title: Cone-like rectification properties of cGMP-gated channels in transmutated retinal photoreceptors of nocturnal geckoes.
abstract: Photoreceptors of nocturnal geckoes are scotopic, with rod-shaped outer segments, and sensitivities to light similar to the one of retinal rods from other species of lower vertebrates. However, these cells are not rods, but they originated from cones of ancestral diurnal geckoes with pure-cone retinas, after being forced to adapt to a nocturnal behavior. Several interesting adaptations of these rod-like cones have been studied to date; molecular biology and functional studies confirmed that several proteins of the phototransductive cascade display structural and functional properties that indicate their origin from cones rather than from rods. In this paper, we investigate, with whole cell voltage clamp in the photoreceptor detached outer segment preparation, the voltage rectification properties of cGMP-gated channels in three species, Gekko gecko, Tarentola mauritanica, and Hemidactylus frenatus. We show that the current-voltage properties in the physiological voltage range are reminiscent of the ones of cGMP-gated channels from cones rather than from rods of other cold-blooded vertebrates. The origin and the relevance of the mechanisms investigated are discussed.
authors.affiliation: Dipartimento di Scienze Biomediche Metabolismo e Neuroscienze, Università di Modena e Reggio Emilia, via Campi 287, 41125 Modena, Italy.
authors.forename: Vittorio
authors.identifier: 0000-0002-3581-6654
authors.initials: V
authors.lastname: Vellani
authors.affiliation: Dipartimento di Economia Scienze e Diritto, c/o Corso di Laurea in Ingegneria, Università della Repubblica di San Marino, Salita alla Rocca 44, 47890 Città di San Marino, San Marino.
authors.forename: Chiara
authors.initials: C
authors.lastname: Giacomoni
mesh_terms: D000818:Animals; D006152:Cyclic GMP / Q000378:metabolism*; D015640:Ion Channel Gating; D007473:Ion Channels / Q000378:metabolism*; D008027:Light; D008116:Lizards / Q000502:physiology*; D009154:Mutation / Q000235:genetics*; D017949:Retinal Cone Photoreceptor Cells / Q000378:metabolism* / Q000528:radiation effects; D055214:Retinal Photoreceptor Cell Outer Segment / Q000378:metabolism / Q000528:radiation effects; D017948:Retinal Rod Photoreceptor Cells / Q000378:metabolism* / Q000528:radiation effects
chemical_list: D007473:Ion Channels; D006152:Cyclic GMP