Mechanical competition alters the cellular interpretation of an endogenous genetic programme

Abstract

The intrinsic genetic programme of a cell is not always sufficient to explain the cell's activities. External mechanical stimuli are increasingly recognized as determinants of cell behaviour. In the epithelial folding event that constitutes the beginning of gastrulation in Drosophila, the genetic programme of the future mesoderm leads to the establishment of a contractile actomyosin network that triggers apical constriction of cells, and thereby, furrow formation. However, some cells do not constrict but instead stretch, even though they share the same genetic programme as their constricting neighbours. We show here that tissue-wide interactions force a subset of cells to expand even when an otherwise sufficient amount of apical, active actomyosin is present. Models based on contractile forces and linear-stress strain responses are not sufficient to reproduce experimental observations, but simulations in which cells behave as ductile materials with non-linear mechanical properties do. Our models show that this behaviour is an emergent property of supracellular actomyosin networks, in accordance with our experimental observations of actin reorganization within stretching cells.

Image Processing Filters for Grids of Cells Analogous to Filters Processing Grids of Pixels

“…Forces between intra-cellular structures, groups of cells and external structures are involved in forming an organism (Stern, 2004;Rauzi et al, 2008;Benton et al, 2013;Münster et al, 2019;Bhide et al, 2020). Processing images using filters for segmenting and analysing sub-cellular structures and cells is a common task for bio-image analysts.…”