Topological defects of integer charge in cell monolayers

Endresen, Kirsten; Kim, Min Su; Pittman, Matthew; Chen, Yun; Serra, Francesca

doi:10.1039/d1sm00100k

Cited by 32 publications

(42 citation statements)

References 46 publications

(79 reference statements)

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“…Similar inference of cell layer material properties based on theories of liquid crystals are also proposed by confining myoblasts in small circular adhesive islands to stabilise spiral topological defects at the centre of the confinement [81]. More recently, it is further shown that pre-patterned micron-sized ridges can be exploited to control alignment of fibroblast (3T6) and epithelial (EpH-4) cell layers to from stable full-integer topological defects [57]. Remarkably, it was shown that such pre-imposed patterns can control the activation/deactivation of mechanotransduction by triggering nuclear/cytoplasmic YAP translocation at topological defects with positive and negative charges and in different cell types.…”

Section: Exploiting Physics Of Liquid Crystals For Guiding Cellular S...mentioning

confidence: 54%

Physics of liquid crystals in cell biology

Doostmohammadi¹,

Ladoux²

2021

Preprint

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Section: Exploiting Physics Of Liquid Crystals For Guiding Cellular S...mentioning

confidence: 54%

Physics of liquid crystals in cell biology

Doostmohammadi¹,

Ladoux²

2021

Preprint

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“…Defects are not purely mathematical tools and have important biophysical implications such as controlling cell death and extrusion from a tissue monolayer [33], localizing proliferation [34], and guiding collective density [35]. Thus the control of defects represents an attempt at harnessing the power of active matter to do work at the collective scale [36][37][38][39]. As we develop these technologies further, we can benefit from insights into new ways to shape and control these defects in a polarized active matter.…”

Section: Review On Defect Dynamics and Inverse Energy Cascadementioning

confidence: 99%

Mobile defects born from an energy cascade shape the locomotive behavior of a headless animal

Bull,

Prakash

2021

Preprint

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The physics of behavior seeks simple descriptions of animal behavior. The field has advanced rapidly by using techniques in low dimensional dynamics distilled from computer vision. Yet, we still do not generally understand the rules which shape these emergent behavioral manifolds in the face of complicated neuro-construction -even in the simplest of animals. In this work, we introduce a non-neuromuscular model system which is complex enough to teach us something new but also simple enough for us to understand. In this simple animal, the manifolds underlying the governing dynamics are shaped and stabilized by a physical mechanism: an active-elastic, inverse-energy cascade. Building upon pioneering work in the field, we explore the formulation of the governing dynamics of a polarized active elastic sheet in terms of the normal modes of an elastic structure decorated by a polarized activity at every node. By incorporating a torque mediated coupling physics, we show that the power is pumped from the shortest length scale up to longer length scale modes via a combination of direct mode coupling and preferential dissipation of higher frequency modes. We use this result to motivate the study of organismal locomotion as an emergent simplicity governing organism-scale behavior. To master the low dimensional dynamics on this manifold, we present a zero-transients limit study of the dynamics of +1 or vortex-like defects in the ciliary field (which is experimentally supported for small organisms). We show, experimentally, numerically and analytically that these defects arise from this energy cascade to generate long-lived, stable modes of locomotive behavior. Using a geometric model, we show how the defect undergoes unbinding. We extend this framework as a tool for studying larger organisms with non-circular shape and introduce local activity modulation for defect steering. We expect this work to inform the foundations of organismal control of distributed actuation without muscles or neurons.

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“…[18,19] New publications continue to cover a wide range of topological defects. These include active motion of topological defects in LC media, [20] decomposition of center and saddle point disclinations, [21,22] ionically charged comet orbit and saddle point disclinations in nematic LCs, [23] skyrmions, [24] motile solitons, [25] and vortex lattices. [26] One example of topological defects, in nematic LCs, is the occurrence of horizontal domains.…”

Section: Introductionmentioning

confidence: 99%

Vertically Stacked Soliton‐Like Domain Walls in Nematic Liquid Crystals

Jones

Melnyk

Macêdo

et al. 2021

Advcd Theory and Sims

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In the standard liquid crystal (LC) geometry, one generally finds a quasi‐parabolic director profile in the vertical direction, where the directors are aligned with an applied field in the center of the cell. In contrast, using a numerical energy minimization approach, we find that there are multiple metastable solutions where the director profile is oscillatory. At low voltages, we find small oscillations, which evolve into standard soliton‐like domain walls as the applied voltage is increased. We predict the thickness of the domain wall with a simple analytic model that gives a good comparison to our numerical calculations, in the standard domain wall regime. For dual‐frequency nematic LCs, the occurrence of this regime can be tuned by a change of the biasing frequency. Moreover, we investigate how domain walls can affect the optical properties of LC‐based devices. For instance, we find that the transmittance curve shifts to higher voltages as domain walls are introduced. This shift can be used to create an efficient tunable filter.

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Topological defects of integer charge in cell monolayers

Abstract: Many cell types spontaneously order like nematic liquid crystals, and, as such, they form topological defects, which influence the cell organization. While defects with topological charge ±1/2 are common in...

Cited by 32 publications

References 46 publications

Physics of liquid crystals in cell biology

Physics of liquid crystals in cell biology

Mobile defects born from an energy cascade shape the locomotive behavior of a headless animal

Vertically Stacked Soliton‐Like Domain Walls in Nematic Liquid Crystals

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