Dl gradient model rationale.
A) The embryo is modeled as a single string of n cuboid cellular compartments. B) Chemical reactions and transport processes considered by the Kanodia model . The DV Toll receptor activation gradient (red) is represented by the space-dependent Dl-Cactus dissociation constant (kD) and results in higher nuclear concentrations of Dl (gray) at the ventral side of the embryo (V) and higher cytoplasmic concentrations at the dorsal side (D). Parameters shown in blue are explained in Table S2. C) Phylogenetic tree of melanogaster subgroup species.