Materials science

Deformation (meteorology)

Chemical physics

Composite material

Combinatorics

Physics

Isotropy

Topological defect

Nanotechnology

Topology (electrical circuits)

Instability

Mathematics

Mechanics

Biology

Optics

Active matter

Cell biology

Turbulence

Monolayer

Condensed matter physics

Liquid crystal

Physical Review Letters

There is now growing evidence of the emergence and biological functionality of liquid crystal features, including nematic order and topological defects, in cellular tissues. However, how such features that intrinsically rely on particle elongation, emerge in monolayers of cells with isotropic shapes is an outstanding question. In this article we present a minimal model of cellular monolayers based on cell deformation and force transmission at the cell-cell interface that explains the formation of topological defects and captures the flow-field and stress patterns around them. By including mechanical properties at the individual cell level, we further show that the instability that drives the formation of topological defects and leads to active turbulence, emerges from a feedback between shape deformation and active driving. The model allows us to suggest new explanations for experimental observations in tissue mechanics, and to propose designs for future experiments.

Emergence of Active Nematic Behavior in Monolayers of Isotropic Cells