Symbiotic Cell Differentiation and Cooperative Growth in Multicellular Aggregates
Fig 3
Behavior of simplified networks.
(A) Network 1. (B) Network 2. In (A) and (B), each number represents the chemical index, with orange-circle and green-square nodes representing diffusible and non-diffusible chemicals, respectively. The difference between networks 1 and 2 lies only in the diffusibility of X5. The dashed arrows denote the diffusive fluxes of chemicals, and the thick arrows indicate catalytic reactions. The chemical at the arrowtail is transformed to the chemical at the arrowhead, catalyzed by the chemical labeled on the edge; e.g., the left arrow from X0 in (A) denotes the catalytic reaction X0 + αX1 → X3 + αX1. When the cells differentiate, type-1 (type-2) cells mainly produce the chemicals X1 and X3 (X2 and X4), and receive X4 (X3) from type-2 (type-1) cells, which are illustrated in the lower panel with color. (C) and (D) are examples of the behavior of network 1 for (C, Vmed, D) = (0.15, 100, 1). (C) Chemical concentrations in N cells surviving at time t = 105 are plotted according to the color code shown in the sidebar, with the vertical axis as the cell index m and the horizontal axis as the chemical index i. The top band designates an “isolated” cell. (D) The time series of the number of cell divisions per cell for interacting (red) and isolated (blue) cells.