Modelling of Yeast Mating Reveals Robustness Strategies for Cell-Cell Interactions
Fig 4
Mating efficiency of isotropic versus polarized pheromone source.
(A) Schematic diagram of isotropic versus polarized (non-isotropic) pheromone source. Top row indicates in black shading the spatial distribution of the pheromone source function. The bottom row depicts the a-factor diffusion profile shown as a concentration contour plot for the isotropic source (left) and the polarized source (right). (B) Polarization plots of u2 showing mating cells at end of simulation. Four sample simulations each from the isotropic source group and from the polarized source group are shown. The normalized level of u2 is color coded on the surface of the cell according to the colormap on right. The polarisome is denoted by the black or gray dot at the projection tip. The polarized source produces higher mating efficiencies; the 1 or 0 indicates a successful or unsuccessful mating. The polarization plots, distance plots, and direction plots are color coded (blue, red, green, brown) for a particular simulation. (C) Distance plots for each of the four simulations. These plots show the distance between polarisomes of the mating partners as a function of time. With the isotropic source, the distances do not converge to 0 for some of the simulations. The green isotropic source simulation was terminated early because it did not meet the distance/direction threshold. (D) Direction plots for polarized source and isotropic source simulations. Each data point represents the averaged direction of the projection from each cell during mating. Axes are described in the legend to Fig 3C. Mating is more likely if the projections are in the same direction i.e. along the diagonal in the top right or bottom left quadrants. The average distance from the diagonal is 0.26 radians for the isotropic source compared to 0.12 for the polarized source matings. Colored filled circles correspond to simulations shown in (B) and (C). (E) Average mating time of successful matings with isotropic and polarized sources. Each bar represents the average time (± standard deviation) for successful matings. We performed 20 simulations for both conditions, and the numbers of successful matings for isotropic and polarized sources are 6 and 15 respectively.