Postnatal changes in [3H]fucosyl glycoconjugates axonally transported into hamster optic nerve endings

The subsynaptosomal distribution of ³H]fucosyl glycoproteins axonally transported into the optic nerve endings of neonatal and adult hamsters changed dramatically at eye-opening. In 12 day-old previsual hamsters, the highest concentration of incorporated fucose was in the axoplasmic reticulum/synaptic vesicle fraction (51%), with only 6% in the dense synaptic membrane fraction. By the end of the eye-opening period four days later proportional labeling of the dense synaptic membrane fraction had increased four-fold to 23% of total sub-synaptosomal radioactivity. Labeling of the synaptic membrane doubled again in adults (41%). Total synaptosomal radioactivity was greatest in 16 day-olds. These results imply that utilization of ³H]fucose by the retinal ganglion cells, as well as composition of the synaptic membrane, change in association with the onset of functional visual activity.