Fig. 9. Differential binding of Cy2-labeled Shiga toxin and Cy3-labeled Cholera toxin to fetal mouse astrocytes and binding of Cy3-labeled CTX to hippocampal neurons. (a) Binding of Cy3-CTX to astrocytes. Binding conditions were the same as in Fig. 1a. During inspection of the live cells under the fluorescence microscope, some CTX is taken up and accumulates in the Golgi. (b,c) Astrocytes that exhibit significant BrdU incoporation (blue-white nuclei in (c)) show only weak binding of ST (b) or CTX (c). (d,e) Binding and uptake of Cy3-CTX by hippocampal neurons. All axons and dendrites exhibit a strong binding of the toxin. In (e), several neuronal cells on top of a Cy3-CTX-binding astrocyte are depicted.