A point mutation (W70A) in the rod PDE gamma gene desensitizing and delaying murine rod photoreceptors

PURPOSE. To examine the corneal electroretinogram (ERG) of transgenic mice (W70A mice) carrying a paint mutation (W70A) in the gene encoding for the g amma-subunit of rod cGMP phosphodiesterase (PDE gamma). METHODS. The ERG of W70A mice was compared with that of normal mice. Cone r esponses were separated from rod responses by light adaptation, whereas rod sensitivity mras assessed by threshold stimulation with dim light. Spectra l sensitivity carves of the ERG were obtained using a constant response cri terion. RESULTS. The ERG of the W70A mouse has a desensitized, delayed rod b-wwe at threshold, and a prolonged Nd b-wave at higher flash intensities. The a-wa ve is absent even at maximal stimulation. The cone ERG of the W70A mouse is indistinguishable from that of normal mice. The spectral sensitivity of th e W70A mouse is maximal in the UV spectrum, in contrast to the normal mouse , which is most sensitive in the green region of the spectrum. This support s the interpretation of the results as normal cone and abnormal rod functio n in the W70A mouse. CONCLUSIONS. The W70A mouse represents new model of stationary nyctalopia t hat can be recognized by its unusual ERG features.