Second Harmonic Generation of Unpolarized Light

Ding, Changqin; Ulcickas, James R. W.; Deng, Fengyuan; Simpson, Garth J.

doi:10.1103/physrevlett.119.193901

Cited by 15 publications

(11 citation statements)

References 26 publications

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“…It is interesting to compare the present results with previous measurements of SHG of collagen tissue obtained with fully depolarized incident light, prepared using a microretarder array depolarizer . In that work, the NLO response was used to directly fit azimuthal and polar orientation of collagen, yielding good agreement between image analysis approaches and direct fitting to the azimuthal orientation angle of collagen.…”

Section: Results and Discussionsupporting

confidence: 53%

“…Equation holds provided that the NLO process itself is intrinsically nondepolarizing, in which case the Mueller tensor M (2) allows prediction of the partially polarized state of the SHG produced by partially polarized incident light. The validity of this framework has been supported previously utilizing SHG measurements of Z -cut quartz and thin collagen sections . It was shown that for fully depolarized incident fields, resultant SHG followed intensity trends predicted by the Stokes–Mueller framework.…”

Section: Theoretical Foundationmentioning

confidence: 57%

“…The complexity of the vectorized tensor determining SHG activity is thus reduced from 64 in the Mueller framework to 8 in the Jones framework. We have demonstrated the validity of the Jones/Mueller framework in the limit of a completely depolarized fundamental, showing excellent predictive capacity for the model system of Z-cut quartz and enabling the recovery of the tensor element ratio ρ as well as orientation of collagen fibers in a thin tissue section of mouse tail …”

Section: Introductionmentioning

confidence: 96%

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Mueller Tensor Nonlinear Optical Polarization Analysis in Turbid Media

Ulcickas

Simpson

2019

J. Phys. Chem. B

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A mathematical framework to treat partial polarization in second harmonic generation imaging of nonlinear optical susceptibility is described and applied to imaging tissue sections 5, 40, and 70 μm thick, sufficient to introduce significant depolarization of the incident field. Polarization analysis becomes complicated in turbid media, in which scattering can result in degradation of polarization purity. The simplest framework for describing the polarization of purely polarized light is the Jones framework, which has been applied to great effect in the polarization analysis of second harmonic generation. However, the Jones framework lacks the necessary generality to describe a partially polarized electric field, (i.e., ones positioned within the volume of the Poincaré sphere rather than on the surface). Recent work connecting the Jones framework to the Mueller–Stokes framework has enabled interpretation of results with the more intuitive Jones framework while maintaining generality of the Mueller–Stokes method. The magnitude and nature of linear interactions of the tissue with the incident infrared field are discussed. Despite substantial depolarization, the nonlinear optical susceptibility tensor elements of collagen was recoverable at each pixel images of thick tissue utilizing the described framework. For thick and thin tissues, values of the tensor element ratio ρ were recovered in good agreement with previous studies. Both hyperpolarizing and depolarizing effects of SHG were observed, and the mechanism of hyperpolarization was determined to rest upon the interplay of orientation and relative contribution of polarized and depolarized incident light to elicit SHG.

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Section: Results and Discussionsupporting

confidence: 53%

Section: Theoretical Foundationmentioning

confidence: 57%

Section: Introductionmentioning

confidence: 96%

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Mueller Tensor Nonlinear Optical Polarization Analysis in Turbid Media

Ulcickas

Simpson

2019

J. Phys. Chem. B

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“…Cell and western blot quantification and analysis were performed using ImageJ. Phalloidin staining (F-actin) images of single cells were analyzed for filament coherency using the OrientationJ plugin for ImageJ 59 .…”

Section: Methodsmentioning

confidence: 99%

TGFβ signaling curbs cell fusion and muscle regeneration

et al. 2021

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Muscle cell fusion is a multistep process involving cell migration, adhesion, membrane remodeling and actin-nucleation pathways to generate multinucleated myotubes. However, molecular brakes restraining cell–cell fusion events have remained elusive. Here we show that transforming growth factor beta (TGFβ) pathway is active in adult muscle cells throughout fusion. We find TGFβ signaling reduces cell fusion, regardless of the cells’ ability to move and establish cell-cell contacts. In contrast, inhibition of TGFβ signaling enhances cell fusion and promotes branching between myotubes in mouse and human. Exogenous addition of TGFβ protein in vivo during muscle regeneration results in a loss of muscle function while inhibition of TGFβR2 induces the formation of giant myofibers. Transcriptome analyses and functional assays reveal that TGFβ controls the expression of actin-related genes to reduce cell spreading. TGFβ signaling is therefore requisite to limit mammalian myoblast fusion, determining myonuclei numbers and myofiber size.

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“…Cell quantification and analysis was performed using ImageJ ® . Phalloidin staining (F-actin) images of single cells were analysed for filament coherency using the Orientationβ plugin for ImageJ 46 .…”

Section: Methodsmentioning

confidence: 99%

TGFβ signaling curbs cell fusion and muscle regeneration

Girardi

Taleb

Giordani

et al. 2019

Preprint

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SummaryFusion of muscle progenitor cells is necessary for skeletal muscle development and repair. Cell fusion is a multistep process involving cell migration, adhesion, membrane remodeling and actin-nucleation pathways to generate multinucleated myotubes. While the cellular and molecular mechanisms promoting muscle cell fusion have been intensely investigated in recent years, molecular brakes restraining cell–cell fusion events to control syncytia formation have remained elusive. Here, we show that transforming growth factor beta (TGFβ) signaling is active in adult muscle cells throughout the fusion process and reduce muscle cell fusion independently of the differentiation step. In contrast, inhibition of TGFβ signaling enhances cell fusion and promotes branching between myotubes. Pharmacological modulation of the pathway in vivo perturbs muscle regeneration after injury. Exogenous addition of TGFβ protein results in a loss of muscle function while inhibition of the TGFβ pathway induces the formation of giant myofibres. Transcriptome analyses and functional assays revealed that TGFβ acts on actin dynamics and reduce cell spreading through modulation of actin-based protrusions. Together our results reveal a signaling pathway that limits mammalian myoblast fusion and add a new level of understanding to the molecular regulation of myogenesis.

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Second Harmonic Generation of Unpolarized Light

Cited by 15 publications

References 26 publications

Mueller Tensor Nonlinear Optical Polarization Analysis in Turbid Media

Mueller Tensor Nonlinear Optical Polarization Analysis in Turbid Media

TGFβ signaling curbs cell fusion and muscle regeneration

TGFβ signaling curbs cell fusion and muscle regeneration

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