@article {166234, title = {Force patterning drives quasistratification and graded tissue-scale spatial order in auditory epithelia}, journal = {Proceedings of the National Academy of Sciences}, volume = {123}, year = {2026}, pages = {e2519341123}, abstract = {

The ordered arrangement of mechanosensory hair cells in vertebrate auditory epithelia relies on mechanical interactions among multiple cell types. Yet, how local mechanical heterogeneity produces tissue-scale organization remains unresolved. Here we combine experiment and theory to show that spatial patterning of junctional contractility links apical surface remodeling to three-dimensional cellular organization and quasi-stratified architecture across the entire extent of the tissue. Building on previous findings on the regulation of force patterning, our results demonstrate how local junctional force heterogeneity generates graded three-dimensional cellular morphology and coordinated cellular movements at the global tissue scale. These findings identify patterned junctional mechanics as a scalable principle for organizing complex epithelia. During development, coordinated cell behaviors drive epithelial morphogenesis toward precise three-dimensional architectures essential for physiological function. How such coordination arises in epithelia composed of multiple cell types remains unclear. Here, we study development of the avian auditory epithelium comprising sensory hair cells (HCs) and nonsensory supporting cells (SCs). Initially, HCs and SCs are arranged into mosaics by Notch{\textendash}Delta signaling. As development proceeds, HCs partially extrude from the epithelium, establish a tenfold gradient in apical surface area across the tissue, and rearrange with SCs to form near-hexagonal order. Using experiments combined with a three-dimensional vertex model, we show that increased contractility at apical junctions between SCs relative to HC{\textendash}SC junctions drives spatial organization both within the epithelial plane and along the apical{\textendash}basal axis. Consistent with experimental findings, our simulation shows systematic differences in HC apical area expansion generate opposing coordinated movements of HCs and SCs, establishing gradients in HC apical surface area and density while maintaining uniform hexagonal order. Together, these results demonstrate that spatial patterning of junctional contractility coordinates cell behavior across both the plane and depth of a mixed epithelium, producing quasi-stratified architecture and tissue-scale three-dimensional order.

}, keywords = {3D vertex model; basilar papilla; development.}, doi = {10.1073/pnas.2519341123}, url = {https://www.pnas.org/doi/abs/10.1073/pnas.2519341123}, author = {Julian Weninger and Anubhav Prakash and Sukanya Raman and Raj k. Ladher and Madan Rao and Karsten Kruse} } @article {158512, title = {Active drive towards elastic spinodals}, year = {2025}, abstract = {

Active matter, exemplified by adaptive living materials such as the actomyosin cytoskeleton, can navigate material parameter space, leading to unconventional mechanical responses. In particular, it can self-drive toward\ elastic spinodal\ regimes, where inhomogeneous floppy modes induce elastic degeneracy and enable a controlled interplay between rigidity loss and recovery. Proximity to such marginal states leads to stress localization and the formation of force chains that can be actively assembled and disassembled. Here we extend the classical notion of spinodal states to active solids and demonstrate how these extreme mechanical regimes can be actively accessed. Moreover, we show that in a nonlinear setting, crossing elastic spinodals generates new energy wells and makes force channeling an intrinsic feature of the emerging microstructure.

}, doi = {DOI: https://doi.org/10.1103/h2yp-d2s2}, url = {https://journals.aps.org/pre/abstract/10.1103/h2yp-d2s2}, author = {Ayan Roychowdhury and Madan Rao and Lev Truskinovsky} } @article {161124, title = {Segregation, finite-time elastic singularities, and coarsening in renewable active matter}, journal = {Physical Review E}, volume = {112(4)}, year = {2025}, month = {24-10-2025}, type = {Journal}, abstract = {

Material renewability in active living systems, such as in cells and tissues, can drive the large-scale patterning of forces, with distinctive phenotypic consequences. This is especially significant in the cell cytoskeleton, where multiple species of myosin bound to actin, apply differential contractile stresses and undergo differential turnover, giving rise to patterned force channeling. Here we study the dynamical patterning of stresses that emerge in a hydrodynamic description of a renewable active actomyosin elastomer comprising two myosin species. Our analytical framework also holds for an actomyosin elastomer with a single myosin species. We find that a uniform active contractile elastomer spontaneously segregates into spinodal stress patterns, followed by a finite-time collapse into tension carrying singular structures that display self-similar scaling and caustics. Our numerical analysis carried out in one dimension shows that these singular structures move and merge and gradually result in a slow coarsening dynamics. We discuss the implications of our findings to the emergence of stress fibers and the spatial patterning of actomyosin. Our study suggests that with state-dependent turnover of crosslinkers and myosin, the\ in vivo\ cytoskeleton can navigate through the space of material parameters to achieve a variety of functional phenotypes.

}, author = {Ayan Roychowdhury{\textquoteright} and Saptarshi Dasgupta{\textquoteright} and Madan Rao} }