Effects of LED Irradiation on the Locomotive Activity of Wild-type Fly and ASD Model Fly

Many studies on the effects of LED on living organisms have been performed recently thanks to the ease and precision with which the power and wavelength of the LED can be regulated. To investigate the effects of LED irradiation on Drosophila activity, we monitored the locomotive activity of Drosophila for six days continuously. The data showed that wild-type flies behave similarly under fluorescent light, incandescent bulb, and white LED irradiation, which is equivalent to the intensity of an incandescent bulb. We next investigated the effects of red, blue, and yellow-green LED irradiation under same intensity as white LED on the locomotive activity of a wild-type fly and a Drosophila model of autism spectrum disorder (ASD). The results showed that the amount of locomotive activity in the wild-type flies with red LED irradiation was significantly in creased throughout the day (excluding morning peaks) while that with blue LED irradiation was decreased in evening peaks and at nighttime. Yellow-green LED irradiation increased the locomotive activity during the midday siesta but decreased the activity of the morning and evening peaks. It is known that the rugose ( rg ) mutant, the Drosophila homolog of human Neurobeachin , shows locomotive hyperactivity. In our study, the red LED irradiation did not affect the locomotive activity of the rg mutant at all. Taken together with the effects of red LED irradiation to the wild-type, it seems that red LED irradiation enhances the neural circuit to positively regulate the locomotive activity, and rg functions in the neuronal cells by negatively regulating the neural circuit enhanced by red LED irradiation. Thus, the neuronal cells expressing the rg gene appear to play an important role for the regulation of activity during the midday siesta and while sleeping at night. In contrast, irradiation with yellow-green and blue LED to the rg mutant had similar effects to those of the wild-type. This demonstrates that irradiation with yellow-green and blue LED negatively regulates the locomotive activity through the neural circuit not related to rg , or downstream of the neural circuit actively regulated by red LED irradiation.