keyword
MENU ▼
Read by QxMD icon Read
search

cryo electron tomography

keyword
https://www.readbyqxmd.com/read/28100648/multi-scale-structural-analysis-of-plant-er-pm-contact-sites
#1
Heather E McFarlane, Eun Kyoung Lee, Laura S van Bezouwen, Bradford Ross, Abel Rosado, A Lacey Samuels
Membrane contact sites (MCS) are recognized across eukaryotic systems as important nanostructures. Endoplasmic reticulum (ER)-plasma membrane (PM) contact sites (EPCS) are involved in excitation-contraction coupling, signalling, and plant responses to stress. In this report, we perform a multi-scale structural analysis of Arabidopsis EPCS that combine live cell imaging, quantitative transmission electron microscopy (TEM), and electron tomography over a developmental gradient. To place EPCS in the context of the entire cortical ER, we examined GFP-HDEL in living cells over a developmental gradient, then SYT1-GFP was used as a specific marker of EPCS...
January 18, 2017: Plant & Cell Physiology
https://www.readbyqxmd.com/read/28052246/synucleins-have-multiple-effects-on-presynaptic-architecture
#2
Karina J Vargas, Nikolas Schrod, Taylor Davis, Ruben Fernandez-Busnadiego, Yumiko V Taguchi, Ulrike Laugks, Vladan Lucic, Sreeganga S Chandra
Synucleins (α, β, γ-synuclein) are a family of abundant presynaptic proteins. α-Synuclein is causally linked to the pathogenesis of Parkinson's disease (PD). In an effort to define their physiological and pathological function or functions, we investigated the effects of deleting synucleins and overexpressing α-synuclein PD mutations, in mice, on synapse architecture using electron microscopy (EM) and cryoelectron tomography (cryo-ET). We show that synucleins are regulators of presynapse size and synaptic vesicle (SV) pool organization...
January 3, 2017: Cell Reports
https://www.readbyqxmd.com/read/27993658/membrane-assisted-viral-dna-ejection
#3
Isaac Santos-Pérez, Hanna M Oksanen, Dennis H Bamford, Felix M Goñi, David Reguera, Nicola G A Abrescia
Genome packaging and delivery are fundamental steps in the replication cycle of all viruses. Icosahedral viruses with linear double-stranded DNA (dsDNA) usually package their genome into a preformed, rigid procapsid using the power generated by a virus-encoded packaging ATPase. The pressure and stored energy due to this confinement of DNA at a high density is assumed to drive the initial stages of genome ejection. Membrane-containing icosahedral viruses, such as bacteriophage PRD1, present an additional architectural complexity by enclosing their genome within an internal membrane vesicle...
December 16, 2016: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/27981875/three-dimensional-imaging-of-drosophila-motor-synapses-reveals-ultrastructural-organizational-patterns
#4
Hong Zhan, Joseph Bruckner, Ziheng Zhang, Kate O'Connor-Giles
We combined cryo-preservation of intact Drosophila larvae and electron tomography with comprehensive segmentation of key features to reconstruct the complete ultrastructure of a model glutamatergic synapse in a near-to-native state. Presynaptically, we detail a complex network of filaments that connects and organizes synaptic vesicles. We link the complexity of this synaptic vesicle network to proximity to the active zone cytomatrix, consistent with the model that these protein structures function together to regulate synaptic vesicle pools...
September 2016: Journal of Neurogenetics
https://www.readbyqxmd.com/read/27980210/the-structure-and-flexibility-of-conical-hiv-1-capsids-determined-within-intact-virions
#5
Simone Mattei, Bärbel Glass, Wim J H Hagen, Hans-Georg Kräusslich, John A G Briggs
HIV-1 contains a cone-shaped capsid encasing the viral genome. This capsid is thought to follow fullerene geometry-a curved hexameric lattice of the capsid protein, CA, closed by incorporating 12 CA pentamers. Current models for core structure are based on crystallography of hexameric and cross-linked pentameric CA, electron microscopy of tubular CA arrays, and simulations. Here, we report subnanometer-resolution cryo-electron tomography structures of hexameric and pentameric CA within intact HIV-1 particles...
December 16, 2016: Science
https://www.readbyqxmd.com/read/27977021/correlated-fluorescence-microscopy-and-cryo-electron-tomography-of-virus-infected-or-transfected-mammalian-cells
#6
Cheri M Hampton, Joshua D Strauss, Zunlong Ke, Rebecca S Dillard, Jason E Hammonds, Eric Alonas, Tanay M Desai, Mariana Marin, Rachel E Storms, Fredrick Leon, Gregory B Melikyan, Philip J Santangelo, Paul W Spearman, Elizabeth R Wright
Correlative light and electron microscopy (CLEM) combines spatiotemporal information from fluorescence light microscopy (fLM) with high-resolution structural data from cryo-electron tomography (cryo-ET). These technologies provide opportunities to bridge knowledge gaps between cell and structural biology. Here we describe our protocol for correlated cryo-fLM, cryo-electron microscopy (cryo-EM), and cryo-ET (i.e., cryo-CLEM) of virus-infected or transfected mammalian cells. Mammalian-derived cells are cultured on EM substrates, using optimized conditions that ensure that the cells are spread thinly across the substrate and are not physically disrupted...
January 2017: Nature Protocols
https://www.readbyqxmd.com/read/27956360/defining-the-hierarchical-organisation-of-collagen-vi-microfibrils-at-nanometre-to-micrometre-length-scales
#7
Alan R F Godwin, Tobias Starborg, Michael J Sherratt, Alan M Roseman, Clair Baldock
: Extracellular matrix microfibrils are critical components of connective tissues with a wide range of mechanical and cellular signalling functions. Collagen VI is a heteromeric network-forming collagen which is expressed in tissues such as skin, lung, blood vessels and articular cartilage where it anchors cells into the matrix allowing for transduction of biochemical and mechanical signals. It is not understood how collagen VI is arranged into microfibrils or how these microfibrils are arranged into tissues...
December 10, 2016: Acta Biomaterialia
https://www.readbyqxmd.com/read/27943193/3d-analysis-of-synaptic-ultrastructure-in-organotypic-hippocampal-slice-culture-by-high-pressure-freezing-and-electron-tomography
#8
Cordelia Imig, Benjamin H Cooper
Transmission electron microscopy serves as a valuable tool for synaptic structure-function analyses aimed at identifying morphological features or modifications associated with specific developmental stages or dysfunctional synaptic states. By utilizing cryo-preparation techniques to minimize the introduction of structural artifacts during sample preparation, and electron tomography to reconstruct the 3D ultrastructural architecture of a synapse, the spatial organization and morphological properties of synaptic organelles and subcompartments can be quantified with unparalleled precision...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/27849173/imaging-the-motility-and-chemotaxis-machineries-in-helicobacter-pylori-by-cryo-electron-tomography
#9
Zhuan Qin, Wei-Ting Lin, Shiwei Zhu, Aime T Franco, Jun Liu
: Helicobacter pylori is a bacterial pathogen that can cause many gastrointestinal diseases including ulcers and gastric cancer. A unique chemotaxis-mediated motility is critical for H. pylori to colonize in the human stomach and to establish chronic infection, but the underlying molecular mechanisms are not well understood. Here we employ cryo-electron tomography to reveal detailed structures of the H. pylori cell envelope including the sheathed flagella and chemotaxis arrays. Notably, H...
November 14, 2016: Journal of Bacteriology
https://www.readbyqxmd.com/read/27836840/three-dimensional-structure-of-the-ultraoligotrophic-marine-bacterium-candidatus-pelagibacter-ubique
#10
Xiaowei Zhao, Cindi L Schwartz, Jason Pierson, Stephen J Giovannoni, J Richard McIntosh, Daniela Nicastro
: SAR11 bacteria are small, heterotrophic, marine alphaproteobacteria found throughout the oceans. They thrive at the low nutrient concentrations typical of open ocean conditions, although the adaptations required for life under those conditions are not well understood. To illuminate this issue, we used cryo-electron tomography to study "Candidatus Pelagibacter ubique" strain HTCC1062, a member of the SAR11 clade. Our results revealed its cellular dimensions and details of its intracellular organization...
February 1, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/27824088/trehalose-prevents-aggregation-of-exosomes-and-cryodamage
#11
Steffi Bosch, Laurence de Beaurepaire, Marie Allard, Mathilde Mosser, Claire Heichette, Denis Chrétien, Dominique Jegou, Jean-Marie Bach
Exosomes are important mediators in intercellular communication. Released by many cell types, they transport proteins, lipids, and nucleic acids to distant recipient cells and contribute to important physiopathological processes. Standard current exosome isolation methods based on differential centrifugation protocols tend to induce aggregation of particles in highly concentrated suspensions and freezing of exosomes can induce damage and inconsistent biological activity. Trehalose is a natural, non-toxic sugar widely used as a protein stabilizer and cryoprotectant by the food and drug industry...
November 8, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27748356/nanoimaging-granule-dynamics-and-subcellular-structures-in-activated-mast-cells-using-soft-x-ray-tomography
#12
Huan-Yuan Chen, Dapi Meng-Lin Chiang, Zi-Jing Lin, Chia-Chun Hsieh, Gung-Chian Yin, I-Chun Weng, Peter Guttermann, Stephan Werner, Katja Henzler, Gerd Schneider, Lee-Jene Lai, Fu-Tong Liu
Mast cells play an important role in allergic responses. During activation, these cells undergo degranulation, a process by which various kinds of mediators stored in the granules are released. Granule homeostasis in mast cells has mainly been studied by electron microscopy (EM), where the fine structures of subcellular organelles are partially destroyed during sample preparation. Migration and fusion of granules have not been studied in detail in three dimensions (3D) in unmodified samples. Here, we utilized soft X-ray tomography (SXT) coupled with fluorescence microscopy to study the detailed structures of organelles during mast cell activation...
October 17, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27742578/hierarchical-detection-and-analysis-of-macromolecular-complexes-in-cryo-electron-tomograms-using-pyto-software
#13
Vladan Lučić, Rubén Fernández-Busnadiego, Ulrike Laugks, Wolfgang Baumeister
Molecular complexes, arguably the basic units carrying cellular function, can be visualized directly in their native environment by cryo-electron tomography. Here we describe a procedure for the detection of small, pleomorphic membrane-bound molecular complexes in cryo-tomograms by a hierarchical connectivity segmentation. Validation on phantom and real data showed above 90% true positive rates. This segmentation procedure is implemented in the Pyto software package, together with methods for quantitative characterization and classification of complexes detected by our segmentation procedure and for statistical analysis between experimental conditions...
December 2016: Journal of Structural Biology
https://www.readbyqxmd.com/read/27731339/ultrastructure-of-compacted-dna-in-cyanobacteria-by-high-voltage-cryo-electron-tomography
#14
Kazuyoshi Murata, Sayuri Hagiwara, Yoshitaka Kimori, Yasuko Kaneko
Some cyanobacteria exhibit compaction of DNA in synchrony with their circadian rhythms accompanying cell division. Since the structure is transient, it has not yet been described in detail. Here, we successfully visualize the ultrastructure of compacted DNA in the cyanobacterium Synechococcus elongatus PCC 7942 under rigorous synchronized cultivation by means of high-voltage cryo-electron tomography. In 3D reconstructions of rapidly frozen cells, the compacted DNA appears as an undulating rod resembling a eukaryotic condensed chromosome...
October 12, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27726354/peptide-directed-assembly-of-single-helical-gold-nanoparticle-superstructures-exhibiting-intense-chiroptical-activity
#15
Andrea D Merg, Jennifer C Boatz, Abhishek Mandal, Gongpu Zhao, Soumitra Mokashi-Punekar, Chong Liu, Xianting Wang, Peijun Zhang, Patrick C A van der Wel, Nathaniel L Rosi
Chiral nanoparticle assemblies are an interesting class of materials whose chiroptical properties make them attractive for a variety of applications. Here, C18-(PEPAu(M-ox))2 (PEPAu(M-ox) = AYSSGAPPM(ox)PPF) is shown to direct the assembly of single-helical gold nanoparticle superstructures that exhibit exceptionally strong chiroptical activity at the plasmon frequency with absolute g-factor values up to 0.04. Transmission electron microscopy (TEM) and cryogenic electron tomography (cryo-ET) results indicate that the single helices have a periodic pitch of approximately 100 nm and consist of oblong gold nanoparticles...
October 11, 2016: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/27716029/simulating-cryo-electron-tomograms-of-crowded-cell-cytoplasm-for-assessment-of-automated-particle-picking
#16
Long Pei, Min Xu, Zachary Frazier, Frank Alber
BACKGROUND: Cryo-electron tomography is an important tool to study structures of macromolecular complexes in close to native states. A whole cell cryo electron tomogram contains structural information of all its macromolecular complexes. However, extracting this information remains challenging, and relies on sophisticated image processing, in particular for template-free particle extraction, classification and averaging. To develop these methods it is crucial to realistically simulate tomograms of crowded cellular environments, which can then serve as ground truth models for assessing and optimizing methods for detection of complexes in cell tomograms...
October 5, 2016: BMC Bioinformatics
https://www.readbyqxmd.com/read/27688057/using-electron-microscopes-to-look-into-the-lung
#17
REVIEW
Matthias Ochs, Lars Knudsen, Jan Hegermann, Christoph Wrede, Roman Grothausmann, Christian Mühlfeld
In the nineteenth century, there was a dispute about the existence of a lung alveolar epithelium which remained unsolved until the invention of electron microscopy (EM) and its application to the lung. From the early 1960s, Ewald Weibel became the master of lung EM. He showed that the alveolar epithelium is covered with a lining layer containing surfactant. Weibel also explained the phenomenon of "non-nucleated plates" observed already in 1881 by Albert Kölliker. Weibel's most significant contribution was to the development of stereological methods...
December 2016: Histochemistry and Cell Biology
https://www.readbyqxmd.com/read/27685097/resolving-macromolecular-structures-from-electron-cryo-tomography-data-using-subtomogram-averaging-in-relion
#18
Tanmay A M Bharat, Sjors H W Scheres
Electron cryo-tomography (cryo-ET) is a technique that is used to produce 3D pictures (tomograms) of complex objects such as asymmetric viruses, cellular organelles or whole cells from a series of tilted electron cryo-microscopy (cryo-EM) images. Averaging of macromolecular complexes found within tomograms is known as subtomogram averaging, and this technique allows structure determination of macromolecular complexes in situ. Subtomogram averaging is also gaining in popularity for the calculation of initial models for single-particle analysis...
November 2016: Nature Protocols
https://www.readbyqxmd.com/read/27678408/exploring-the-theoretical-basis-and-limitations-of-cryo-stem-tomography-for-thick-biological-specimens
#19
Peter Rez, Thomas Larsen, Michael Elbaum
Scanning transmission electron microscope (STEM) imaging has recently been applied to the cryo-tomography of thick biological specimens. As previously shown for plastic sections, STEM has a number of advantages for cryo-imaging compared to conventional wide-field TEM imaging. STEM is insensitive to phase coherence and is therefore suitable for much thicker specimens than TEM. Imaging in focus, with a long depth of field, also circumvents the complications of an oscillatory contrast transfer function and missing information at low spatial frequencies...
December 2016: Journal of Structural Biology
https://www.readbyqxmd.com/read/27671779/cryo-electron-tomography-can-it-reveal-the-molecular-sociology-of-cells-in-atomic-detail
#20
Martin Beck, Wolfgang Baumeister
Traditionally, macromolecular structure determination is performed ex situ, that is, with purified materials. But, there are strong incentives to develop approaches to study them in situ in their native functional context. In recent years, cryo-electron tomography (cryo-ET) has emerged as a powerful method for visualizing the molecular organization of unperturbed cellular landscapes with the potential to attain near-atomic resolution. Here, we review recent work on several macromolecular assemblies, demonstrating the power of in situ studies...
September 23, 2016: Trends in Cell Biology
keyword
keyword
76654
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"