PubMed1983
In an accompanying report (Bozzaro, S., and Roseman, S. (1983) J. Biol. Chem. 258, 13882-13889), evidence is presented that the slime mold Dictyostelium discoideum contains three cell surface receptors specific for D-glucose, D-mannose, and N-acetyl-D-glucosamine, respectively. The synthetic probes used for these studies consisted of the sugars covalently linked to polyacrylamide gels. In the present experiments, starved cells were placed on these and other immobilized sugars to determine whether the sugar derivatives influenced normal development in this organism. When D. discoideum cells are on a solid surface under water, they form aggregation centers and strands of cells (which radiate from the center), send "signals" i.e. pulses of cyclic AMP from the center down the strands, and finally, after cells in the strands migrate to the center, form tight aggregates. These results were obtained on all polyacrylamide gel derivatives tested except one class, derivatives of D-glucose (O- and S-glucosides, cellobiosides, and maltosides). On these gels, aggregation centers and strands formed normally, but at a certain point stopped "signaling" and suddenly dissociated, with the cells rapidly migrating away from one another by negative chemotaxis (see Appendix to this report). Furthermore, a simultaneous dissociation of several centers was often observed. Following a brief period of random movement after dissociation, aggregation centers once again formed and the cycle was repeated. This cycle was repeated as often as 30 times or more over a 24-h period. The cells on the glucoside gels became aggregation-competent at the same time as the control cells, and the adhesion-dissociation cycle appeared to have no effect on the synthesis of some developmentally regulated proteins, such as UDP-glucose pyrophosphorylase. Interpretations of the phenomenon and its potential for studying gene regulation in this organism are discussed.