3-DIMENSIONAL SCROLL WAVES OF CAMP COULD DIRECT CELL-MOVEMENT AND GENE-EXPRESSION IN DICTYOSTELIUM SLUGS

Complex three-dimensional waves of excitation can explain the observed cell movement pattern in Dictyostelium slugs. Here we show that these three-dimensional waves can be produced by a realistic model for the cAMP relay system [Martiel, J, L, & Goldbeter, A, (1987) Biophys J. 52 , 807-828]. The conversion of scroll waves in the prestalk zone of the slug into planar wave fronts in the prespore zone can result from a s maller fraction of relaying cells in the prespore zone, Further, we sh ow that the cAMP concentrations to which cells in a slug are exposed o ver time display a simple pattern, despite the complex spatial geometr y of the waves, This cAMP distribution agrees well with observed patte rns of cAMP-regulated cell type-specific gene expression. The core of the spiral, which is a region of low cAMP concentration, might direct expression of stalk-specific genes during culmination.