How tissue shape emerges from the collective mechanical properties and behavior of individual cells is not understood. We combine experiment theory to study this problem in developing wing epithelium Drosophila. At pupal stages, wing-hinge contraction contributes anisotropic flows that reshape blade. Here, we quantitatively account for wing-blade change on basis cell divisions, rearrangements changes. show both generate respond epithelial stresses during process, nature interplay specifies...

The propagation of electrical impulses along axons is highly accelerated by the myelin sheath and produces saltating or "jumping" action potentials across internodes, from one node Ranvier to next. underlying circuit, as well existence role submyelin conduction in saltatory remain, however, elusive. Here, we made patch-clamp high-speed voltage-calibrated optical recordings nodal internodal axolemma myelinated neocortical pyramidal combined with electron microscopy experimentally constrained...

Recent studies identified two main components of store-operated calcium entry (SOCE): the endoplasmic reticulum-localized Ca2+ sensor protein, STIM1, and plasma membrane (PM)-localized channel, Orai1/CRACM1. In present study, we investigated phosphoinositide dependence Orai1 channel activation in PM STIM1 movements from tubular to PM-adjacent reticulum regions during store depletion. Phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) levels were changed either with agonist stimulation or...

Purkinje neurons are the output cells of cerebellar cortex and generate spikes in two distinct modes, known as simple complex spikes. Revealing point origin these action potentials, how they conduct into local axon collaterals, is important for understanding distal neuronal processing communication. By using a recent improvement voltage-sensitive dye imaging technique that provided exceptional spatial temporal resolution, we were able to resolve region spike initiation well follow...

Segmentation and tracking of cells in long-term time-lapse experiments has emerged as a powerful method to understand how tissue shape changes emerge from the complex choreography constituent cells. However, methods store interrogate large datasets produced by these are not widely available. Furthermore, recently developed for relating cell dynamics have yet been applied biologists because their technical complexity. We therefore database format that stores cellular connectivity geometry...

Non‐technical summary Axons are long process of nerve cells that mediate communication and control within the organism. Mammalian neurons have developed a complex ion channel clustering mechanism in axons to optimize rapid signalling. It has been discovered recently intricate details spatial pattern play critical role signal processing axon. The electrical properties axons, however, difficult study using electrodes because very small diameter. We took advantage methodological improvement...

Quantitative analysis of the dynamic cellular mechanisms shaping Drosophila wing during its larval growth phase has been limited, impeding our ability to understand how morphogen patterns regulate tissue shape. Such requires imaging explants under conditions that maintain both and patterning, as well methods quantify much behaviors change Here, we demonstrate a key requirement for steroid hormone 20-hydroxyecdysone (20E) in maintenance numerous patterning systems vivo explant culture. We...

Abstract Thousands of dendritic spines on individual neurons process information and mediate plasticity by generating electrical input signals using a sophisticated assembly transmitter receptors voltage-sensitive ion channel molecules. Our understanding, however, the behaviour is limited because it has not been possible to record from these structures with adequate sensitivity spatiotemporal resolution. Current interpretation indirect data speculations based theoretical considerations are...

ABSTRACT The formation of a new head during Hydra regeneration involves the establishment organizer that functions as signaling center and contains an aster-shaped topological defect in organization supracellular actomyosin fibers. Here, we show future region regenerating tissue fragments undergoes multiple instances extensive stretching rupture events from onset regeneration. These recurring localized deformations arise due to transient contractions ectodermal fibers focus mechanical strain...

The shape of action potentials invading presynaptic terminals, which can vary significantly from spike waveforms recorded at the soma, may critically influence probability synaptic neurotransmitter release. Revealing conductances that determine in boutons is important for understanding how changes electrochemical context a generated, such as subthreshold depolarization spreading modulate strength. Utilizing recent improvements signal-to-noise ratio voltage-sensitive dye imaging mouse brain...

There is a pressing need in neuroscience for genetically-encoded, fluorescent voltage probes that can be targeted to specific neurons and circuits allow study of neural activity using imaging. We created 90 constructs which the sensing portion (S1-S4) Ciona intestinalis sensitive phosphatase (CiVSP) was fused circularly permuted eGFP. This led ElectricPk, probe an order magnitude faster (taus ~1-2 ms) than any currently published protein-based probe. ElectricPk follow rise fall neuronal...

This paper addresses the deformation of two-dimensional networks cells, such as thin biological tissues, using geometrical considerations. The authors use a triangulation scheme to identify main contributions strain generated when tissue is deformed, and apply their method particular case fruit-fly wing.

The response of amorphous materials to an applied strain can be continuous, or instead display a macroscopic stress drop when shear band nucleates. Such discontinuous observed if the initial configuration is very stable. We study theoretically how such brittleness emerges in athermal, quasi-statically driven, as their stability increased. show that this emergence well reproduced by elasto-plastic models and predicted mean field approximation, where it corresponds continuous transition. In...

Alzheimer's disease, progressive supranuclear palsy and frontotemporal dementia are characterized by neuronal expression of aberrant tau protein, hyperphosphorylation (pTAU), aggregation neurofibrillary tangle formation sequentially culminating into cell death, a process termed tauopathy. Our aim was to address at which tauopathy stage neuroinflammation starts study the related microglial phenotype. We used Thy1-hTau.P301S (PS) mice expressing human with P301S mutation specifically in...

Ensheathment of axons by myelin is a highly complex and multi-cellular process. Cytosolic calcium (Ca2+) changes in the sheath have been implicated synthesis, but source this Ca2+ role neuronal activity not well understood. Using one-photon imaging, we investigated formation mouse somatosensory cortex found high rate spontaneous microdomain transients large-amplitude waves propagating along internode. The frequency rapidly declines with maturation reactivates during remyelination....

Tissue organization is often characterized by specific patterns of cell morphology. How such emerge in developing tissues a fundamental open question. Here, we investigate the emergence tissue-scale shape and mechanical tissue stress

We provide a theoretical description of dynamical heterogeneities in glass-forming liquids, based on the premise that relaxation occurs via local rearrangements coupled by elasticity. In our framework, growth correlation length ξ and volume χ4 are controlled zero-temperature fixed point. connect this critical behavior to properties distribution energy barriers at zero temperature. Our makes direct connection between avalanche-type associated dynamic facilitation, allowing us relate size...

The formation of a new head during Hydra regeneration involves the establishment organizer that functions as signaling center and contains an aster-shaped topological defect in organization supracellular actomyosin fibers. Here we show future region regenerating tissue fragments undergoes multiple instances extensive stretching rupture events from onset regeneration. These recurring localized deformations arise due to transient contractions ectodermal fibers focus mechanical strain at sites....

In cortical pyramidal neurons the presynaptic terminals controlling transmitter release are located along unmyelinated axon collaterals, far from original action potential (AP) initiation site, initial segment (AIS). Once initiated, APs will need to propagate over long distances and regions of geometrical inhomogeneity like branch points (BPs) rapidly depolarize containing vesicles machinery. While pathologies such as demyelinating diseases well established impede fidelity AP propagation...

Quasilocalized modes appear in the vibrational spectrum of amorphous solids at low frequency. Though never formalized, these are believed to have a close relationship with other important local excitations, including shear transformations and two-level systems. We provide theory for their frequency density, D_{L}(ω)∼ω^{α}, that establishes this link systems zero temperature under quasistatic loading. It predicts two regimes depending on density P(x)∼x^{θ} (with x additional stress needed...

Abstract Amorphous materials exhibit complex material properties with strongly nonlinear behaviors. Below a yield stress they behave as plastic solids, while start to above critical Σ c . A key quantity controlling plasticity which is, however, hard measure is the density P ( x ) of weak spots, where additional required for local failure. In thermodynamic limit ∼ θ singular at = 0 in solid phase below This singularity related presence system spanning avalanches events. Here we address...

This study introduces a rheological model to elucidate the aging behavior observed in biological condensates, providing foundational theoretical framework better understand complex material properties of these membraneless biomolecular assemblies.