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Single particle electron microscopy

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https://www.readbyqxmd.com/read/28812314/self-assembled-chiral-nanostructures-of-amphiphilic-peptide-from-single-molecule-to-aggregate
#1
Ting Zhou, Zhiqing Zhang, Xuemei Zhang, Chen Wang, Guiying Xu, Yanlian Yang
We report interesting hierarchical self-assembled architectures from a designed amphiphilic peptide. The bisignate cotton effects in circular dichroism spectra show typical peptide aggregation-induced. The observation of peptide assembly structures from initial particles and fibrils to ribbon structures is supported by microscopy (atomic force microscopy and transmission electron microscopy). The visualization of individual peptide at the single molecular level offered insights of the intermolecular interactions responsible for the formation of aggregates, which is investigated by scanning tunneling microscopy...
August 15, 2017: Journal of Peptide Science: An Official Publication of the European Peptide Society
https://www.readbyqxmd.com/read/28811473/plant-made-polio-type-3-stabilized-vlps-a-candidate-synthetic-polio-vaccine
#2
Johanna Marsian, Helen Fox, Mohammad W Bahar, Abhay Kotecha, Elizabeth E Fry, David I Stuart, Andrew J Macadam, David J Rowlands, George P Lomonossoff
Poliovirus (PV) is the causative agent of poliomyelitis, a crippling human disease known since antiquity. PV occurs in two distinct antigenic forms, D and C, of which only the D form elicits a robust neutralizing response. Developing a synthetically produced stabilized virus-like particle (sVLP)-based vaccine with D antigenicity, without the drawbacks of current vaccines, will be a major step towards the final eradication of poliovirus. Such a sVLP would retain the native antigenic conformation and the repetitive structure of the original virus particle, but lack infectious genomic material...
August 15, 2017: Nature Communications
https://www.readbyqxmd.com/read/28811371/angular-reconstitution-based-3d-reconstructions-of-nanomolecular-structures-from-superresolution-light-microscopy-images
#3
Desirée Salas, Antoine Le Gall, Jean-Bernard Fiche, Alessandro Valeri, Yonggang Ke, Patrick Bron, Gaetan Bellot, Marcelo Nollmann
Superresolution light microscopy allows the imaging of labeled supramolecular assemblies at a resolution surpassing the classical diffraction limit. A serious limitation of the superresolution approach is sample heterogeneity and the stochastic character of the labeling procedure. To increase the reproducibility and the resolution of the superresolution results, we apply multivariate statistical analysis methods and 3D reconstruction approaches originally developed for cryogenic electron microscopy of single particles...
August 15, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28810688/exhaled-breath-condensate-a-novel-matrix-for-biological-monitoring-to-assess-occupational-exposure-to-respirable-crystalline-silica
#4
Elizabeth Leese, James F Staff, Vikki A Carolan, Jackie Morton
Biological monitoring (BM) is a useful way of determining overall exposures to chemical substances; however, in the case of respirable crystalline silica (RCS), this has not been analytically feasible in conventional biological matrices. The aim of this study was to investigate the utility of exhaled breath condensate (EBC) as a potential biological matrix in which to determine exposure to RCS. A small pilot study was undertaken collecting EBC from six quarry workers and six occupationally unexposed persons; the samples were analysed using both single particle inductively coupled plasma mass spectrometry (spICP-MS) and transmission electron microscopy (TEM)...
August 1, 2017: Annals of Work Exposures and Health
https://www.readbyqxmd.com/read/28809003/preparation-of-disease-related-protein-assemblies-for-single-particle-electron-microscopy
#5
A Cameron Varano, Naoe Harafuji, William Dearnaley, Lisa Guay-Woodford, Deborah F Kelly
Electron microscopy (EM) is a rapidly growing area of structural biology that permits us to decode biological assemblies at the nanoscale. To examine biological materials for single particle EM analysis, purified assemblies must be obtained using biochemical separation techniques. Here, we describe effective methodologies for isolating histidine (his)-tagged protein assemblies from the nucleus of disease-relevant cell lines. We further demonstrate how isolated assemblies are visualized using single particle EM techniques and provide representative results for each step in the process...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28806061/construction-of-a-polyhedral-dna-12-arm-junction-for-self-assembly-of-wireframe-dna-lattices
#6
Ilenia Manuguerra, Guido Grossi, Rasmus P Thomsen, Jeppe Lyngsø, Jan Skov Pedersen, Jørgen Kjems, Ebbe Sloth Andersen, Kurt Vesterager Gothelf
A variety of different tiles for the construction of DNA lattices have been developed since the structural DNA nanotechnology field was born. The majority of these are designed for the realization of close-packed structures where DNA helices are arranged in parallel and tiles are connected through sticky ends. Assembly of such structures requires to the use of cation rich buffers to minimize repulsion between parallel helices, which poses limits to the application of DNA nanostructures. Wireframe structures on the other hand are less susceptible to salt concentration, but the assembly of wireframe lattices is limited by the availability of tiles and 2 motifs...
August 14, 2017: ACS Nano
https://www.readbyqxmd.com/read/28801216/a-novel-process-for-separation-of-hazardous-poly-vinyl-chloride-from-mixed-plastic-wastes-by-froth-flotation
#7
Jianchao Wang, Hui Wang, Chongqing Wang, Lingling Zhang, Tao Wang, Long Zheng
A novel method, calcium hypochlorite (CHC) treatment, was proposed for separation of hazardous poly(vinyl chloride) (PVC) plastic from mixed plastic wastes (MPWs) by froth flotation. Flotation behavior of single plastic indicates that PVC can be separated from poly(ethylene terephthalate) (PET), poly(acrylonitrile-co-butadiene-co-styrene) (ABS), polystyrene (PS), polycarbonate (PC) and poly(methyl methacrylate) (PMMA) by froth flotation combined with CHC treatment. Mechanism of CHC treatment was examined by contact angle measurement, scanning electron microscopy, Fourier transform infrared and X-ray photoelectron spectroscopy...
August 8, 2017: Waste Management
https://www.readbyqxmd.com/read/28799330/imaging-dynamic-collision-and-oxidation-of-single-silver-nanoparticles-at-the-electrode-solution-interface
#8
Rui Hao, Yunshan Fan, Bo Zhang
The electrochemical interface is an ultrathin interfacial region between the electrode surface and the electrolyte solution and is often characterized by numerous dynamic processes, such as solvation and desolvation, heterogeneous electron transfer, molecular adsorption and desorption, diffusion, and surface rearrangement. Many of these processes are driven and modulated by the presence of a large interfacial potential gradient. The study and better understanding of the electrochemical interface is important for designing better electrochemical systems where their applications may include batteries, fuel cells, electrocatalytic water splitting, corrosion protection, and electroplating...
August 11, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28795512/single-particle-cryo-em-improved-ab-initio-3d-reconstruction-with-simple-prime
#9
Cyril F Reboul, Michael Eager, Dominika Elmlund, Hans Elmlund
Cryogenic electron microscopy (cryo-EM) and single-particle analysis now enables the determination of high-resolution structures of macromolecular assemblies that have resisted X-ray crystallography and other approaches. We developed the SIMPLE open-source image-processing suite for analysing cryo-EM images of single-particles. A core component of SIMPLE is the probabilistic PRIME algorithm for identifying clusters of images in 2D and determine relative orientations of single-particle projections in 3D. Here we extend our previous work on PRIME and introduce new stochastic optimisation algorithms that improve the robustness of the approach...
August 10, 2017: Protein Science: a Publication of the Protein Society
https://www.readbyqxmd.com/read/28790440/adenoviral-e4-34k-protein-interacts-with-virus-packaging-components-and-may-serve-as-the-putative-portal
#10
Yadvinder S Ahi, Ahmed O Hassan, Sai V Vemula, Kunpeng Li, Wen Jiang, Guang Jun Zhang, Suresh K Mittal
Studies on dsDNA bacteriophages have revealed that a DNA packaging complex assembles at a special vertex called the 'portal vertex' and consists of a portal, a DNA packaging ATPase and other components. AdV protein IVa2 is presumed to function as a DNA packaging ATPase. However, a protein that functions as a portal is not yet identified in AdVs. To identify the AdV portal, we performed secondary structure analysis on a set of AdV proteins and compared them with the clip region of the portal proteins of bacteriophages phi29, SPP1 and T4...
August 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28783549/single-particle-aerosol-mass-spectrometry-of-coal-combustion-particles-associated-with-high-lung-cancer-rates-in-xuanwei-and-fuyuan-china
#11
Senlin Lu, Zhengying Tan, Pinwei Liu, Hui Zhao, Dingyu Liu, Shang Yu, Ping Cheng, Myat Sandar Win, Jiwen Hu, Linwei Tian, Minghong Wu, Shinich Yonemochi, Qingyue Wang
Coal combustion particles (CCPs) are linked to the high incidence of lung cancer in Xuanwei and in Fuyuan, China, but studies on the chemical composition of the CCPs are still limited. Single particle aerosol mass spectrometry (SPAMS) was recently developed to measure the chemical composition and size of single particles in real-time. In this study, SPAMS was used to measure individual combustion particles emitted from Xuanwei and Fuyuan coal samples and the results were compared with those by ICP-MS and transmission electron microscopy (TEM)...
August 1, 2017: Chemosphere
https://www.readbyqxmd.com/read/28782932/visualization-of-colloidal-nanocrystal-formation-and-electrode-electrolyte-interfaces-in-liquids-using-tem
#12
Zhiyuan Zeng, Wenjing Zheng, Haimei Zheng
Transmission electron microscopy (TEM) has become a powerful analytical tool for addressing unique scientific problems in chemical sciences as well as in materials sciences and other disciplines. There has been a lot of recent interest in the development and applications of liquid phase environmental TEM. In this Account, we review the development and applications of liquid cell TEM for the study of dynamic phenomena at liquid-solid interfaces, focusing on two areas: (1) nucleation, growth, and self-assembly of colloidal nanocrystals and (2) electrode-electrolyte interfaces during charge and discharge processes...
August 7, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28782000/particle-segmentation-algorithm-for-flexible-single-particle-reconstruction
#13
Qiang Zhou, Niyun Zhou, Hong-Wei Wang
As single particle cryo-electron microscopy has evolved to a new era of atomic resolution, sample heterogeneity still imposes a major limit to the resolution of many macromolecular complexes, especially those with continuous conformational flexibility. Here, we describe a particle segmentation algorithm towards solving structures of molecules composed of several parts that are relatively flexible with each other. In this algorithm, the different parts of a target molecule are segmented from raw images according to their alignment information obtained from a preliminary 3D reconstruction and are subjected to single particle processing in an iterative manner...
2017: Biophysics Reports
https://www.readbyqxmd.com/read/28781996/opinion-hazards-faced-by-macromolecules-when-confined-to-thin-aqueous-films
#14
REVIEW
Robert M Glaeser, Bong-Gyoon Han
Samples prepared for single-particle electron cryo-microscopy (cryo-EM) necessarily have a very high surface-to-volume ratio during the short period of time between thinning and vitrification. During this time, there is an obvious risk that macromolecules of interest may adsorb to the air-water interface with a preferred orientation, or that they may even become partially or fully unfolded at the interface. In addition, adsorption of macromolecules to an air-water interface may occur even before thinning. This paper addresses the question whether currently used methods of sample preparation might be improved if one could avoid such interfacial interactions...
2017: Biophysics Reports
https://www.readbyqxmd.com/read/28779844/saposin-lipoprotein-scaffolds-for-structure-determination-of-membrane-transporters
#15
Joseph A Lyons, Andreas Bøggild, Poul Nissen, Jens Frauenfeld
Membrane proteins depend on their natural lipid environment for function, which makes them more difficult to study in isolation. A number of approaches that mimic the lipid bilayer of biological membranes have been described (nanodiscs, SMALPs), enabling novel ways to assay activity and elucidate structures of this important class of proteins. More recently, the use of saposin A, a protein that is involved in lipid transport, to form Salipro (saposin-lipid-protein) complexes was demonstrated for a range of membrane protein targets (Frauenfeld et al...
2017: Methods in Enzymology
https://www.readbyqxmd.com/read/28777911/multiple-method-analysis-of-tio2-nanoparticle-uptake-in-rice-oryza-sativa-l-plants
#16
Yingqing Deng, Elijah J Petersen, Katie Challis, Savelas A Rabb, Richard David Holbrook, James F Ranville, Bryant C Nelson, Baoshan Xing
Understanding the translocation of nanoparticles (NPs) into plants is challenging because qualitative and quantitative methods are still being developed and the comparability of results among different methods is unclear. In this study, uptake of titanium dioxide NPs and larger bulk particles (BPs) at 5 mg/L and 50 mg/L concentrations in rice plant (Oryza sativa L.) tissues was evaluated using three orthogonal techniques: electron microscopy, single-particle inductively coupled plasma mass spectroscopy (spICP-MS) with two different plant digestion approaches, and total elemental analysis using ICP optical emission spectroscopy...
August 4, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28774076/microstructure-and-characteristics-of-calcium-phosphate-layers-on-bioactive-oxide-surfaces-of-air-sintered-titanium-foams-after-immersion-in-simulated-body-fluid
#17
Hung-Bin Lee, Hsueh-Chuan Hsu, Shih-Ching Wu, Shih-Kuang Hsu, Peng-Hsiang Wang, Wen-Fu Ho
We propose a simple and low-cost process for the preparation of porous Ti foams through a sponge replication method using single-step air sintering at various temperatures. In this study, the apatite-forming ability of air-sintered Ti samples after 21 days of immersion in simulated body fluid (SBF) was investigated. The microstructures of the prepared Ca-P deposits were examined by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FTIR) spectroscopy, and cross-sectional transmission electron microscopy (TEM)...
November 24, 2016: Materials
https://www.readbyqxmd.com/read/28772671/new-developments-in-cathodoluminescence-spectroscopy-for-the-study-of-luminescent-materials
#18
Daniel den Engelsen, George R Fern, Paul G Harris, Terry G Ireland, Jack Silver
Herein, we describe three advanced techniques for cathodoluminescence (CL) spectroscopy that have recently been developed in our laboratories. The first is a new method to accurately determine the CL-efficiency of thin layers of phosphor powders. When a wide band phosphor with a band gap (Eg > 5 eV) is bombarded with electrons, charging of the phosphor particles will occur, which eventually leads to erroneous results in the determination of the luminous efficacy. To overcome this problem of charging, a comparison method has been developed, which enables accurate measurement of the current density of the electron beam...
March 17, 2017: Materials
https://www.readbyqxmd.com/read/28772453/idealized-vs-realistic-microstructures-an-atomistic-simulation-case-study-on-%C3%AE-%C3%AE-microstructures
#19
Aruna Prakash, Erik Bitzek
Single-crystal Ni-base superalloys, consisting of a two-phase γ/ γ ' microstructure, retain high strengths at elevated temperatures and are key materials for high temperature applications, like, e.g., turbine blades of aircraft engines. The lattice misfit between the γ and γ ' phases results in internal stresses, which significantly influence the deformation and creep behavior of the material. Large-scale atomistic simulations that are often used to enhance our understanding of the deformation mechanisms in such materials must accurately account for such misfit stresses...
January 23, 2017: Materials
https://www.readbyqxmd.com/read/28768871/isolation-and-characterization-of-metallosphaera-turreted-icosahedral-virus-mtiv-a-founding-member-of-a-new-family-of-archaeal-viruses
#20
Cassia Wagner, Vijay Reddy, Francisco Asturias, Maryam Khoshouei, John E Johnson, Pilar Manrique, Jacob Munson-McGee, Wolfgang Baumeister, C Martin Lawrence, Mark J Young
Our understanding of archaeal virus diversity and structure is just beginning to emerge. Here we describe a new archaeal virus, tentatively named Metallosphaera turreted icosahedral virus (MTIV), that was isolated from an acidic hot spring in Yellowstone National Park, USA. Two strains of the virus were identified and found to replicate in an archaeal host species closely related to Metallosphaera yellowstonensis Each strain encodes for a 9.8-9.9 kb, linear dsDNA genome with large inverted terminal repeats...
August 2, 2017: Journal of Virology
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