scholarly journals Membrane fusion studied by colloidal probes

2021 ◽  
Vol 50 (2) ◽  
pp. 223-237 ◽  
Author(s):  
Hannes Witt ◽  
Filip Savić ◽  
Sarah Verbeek ◽  
Jörn Dietz ◽  
Gesa Tarantola ◽  
...  
Keyword(s):  
Membrane Fusion ◽  
Optical Tweezers ◽  
Three Dimensional ◽  
Biological Processes ◽  
Supported Membranes ◽  
Supported Bilayers ◽  
Force Microscopy ◽  
Advantages And Disadvantages ◽  
Atomic Force ◽  
Colloidal Probes

AbstractMembrane-coated colloidal probes combine the benefits of solid-supported membranes with a more complex three-dimensional geometry. This combination makes them a powerful model system that enables the visualization of dynamic biological processes with high throughput and minimal reliance on fluorescent labels. Here, we want to review recent applications of colloidal probes for the study of membrane fusion. After discussing the advantages and disadvantages of some classical vesicle-based fusion assays, we introduce an assay using optical detection of fusion between membrane-coated glass microspheres in a quasi two-dimensional assembly. Then, we discuss free energy considerations of membrane fusion between supported bilayers, and show how colloidal probes can be combined with atomic force microscopy or optical tweezers to access the fusion process with even greater detail.

scholarly journals Accurate nanoscale flexibility measurement of DNA and DNA–protein complexes by atomic force microscopy in liquid

Nanoscale ◽  
2017 ◽  
Vol 9 (31) ◽  
pp. 11327-11337 ◽  
Author(s):  
Divakaran Murugesapillai ◽  
Serge Bouaziz ◽  
L. James Maher ◽  
Nathan E. Israeloff ◽  
Craig E. Cameron ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Optical Tweezers ◽  
Protein Complexes ◽  
Persistence Length ◽  
Three Dimensional ◽  
Force Microscopy ◽  
Atomic Force ◽  
Afm Imaging ◽  
Flexibility Measurement ◽  
Length Measurements

We obtain accurate three-dimensional persistence length measurements for DNA and DNA–protein complexes using liquid AFM imaging, validated by optical tweezers.

scholarly journals Mg2+-binding shifts the IM30 activity from membrane protection to membrane destabilization

2020 ◽  
Author(s):  
Benedikt Junglas ◽  
Amelie Axt ◽  
Carmen Siebenaller ◽  
Hilal Sonel ◽  
Nadja Hellmann ◽  
...  
Keyword(s):  
Membrane Fusion ◽  
Thylakoid Membrane ◽  
Cellular Localization ◽  
Supported Bilayers ◽  
Force Microscopy ◽  
Membrane Surfaces ◽  
Atomic Force ◽  
Spatio Temporal ◽  
Chloroplast Stroma ◽  
External Stimuli

ABSTRACTThe inner membrane-associated protein of 30 kDa (IM30) is essential in chloroplasts and cyanobacteria. The spatio-temporal cellular localization of the protein appears to be highly dynamic and triggered by internal as well as external stimuli, mainly light intensity. A soluble fraction of the protein is localized in the cyanobacterial cytoplasm or the chloroplast stroma, respectively. Additionally, the protein attaches to the thylakoid membrane as well as to the chloroplast inner envelope or the cyanobacterial cytoplasmic membrane, respectively, especially under conditions of membrane stress. IM30 is involved in thylakoid membrane biogenesis and/or maintenance, where it either stabilizes membranes and/or triggers membrane-fusion processes. These apparently contradicting processes have to be tightly controlled and separated spatiotemporally in chloroplasts and cyanobacteria. The latter process depends on Mg2+-binding to IM30; yet, it still is unclear how Mg2+-loaded IM30 interacts with membranes and promotes membrane fusion. Here we show that interaction of Mg2+ with IM30 results in increased binding of IM30 to native as well as model membranes. Via Atomic Force Microscopy in liquid, IM30-induced bilayer defects were observed in solid-supported bilayers in presence of Mg2+. The observed interaction of IM30 with membrane surfaces differs dramatically from previously observed membrane-stabilizing, carpet-like structures in the absence of Mg2+. Mg2+-induced alterations of the IM30 structure switches the IM30 activity from a membrane-stabilizing to a membrane-destabilizing function, a crucial step in membrane fusion.

Cryogenic atomic force microscopy

1991 ◽  
Vol 49 ◽  
pp. 54-55
Author(s):  
K. A. Fisher ◽  
M. G. L. Gustafsson ◽  
M. B. Shattuck ◽  
J. Clarke
Keyword(s):  
Room Temperature ◽  
Rapid Freezing ◽  
Cryogenic Temperatures ◽  
Soft Or ◽  
Electrically Conductive ◽  
Force Microscopy ◽  
Flexible Molecules ◽  
Advantages And Disadvantages ◽  
Atomic Force ◽  
Chemical Perturbation

The atomic force microscope (AFM) is capable of imaging electrically conductive and non-conductive surfaces at atomic resolution. When used to image biological samples, however, lateral resolution is often limited to nanometer levels, due primarily to AFM tip/sample interactions. Several approaches to immobilize and stabilize soft or flexible molecules for AFM have been examined, notably, tethering coating, and freezing. Although each approach has its advantages and disadvantages, rapid freezing techniques have the special advantage of avoiding chemical perturbation, and minimizing physical disruption of the sample. Scanning with an AFM at cryogenic temperatures has the potential to image frozen biomolecules at high resolution. We have constructed a force microscope capable of operating immersed in liquid n-pentane and have tested its performance at room temperature with carbon and metal-coated samples, and at 143° K with uncoated ferritin and purple membrane (PM).

scholarly journals Biomechanics of Neutrophil Tethers

Life ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 515
Author(s):  
Andrea Cugno ◽  
Alex Marki ◽  
Klaus Ley
Keyword(s):  
Cell Activation ◽  
Optical Trap ◽  
Biomechanical Properties ◽  
Force Microscopy ◽  
Advantages And Disadvantages ◽  
Atomic Force ◽  
Microfluidic Flow ◽  
Biomembrane Force Probe ◽  
Membrane Reservoir

Leukocytes, including neutrophils, which are propelled by blood flow, can roll on inflamed endothelium using transient bonds between selectins and their ligands, and integrins and their ligands. When such receptor–ligand bonds last long enough, the leukocyte microvilli become extended and eventually form thin, 20 m long tethers. Tether formation can be observed in blood vessels in vivo and in microfluidic flow chambers. Tethers can also be extracted using micropipette aspiration, biomembrane force probe, optical trap, or atomic force microscopy approaches. Here, we review the biomechanical properties of leukocyte tethers as gleaned from such measurements and discuss the advantages and disadvantages of each approach. We also review and discuss viscoelastic models that describe the dependence of tether formation on time, force, rate of loading, and cell activation. We close by emphasizing the need to combine experimental observations with quantitative models and computer simulations to understand how tether formation is affected by membrane tension, membrane reservoir, and interactions of the membrane with the cytoskeleton.

Study of NSCLC cell migration promoted by NSCLC-Derived Extracellular Vesicle using atomic force microscopy

2021 ◽  
Author(s):  
Shuwei Wang ◽  
Jiajia Wang ◽  
Tuoyu Ju ◽  
Kaige Qu ◽  
Fan Yang ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Cell Migration ◽  
Cancer Cells ◽  
Extracellular Vesicles ◽  
Extracellular Vesicle ◽  
Cancer Microenvironment ◽  
Biological Processes ◽  
Force Microscopy ◽  
Atomic Force ◽  
Cellular Components

Extracellular Vesicles (EVs) secreted by cancer cells have a key role in the cancer microenvironment and progression. Previous studies have mainly focused on molecular functions, cellular components and biological processes...

scholarly journals Acoustic subsurface-atomic force microscopy: Three-dimensional imaging at the nanoscale

2021 ◽  
Vol 129 (3) ◽  
pp. 030901
Author(s):  
Hossein J. Sharahi ◽  
Mohsen Janmaleki ◽  
Laurene Tetard ◽  
Seonghwan Kim ◽  
Hamed Sadeghian ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Three Dimensional ◽  
Three Dimensional Imaging ◽  
Force Microscopy ◽  
Atomic Force

scholarly journals Measuring the Autocorrelation Function of Nanoscale Three-Dimensional Density Distribution in Individual Cells Using Scanning Transmission Electron Microscopy, Atomic Force Microscopy, and a New Deconvolution Algorithm

2017 ◽  
Vol 23 (3) ◽  
pp. 661-667 ◽  
Author(s):  
Yue Li ◽  
Di Zhang ◽  
Ilker Capoglu ◽  
Karl A. Hujsak ◽  
Dhwanil Damania ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Density Distribution ◽  
Scanning Transmission Electron Microscopy ◽  
Mass Density ◽  
Three Dimensional ◽  
Force Microscopy ◽  
Statistical Measures ◽  
Atomic Force ◽  
Transmission Electron ◽  
Scanning Transmission

AbstractEssentially all biological processes are highly dependent on the nanoscale architecture of the cellular components where these processes take place. Statistical measures, such as the autocorrelation function (ACF) of the three-dimensional (3D) mass–density distribution, are widely used to characterize cellular nanostructure. However, conventional methods of reconstruction of the deterministic 3D mass–density distribution, from which these statistical measures can be calculated, have been inadequate for thick biological structures, such as whole cells, due to the conflict between the need for nanoscale resolution and its inverse relationship with thickness after conventional tomographic reconstruction. To tackle the problem, we have developed a robust method to calculate the ACF of the 3D mass–density distribution without tomography. Assuming the biological mass distribution is isotropic, our method allows for accurate statistical characterization of the 3D mass–density distribution by ACF with two data sets: a single projection image by scanning transmission electron microscopy and a thickness map by atomic force microscopy. Here we present validation of the ACF reconstruction algorithm, as well as its application to calculate the statistics of the 3D distribution of mass–density in a region containing the nucleus of an entire mammalian cell. This method may provide important insights into architectural changes that accompany cellular processes.

High-resolution transmission electron microscopic investigations of molybdenum thin films on faceted α-Al2O3

2005 ◽  
Vol 38 (2) ◽  
pp. 260-265 ◽  
Author(s):  
Leonore Wiehl ◽  
Jens Oster ◽  
Michael Huth
Keyword(s):  
High Resolution ◽  
Three Dimensional ◽  
Epitaxial Relationship ◽  
Electron Microscopic ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
High Resolution Images ◽  
Α Al2o3 ◽  
Relationship Of

Epitaxially grown Mo films on a faceted corundum (α-Al2O3)mplane were investigated by transmission electron microscopy. Low- and high-resolution images were taken from a cross-section specimen cut perpendicular to the facets. It was possible to identify unambiguously the crystallographic orientation of these facets and explain the considerable deviation (∼10°) of the experimental interfacet angle, as measured with atomic force microscopy (AFM), from the expected value. For the first time, proof is given for a smooth \{10\bar{1}1\} facet and a curvy facet with orientation near to \{10\bar{1}\bar{2}\}. Moreover, the three-dimensional epitaxial relationship of an Mo film on a faceted corundummsurface was determined.

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