁸ n = 189, GMR-Gal4 x UAS-TrpA1 n = 202; P < 0.0001). (E, F) Similarly, spatiotemporal activation of blue light photoreceptor Rh1 neurons was sufficient to cause a significantly shorter lifespan. This was observed in both male (E) (Rh1-Gal4 x w¹¹¹⁸ n = 202, Rh1-Gal4 x UAS-TrpA1 n = 203; P < 0.0001), and female flies (Rh1-Gal4 x w¹¹¹⁸ n = 200, Rh1-Gal4 x UAS-TrpA1 n = 200; P = 0.0002).