Computational modeling of mound development in Dictyostelium

One of the structures seen during the course of Dictyostelium discoideum development is the loose aggregate or early mound structure. In this work, we attempt to simulate the formation of this three-dimensional mound by a model which incorporates cAMP chemical signaling and resultant cell motions due to chemotaxis. Simulation results are compared to measurements of the mound morphology as determined by confocal fluorescence microscopy. Good agreement is obtained only if the cells exhibit an adaptive response to high cell density and change their basic motion patterns. We argue that in the actual biological system, this occurs because the high resting value of cAMP in the mound can effectively saturate the high-affinity receptors responsible for aggregation stage dynamics. Tests of our ideas using mutant cell lines are briefly discussed.