Biophysics and soft condensed matter physics

Mechanical characterization of regenerating Hydra tissue spheres, with T. Perros, A. BiquetBisquert, Z. Ben Meriem, M. Delarue, P. Joseph and O. CochetEscartin, (bioRXiv)

2.5D Traction Force Microscopy: Imaging threedimensional cell forces at interfaces and biological applications, with H. DelanoëAyari, T. Hiraiwa, J.P. Rieu and T. B. Saw, (journal)
 Mapping cell cortex rheology to tissue rheology, and viceversa, with E. Moisdon, P. Seez, C. Noûs, F. Molino and C. Gay (journal, ArXiV)
 Allinone rheology of multicellular aggregates, with G. Mary, F. Mazuel, V. Nier, F. Fage, I. Nagle, L. Devaud, J.C. Bacri, S. Asnacios, A. Asnacios, C. Gay, C. Wilhelm and M. Reffay (journal,HAL)
 The role of single cell mechanical behavior and polarity in driving collective cell migration, with S. Jain, V. Cachoux, G. Narayana, S. de Beco, J. D’Alessandro, V. Cellerin, T. Chen, M. Heuzé, R.M. Mège, A. Kabla, C.T. Lim and B. Ladoux (journal, bioRXiv)
 Collective stresses drive competition between monolayers of normal and Rastransformed cells, with S. Moitrier, C. BlanchMercader, S. Garcia, K. Sliogeryte, T. Martin, J. Camonis, P. Silberzan and I. Bonnet (journal, arXiv)
 From cells to tissue: A continuum model of epithelial mechanics, with S. Ishihara and K. Sugimura (journal, arXiv)
 Cell growth, division and death in cohesive tissues: a thermodynamic approach, with S. Yabunaka (journal, arXiv)
 Onedimensional collective migration of a proliferating cell monolayer, with P. Recho and J. Ranft (journal, arXiv)
 Mechanical formalisms for tissue dynamics, with S. Tlili, C. Gay, F. Graner, F. Molino and P. Saramito (journal, erratum, arXiv)
 Border forces and friction control epithelial closure dynamics, with O. CochetEscartin, J. Ranft and P. Silberzan (journal, arXiv)
We study the closure dynamics of a large number of wellcontrolled circular apertures within an epithelial monolayer, where the collective cell migration responsible for epithelization is triggered by the removal of a spatial constraint rather than by scratching. Based on experimental observations, we propose a physical model that takes into account border forces, friction with the substrate, and tissue rheology. Border protrusive activity drives epithelization despite the presence of a contractile actomyosin cable at the periphery of the wound. The closure dynamics is quantified by an epithelization coefficient, defined as the ratio of protrusive stress to tissuesubstrate friction, that allows classification of different phenotypes. The same analysis demonstrates a distinct signature for human cells bearing the oncogenic RasV12 mutation, demonstrating the potential of the approach to quantitatively characterize metastatic transformations.
 Contraction of crosslinked actomyosin bundles, with N. Yoshinaga (journal, arXiv)
 Mechanical state, material properties and continuous description of an epithelial tissue, with I. Bonnet, F. Bosveld, L.Fetler, Y. Bellaïche and F. Graner (journal, arXiv)
 Mechanical control of tissue morphogenesis by the Fat/Dachsous/Fourjointed planar cell polarity pathway, with F. Bosveld, I. Bonnet, B. Guirao, S. Titli, Z. Wang, A. Petitalot, R. Marchand, P.L. Bardet, F. Graner and Y. Bellaïche (journal)
 Rigidity sensing explained by active matter theory, with N. Yoshinaga and J. Prost (journal, arXiv)
Biophysics and machine learning
 Mechanical stress driven by rigidity sensing governs epithelial stability, with S. Sonam, L. Balasubramaniam, S.Z. Lin, Y.M. Yow, I.P. Jauma, C. Jebane, M. Karnat, Y. Toyama, J. Prost, R.M. Mège, J.F. Rupprecht and B. Ladoux (journal, bioRXiv)
 Enhanced RhoA signaling stabilizes Ecadherin in migrating epithelial monolayers, with S. Gupta, K. Duszyc, S. Verma, S. Budnar, G.A. Gomez, I. Noordstra and A.S. Yap (journal, bioRXiv)
 An optochemical tool for lightinduced dissociation of adherens junctions to control mechanical coupling between cells, with D. Ollech, T. Pflästerer, A. Shellard, C. Zambarda, J.P. Spatz, R. Mayor, R.Wombacher and E.A. CavalcantiAdam (journal,HAL)
 Myosin II isoforms play distinct roles in adherens junction biogenesis, with M. Heuzé, G. Sankara, T. Dang, J. d’Alessandro, V. Cellerin, D. Williams, J. van Hest, R.M. Mège, and B. Ladoux (journal, bioRXiv)
 Sustained oscillations of epithelial cell sheets, with G. Peyret, R. Mueller, J. d’Alessandro, S. Begnaud, R.M. Mège, J. M. Yeomans, A. Doostmohammadi, and B. Ladoux (journal, bioRXiv)
 Kalman inversion stress microscopy, with V. Nier, G. Peyret, J. d’Alessandro, S. Ishihara and B. Ladoux (journal, arXiv)
 A mechanosensitive RhoA pathway that protects epithelia against acute tensile stress, with B.R. Acharya, A. NestorBergmann, X. Liang, S. Gupta, K. Duszyc, E. Gauquelin, G.A. Gomez, S. Budnar, O.E. Jensen, Z. Bryant and A.S. Yap (journal)
 Topological defects in epithelia govern cell death and extrusion, with T. B. Saw, A. Doostmohammadi, V. Nier, L. Kocgozlu, S. Thampi, Y. Toyama, C. T. Lim, J. M. Yeomans and B. Ladoux (journal)
 Inference of internal stress in a cell monolayer, with V. Nier, S. Jain, C. T. Lim, S. Ishihara and B. Ladoux (journal, arXiv)
We combine traction force data with Bayesian inversion to obtain an absolute estimate of the internal stress field of a cell monolayer. The method, Bayesian inversion stress microscopy, is validated using numerical simulations performed in a wide range of conditions. It is robust to changes in each ingredient of the underlying statistical model. Importantly, its accuracy does not depend on the rheology of the tissue. We apply Bayesian inversion stress microscopy to experimental traction force data measured in a narrow ring of cohesive epithelial cells, and check that the inferred stress field coincides with that obtained by direct spatial integration of the traction force data in this quasi onedimensional geometry
 Robustness of force and stress inference in an epithelial tissue, with K. Sugimura, Y. Bellaïche, F. Graner and S. Ishihara (journal, arXiv)
Pattern formation
Stress fibers are contractile actomyosin bundles commonly observed in the cytoskeleton of metazoan cells. The spatial profile of the polarity of actin filaments inside contractile actomyosin bundles is either monotonic (graded) or periodic (alternating). In the framework of linear irreversible thermodynamics, we write the constitutive equations for a polar, active, elastic onedimensional medium. An analysis of the resulting equations for the dynamics of polarity shows that the transition from graded to alternating polarity patterns is a nonequilibrium Lifshitz point. Active contractility is a necessary condition for the emergence of sarcomeric, alternating polarity patterns.
 Cotransportinduced instability of membrane voltage in tipgrowing cells, with M.Léonetti, J. Nübler and F. Homblé (journal, arXiv)
 Exact solutions of the onedimensional quintic complex Ginzburg Landau equation, with H. Chaté and R. Conte (journal, arXiv)
 Timeaveraging of chaotic spatiotemporal wave patterns, with B.J. Gluckman, J. Bridger and J. Gollub (journal)
Nonequilibrium statistical physics
 Tissue fusion over nonadhering surfaces, with V. Nier, M. Deforet, G. Duclos, H.G. Yevick, O. CochetEscartin and P. Silberzan (journal, arXiv)
 Nonlinear oscillator with parametric colored noise: some analytical results, with K. Mallick (journal, arXiv)
 Anharmonic oscillator driven by additive OrnsteinUhlenbeck noise, with K. Mallick (journal, arXiv)
 On the stochastic pendulum with OrnsteinUhlenbeck noise, with K. Mallick (journal, arXiv)
 Noiseinduced reentrant transition of the stochastic Duffing oscillator, with K. Mallick (journal, arXiv)
We derive the exact bifurcation diagram of the Duffing oscillator with parametric noise thanks to the analytical study of the associated Lyapunov exponent. When the fixed point is unstable for the underlying deterministic dynamics, we show that the system undergoes a noiseinduced reentrant transition in a given range of parameters. The fixed point is stabilised when the amplitude of the noise belongs to a welldefined interval. Noisy oscillations are found outside that range, i.e., for both weaker and stronger noise.
 Stability analysis of a noiseinduced Hopf bifurcation, with K. Mallick (journal, arXiv)
 Scaling behavior of a nonlinear oscillator with additive noise, white and colored, with K. Mallick (journal, arXiv)
 Effects of parametric noise on a nonlinear oscillator, with K. Mallick (journal, arXiv)
 Anomalous diffusion in nonlinear oscillators with multiplicative noise, with K. Mallick (journal, arXiv)
 A Langevin equation for turbulent velocity increments, with A. Naert (journal, HAL)
 A Langevin equation for the energy cascade in fullydeveloped turbulence, with A. Naert (journal, arXiv)
 Critical properties of perioddoubling phase transitions in lattices of coupled logistic maps, with H. Chaté and P. Manneville (journal, arXiv)
 Earlytime critical dynamics of lattices of coupled chaotic maps, with H. Chaté and P. Manneville (journal, arXiv)
 Universality in Isinglike phase transitions of lattices of coupled chaotic maps, with H. Chaté and P. Manneville (journal)
 Universal critical behavior in twodimensional coupled map lattices, with H. Chaté and P. Manneville (journal)
 Nontrivial collective behavior in extensivelychaotic dynamical systems: an update, with H. Chaté, A. Lemaître and P. Manneville (journal)