In the eye of many animals is a tissue called the retinal pigment epithelium, which contains dark pigment in cells that can disperse or aggregate the pigment. The relative dispersal is related to the amount of darkness and to the circadian day-night cycle, and is part of the process of light adaptation for vision. This research planning grant project is to get preliminary data on how the photoreceptors in the retina communicate the relative light levels to the pigment epithelium. A compound known as cyclic-AMP is known to act within cells as a second messenger to alter cellular functions in response to a signal received at the cell surface. This study tests the novel hypothesis that cyclic-AMP may serve directly as an extracellular second messenger as well. Microscopy, cell fractionation, and biochemical analysis are used to determine pigment localization and its possible mechanisms using the eye of a fish as a model system. This work will be important to this minority scientist's career development, it will have an impact on undergraduate training at this institution, and the results will be important for visual neuroscience, for the biology of circadian rhythms, and for cell biology.
