This project examines biochemical events unique to the retina, particularly the synthesis and modification of photoreceptor membrane components, in the retinas of vertebrates which can be affected by inherited retinal degenerations. The synthesis of the visual pigment, rhodopsin, occurs at a normal rate as measured by radioactive leucine incorporation following intravitreal injection in the eyes of miniature poodles affected with progressive rod- cone degeneration. Similarly, the glycosylation and acylation of rhodopsin were found to be normal following intravitreal injection of labeled fucose or palmitic acid, respectively. However, phospholipid synthesis or degradation, measured by radioactive palmitic acid incorporation, appears to be different in the affected dogs, suggesting a possible metabolic defect in this inherited disorder. The evidence suggests a significant diminution in the esterification of palmitic acid but not of arachidonic acid. Moreover, glycerol incorporation into phospholipid is not decreased in the affected animals, thus the defect may specifically involve palmitate.
