3-DIMENSIONAL WAVES OF EXCITATION DURING DICTYOSTELIUM MORPHOGENESIS

Cells in Dictyostelium slugs follow well-defined patterns of motion. W e found that the chemotactic cell response is controlled by a scroll w ave of messenger concentration in the highly excitable prestalk zone o f the slug that decays in the less-excitable prespore region into plan ar wave fronts. This phenomenon is investigated by numerical solutions of partial differential equations that couple local nonlinear kinetic s and diffusive transport of the chemotactic signal. In the interface of both regions a complex twisted scroll wave is formed that reduces t he wave frequency in the prespore zone. The spatio-temporal dynamics o f waves and filaments are followed over 33 periods of rotation. These results yield an explanation of collective self-organized cell motion in a multicellular organism.