scholarly journals Microtopographical guidance of macropinocytic signaling patches

2021 ◽  
Vol 118 (50) ◽  
pp. e2110281118
Author(s):  
Gen Honda ◽  
Nen Saito ◽  
Taihei Fujimori ◽  
Hidenori Hashimura ◽  
Mitsuru J. Nakamura ◽  
...  
Keyword(s):  
Immune Cells ◽  
Large Scale ◽  
Nanometer Scale ◽  
Distinct Mode ◽  
Structured Surfaces ◽  
Curvature Sensing ◽  
Quantitative Image ◽  
Membrane Protrusions ◽  
Particle Ingestion ◽  
Micrometer Scale

In fast-moving cells such as amoeba and immune cells, dendritic actin filaments are spatiotemporally regulated to shape large-scale plasma membrane protrusions. Despite their importance in migration, as well as in particle and liquid ingestion, how their dynamics are affected by micrometer-scale features of the contact surface is still poorly understood. Here, through quantitative image analysis of Dictyostelium on microfabricated surfaces, we show that there is a distinct mode of topographical guidance directed by the macropinocytic membrane cup. Unlike other topographical guidance known to date that depends on nanometer-scale curvature sensing protein or stress fibers, the macropinocytic membrane cup is driven by the Ras/PI3K/F-actin signaling patch and its dependency on the micrometer-scale topographical features, namely PI3K/F-actin–independent accumulation of Ras-GTP at the convex curved surface, PI3K-dependent patch propagation along the convex edge, and its actomyosin-dependent constriction at the concave edge. Mathematical model simulations demonstrate that the topographically dependent initiation, in combination with the mutually defining patch patterning and the membrane deformation, gives rise to the topographical guidance. Our results suggest that the macropinocytic cup is a self-enclosing structure that can support liquid ingestion by default; however, in the presence of structured surfaces, it is directed to faithfully trace bent and bifurcating ridges for particle ingestion and cell guidance.

scholarly journals Micro-topographical guidance of macropinocytic signaling patches

2020 ◽  
Author(s):  
Gen Honda ◽  
Nen Saito ◽  
Taihei Fujimori ◽  
Hidenori Hashimura ◽  
Mitsuru J. Nakamura ◽  
...  
Keyword(s):  
Immune Cells ◽  
Large Scale ◽  
Quantitative Imaging ◽  
Surface Features ◽  
Temporal Regulation ◽  
Large Particles ◽  
Membrane Protrusions ◽  
Spatio Temporal ◽  
Micrometer Scale ◽  
Scale Surface

AbstractIn fast moving cells such as amoeba and immune cells, spatio-temporal regulation of dendritic actin filaments shapes large-scale plasma membrane protrusions. Despite the importance in migration as well as in particle and liquid ingestion, how these processes are affected by the micrometer-scale surface features is poorly understood. Here, through quantitative imaging analysis of Dictyostelium on micro-fabricated surfaces, we show that there is a distinct mode of topographically guided cell migration ‘phagotaxis’ directed by the macropinocytic Ras/PI3K signaling patches. The topography guidance was PI3K-dependent and involved nucleation of a patch at the convex curved surface and confinement at the concave surface. Due to the topography-dependence, constitutive cup formation for liquid uptake in the axenic strain is also destined to trace large surface features. Given the fact that PI3K-dependency of phagocytosis are restricted to large particles in both Dictyostelium and immune cells, topography-dependency and the dual-use of membrane cups may be wide-spread.

scholarly journals Additive-Enhanced Exfoliation for High-Yield 2D Materials Production

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 601
Author(s):  
Dinh-Tuan Nguyen ◽  
Hsiang-An Ting ◽  
Yen-Hsun Su ◽  
Mario Hofmann ◽  
Ya-Ping Hsieh
Keyword(s):  
Large Scale ◽  
2D Materials ◽  
Transition Metal Dichalcogenides ◽  
Spectroscopic Characterization ◽  
High Yield ◽  
Nanometer Scale ◽  
Efficient Production ◽  
Device Performance ◽  
Metal Dichalcogenides ◽  
Scale Deposition

The success of van-der-Waals electronics, which combine large-scale-deposition capabilities with high device performance, relies on the efficient production of suitable 2D materials. Shear exfoliation of 2D materials’ flakes from bulk sources can generate 2D materials with low amounts of defects, but the production yield has been limited below industry requirements. Here, we introduce additive-assisted exfoliation (AAE) as an approach to significantly increase the efficiency of shear exfoliation and produce an exfoliation yield of 30%. By introducing micrometer-sized particles that do not exfoliate, the gap between rotor and stator was dynamically reduced to increase the achievable shear rate. This enhancement was applied to WS2 and MoS2 production, which represent two of the most promising 2D transition-metal dichalcogenides. Spectroscopic characterization and cascade centrifugation reveal a consistent and significant increase in 2D material concentrations across all thickness ranges. Thus, the produced WS2 films exhibit high thickness uniformity in the nanometer-scale and can open up new routes for 2D materials production towards future applications.

scholarly journals An amphipathic helix enables septins to sense micrometer-scale membrane curvature

2019 ◽  
Vol 218 (4) ◽  
pp. 1128-1137 ◽  
Author(s):  
Kevin S. Cannon ◽  
Benjamin L. Woods ◽  
John M. Crutchley ◽  
Amy S. Gladfelter
Keyword(s):  
Membrane Curvature ◽  
Amphipathic Helix ◽  
Curvature Sensing ◽  
C Terminus ◽  
Number Of Binding Sites ◽  
Curved Membranes ◽  
Necessary And Sufficient ◽  
Micrometer Scale

Cell shape is well described by membrane curvature. Septins are filament-forming, GTP-binding proteins that assemble on positive, micrometer-scale curvatures. Here, we examine the molecular basis of curvature sensing by septins. We show that differences in affinity and the number of binding sites drive curvature-specific adsorption of septins. Moreover, we find septin assembly onto curved membranes is cooperative and show that geometry influences higher-order arrangement of septin filaments. Although septins must form polymers to stay associated with membranes, septin filaments do not have to span micrometers in length to sense curvature, as we find that single-septin complexes have curvature-dependent association rates. We trace this ability to an amphipathic helix (AH) located on the C-terminus of Cdc12. The AH domain is necessary and sufficient for curvature sensing both in vitro and in vivo. These data show that curvature sensing by septins operates at much smaller length scales than the micrometer curvatures being detected.

scholarly journals Ramesh Shrestha, Sheng Shen and Maarten P. de Boer *

Actuators ◽  
2018 ◽  
Vol 7 (4) ◽  
pp. 71 ◽  
Author(s):  
Ramesh Shrestha ◽  
Sheng Shen ◽  
Maarten P. de Boer
Keyword(s):  
Thermal Properties ◽  
Molecular Chain ◽  
Nanometer Scale ◽  
Mechanical And Thermal Properties ◽  
Polymer Nanofibers ◽  
Scale Size ◽  
Scale Test ◽  
High Degree ◽  
Micrometer Scale ◽  
Measurement Artifacts

Because they can achieve a high degree of molecular chain alignment in comparison with their bulk counterparts, the mechanical and thermal properties of polymer nanofibers are of great interest. However, due to their nanometer-scale size, it is difficult to manipulate, grip, and test these fibers. Here, we demonstrate simple repeatable methods to transfer as-drawn fibers to micrometer-scale test platforms where their properties can be directly measured. Issues encountered and methods to minimize measurement artifacts are also discussed.

Nanometer-scale features on micrometer-scale surface texturing: A bone histological, gene expression, and nanomechanical study

Bone ◽  
2014 ◽  
Vol 65 ◽  
pp. 25-32 ◽  
Author(s):  
Paulo G. Coelho ◽  
Tadahiro Takayama ◽  
Daniel Yoo ◽  
Ryo Jimbo ◽  
Sanjay Karunagaran ◽  
...  
Keyword(s):  
Gene Expression ◽  
Surface Texturing ◽  
Nanometer Scale ◽  
Micrometer Scale ◽  
Scale Surface

Sub-nanometer scale size-control of iron oxide nanoparticles with drying time of iron oleate

CrystEngComm ◽  
2019 ◽  
Vol 21 (27) ◽  
pp. 4063-4071 ◽  
Author(s):  
Thiruparasakthi Balakrishnan ◽  
Min-Jae Lee ◽  
Jahar Dey ◽  
Sung-Min Choi
Keyword(s):  
Decomposition Method ◽  
Large Scale ◽  
Size Control ◽  
Nanometer Scale ◽  
Reliable Control ◽  
Drying Time ◽  
Thermal Decomposition Method ◽  
Scale Size ◽  
Fine Size ◽  
Scale Step

The drying time of iron oleate as a single and reliable control parameter for the fine size control (with a sub-nanometer scale step) of monodisperse IONPs in the large-scale thermal decomposition method.

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