Thousands of patients lose vision from retinitis pigmentosa and other hereditary retinal degenerations. The proposed research seeks to define biochemical defects in the photoreceptor cells in some animal models for these human diseases (rd mice, Irish setters with rod-cone dysplasia, RCS rats and taurine-deficient cats). Projects include study of patterns of phospholipid and phosphoprotein synthesis from labeled precursors in retina and microdissected photoreceptor cell layer, comparison of centralmacular and peripheral regions with respect to these synthetic processes and research on the effects of illumination on phospholipid, phosphoprotein synthesis and phospholipid hydrolysis. In addition studies will be continued on the taurine-deficient cat to explore the mechanism whereby taurine deficiency affects photoreceptor cell viability.