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Single particle electron microscopy

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https://www.readbyqxmd.com/read/28916391/zika-virus-structural-biology-and-progress-in-vaccine-development
#1
REVIEW
Hsiao-Han Lin, Bak-Sau Yip, Li-Min Huang, Suh-Chin Wu
The growing number of zika virus (ZIKV) infections plus a 20-fold increase in neonatal microcephaly in newborns in Brazil have raised alarms in many countries regarding the threat to pregnant women. Instances of microcephaly and central nervous system malformations continue to increase in ZIKV outbreak regions. ZIKV is a small enveloped positive-strand RNA virus belonging to the Flavivirus genus of the Flaviviridae family. High-resolution ZIKV structures recently identified by cryo-electron microscopy indicate that the overall ZIKV structure is similar to those of other flaviviruses...
September 12, 2017: Biotechnology Advances
https://www.readbyqxmd.com/read/28903564/impact-of-an-artificial-digestion-procedure-on-aluminum-containing-nanomaterials
#2
Holger Sieg, Claudia Kästner, Benjamin Christoph Krause, Thomas Meyer, Agnes Burel, Linda Böhmert, Dajana Lichtenstein, Harald Jungnickel, Jutta Tentschert, Peter Laux, Albert Braeuning, Irina Estrela-Lopis, Fabienne Gauffre, Valerie Fessard, Jan Meijer, Andreas Luch, Andreas F Thünemann, Alfonso Lampen
Aluminum has gathered toxicological attention based on relevant human exposure and its suspected hazardous potential. Nanoparticles from food supplements or food contact materials may reach the human gastrointestinal tract. Here, we monitored the physico-chemical fate of aluminum-containing nanoparticles and aluminum ions when passaging an in vitro model of the human gastrointestinal tract. Small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), ion beam microscopy (IBM), secondary ion beam mass spectrometry (TOF-SIMS), and inductively coupled plasma mass spectrometry (ICP-MS) in the single-particle mode were employed to characterize two aluminum-containing nanomaterials with different particle core materials (Al0, γAl2O3) and soluble AlCl3...
September 13, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28902501/catalyst-architecture-for-stable-single-atom-dispersion-en-ables-site-specific-spectroscopic-and-reactivity-measurements-of-co-adsorbed-to-pt-atoms-oxidized-pt-clusters-and-metallic-pt-clusters-on-tio2
#3
Leo DeRita, Sheng Dai, Kimberly Lopez-Zepeda, Nicholas Pham, George W Graham, Xiaoqing Pan, Phillip Christopher
Oxide-supported precious metal nanoparticles are widely used industrial catalysts. Due to expense and rarity, developing synthetic protocols that reduce precious metal nanoparticle size and stabilize dispersed species is essential. Supported atomically dispersed, single precious metal atoms represents the most efficient metal utilization geometry, although debate regarding the catalytic activity of supported single precious atom species has arisen from difficulty in synthesizing homogeneous and stable single atom dispersions and a lack of site-specific characterization approaches...
September 13, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28901145/hollow-polycaprolactone-microspheres-with-without-single-surface-hole-by-co-electrospraying
#4
Fenglei Zhou, Ali Chirazi, Julie E Gough, Penny L Hubbard Cristinacce, Geoff J M Parker
We describe the co-electrospraying of hollow microspheres from a polycaprolactone (PCL) shell solution and various core solutions including water, cyclohexane, polyethylene oxide (PEO) and polyethylene glycol (PEG), using different collectors. The morphologies of resultant microspheres were characterized by scanning electron microscopy (SEM), confocal microscopy and nano-XCT. The core/shell solution miscibility played an important role in the co-electrospraying process and the formation of microsphere structures...
September 13, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28895249/salt-responsive-morphologies-of-ssdna-based-triblock-polyelectrolytes-in-semi-dilute-regime-effect-of-volume-fractions-and-polyelectrolyte-length
#5
Nan K Li, Huihui Kuang, William H Fuss, Stefan Zauscher, Efrosini Kokkoli, Yaroslava G Yingling
A comprehensive study is reported on the effect of salt concentration, polyelectrolyte block length, and polymer concentration on the morphology and structural properties of nanoaggregates self-assembled from BAB single-strand DNA (ssDNA) triblock polynucleotides in which A represents polyelectrolyte blocks and B represents hydrophobic neutral blocks. A morphological phase diagram above the gelation point is developed as a function of solvent ionic strength and polyelectrolyte block length utilizing an implicit solvent ionic strength method for dissipative particle dynamics simulations...
September 12, 2017: Macromolecular Rapid Communications
https://www.readbyqxmd.com/read/28891250/guidelines-for-using-bsoft-for-high-resolution-reconstruction-and-validation-of-biomolecular-structures-from-electron-micrographs
#6
J Bernard Heymann
Cryo-electron microscopy (cryoEM) is becoming popular as a tool to solve biomolecular structures with the recent availability of direct electron detectors allowing automated acquisition of high resolution data. The Bsoft software package, developed over 20 years for analyzing electron micrographs, offers a full workflow for validated single particle analysis with extensive functionality, enabling customization for specific cases. With the increasing use of cryoEM and its automation, proper validation of the results is a bigger concern...
September 10, 2017: Protein Science: a Publication of the Protein Society
https://www.readbyqxmd.com/read/28886335/macromolecular-assemblies-of-the-mammalian-circadian-clock
#7
Rajindra P Aryal, Pieter Bas Kwak, Alfred G Tamayo, Michael Gebert, Po-Lin Chiu, Thomas Walz, Charles J Weitz
The mammalian circadian clock is built on a feedback loop in which PER and CRY proteins repress their own transcription. We found that in mouse liver nuclei all three PERs, both CRYs, and Casein Kinase-1δ (CK1δ) are present together in an ∼1.9-MDa repressor assembly that quantitatively incorporates its CLOCK-BMAL1 transcription factor target. Prior to incorporation, CLOCK-BMAL1 exists in an ∼750-kDa complex. Single-particle electron microscopy (EM) revealed nuclear PER complexes purified from mouse liver to be quasi-spherical ∼40-nm structures...
September 7, 2017: Molecular Cell
https://www.readbyqxmd.com/read/28884709/hydrothermal-synthesis-of-snq-q-te-se-s-and-their-thermoelectric-properties
#8
Dan Feng, Zhenhua Ge, Yuexing Chen, Ju Li, Jiaqing He
Lead-free IV-VI semiconductors SnQ (Q=Te, Se, S) are deemed as promising thermoelectric materials. In this work, we designed a hydrothermal route to selectively synthesize single phase SnTe, SnSe and SnS nanopowders. For all three samples, the phase structure were characterized by X-ray diffraction, SnTe particles with octahedron structure and SnSe/SnS particles with plate-like shape were observed by field emission scanning electron microscopy and transmission electron microscopy, the formation mechanism was discussed in detail...
September 8, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28869968/structural-basis-of-msba-mediated-lipopolysaccharide-transport
#9
Wei Mi, Yanyan Li, Sung Hwan Yoon, Robert K Ernst, Thomas Walz, Maofu Liao
Lipopolysaccharide (LPS) in the outer membrane of Gram-negative bacteria is critical for the assembly of their cell envelopes. LPS synthesized in the cytoplasmic leaflet of the inner membrane is flipped to the periplasmic leaflet by MsbA, an ATP-binding cassette transporter. Despite substantial efforts, the structural mechanisms underlying MsbA-driven LPS flipping remain elusive. Here we use single-particle cryo-electron microscopy to elucidate the structures of lipid-nanodisc-embedded MsbA in three functional states...
September 6, 2017: Nature
https://www.readbyqxmd.com/read/28855679/pea-psii-lhcii-supercomplexes-form-pairs-by-making-connections-across-the-stromal-gap
#10
Pascal Albanese, Roberto Melero, Benjamin D Engel, Alessandro Grinzato, Paola Berto, Marcello Manfredi, Angelica Chiodoni, Javier Vargas, Carlos Óscar Sánchez Sorzano, Emilio Marengo, Guido Saracco, Giuseppe Zanotti, Jose-Maria Carazo, Cristina Pagliano
In higher plant thylakoids, the heterogeneous distribution of photosynthetic protein complexes is a determinant for the formation of grana, stacks of membrane discs that are densely populated with Photosystem II (PSII) and its light harvesting complex (LHCII). PSII associates with LHCII to form the PSII-LHCII supercomplex, a crucial component for solar energy conversion. Here, we report a biochemical, structural and functional characterization of pairs of PSII-LHCII supercomplexes, which were isolated under physiologically-relevant cation concentrations...
August 30, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28855564/correlation-between-particle-size-domain-structure-and-magnetic-properties-of-highly-crystalline-fe3o4-nanoparticles
#11
Qing Li, Christina W Kartikowati, Shinji Horie, Takashi Ogi, Toru Iwaki, Kikuo Okuyama
Highly crystalline single-domain magnetite Fe3O4 nanoparticles (NPs) are important, not only for fundamental understanding of magnetic behaviour, but also for their considerable potential applications in biomedicine and industry. Fe3O4 NPs with sizes of 10-300 nm were systematically investigated to reveal the fundamental relationship between the crystal domain structure and the magnetic properties. The examined Fe3O4 NPs were prepared under well-controlled crystal growth conditions using a large-scale liquid precipitation method...
August 30, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28851880/low-dose-cryo-electron-ptychography-via-non-convex-bayesian-optimization
#12
Philipp Michael Pelz, Wen Xuan Qiu, Robert Bücker, Günther Kassier, R J Dwayne Miller
Electron ptychography has seen a recent surge of interest for phase sensitive imaging at atomic or near-atomic resolution. However, applications are so far mainly limited to radiation-hard samples, because the required doses are too high for imaging biological samples at high resolution. We propose the use of non-convex Bayesian optimization to overcome this problem, and show via numerical simulations that the dose required for successful reconstruction can be reduced by two orders of magnitude compared to previous experiments...
August 29, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28842499/human-copper-transporter-atp7b-wilson-disease-protein-forms-stable-dimers-in-vitro-and-in-cells
#13
Samuel Jayakanthan, Lelita T Braiterman, Nesrin M Hasan, Vinzenz M Unger, Svetlana Lutsenko
ATP7B is a copper-transporting P1B-type ATPase (Cu-ATPase) with an essential role in human physiology. Mutations in ATP7B cause a potentially fatal Wilson disease, and changes in ATP7B expression are observed in several cancers. Despite its physiologic importance, the biochemical information about ATP7B remains limited owing to a complex multi-domain organization of the protein. By analogy with the better characterized prokaryotic Cu-ATPases, ATP7B is assumed to be a single-chain monomer. We show that in eukaryotic cells, human ATP7B forms dimers that can be purified following solubilization...
August 24, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28841979/quantification-and-size-characterisation-of-silver-nanoparticles-in-environmental-aqueous-samples-and-consumer-products-by-single-particle-icpms
#14
Ramón Aznar, Francisco Barahona, Otmar Geiss, Jessica Ponti, Tadeo José Luis, Josefa Barrero-Moreno
Single particle-inductively coupled plasma mass spectrometry (SP-ICPMS) is a promising technique able to generate the number based-particle size distribution (PSD) of nanoparticles (NPs) in aqueous suspensions. However, SP-ICPMS analysis is not consolidated as routine-technique yet and is not typically applied to real test samples with unknown composition. This work presents a methodology to detect, quantify and characterise the number-based PSD of Ag-NPs in different environmental aqueous samples (drinking and lake waters), aqueous samples derived from migration tests and consumer products using SP-ICPMS...
December 1, 2017: Talanta
https://www.readbyqxmd.com/read/28831493/building-with-ions-towards-direct-write-of-platinum-nanostructures-using-in-situ-liquid-cell-helium-ion-microscopy
#15
Anton V Ievlev, Jacek Jakowski, Matthew J Burch, Vighter Iberi, Holland Hysmith, David C Joy, Bobby G Sumpter, Alex Belianinov, Raymond R Unocic, Olga S Ovchinnikova
Direct write with a liquid precursor using an ion beam in situ, allows fabrication of nanostructures with higher purity than using gas phase deposition. Specifically, positively charged helium ions, when compared to electrons, localize the reaction zone to a single-digit nanometer scale. However, to control the interaction of the ion beam with the liquid precursor, as well as enable single digit fabrication, a comprehensive understanding of the radiolytic process, and the role of secondary electrons has to be developed...
September 14, 2017: Nanoscale
https://www.readbyqxmd.com/read/28828660/detection-and-characterization-of-extracellular-vesicles-by-transmission-and-cryo-transmission-electron-microscopy
#16
Petr Cizmar, Yuana Yuana
Transmission electron microscopy (TEM) and transmission scanning electron Microscopy (TSEM), which denotes application of a scanning electron microscope (SEM) in the transmission mode, have been used to detect and characterize particles down to an imaging resolution of ~1 nm. In the field of EVs, TEM also has been valued for its capability to detect and characterize single EV. Furthermore, employing immunogold labeling in TEM could give information regarding biochemical properties of EV surface proteins. Significant shortcomings in TEM such as dehydration, chemical fixation, and/or staining of the biological specimens are eluded by the use of cryo-TEM...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28820312/architecture-of-the-atg2b-wdr45-complex-and-an-aromatic-y-hf-motif-crucial-for-complex-formation
#17
Jing-Xiang Zheng, Yan Li, Yue-He Ding, Jun-Jie Liu, Mei-Jun Zhang, Meng-Qiu Dong, Hong-Wei Wang, Li Yu
PtdIns3P signaling is critical for dynamic membrane remodeling during autophagosome formation. Proteins in the Atg18/WIPI family are PtdIns3P-binding effectors which can form complexes with proteins in the Atg2 family, and both families are essential for macroautophagy/autophagy. However, little is known about the biophysical properties and biological functions of the Atg2-Atg18/WIPI complex as a whole. Here, we demonstrate that an ortholog of yeast Atg18, mammalian WDR45/WIPI4 has a stronger binding capacity for mammalian ATG2A or ATG2B than the other 3 WIPIs...
August 18, 2017: Autophagy
https://www.readbyqxmd.com/read/28819229/cryo-em-analysis-of-homodimeric-full-length-lrrk2-and-lrrk1-protein-complexes
#18
Kushal Sejwal, Mohamed Chami, Hervé Rémigy, Renée Vancraenenbroeck, William Sibran, Rosmarie Sütterlin, Paul Baumgartner, Robert McLeod, Marie-Christine Chartier-Harlin, Veerle Baekelandt, Henning Stahlberg, Jean-Marc Taymans
Leucine-rich repeat kinase 2 (LRRK2) is a large multidomain protein implicated in the pathogenesis of both familial and sporadic Parkinson's disease (PD), and currently one of the most promising therapeutic targets for drug design in Parkinson's disease. In contrast, LRRK1, the closest homologue to LRRK2, does not play any role in PD. Here, we use cryo-electron microscopy (cryo-EM) and single particle analysis to gain structural insight into the full-length dimeric structures of LRRK2 and LRRK1. Differential scanning fluorimetry-based screening of purification buffers showed that elution of the purified LRRK2 protein in a high pH buffer is beneficial in obtaining high quality cryo-EM images...
August 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28812314/self-assembled-chiral-nanostructures-of-amphiphilic-peptide-from-single-molecule-to-aggregate
#19
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
#20
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
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