DISTRIBUTION OF CARBOHYDRATE EPITOPES AMONG DISJOINT SUBSETS OF LEECHSENSORY AFFERENT NEURONS

Carbohydrate recognition plays an important role in the development of normal projections of sensory afferent neurons in the leech CNS. Four different carbohydrate epitopes are expressed by sensory afferents on their 130 kDa surface proteins: all sensory afferents share a common carbohydrate epitope (CE0) that helps them to enter and project diffus ely across the synaptic neuropil; a restricted expression of three oth er carbohydrate epitopes (CE1, CE2, and CE3) serves to distinguish thr ee subsets of sensory afferents. We examined the subsets of sensory af ferents defined by their subset carbohydrate epitopes in the leech lip , skin, gut, and CNS. We established that the CE1, CE2, and CE3 subset epitopes define disjoint subsets of neurons by double labeling sensor y afferents with monoclonal antibodies for different pairs of subset e pitopes. We found that CE2 and CE3 afferents populate the lip and skin , but not the gut, and that these two subsets of sensory afferents hav e convergent projection patterns in the CNS. We found that CE1 afferen ts populate the gut and skin, but not lips; furthermore, their CNS pro jections diverge from those of CE2 and CE3 afferents. Our data fit the hypothesis that these carbohydrate epitopes are related to sensory mo dality of afferent subsets.