Lectin receptors on cells isolated from the turtle retina

The presence of specific oligosaccharides on the surface of retinal cells was examined by incubating FITC-labeled lectins with cells dissociated from papain-treated turtle retinas. The pattern and intensity of binding was found to vary among the cells examined. With Con A, there was strong surface staining of both rods and cones, with an intense ring of fluorescence above the nucleus. The bipolar and ganglion cells also showed strong surface labeling. In Müller (glial) cells there was intense fluorescence in the apical, microvillous region. In contrast, the horizontal cells and their axons showed weak staining. When RCA-60, RCA-120, and WGA were incubated with photoreceptors, bipolar cells, or horizontal cells, little fluorescence was visible. However, all three lectins bound strongly to the Müller cells. In contrast, the Lotus lectin did not bind to any of the cells examined. In all the cases, lectin binding was inhibited by the appropriate haptene sugar. Further, prior treatment cells with neuraminidase did not alter lectin binding to any cell type. These results suggest differences in the distribution of lectin receptors among specific cell types, and particularly between neurons and glial cells in the vertebrate retina.