Geometry-dependent pattern formation in active biological materials

Robust and precise patterning of cytoskeletal dynamics such as actin polymerization and myosin activity is crucial for embryos to generate proper mechanical form. In turn, the mechanical stresses that arise can induce shape deformation or shear-induced flow, modulating the reaction-diffusion dynamics of biochemical processes inside these cells. The general mechanisms of such mechanochemical feedback, underlying the formation of self-organized spatiotemporal patterns important for development, have remained largely unexplored. Here, we use the Rho wave dynamics in meiotic starfish oocytes to study the coupling between geometry and biochemical regulation. We can modulate the speed and the wavelength of the Rho waves by manipulating the geometrical shape parameters of the oocytes confined in micro-fabricated PDMS chambers. By combining our experimental results with a mass-conserved reaction-diffusion theoretical model, we discover a close interplay between geometry and biochemical regulation in biological pattern formation.