title: Activity of long-wavelength cones under scotopic conditions in the cyprinid fish Danio aequipinnatus.
abstract: In carp (Cyprinus) and goldfish (Carassius), long-wavelength cones are reported to be active under scotopic conditions. Using the electroretinogram (ERG), we tested another cyprinid fish, Danio aequipinnatus, which contains A1-based visual pigments and for which we had previously measured the spectral sensitivities of individual cones. Dark adaptation curves show a rod/cone break at about 45 min. When thoroughly dark-adapted, the spectral sensitivity function is broader than can be accounted for by self-screening of rhodopsin, but it can be modeled by an additive combination of rods and the 560-nm cones. Dim, red background light causes adaptation of rods and a broadening of the spectral sensitivity function, which can be simulated by increasing the proportion of cones in the model. Brighter red backgrounds adapt the 560-nm cones. Because of the effect of red adapting lights, the ERG evidence for the participation of long-wavelength cones close to visual threshold appears to be different in Danio than in the goldfish Carassius.
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven 06520-8103, USA.
authors.forename: P
authors.initials: P
authors.lastname: van Roessel
authors.forename: A G
authors.initials: AG
authors.lastname: Palacios
authors.forename: T H
authors.initials: TH
authors.lastname: Goldsmith
mesh_terms: D000818:Animals; D003530:Cyprinidae / Q000502:physiology*; D003623:Dark Adaptation / Q000502:physiology*; D004596:Electroretinography; D006054:Goldfish / Q000502:physiology; D066298:In Vitro Techniques; D010775:Photic Stimulation; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology*; D017948:Retinal Rod Photoreceptor Cells / Q000502:physiology; D012243:Rhodopsin / Q000502:physiology; D013045:Species Specificity
chemical_list: D012243:Rhodopsin