The interplay between cell size control, cell cycle regulation, and growth morphology in budding yeast

Abstract

Organisms from all domains of life display size control, coupling growth and division to constrain the spread in cell sizes observed throughout a population. However, the means by which this coupling takes place remains unclear. Here we present our work studying the molecular mechanism underpinning size control using a combination of theoretical and experimental approaches. First we explore a set of abstracted molecular models and their implications for the regulation of size control in different growth morphologies. This approach revealed rich dependence of the robustness of different strategies on division asymmetry and growth morphology. We then use a series of microscopy-based experiments to interrogate the molecular mechanism underpinning cell size control in the model organism budding yeast S. cerevisiae. Within this work we disprove a widely supported hypothesis for size control in this organism, highlighting the challenges that remain in addressing the fundamental question of how cells regulate their size. Finally, we use a theoretical approach to address the question of how cell size and division asymmetry affect the population growth rate. This project demonstrates a previously unobserved dependence of population growth rate on division asymmetry and a cell's strategy of size control.