scholarly journals Periodic traction in migrating large amoeba of Physarum polycephalum

2015 ◽  
Vol 12 (106) ◽  
pp. 20150099 ◽  
Author(s):  
Jean-Paul Rieu ◽  
Hélène Delanoë-Ayari ◽  
Seiji Takagi ◽  
Yoshimi Tanaka ◽  
Toshiyuki Nakagaki
Keyword(s):  
Physarum Polycephalum ◽  
Traction Force ◽  
Cortical Layer ◽  
Force Distribution ◽  
Locomotory Activity ◽  
Multinucleated Cell ◽  
Force Microscopy ◽  
Giant Multinucleated Cell ◽  
Shuttle Streaming

The slime mould Physarum polycephalum is a giant multinucleated cell exhibiting well-known Ca 2+ -dependent actomyosin contractions of its vein network driving the so-called cytoplasmic shuttle streaming. Its actomyosin network forms both a filamentous cortical layer and large fibrils. In order to understand the role of each structure in the locomotory activity, we performed birefringence observations and traction force microscopy on excised fragments of Physarum . After several hours, these microplasmodia adopt three main morphologies: flat motile amoeba, chain types with round contractile heads connected by tubes and motile hybrid types. Each type exhibits oscillations with a period of about 1.5 min of cell area, traction forces and fibril activity (retardance) when fibrils are present. The amoeboid types show only peripheral forces while the chain types present a never-reported force pattern with contractile rings far from the cell boundary under the spherical heads. Forces are mostly transmitted where the actomyosin cortical layer anchors to the substratum, but fibrils maintain highly invaginated structures and contribute to forces by increasing the length of the anchorage line. Microplasmodia are motile only when there is an asymmetry in the shape and/or the force distribution.

scholarly journals Traction force screening enabled by compliant PDMS elastomers

2017 ◽  
Author(s):  
Haruka Yoshie ◽  
Newsha Koushki ◽  
Rosa Kaviani ◽  
Kavitha Rajendran ◽  
Quynh Dang ◽  
...  
Keyword(s):  
Retinal Pigment ◽  
Traction Force ◽  
Essential Element ◽  
Retinal Pigment Epithelial Cells ◽  
Airway Smooth Muscle Cells ◽  
Traction Forces ◽  
Force Microscopy ◽  
Dose Dependent ◽  
Pigment Epithelial Cells

AbstractActo-myosin contractility is an essential element of many aspects of cellular biology, and manifests as traction forces that cells exert on their surroundings. The central role of these forces makes them a novel principal therapeutic target in diverse diseases. This requires accurate and higher capacity measurements of traction forces; however, existing methods are largely low throughput, limiting their utility in broader applications. To address this need, we employ Fourier-transform traction force microscopy in a parallelized 96-well format, which we refer to as contractile force screening (CFS).Critically, rather than the frequently employed hydrogel polyacrylamide (PAA), we fabricate these plates using polydimethylsiloxane (PDMS) rubber. Key to this approach is that the PDMS used is very compliant, with a lower-bound Young’s modulus of approximately 0.7 kPa. We subdivide these monolithic substrates spatially into biochemically independent wells, creating a uniform multiwell platform for traction force screening. We demonstrate the utility and versatility of this platform by quantifying the compound and dose-dependent contractility responses of human airway smooth muscle cells and retinal pigment epithelial cells.

ANDROST-5-ENE-3β,17β-DIOL IN OVARY OF POST-MENOPAUSAL HYPEROESTROGENIC WOMEN

1968 ◽  
Vol 58 (3) ◽  
pp. 364-376 ◽  
Author(s):  
S. Pesonen ◽  
M. Ikonen ◽  
B-J. Procopé ◽  
A. Saure
Keyword(s):  
Ovarian Tissue ◽  
Cortical Layer ◽  
Vaginal Smears ◽  
Incubation Experiments ◽  
Cell Groups ◽  
Post Menopause ◽  
Reducing Activity ◽  
Post Menopausal ◽  
One Year

ABSTRACT The ovaries of ten patients, at least one year after the post-menopause, were incubated with two Δ5-C19-steroids and also studied histochemically. All these patients had post-menopausal uterine bleeding and increased oestrogen excretion of the urine. The urinary estimations of gonadotrophins, 17-KS, 17-OHCS and pregnanediol were carried out on all patients. Vaginal smears were read according to Papanicolaou, and the endometrium and ovaries were studied histologically. The incubation experiments indicate the presence of Δ5-3β-hydroxysteroid-dehydrogenase. When androst-5-ene-3β,17β-diol was used as precursor the formation of testosterone occurred without any concomitant production of DHA and/or androstenedione. This seems to indicate the possible role of the Δ5-pathway in the formation of testosterone by post-menopausal ovarian tissue. The histochemical reactions indicated a reducing activity on NADH, lactate and glucose-6-phosphate, in certain corpora albicantia, atretic follicles and in diffuse thecoma regions in the cortical layer of the ovary. Steroid-3β-ol-dehydrogenase and β-hydroxybutyrate-dehydrogenase were found only at the edges of certain corpora albicantia, in some individual stroma cell groups and in some atretic follicles. Our studies, both biochemical and histochemical, suggest that the observed increase in the urinary oestrogens of the patients studied might in part at least, be of ovarian origin. This opinion is also supported by the postoperative oestrogen values.

scholarly journals Two-dimensional TIRF-SIM–traction force microscopy (2D TIRF-SIM-TFM)

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Liliana Barbieri ◽  
Huw Colin-York ◽  
Kseniya Korobchevskaya ◽  
Di Li ◽  
Deanna L. Wolfson ◽  
...  
Keyword(s):  
Resolution Enhancement ◽  
Traction Force ◽  
Super Resolution ◽  
Traction Force Microscopy ◽  
Two Dimensional ◽  
Structured Illumination ◽  
Structured Illumination Microscopy ◽  
Force Microscopy ◽  
Health And Disease ◽  
Spatio Temporal

AbstractQuantifying small, rapidly evolving forces generated by cells is a major challenge for the understanding of biomechanics and mechanobiology in health and disease. Traction force microscopy remains one of the most broadly applied force probing technologies but typically restricts itself to slow events over seconds and micron-scale displacements. Here, we improve >2-fold spatially and >10-fold temporally the resolution of planar cellular force probing compared to its related conventional modalities by combining fast two-dimensional total internal reflection fluorescence super-resolution structured illumination microscopy and traction force microscopy. This live-cell 2D TIRF-SIM-TFM methodology offers a combination of spatio-temporal resolution enhancement relevant to forces on the nano- and sub-second scales, opening up new aspects of mechanobiology to analysis.

scholarly journals Different Cell Migration Modes: Insights from Traction Force Microscopy and Modeling

2021 ◽  
Vol 120 (3) ◽  
pp. 113a
Author(s):  
Wouter-Jan Rappel ◽  
Elisabeth Ghabache ◽  
Yuansheng Cao ◽  
Yuchuan Miao ◽  
Alexander Groisman ◽  
...  
Keyword(s):  
Cell Migration ◽  
Traction Force ◽  
Traction Force Microscopy ◽  
Force Microscopy

scholarly journals Real-space observation of ferroelectrically induced magnetic spin crystal in SrRuO3

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
S. D. Seddon ◽  
D. E. Dogaru ◽  
S. J. R. Holt ◽  
D. Rusu ◽  
J. J. P. Peters ◽  
...  
Keyword(s):  
Hall Effect ◽  
Density Functional ◽  
Hysteresis Loops ◽  
Real Space ◽  
Zero Field ◽  
Force Microscopy ◽  
Switching Regime ◽  
Conflicting Evidence ◽  
Magnetic Spin

AbstractUnusual features in the Hall Resistivity of thin film systems are frequently associated with whirling spin textures such as Skyrmions. A host of recent investigations of Hall Hysteresis loops in SrRuO3 heterostructures have provided conflicting evidence for different causes for such features. We have constructed an SrRuO3-PbTiO3 (Ferromagnetic – Ferroelectric) bilayer that exhibits features in the Hall Hysteresis previously attributed to a Topological Hall Effect, and Skyrmions. Here we show field dependent Magnetic Force Microscopy measurements throughout the key fields where the ‘THE’ presents, revealing the emergence to two periodic, chiral spin textures. The zero-field cycloidal phase, which then transforms into a ‘double-q’ incommensurate spin crystal appears over the appearance of the ‘Topological-like’ Hall effect region, and develop into a ferromagnetic switching regime as the sample reaches saturation, and the ‘Topological-like’ response diminishes. Scanning Tunnelling Electron Microscopy and Density Functional Theory is used to observe and analyse surface inversion symmetry breaking and confirm the role of an interfacial Dzyaloshinskii–Moriya interaction at the heart of the system.

Characterization of the porous nature of a phthalocyanine derivative with axial ligation designed to prevent aggregation

2010 ◽  
Vol 14 (05) ◽  
pp. 389-396
Author(s):  
Carl A. Barker ◽  
Alan Massey ◽  
Aidan Rhodes ◽  
Martin R. Bryce ◽  
Ritu Kataky
Keyword(s):  
Force Microscopy ◽  
Selective Transport ◽  
Electrode Surfaces ◽  
Axial Ligation ◽  
Nanoporous Films ◽  
Atom Force Microscopy ◽  
Solvent Cast ◽  
Complementary Techniques

Judiciously designed phthalocyanines (Pcs), such as silicon-Pc bis(3,5-diphenyl)benzoate (1c), with axial substituents which prevent aggregation, can self-assemble to form ordered nanoporous films on electrode surfaces. In this paper, complementary techniques such as Scanning Kelvin Nanoprobe (SKN) microscopy, Atom Force Microscopy (AFM) and electrochemical measurements are used to demonstrate that films formed by silicon-Pc bis(3,5-diphenyl)benzoate allow size- and charge- selective transport of probe molecules through well-defined intermolecular cavities. In contrast, the analogs silicon-Pc bis(4-tert-butylbenzoate) (1a) and silicon-Pc bis(3-thienyl)acetate (1b) have different film morphologies when solvent-cast in the same manner and block the electrode surface. The role of the different axial substituents in orienting the molecules on the substrate is discussed.

scholarly journals Quantification of electron accumulation at grain boundaries in perovskite polycrystalline films by correlative infrared-spectroscopic nanoimaging and Kelvin probe force microscopy

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Ting-Xiao Qin ◽  
En-Ming You ◽  
Mao-Xin Zhang ◽  
Peng Zheng ◽  
Xiao-Feng Huang ◽  
...  
Keyword(s):  
Solar Cell ◽  
Grain Boundaries ◽  
Cell Performance ◽  
Kelvin Probe Force Microscopy ◽  
Light Illumination ◽  
Kelvin Probe ◽  
Solar Cell Performance ◽  
Force Microscopy ◽  
Infrared Spectroscopic

AbstractOrganic–inorganic halide perovskites are emerging materials for photovoltaic applications with certified power conversion efficiencies (PCEs) over 25%. Generally, the microstructures of the perovskite materials are critical to the performances of PCEs. However, the role of the nanometer-sized grain boundaries (GBs) that universally existing in polycrystalline perovskite films could be benign or detrimental to solar cell performance, still remains controversial. Thus, nanometer-resolved quantification of charge carrier distribution to elucidate the role of GBs is highly desirable. Here, we employ correlative infrared-spectroscopic nanoimaging by the scattering-type scanning near-field optical microscopy with 20 nm spatial resolution and Kelvin probe force microscopy to quantify the density of electrons accumulated at the GBs in perovskite polycrystalline thin films. It is found that the electron accumulations are enhanced at the GBs and the electron density is increased from 6 × 1019 cm−3 in the dark to 8 × 1019 cm−3 under 10 min illumination with 532 nm light. Our results reveal that the electron accumulations are enhanced at the GBs especially under light illumination, featuring downward band bending toward the GBs, which would assist in electron-hole separation and thus be benign to the solar cell performance.

The role of cross-linking in the scratch resistance of organic coatings: An investigation using Atomic Force Microscopy

Wear ◽  
2019 ◽  
Vol 418-419 ◽  
pp. 151-159 ◽  
Author(s):  
Juan F. Gonzalez-Martinez ◽  
Erum Kakar ◽  
Stefan Erkselius ◽  
Nicola Rehnberg ◽  
Javier Sotres
Keyword(s):  
Atomic Force Microscopy ◽  
Scratch Resistance ◽  
Organic Coatings ◽  
Cross Linking ◽  
Force Microscopy ◽  
Atomic Force

scholarly journals Epifluorescence-based three-dimensional traction force microscopy

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Lauren Hazlett ◽  
Alexander K. Landauer ◽  
Mohak Patel ◽  
Hadley A. Witt ◽  
Jin Yang ◽  
...  
Keyword(s):  
Spatial Frequency ◽  
Open Source ◽  
Single Particle ◽  
Three Dimensional ◽  
Traction Force ◽  
High Spatial Frequency ◽  
Epifluorescence Microscopy ◽  
Traction Force Microscopy ◽  
Force Microscopy ◽  
Out Of Plane

Abstract We introduce a novel method to compute three-dimensional (3D) displacements and both in-plane and out-of-plane tractions on nominally planar transparent materials using standard epifluorescence microscopy. Despite the importance of out-of-plane components to fully understanding cell behavior, epifluorescence images are generally not used for 3D traction force microscopy (TFM) experiments due to limitations in spatial resolution and measuring out-of-plane motion. To extend an epifluorescence-based technique to 3D, we employ a topology-based single particle tracking algorithm to reconstruct high spatial-frequency 3D motion fields from densely seeded single-particle layer images. Using an open-source finite element (FE) based solver, we then compute the 3D full-field stress and strain and surface traction fields. We demonstrate this technique by measuring tractions generated by both single human neutrophils and multicellular monolayers of Madin–Darby canine kidney cells, highlighting its acuity in reconstructing both individual and collective cellular tractions. In summary, this represents a new, easily accessible method for calculating fully three-dimensional displacement and 3D surface tractions at high spatial frequency from epifluorescence images. We released and support the complete technique as a free and open-source code package.

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