Figure 2. ERG responses to a bright flash imparted by AAV-mediated expression of human wild-type (hWT), S248W, and R1091x RetGC1. A: Representative scotopic electroretinography (ERG) in (top to bottom) S248W, R1091x, or wild-type GUCY2D adenoassociated virus (AAV)-injected eyes, each shown above the traces from the non-injected eyes; the small vertical arrows indicate timing of a 505 nm 1.2 × 10⁶ photon µm⁻² flash. B: Representative photopic ERG in (top to bottom) S248W, R1091x, or wild-type GUCY2D AAV-injected eyes; each group of three traces shows responses to 505 nm (upper trace) or 365 nm (middle trace) 6 × 10⁵ photon µm⁻² flash (small vertical arrows) delivered in the injected eyes and the 365 nm flash delivered in a non-injected eye, all in a constant background light equivalent of 33 × 10³ photoisomerizations rod⁻¹ s⁻¹. C: Maximal voltage deflection amplitudes (mean ± standard deviation, SD) of the scotopic ERG a-wave in the injected eyes among the hWT (136 ± 60 µV, n = 9), S248W (0.4 ± 4 µV, n = 9), and R1091x (105 ± 28 µV, n = 10) treated mice. Note that because the a-wave could not be identified in the ERG traces recorded from the S248W-injected mice, the amplitude of the voltage deflection at 8 ms after the flash was arbitrarily taken for comparison with the two other groups. The differences between the ERG responses in the S248W-injected eyes and the other two groups were statistically highly significant (p≤0.0001; here and from Student t test using unpaired data). There was no statistically significant difference between the hWT and R1091x-injected mice (p = 0.177). D: Maximal voltage deflection amplitudes of the scotopic b-wave in the same mouse group as panel C (305 ± 119, 229 ± 50, and 38 ± 14 µV for the hWT, R1091x, and S248W- injected eyes, respectively). The differences between the ERG responses in the S248W-injected eyes and the other two groups were highly statistically significant (p≤0.00013), but the difference between the hWT and the R1091x-injected mice was not (p = 0.102).