| Author Title Journal |
Shettigar N, Chakravarthy A, Umashankar S, Lakshmanan V, Palakodeti D, Gulyani A (2021) Discovery of a body-wide photosensory array that matures in an adult-like animal and mediates eye-brain-independent movement and arousal. Proceedings of the National Academy of Sciences of the United States of America, Vol 118(20): 2021426118 [doi: 10.1073/pnas.2021426118 goto] |
Abstract / Notes
"The ability to respond to light has profoundly shaped life. Animals with eyes overwhelmingly rely on their visual circuits for mediating light-induced coordinated movements. Building on previously reported behaviors, we report the discovery of an organized, eyeindependent (extraocular), body-wide photosensory framework that allows even a head-removed animal to move like an intact animal. Despite possessing sensitive cerebral eyes and a centralized brain that controls most behaviors, head-removed planarians show acute, coordinated ultraviolet-A (UV-A) aversive phototaxis. We find this eye-brain-independent phototaxis is mediated by two noncanonical rhabdomeric opsins, the first known function for this newly classified opsin-clade. We uncover a unique array of dualopsin-expressing photoreceptor cells that line the periphery of animal body, are proximal to a body-wide nerve net, and mediate UVA phototaxis by engaging multiple modes of locomotion. Unlike embryonically developing cerebral eyes that are functional when animals hatch, the body-wide photosensory array matures postembryonically in "adult-like animals." Notably, apart from headremoved phototaxis, the body-wide, extraocular sensory organization also impacts physiology of intact animals. Low-dose UV-A, but not visible light (ocular-stimulus), is able to arouse intact worms that have naturally cycled to an inactive/rest-like state. This wavelength selective, low-light arousal of resting animals is noncanonical-opsin dependent but eye independent. Our discovery of an autonomous, multifunctional, late-maturing, organized body-wide photosensory system establishes a paradigm in sensory biology and evolution of light sensing."| Home page -- (Main hierarchy) |