title: Temporal analysis of electroretinographic responses in fishes with rod-dominated and mixed rod-cone retina.
abstract: Photoreceptor content of fish retinas could be accessed by comparative electroretinographic (ERG) studies using flickering light stimuli that could separate rod-mediated vision where critical flicker frequency (CFF, frequency when the eye loses its ability to resolve individual light pulses) is usually less than 15 Hz from cone-mediated vision. Four fish species inhabiting different photic environments (small-spotted dogfish shark--Scyliorhinus canicula, eel--Anguilla anguilla, painted comber--Serranus scriba, Prussian carp--Carassius gibelio) were investigated. Dogfish shark b-wave amplitudes significantly decreased at low frequency of stimulation and CFF was reached at 3.2 Hz. A similar effect on the b-wave amplitude was observed in the eel, but CFF occurred at around 20 Hz. Conversely, b-waves of painted comber and Prussian carp remained unaltered under intermittent low-frequency stimulation, and CFFs were around 25 and 30 Hz, respectively. Additional support in accessing the receptor content of fish retinas was given by the characterization of the OFF-response (d-wave) after light adaptation. Monotonous time course of the b-wave dark adaptation indicated a rod dominated retina of the dogfish shark. Observed results indicate that the dogfish shark possesses preponderantly rod retina, that of the eel is rod-dominated, while Prussian carp and painted comber have cone-rich retinae.
authors.affiliation: School of Biology, University of Belgrade, Studentski trg 3, 11001 Belgrade, Serbia. milmi@bio.bg.ac.rs
authors.forename: Milena
authors.initials: M
authors.lastname: Milosević
authors.forename: Zeljka
authors.initials: Z
authors.lastname: Visnjić-Jeftić
authors.forename: Ilija
authors.initials: I
authors.lastname: Damjanović
authors.forename: Miroslav
authors.initials: M
authors.lastname: Nikcević
authors.forename: Pavle
authors.initials: P
authors.lastname: Andjus
authors.forename: Zoran
authors.initials: Z
authors.lastname: Gacić
mesh_terms: D000221:Adaptation, Ocular / Q000502:physiology; D000811:Anguilla / Q000502:physiology; D000818:Animals; D002347:Carps / Q000502:physiology; D004284:Dogfish / Q000502:physiology; D004596:Electroretinography; D005071:Evoked Potentials / Q000502:physiology; D005399:Fishes / Q000502:physiology*; D066298:In Vitro Techniques; D010473:Perciformes / Q000502:physiology; D010775:Photic Stimulation; D012160:Retina / Q000502:physiology*; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology*; D017948:Retinal Rod Photoreceptor Cells / Q000502:physiology*; D013045:Species Specificity; D013997:Time Factors