Search results for "Microscopy"
showing 10 items of 3390 documents
Field performance of the Abbott RealTime MTB assay for the diagnosis of extrapulmonary tuberculosis in a low-prevalence setting
2020
Introduction: The sensitivities of conventional mycobacterial culture in solid or liquid media and acid-fast bacilli (AFB) smear microscopy for Mycobacterium tuberculosis complex (MTBC) detection in extrapulmonary specimens are suboptimal. We evaluated the field performance of the Abbott RealTime MTB assay for the diagnosis of extrapulmonary tuberculosis in a low-prevalence setting. Methods: The total number of extrapulmonary specimens with mycobacterial culture and PCR results was 566: sterile fluids (n = 278), non-sterile fluids (n = 147), lymph node material (n = 69) tissue biopsies (n = 63), and abscess aspirates (n = 9). A composite standard consisting of mycobacterial culture results,…
Flor Yeast Diversity and Dynamics in Biologically Aged Wines
2018
International audience; Wine biological aging is characterized by the development of yeast strains that form a biofilm on the wine surface after alcoholic fermentation. These yeasts, known as flor yeasts, form a velum that protects the wine from oxidation during aging. Thirty-nine velums aged from 1 to 6 years were sampled from "Vin jaune" from two different cellars. We show for the first time that these velums possess various aspects in term of color and surface aspects. Surprisingly, the heterogeneous velums are mostly composed of one species, S. cerevisiae. Scanning electron microscope observations of these velums revealed unprecedented biofilm structures and various yeast morphologies f…
Multi-virion infectious units arise from free viral particles in an enveloped virus
2017
Many animal viruses are enveloped in a lipid bilayer uptaken from cellular membranes. Since viral surface proteins bind to these membranes to initiate infection, we hypothesized that free virions may also be capable of interacting with the envelopes of other virions extracellularly. Here, we demonstrate this hypothesis in the vesicular stomatitis virus (VSV), a prototypic negative-strand RNA virus composed by an internal ribonucleocapsid, a matrix protein, and an external envelope1. Using microscopy, dynamic light scattering, differential centrifugation, and flow cytometry, we show that free viral particles can spontaneously aggregate into multi-virion infectious units. We also show that, f…
Tunable-frequency three-dimensional structured illumination microscopy with reduced data-acquisition
2018
The performance of a tunable three-dimensional (3D) structured illumination microscope (SIM) system and its ability to provide simultaneously super-resolution (SR) and optical-sectioning (OS) capabilities are investigated. Numerical results show that the performance of our 3D-SIM system is comparable with the one provided by a three-wave interference SIM, while requiring 40% fewer images for the reconstruction and providing frequency tunability in a cost-effective implementation. The performance of the system has been validated experimentally with images from test samples, which were also imaged with a commercial SIM based on incoherent-grid projection for comparison. Restored images from d…
Mitochondria during sea urchin oogenesis.
2017
SummarySea urchin represents an ideal model for studies on fertilization and early development, but the achievement of egg competence and mitochondrial behaviour during oogenesis remain to be enlightened. Oocytes of echinoid, such as sea urchin, unlike other echinoderms and other systems, complete meiotic maturation before fertilization. Mitochondria, the powerhouse of eukaryotic cells, contain a multi-copy of the maternally inherited genome, and are involved directly at several levels in the reproductive processes, as their functional status influences the quality of oocytes and contributes to fertilization and embryogenesis. In the present paper, we report our latest data on mitochondrial…
Insulin Resistance in PCOS Patients Enhances Oxidative Stress and Leukocyte Adhesion: Role of Myeloperoxidase
2016
Cardiovascular diseases and oxidative stress are related to polycystic ovary syndrome (PCOS) and insulin resistance (IR). We have evaluated the relationship between myeloperoxidase (MPO) and leukocyte activation in PCOS patients according to homeostatic model assessment of IR (HOMA-IR), and have explored a possible correlation between these factors and endocrine and inflammatory parameters. This was a prospective controlled study conducted in an academic medical center. The study population consisted of 101 PCOS subjects and 105 control subjects. We divided PCOS subjects into PCOS non-IR (HOMA-IR2.5). Metabolic and anthropometric parameters, total and mitochondrial reactive oxygen species (…
Functional display of an alpha2 integrin-specific motif (RKK) on the surface of baculovirus particles.
2005
The use of baculovirus vectors shows promise as a tool for gene delivery into mammalian cells. These insect viruses have been shown to transduce a variety of mammalian cell lines, and gene transfer has also been demonstrated in vivo. In this study, we generated two recombinant baculovirus vectors displaying an integrin-specific motif, RKK, as a part of two different loops of the green fluorescent protein (GFP) fused with the major envelope protein gp64 of Autographa californica M nucleopolyhedrovirus. By enzyme linked immunosorbent assays, these viruses were shown to bind a peptide representing the receptor binding site of an α2 integrin, the α2I-domain. However, the interaction was not st…
High-Pressure-Driven Reversible Dissociation of α-Synuclein Fibrils Reveals Structural Hierarchy
2017
The analysis of the α-synuclein (aS) aggregation process, which is involved in Parkinson's disease etiopathogenesis, and of the structural feature of the resulting amyloid fibrils may shed light on the relationship between the structure of aS aggregates and their toxicity. This may be considered a paradigm of the ground work needed to tackle the molecular basis of all the protein-aggregation-related diseases. With this aim, we used chemical and physical dissociation methods to explore the structural organization of wild-type aS fibrils. High pressure (in the kbar range) and alkaline pH were used to disassemble fibrils to collect information on the hierarchic pathway by which distinct β-sh…
Recombinant anthrax protective antigen: Observation of aggregation phenomena by TEM reveals specific effects of sterols.
2017
Abstract Negatively stained transmission electron microscope images are presented that depict the aggregation of recombinant anthrax protective antigen (rPA83 monomer and the PA63 prepore oligomer) under varying in vitro biochemical conditions. Heat treatment (50 °C) of rPA83 produced clumped fibrils, but following heating the PA63 prepore formed disordered aggregates. Freeze-thaw treatment of the PA63 prepore generated linear flexuous aggregates of the heptameric oligomers. Aqueous suspensions of cholesterol microcrystals were shown to bind small rPA83 aggregates at the edges of the planar bilayers. With PA63 a more discrete binding of the prepores to the crystalline cholesterol bilayer ed…
Structure of AP205 Coat Protein Reveals Circular Permutation in ssRNA Bacteriophages.
2016
We are thankful to the MAX-lab staff for their support during our visit at the synchrotron.; International audience; AP205 is a single-stranded RNA bacteriophage that has a coat protein sequence not similar to any other known single-stranded RNA phage. Here, we report an atomic-resolution model of the AP205 virus-like particle based on a crystal structure of an unassembled coat protein dimer and a cryo-electron microscopy reconstruction of the assembled particle, together with secondary structure information from site-specific solid-state NMR data. The AP205 coat protein dimer adopts the conserved Leviviridae coat protein fold except for the N-terminal region, which forms a beta-hairpin in …