Interphotoreceptor retinoid-binding protein (irbp) is expressed in the retinal pigment epithelium and pineal gland during zebrafish development

IRBP is proposed to function in the visual cycle by transporting retinoids between the photoreceptors and the retinal pigment epithelium (RPE). IRBP expression is thought to be limited to pinealocytes and retinal photoreceptors. IRBP is expressed in the retinas of some animals before it is needed for the visual cycle, suggesting that IRBP may play a role in developmental interactions between the retina and RPE (Reviewed in: JCN (1996) 367:329). Purpose: In order to explore the potential role of IRBP in development, we have studied the expression pattern of IRBP mRNA in the developing zebrafish. Methods: Expression of zebrafish IRBP was examined using in situ hybridization. Results: IRBP mRNA is present in the embryonic zebrafish RPE at 51 hours post-fertilization. IRBP mRNA is also present in the developing pineal and retina at 35 and 51 hours post-fertilization, respectively . Conclusions: IRBP mRNA is expressed by the RPE during zebrafish development. This unexpected expression may provide a mechanism for transport of the retinoids and fatty acids necessary for retinal development. IRBP mRNA expression in the pineal gland begins early in zebrafish development. Supported by NIHEY09412, NIHF32EY06612, and NSF IBN 9222046. NONE.