IN-VITRO CHANGES OF GANGLIOSIDE IMMUNOSTAIN LOCALIZATION IN DEVELOPING NEURAL CELLS

The immunostains of GD3, c-pathway polysialogangliosides and gangliote traosylgangliosides belonging to the a- and b-pathways were analyzed i n embryo optic lobe cells. Cells were cultured in serum free media wit h, and without, bovine brain ganglioside mixture (largely gangliotetra osylgangliosides). Control cells differentiated in vitro, whereas gang lioside treated cells emitted almost no neurites. In immature cells, G D3 and c-gangliosides were extensively expressed and their immunostain s were observed all over the cell (general localization), whereas gang liotetraosylgangliosides were scanty and their stain was preferentiall y restricted to discrete areas (in clusters). In control differentiate d cells, the GD3 expression was strikingly reduced and its immunostain appeared in clusters; c-gangliosides were abundant and their stain wa s found with general localization; the expression of gangliotetraosylg angliosides became important and their stain was observed with general localization in most of the positive cells. In ganglioside treated ce lls, in spite of their undifferentiated morphology, the gangliotetraos ylganglioside stain appeared with general localization. These results suggest that gangliosides involved in neural ontogenesis are preferent ially located in clusters when they are scarce and have general locali zation when they are abundant in membranes.