A point mutation (W70A) in the rod PDE-gamma gene desensitizing and delaying murine rod photoreceptors.
OBJECTIVE
To examine the corneal electroretinogram (ERG) of transgenic mice (W70A mice) carrying a point mutation (W70A) in the gene encoding for the gamma-subunit of rod cGMP phosphodiesterase (PDEgamma).


METHODS
The ERG of W70A mice was compared with that of normal mice. Cone responses were separated from rod responses by light adaptation, whereas rod sensitivity was assessed by threshold stimulation with dim light. Spectral sensitivity curves of the ERG were obtained using a constant response criterion.


RESULTS
The ERG of the W70A mouse has a desensitized, delayed rod b-wave at threshold, and a prolonged rod b-wave at higher flash intensities. The a-wave is absent even at maximal stimulation. The cone ERG of the W70A mouse is indistinguishable from that of normal mice. The spectral sensitivity of the 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 supports the interpretation of the results as normal cone and abnormal rod function in the W70A mouse.


CONCLUSIONS
The W70A mouse represents new model of stationary nyctalopia that can be recognized by its unusual ERG features.
Salchow
D J
DJ
Edward S. Harkness Eye Institute, Department of Ophthalmology, Columbia University, New York, New York 10032, USA. pg10@columbia.edu
Gouras
P
P
Doi
K
K
Goff
S P
SP
Schwinger
E
E
Tsang
S H
SH
D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000235:genetics*; D000818:Animals; D054707:Cyclic Nucleotide Phosphodiesterases, Type 6; D003623:Dark Adaptation; D004596:Electroretinography; D051379:Mice; D008822:Mice, Transgenic; D009755:Night Blindness / Q000201:enzymology / Q000235:genetics* / Q000503:physiopathology; D010775:Photic Stimulation; D017354:Point Mutation; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology; D012162:Retinal Degeneration / Q000201:enzymology / Q000235:genetics* / Q000503:physiopathology; D012374:Rod Cell Outer Segment / Q000201:enzymology* / Q000503:physiopathology; D012684:Sensory Thresholds
D015106:3',5'-Cyclic-GMP Phosphodiesterases; D054707:Cyclic Nucleotide Phosphodiesterases, Type 6; C517438:Pde6b protein, mouse