FIGURE 4.

Retinol and retinal were distinguished by exciting mouse rod photoreceptors with 340 nm (top rows of fluorescence images) and 380 nm (bottom rows) light. Fluorescence emission was collected for >420 nm. IR, infrared images. For each top and bottom pair, the images are shown at the same intensity scaling. All bars are 5 μm. A, fluorescence images 15 min after the addition of 50 μm retinol or retinal. B, fluorescence images 30 min after bleaching of Rdh12^−/−, Rdh8^−/−, and Rdh8^−/−;Rdh12^−/− cells. All of the experiments were done at 37 °C. The reason the Rdh8^−/− image acquired with 340-nm excitation appears brighter is the higher intensity value of the background compared with the intensity of the background in the 380-nm excitation image; both images are displayed with the same offset.