title: Biophotons Contribute to Retinal Dark Noise.
abstract: The discovery of dark noise in retinal photoreceptors resulted in a long-lasting controversy over its origin and the underlying mechanisms. Here, we used a novel ultra-weak biophoton imaging system (UBIS) to detect biophotonic activity (emission) under dark conditions in rat and bullfrog (Rana catesbeiana) retinas in vitro. We found a significant temperature-dependent increase in biophotonic activity that was completely blocked either by removing intracellular and extracellular Ca(2+) together or inhibiting phosphodiesterase 6. These findings suggest that the photon-like component of discrete dark noise may not be caused by a direct contribution of the thermal activation of rhodopsin, but rather by an indirect thermal induction of biophotonic activity, which then activates the retinal chromophore of rhodopsin. Therefore, this study suggests a possible solution regarding the thermal activation energy barrier for discrete dark noise, which has been debated for almost half a century.
authors.affiliation: Wuhan Institute for Neuroscience and Neuroengineering, South Central University for Nationalities, Wuhan, 430074, China.|Department of Neurobiology, College of Life Sciences, South Central University for Nationalities, Wuhan, 430074, China.
authors.forename: Zehua
authors.initials: Z
authors.lastname: Li
authors.affiliation: Wuhan Institute for Neuroscience and Neuroengineering, South Central University for Nationalities, Wuhan, 430074, China. jdai@mail.scuec.edu.cn.|Department of Neurobiology, College of Life Sciences, South Central University for Nationalities, Wuhan, 430074, China. jdai@mail.scuec.edu.cn.
authors.forename: Jiapei
authors.initials: J
authors.lastname: Dai
mesh_terms: D000818:Animals; D001001:Anura; D005075:Biological Evolution; D002118:Calcium / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D003624:Darkness; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D008954:Models, Biological; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D017785:Photons; D051381:Rats; D017208:Rats, Wistar; D012160:Retina / Q000187:drug effects / Q000502:physiology*; D013696:Temperature; D013997:Time Factors
chemical_list: D004791:Enzyme Inhibitors; D010727:Phosphoric Diester Hydrolases; D006152:Cyclic GMP; D002118:Calcium
keywords: Biophoton; Biophoton imaging; Ca2+; Phosphodiesterase 6; Rat and bullfrog retinas; Retinal dark noise