Animals

All animal procedures were approved by the Animal Care and Use Committee of the National Eye Institutes (Animal study protocol 650). Mice were housed in an atmosphere-controlled environment (temperature: 22°C +/− 2°C, humidity: 30-70%), under a 12 hours dark/12 hours light cycle and supplied with food and water ad libitum. Food, water and nesting material were changed weekly. The absence of the rd8 mutation in the colony was assessed by PCR. Nrl^−/− mice have been described previously (Mears et al., 2001; Akimoto et al., 2006) and were backcrossed onto C57BL/6J more than 10 times. All mice were maintained in the National Institutes of Health (NIH) animal care facilities.