Rhodopsin replacement rescues photoreceptor structure during a critical developmental window

Rhodopsin is essential for normal photoreceptor development in Drosophila (O'Tousa et al., 1989; Leonard et al., 1992; Kumar and Ready, 1995) and in mice (Humphries et al., 1997). Here we report studies in which a rhodopsin transgene is expressed at restricted stages during the development of Drosophila photoreceptors otherwise lacking rhodopsin. Substantial rescue of normal photoreceptor structure and physiology is effected by rhodopsin expression during the time of the normal onset of rhodopsin synthesis. Expression shortly before or after this critical period does not rescue these deficits. There is a critical developmental period in which rhodopsin plays its key role in photoreceptor morphogenesis.