Quantifying mechanochemical coupling in the actomyosin cortex during early development in vivo

Spatiotemporal symmetry-breaking transitions in biochemical patterns are essential in triggering morphological changes during the development of all life forms, both at the unicellular and multicellular level. The realization of cell and tissue-scale deformations is achieved through intra-cellular force networks that translate localized biochemical signals into effective mechanical stresses that determine the global shape dynamics. However, the mechanochemical coupling between the biochemical patterns, force network activity and the resulting stresses is not well understood. Here, we quantify the local coupling between membrane-bound Rho-GTP and the mechanical deformations of the actomyosin cortex in the starfish oocytes during meiosis. We generate various Rho-GTP dynamic patterns and map the resulting stress patterns via tracking endogenous tracer particles embedded in the cell cortex. This method provides a novel approach to probe the local coupling between biochemistry and mechanics and the resulting morphological changes.