Studying Underlying Mechanisms of Usher Syndrome using Electroretinographic Recordings from Morphant Zebrafish, Dania Rerio

Abstract

The immediate goal of this study was to gain insight into the molecular basis of Usher Syndrome. Usher Syndrome is the leading cause of hereditary deaf-blindness and its underlying mechanisms are studied at the University of Oregon using zebrafish as the model organism. The Westerfield lab investigates the disorder using cytological, molecular and behavioral analyses to unearth the molecular events that give rise to Usher Syndrome's phenotypes. This study focused on understanding the visual aspect of the disorder using the electroretinogram (ERG) as a mode of analysis. Electroretinographic recordings of morphant zebrafish-fish displaying Usher Syndrome phenotypes-were contrasted against wild-type zebrafish with hopes of gaining insight into the disorder's underlying mechanisms and possibly drawing conclusions regarding the nature of the Usher Syndrome based on experimental recordings. Analyzing the major components of the ERG waveform was a central part of this study. The a-wave, b-wave and d-wave of the ERG correspond to specific neuronal synapses within the retina-the width and amplitude of each component reveals something about the cellular activity at a particular layer within the retina. Our experimental protocol met some challenges in controlling a number of parameters, making the acquisition of meaningful data very difficult. Once a protocol with the proper combination of parameters is developed, making meaningful contributions to the study of Usher Syndrome will be possible.