Fig. 2.

Opn4^−/−;rd1/rd1 retinas are entrained by light/dark cycles. (A) Background-subtracted Per2^Luciferase luminescence traces of retinas from WT and Opn4^−/−;rd1/rd1 mice recorded in constant darkness after being exposed to 4 d of light/dark cycle in 0° (blue) or 180° (red) positions in a light/dark clock apparatus. (B) Average time of peak Per2^Luciferase luminescence on the first day of constant darkness following a 4 d light/dark treatment (error bars represent 1 SEM) in the 0° (blue) or 180° (red) position. Gray bars indicate times of day when tissues previously experienced dark. WT, n = 6 each; Opn4^−/−;rd1/rd1, n = 6.