title: Physiological basis of phototaxis to near-infrared light in Nephotettix cincticeps.
abstract: In a previous study of the phototaxis of green rice leafhoppers, Nephotettix cincticeps (Hemiptera, Cicadellidae), we found positive responses to 735 nm light. Here, we investigated the mechanism underlying this sensitivity to near-infrared light. We first measured the action spectrum using a Y-maze with monochromatic lights from 480 to 740 nm. We thus found that the action spectrum peaks at 520 nm in the tested wavelength range, but that a significant effect is still observed at 740 nm, albeit with a sensitivity 5 log units lower than the peak. Second, we measured the spectral sensitivity of the eye, and found that the sensitivity in the long-wavelength region parallels the behaviorally determined action spectrum. We further identified mRNAs encoding opsins of ultraviolet, blue, and green-absorbing visual pigments, and localized the mRNAs in the ommatidia by in situ hybridization. The electrophysiology, molecular biology and the anatomy of the eye together indicate that the eyes of N. cincticeps do not contain true "red" receptors, but rather that the behavioral response to near-infrared light is mediated by the tail sensitivity of the green receptors in the long-wavelength region of the spectrum.
authors.affiliation: Laboratory of Neuroethology, Sokendai-Hayama (The Graduate University for Advanced Studies), Shonan Village, Hayama, Kanagawa, 240-0193, Japan.
authors.forename: Motohiro
authors.initials: M
authors.lastname: Wakakuwa
authors.forename: Finlay
authors.initials: F
authors.lastname: Stewart
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Matsumoto
authors.forename: Shigeru
authors.initials: S
authors.lastname: Matsunaga
authors.forename: Kentaro
authors.initials: K
authors.lastname: Arikawa
mesh_terms: D000818:Animals; D002080:Butterflies / Q000502:physiology*; D003116:Color; D003118:Color Perception / Q000502:physiology* / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D008297:Male; D018782:Maze Learning / Q000528:radiation effects; D055355:Opsins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D010775:Photic Stimulation / Q000379:methods; D017956:Photoreceptor Cells, Invertebrate / Q000378:metabolism / Q000502:physiology* / Q000528:radiation effects; D012333:RNA, Messenger; D014466:Ultraviolet Rays
chemical_list: D055355:Opsins; D012333:RNA, Messenger