The Experts below are selected from a list of 16989 Experts worldwide ranked by ideXlab platform
Matthew J. Tyska - One of the best experts on this subject based on the ideXlab platform.
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nonmuscle myosin 2 contractility dependent actin turnover limits the length of epithelial microvilli
Molecular Biology of the Cell, 2020Co-Authors: Colbie R. Chinowsky, Julia A. Pinette, Leslie M. Meenderink, Ken S Lau, Matthew J. TyskaAbstract:Brush border microvilli enable functions that are critical for epithelial homeostasis, including solute uptake and host defense. However, the mechanisms that regulate the assembly and morphology of these protrusions are poorly understood. The parallel actin bundles that support microvilli have their pointed-end rootlets anchored in a filamentous meshwork referred to as the "terminal web." Although classic electron microscopy studies revealed complex ultrastructure, the composition and function of the terminal web remain unclear. Here we identify nonmuscle myosin-2C (NM2C) as a component of the terminal web. NM2C is found in a dense, Isotropic Layer of puncta across the subapical domain, which transects the rootlets of microvillar actin bundles. Puncta are separated by ∼210 nm, the expected size of filaments formed by NM2C. In intestinal organoid cultures, the terminal web NM2C network is highly dynamic and exhibits continuous remodeling. Using pharmacological and genetic perturbations in cultured intestinal epithelial cells, we found that NM2C controls the length of growing microvilli by regulating actin turnover in a manner that requires a fully active motor domain. Our findings answer a decades-old question on the function of terminal web myosin and hold broad implications for understanding apical morphogenesis in diverse epithelial systems.
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Non-muscle myosin-2 contractility-dependent actin turnover limits the length of epithelial microvilli
2020Co-Authors: Colbie R. Chinowsky, Julia A. Pinette, Leslie M. Meenderink, Matthew J. TyskaAbstract:ABSTRACT Epithelial brush borders are large arrays of microvilli that enable efficient solute uptake from luminal spaces. In the context of the intestinal tract, brush border microvilli drive functions that are critical for physiological homeostasis, including nutrient uptake and host defense. However, cytoskeletal mechanisms that regulate the assembly and morphology of these protrusions are poorly understood. The parallel actin bundles that support microvilli have their pointed-end rootlets anchored in a highly crosslinked filamentous meshwork referred to as the “terminal web”. Although classic EM studies revealed complex ultrastructure, the composition, organization, and function of the terminal web remains unclear. Here, we identify non-muscle myosin-2C (NM2C) as a major component of the brush border terminal web. NM2C is found in a dense, Isotropic Layer of puncta across the sub-apical domain, which transects the rootlets of microvillar actin bundles. Puncta in this network are separated by ∼210 nm, dimensions that are comparable to the expected size of filaments formed by NM2C. In primary intestinal organoid cultures, the terminal web NM2C network is highly dynamic and exhibits continuous remodeling. Using pharmacological and genetic perturbations to disrupt NM2C activity in cultured intestinal epithelial cells, we found that this motor controls the length of growing microvilli by regulating actin turnover in a manner that requires a fully active motor domain. Our findings answer a decades old question on the function of terminal web myosin and hold broad implications for understanding apical morphogenesis in diverse epithelial systems.
Shishir Gupta - One of the best experts on this subject based on the ideXlab platform.
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love type wave propagation in a hydrostatic stressed magneto elastic transversely Isotropic strip over an inhomogeneous substrate caused by a disturbance point source
Journal of Intelligent Material Systems and Structures, 2018Co-Authors: Parvez Alam, Santimoy Kundu, Shishir GuptaAbstract:Propagation of Love-type waves emanating due to a disturbance point source in a transversely Isotropic Layer of finite thickness laid over a semi-infinite half-space is investigated. The Layer is a...
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love wave propagation in a fiber reinforced medium sandwiched between an Isotropic Layer and gravitating half space
Journal of Engineering Mathematics, 2016Co-Authors: Santimoy Kundu, Shishir Gupta, Deepak Kr Pandit, Santanu MannaAbstract:This paper is devoted to study of the dispersion equation of Love waves in a fiber-reinforced medium sandwiched between an Isotropic Layer and elastic half-space under the influence of gravity. The equations of motion have been discussed in each media. The frequency equation of a Love wave was obtained using the separation of variables method and Whittaker’s function expansion under a suitable assumption. The boundary conditions were introduced at interfaces of the upper Layer, intermediate medium, and half-space. The dispersion equation was derived in closed form by means of Biot’s gravity parameter. The particular cases have been derived in the absence of reinforcement and gravitational force of the reinforced Layer and half-space, respectively. Numerical solutions were discussed graphically to show the nature of wave propagation. Dimensionless phase velocity was obtained against non-dimensional wave number for different values of reinforced parameters, Biot’s gravity parameter, and thickness ratio of the upper Layer and intermediate Layer.
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torsional wave propagation in non homogeneous Layer between non homogeneous half spaces
International Journal for Numerical and Analytical Methods in Geomechanics, 2013Co-Authors: Amares Chattopadhyay, Shishir Gupta, Pato Kumari, V K SharmaAbstract:SUMMARY The study of surface wave in a Layered medium has their possible application in geophysical prospecting. In the present work, dispersion equation for torsional wave in an inhomogeneous Isotropic Layer between inhomogeneous Isotropic half-spaces has been derived. Two cases are discussed separately for torsional wave propagation in inhomogeneous Layer between homogeneous and non-homogeneous half-spaces, respectively. Further, two possible modes for torsional wave propagation are obtained in case of inhomogeneous Layer sandwiched between non-homogeneous half-spaces. Closed form solutions for displacement in the Layer and half-spaces are obtained in each case. The study reveals that the Layer width, Layer inhomogeneity, frequency of inhomogeneity, as well as inhomogeneity in the half-space has significant effect on the propagation of torsional surface waves. Displacement and implicit dispersion equation for torsional wave velocities are expressed in terms of Heun functions and their derivatives. Effects of inhomogeneity on torsional wave velocity are also discussed graphically by plotting the dimensionless phase velocity against dimensionless and scaled wave number for different values of inhomogeneity parameter. Copyright © 2012 John Wiley & Sons, Ltd.
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propagation of shear waves in an irregular magnetoelastic monoclinic Layer sandwiched between two Isotropic half spaces
International journal of engineering science and technology, 2010Co-Authors: Amares Chattopadhyay, Shishir Gupta, Abhishek Singh, Sanjeev A SahuAbstract:In the present paper we study the propagation of horizontally polarised shear waves (SH waves) in an internal magnetoelastic monoclinic stratum with rectangular irregularity in lower interface and is sandwiched between two semi-infinite Isotropic elastic media. The dispersion equation has been obtained. It is observed that the dispersion equation is in assertion with the classical Love-type wave equation, for Isotropic Layer sandwiched between two Isotropic half spaces, in the absence of magnetic field and irregularity. The effects of depth of irregularity and monoclinic-magnetoelastic coupling parameters on dispersion curves are depicted by means of graphs. This study shows the remarkable effect of wave number, size of irregularity and magnetic field on the phase velocity. Keywords: SH wave, magnetoelastic monoclinic, irregularity, dispersion equation, perturbation
Colbie R. Chinowsky - One of the best experts on this subject based on the ideXlab platform.
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nonmuscle myosin 2 contractility dependent actin turnover limits the length of epithelial microvilli
Molecular Biology of the Cell, 2020Co-Authors: Colbie R. Chinowsky, Julia A. Pinette, Leslie M. Meenderink, Ken S Lau, Matthew J. TyskaAbstract:Brush border microvilli enable functions that are critical for epithelial homeostasis, including solute uptake and host defense. However, the mechanisms that regulate the assembly and morphology of these protrusions are poorly understood. The parallel actin bundles that support microvilli have their pointed-end rootlets anchored in a filamentous meshwork referred to as the "terminal web." Although classic electron microscopy studies revealed complex ultrastructure, the composition and function of the terminal web remain unclear. Here we identify nonmuscle myosin-2C (NM2C) as a component of the terminal web. NM2C is found in a dense, Isotropic Layer of puncta across the subapical domain, which transects the rootlets of microvillar actin bundles. Puncta are separated by ∼210 nm, the expected size of filaments formed by NM2C. In intestinal organoid cultures, the terminal web NM2C network is highly dynamic and exhibits continuous remodeling. Using pharmacological and genetic perturbations in cultured intestinal epithelial cells, we found that NM2C controls the length of growing microvilli by regulating actin turnover in a manner that requires a fully active motor domain. Our findings answer a decades-old question on the function of terminal web myosin and hold broad implications for understanding apical morphogenesis in diverse epithelial systems.
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Non-muscle myosin-2 contractility-dependent actin turnover limits the length of epithelial microvilli
2020Co-Authors: Colbie R. Chinowsky, Julia A. Pinette, Leslie M. Meenderink, Matthew J. TyskaAbstract:ABSTRACT Epithelial brush borders are large arrays of microvilli that enable efficient solute uptake from luminal spaces. In the context of the intestinal tract, brush border microvilli drive functions that are critical for physiological homeostasis, including nutrient uptake and host defense. However, cytoskeletal mechanisms that regulate the assembly and morphology of these protrusions are poorly understood. The parallel actin bundles that support microvilli have their pointed-end rootlets anchored in a highly crosslinked filamentous meshwork referred to as the “terminal web”. Although classic EM studies revealed complex ultrastructure, the composition, organization, and function of the terminal web remains unclear. Here, we identify non-muscle myosin-2C (NM2C) as a major component of the brush border terminal web. NM2C is found in a dense, Isotropic Layer of puncta across the sub-apical domain, which transects the rootlets of microvillar actin bundles. Puncta in this network are separated by ∼210 nm, dimensions that are comparable to the expected size of filaments formed by NM2C. In primary intestinal organoid cultures, the terminal web NM2C network is highly dynamic and exhibits continuous remodeling. Using pharmacological and genetic perturbations to disrupt NM2C activity in cultured intestinal epithelial cells, we found that this motor controls the length of growing microvilli by regulating actin turnover in a manner that requires a fully active motor domain. Our findings answer a decades old question on the function of terminal web myosin and hold broad implications for understanding apical morphogenesis in diverse epithelial systems.
V K Sharma - One of the best experts on this subject based on the ideXlab platform.
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reflection refraction pattern of quasi p sv waves in dissimilar monoclinic media separated with finite Isotropic Layer
Journal of Vibration and Control, 2016Co-Authors: Pato Kumari, V K Sharma, Chitra ModiAbstract:This paper concentrates on the study of reflection and refraction of incident quasi (P/SV) waves in dissimilar monoclinic media separated by an Isotropic Layer of finite thickness. It is shown that...
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propagation of torsional waves in a viscoelastic Layer over an inhomogeneous half space
Acta Mechanica, 2014Co-Authors: Pato Kumari, V K SharmaAbstract:This paper presents a theoretical study on propagation of torsional surface waves in a homogeneous viscoelastic Isotropic Layer with Voigt type viscosity over an inhomogeneous Isotropic infinite half space. The non-homogeneity in half space is assumed to arise due to exponential variation in shear modulus and density. A closed-form solution has been obtained for the displacement in the Layer as well as for a infinite half space. The dispersion and absorption relations for an torsional wave under the assumed geometry have been found. Numerical results are presented for propagation characteristics in terms of a number of non-dimensionalized parameters and have been produced graphically. This study investigates the effect of various parameters, namely non-homogeneity parameter, internal friction, the Layer width and complex wave number on dissipation function and phase velocity of the torsional wave. Results in some special cases are also compared with existing solutions available from analytical methods, which show a close agreement.
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torsional wave propagation in non homogeneous Layer between non homogeneous half spaces
International Journal for Numerical and Analytical Methods in Geomechanics, 2013Co-Authors: Amares Chattopadhyay, Shishir Gupta, Pato Kumari, V K SharmaAbstract:SUMMARY The study of surface wave in a Layered medium has their possible application in geophysical prospecting. In the present work, dispersion equation for torsional wave in an inhomogeneous Isotropic Layer between inhomogeneous Isotropic half-spaces has been derived. Two cases are discussed separately for torsional wave propagation in inhomogeneous Layer between homogeneous and non-homogeneous half-spaces, respectively. Further, two possible modes for torsional wave propagation are obtained in case of inhomogeneous Layer sandwiched between non-homogeneous half-spaces. Closed form solutions for displacement in the Layer and half-spaces are obtained in each case. The study reveals that the Layer width, Layer inhomogeneity, frequency of inhomogeneity, as well as inhomogeneity in the half-space has significant effect on the propagation of torsional surface waves. Displacement and implicit dispersion equation for torsional wave velocities are expressed in terms of Heun functions and their derivatives. Effects of inhomogeneity on torsional wave velocity are also discussed graphically by plotting the dimensionless phase velocity against dimensionless and scaled wave number for different values of inhomogeneity parameter. Copyright © 2012 John Wiley & Sons, Ltd.
Ivan Argatov - One of the best experts on this subject based on the ideXlab platform.
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jkr adhesive contact for a transversely Isotropic Layer of finite thickness
Journal of Physics D, 2016Co-Authors: Ivan Argatov, Feodor M Borodich, Valentin L PopovAbstract:A frictionless contact interaction with a circular area of contact between an arbitrary axisymmetric rigid probe and a transversely isotopic elastic Layer deposited on a substrate is studied in the framework of the JKR (Johnson, Kendall, and Roberts) adhesion theory. Under the assumption that the diameter of the contact area is less than the thickness of the elastic Layer, the forth-order asymptotic model is explicitly written out. The effect of the Layer thickness and the material anisotropy is taken into account via the asymptotic coefficients, which are integral characteristics of the elastic Layer and also depend on the boundary conditions at the Layer/substrate interface. A special case of an Isotropic elastic Layer bonded to an Isotropic elastic half-space is considered in detail.
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depth sensing indentation of a transversely Isotropic elastic Layer second order asymptotic models for canonical indenters
International Journal of Solids and Structures, 2011Co-Authors: Ivan ArgatovAbstract:Simple analytical approximations to the frictionless indentation problem for a transversely Isotropic Layer are obtained for spherical, conical, and pyramidal indenters as well as for axisymmetric indenters of power-low profile and self-similar non-axisymmetric indenters. These approximations are asymptotically exact in the small-contact limit. The results obtained are validated in the case of an Isotropic Layer for spherical and conical indenters.
