SPATIAL PATTERN-FORMATION DURING AGGREGATION OF THE SLIME-MOLD DICTYOSTELIUM-DISCOIDEUM

Stream formation and spiral wave behaviour during the aggregation of D ictyostelium discoideum (Dd) are studied in a model based on the Marti el-Goldbeter equations for cAMP relay, combined with chemotactic motio n of Dd cells. The results show that stream formation occurs if the tu rnover rate of intracellular cAMP is increased. This increase in the t urnover rate of cAMP([in]) leads to a dependence of the speed of the c AMP wave on the cell density. We propose that this dependence of wave speed on cell density is the underlying mechanism for stream formation . Besides stream formation, increasing the turnover rate of cAMP([in]) also results in a spiral wave period that decreases during aggregatio n, a phenomenon that is commonly observed in situ. Furthermore, the de pendence of wave speed on cell density is measured empirically. The sp eed of the cAMP wave is found to decrease as the wave travels from hig h to low cell density. This indicates that in situ, wave speed does de pend on cell density. (C) 1996 Academic Press Limited.