A ligand-receptor model for the cohesive behaviour of Dictyostelium discoideum axenic cells.
Axenically grown cells of D. discoideum Ax-2 harvested in the log phase of growth, cohere rapidly when shaken in phosphate buffer. After 3.5 days in the stationary phase of growth, cells become completely non-cohesive. Although they do not stick to each other, stationary phase cells do stick to both log phase cells and aggregation-competent cells. The cohesion of stationary phase cells with these other 2 cell types is inhibited by both EDTA and the low-molecular-weight factor which we have previously demonstrated in stationary-phase growth medium. There is a decline in the sensitivity of slime mould cell cohesion to the low-molecular-weight inhibitory factor as the cells become aggregation-competent. This effect parallels the developmentally-regulated decline in sensitivity to EDTA. The low-molecular-weight inhibitor is not a chelating agent, however. The effect of the inhibitor seems to be specifically against contact sites-B mediated cohesion. We suggest that the simplest cohesive mechanism which can explain our results, is that the EDTA-sensitive cohesion of log phase cells could be dependent on a ligand-receptor system.
D000268:Adhesiveness; D001665:Binding Sites; D004023:Dictyostelium / Q000166:cytology* / Q000187:drug effects / Q000254:growth & development; D004492:Edetic Acid / Q000494:pharmacology; D008024:Ligands; D008970:Molecular Weight; D013997:Time Factors
D008024:Ligands; D004492:Edetic Acid