During development, cells take a series of fate decisions to acquire different roles in the future organism. The decisions that make a cell specify into one role and not the others depend on complex and dynamic inter/intracellular signals. However, at each decision point, cells typically only decide between a limited repertoire of fates. This suggests that simple, intuitive regulatory biophysical principles may successfully summarize pathway complexity. Here, we propose to establish and quantitatively test such principles, using the vulval development of C. elegans as a model system. To do so, we propose to combine: (i) Controlled perturbations of in-vivo signaling dynamics using Auxin-Inducible Degradation (AID) System and Temperature-Sensitive strains (Zhang et al., 2015; Martinez et al., 2020) (ii) In-vivo measurements of the perturbations using a real-time biosensor for ERK activity (de la Cova et al., 2017) (iii) Large-scale 4D live imaging to capture cell-fate transformations in response to perturbed signaling in microfluidics (Keil et al., 2017) (iv) Parsimonious mathematical modeling of the underlying cell-fate acquisition dynamics (Corson and Siggia, 2012, 2017) Our preliminary results confirm the counter-intuitive asymmetry between P4/8.p in the degree to which they are induced to 2° fates by an EGF pulse (
lin-15(
n765)), as predicted by (Corson and Siggia, 2017). We will also compare our model predictions to experimental measurements in a background with weak ectopic Notch activity and no Anchor Cell (
lin-12(
n302)). Our project promises fundamental insights into stem cell behavior by experimental consolidating a generic mathematical modeling approach, applicable to a wide range of stem-cell paradigms.