scholarly journals Phage-Mediated Explosive Cell Lysis Induces the Formation of a Different Type of O-IMV in Shewanella vesiculosa M7T

2021 ◽  
Vol 12 ◽  
Author(s):  
Nicolás Baeza ◽  
Lidia Delgado ◽  
Jaume Comas ◽  
Elena Mercade
Keyword(s):  
Electron Microscopy ◽  
Flow Cytometry ◽  
Membrane Vesicles ◽  
Cell Lysis ◽  
Outer Membrane Vesicles ◽  
Nucleic Acid Content ◽  
Entire Genome ◽  
Great Capacity ◽  
Transmission Electron ◽  
First Time

Shewanella vesiculosa M7T is a cold-adapted Antarctic bacterium that has a great capacity to secrete membrane vesicles (MVs), making it a potentially excellent model for studying the vesiculation process. S. vesiculosa M7T undergoes a blebbing mechanism to produce different types of MVs, including outer membrane vesicles and outer-inner membrane vesicles (O-IMVs). More recently, other mechanisms have been considered that could lead to the formation of O-IMVs derived from prophage-mediated explosive cell lysis in other bacteria, but it is not clear if they are of the same type. The bacterial growth phase could also have a great impact on the type of MVs, although there are few studies on the subject. In this study, we used high-resolution flow cytometry, transmission electron microscopy, and cryo-electron microscopy (Cryo-EM) analysis to determine the amount and types of MVs S. vesiculosa M7T secreted during different growth phases. We show that MV secretion increases during the transition from the late exponential to the stationary phase. Moreover, prophage-mediated explosive cell lysis is activated in S. vesiculosa M7T, increasing the heterogeneity of both single- and double-layer MVs. The sequenced DNA fragments from the MVs covered the entire genome, confirming this explosive cell lysis mechanism. A different structure and biogenesis mechanisms for the explosive cell lysis-derived double-layered MVs was observed, and we propose to name them explosive O-IMVs, distinguishing them from the blebbing O-IMVs; their separation is a first step to elucidate their different functions. In our study, we used for the first time sorting by flow cytometry and Cryo-EM analyses to isolate bacterial MVs based on their nucleic acid content. Further improvements and implementation of bacterial MV separation techniques is essential to develop more in-depth knowledge of MVs.

scholarly journals Isolation and Characterization of Outer Membrane Vesicles of Pectobacterium brasiliense 1692

2021 ◽  
Vol 9 (9) ◽  
pp. 1918
Author(s):  
Silindile Maphosa ◽  
Lucy Novungayo Moleleki
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Outer Membrane ◽  
Critical Role ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Broad Host Range ◽  
Isolation And Characterization ◽  
Transmission Electron ◽  
Animal Pathogens

Pectobacterium brasiliense (Pbr) 1692 is an aggressive phytopathogen affecting a broad host range of crops and ornamental plants, including potatoes. Previous research on animal pathogens, and a few plant pathogens, revealed that Outer Membrane Vesicles (OMVs) are part of Gram-negative bacteria’s (GNB) adaptive toolkit. For this reason, OMV production and subsequent release from bacteria is a conserved process. Therefore, we hypothesized that OMVs might transport proteins that play a critical role in causing soft rot disease and in the survival and fitness of Pbr1692. Here, we show that the potato pathogen, Pbr1692, releases OMVs of various morphologies in Luria Bertani media at 31 °C. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) confirmed the production of OMVs by Pbr1692 cells. Transmission Electron Microscopy showed that these exist as chain-, single-, and double-membrane morphologies. Mass spectrometry followed by Gene Ontology, Clusters of Orthologous Groups, Virulence Factor, CAZymes, Antibiotic Resistance Ontology, and Bastion6 T6SE annotations identified 129 OMV-associated proteins with diverse annotated roles, including antibiotic stress response, virulence, and competition. Pbr1692 OMVs contributed to virulence in potato tubers and elicited a hypersensitive response in Nicotiana benthamiana leaves. Furthermore, Pbr1692 OMVs demonstrated antibacterial activity against Dickeya dadantii.

scholarly journals Quartz Crystallite Size and Moganite Content as Indicators of the Mineralogical Maturity of the Carboniferous Chert: The Case of Cherts from Eastern Asturias (Spain)

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 611
Author(s):  
Celia Marcos ◽  
María de Uribe-Zorita ◽  
Pedro Álvarez-Lloret ◽  
Alaa Adawy ◽  
Patricia Fernández ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Crystallite Size ◽  
Archaeological Sites ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Infrared And Raman Spectroscopy ◽  
First Time ◽  
Geological Formations

Chert samples from different coastal and inland outcrops in the Eastern Asturias (Spain) were mineralogically investigated for the first time for archaeological purposes. X-ray diffraction, X-ray fluorescence, transmission electron microscopy, infrared and Raman spectroscopy and total organic carbon techniques were used. The low content of moganite, since its detection by X-ray diffraction is practically imperceptible, and the crystallite size (over 1000 Å) of the quartz in these cherts would be indicative of its maturity and could potentially be used for dating chert-tools recovered from archaeological sites. Also, this information can constitute essential data to differentiate the cherts and compare them with those used in archaeological tools. However, neither composition nor crystallite size would allow distinguishing between coastal and inland chert outcrops belonging to the same geological formations.

scholarly journals Direct TEM observation of the “acanthite α-Ag2S–argentite β-Ag2S” phase transition in a silver sulfide nanoparticle

2019 ◽  
Vol 1 (4) ◽  
pp. 1581-1588 ◽  
Author(s):  
S. I. Sadovnikov ◽  
E. Yu. Gerasimov
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
Transmission Electron Microscopy ◽  
Silver Sulfide ◽  
Transmission Electron ◽  
Silver Sulfide Nanoparticles ◽  
Microscopy Method ◽  
Electron Microscopy Method ◽  
First Time

For the first time, the α-Ag2S (acanthite)–β-Ag2S (argentite) phase transition in a single silver sulfide nanoparticles has been observed in situ using a high-resolution transmission electron microscopy method in real time.

TRANSMISSION ELECTRON MICROSCOPY OF SURFACE AND INTERFACIAL STEPS

1997 ◽  
Vol 04 (03) ◽  
pp. 559-566 ◽  
Author(s):  
J. M. GIBSON ◽  
X. CHEN ◽  
O. POHLAND
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Free Surface ◽  
Significant Loss ◽  
Stress Fields ◽  
Preliminary Results ◽  
Surface Steps ◽  
Transmission Electron ◽  
First Time

Transmission electron microscopy is uniquely able to extend techniques for imaging free surface steps to the buried interface regime, without significant loss of detail. Two mechanisms for imaging surface and interfacial steps by transmission electron microscopy are described. They are thickness contrast and strain contrast. The former reveals the position and approximate height of steps, whereas the latter detects stress fields which are commonly associated with steps. The basis for each of these methods is elaborated, and preliminary results are shown for step images at Si/SiO2 interfaces, where measurable stress fields have been directly detected for the first time.

ARCHITECTURE OF FLOWER-LIKE rGO/CNTs-LOADED CuxO NANOPARTICLES AND ITS PHOTOCATALYTIC PROPERTIES

NANO ◽  
2013 ◽  
Vol 08 (05) ◽  
pp. 1350052 ◽  
Author(s):  
BIN ZENG ◽  
XIAOHUA CHEN ◽  
XUTAO NING ◽  
CHUANSHENG CHEN ◽  
HUI LONG
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Performance ◽  
Degradation Process ◽  
Photocatalytic Properties ◽  
High Concentration ◽  
Graphene Oxides ◽  
Transmission Electron ◽  
Time Scanning ◽  
Reduced Graphene ◽  
First Time

Novel flower-like composite architecture was successfully synthesized by spray drying and post-calcinating method for the first time. Scanning electron microscopy and transmission electron microscopy observations confirmed that reduced graphene oxides/carbon nanotubes hybrid (rGO/CNTs) formed a flower-like micrometer structure and Cu2O , CuO ( Cu x O , x = 1 or 2) nanoparticles were decorated inside them. The photocatalytic properties were further investigated by evaluating the photodegradation of a pollutant methyl orange (MO). The experimental results indicated that this novel architecture enhanced photocatalytic performance with 96.2% decomposition of MO after 25 min in the presence of H 2 O 2 under visible light irradiation, which was much higher than that of Cu x O powders (33.2%). This could be attributed to the more efficient adsorption of MO molecules on flower-like rGO/CNTs and provide a high concentration of MO near to the Cu x O nanoparticles, thus promoting the photocatalytic degradation process.

scholarly journals Effect of 2,4-Diacetylphloroglucinol on Pythium: Cellular Responses and Variation in Sensitivity Among Propagules and Species

2003 ◽  
Vol 93 (8) ◽  
pp. 966-975 ◽  
Author(s):  
Jorge T. de Souza ◽  
Christine Arnould ◽  
Chrystel Deulvot ◽  
Philippe Lemanceau ◽  
Vivienne Gianinazzi-Pearson ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Plant Pathogens ◽  
Pythium Ultimum ◽  
Cellular Responses ◽  
Low Ph ◽  
Cell Content ◽  
Pseudomonas Spp ◽  
Transmission Electron ◽  
First Time ◽  
Resistant Structure

The antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG) plays an important role in the suppression of plant pathogens by several strains of Pseudomonas spp. Based on the results of this study, there is variation within and among Pythium spp. to 2,4-DAPG. Also, various propagules of Pythium ultimum var. sporangiiferum, that are part of the asexual stage of the life cycle, differ considerably in their sensitivity to 2,4-DAPG. Mycelium was the most resistant structure, followed by zoosporangia, zoospore cysts, and zoospores. Additionally, we report for the first time that pH has a significant effect on the activity of 2,4-DAPG, with a higher activity at low pH. Furthermore, the level of acetylation of phloroglucinols is also a major determinant of their activity. Transmission electron microscopy studies revealed that 2,4-DAPG causes different stages of disorganization in hyphal tips of Pythium ultimum var. sporangiiferum, including alteration (proliferation, retraction, and disruption) of the plasma membrane, vacuolization, and cell content disintegration. The implications of these results for the efficacy and consistency of biological control of plant-pathogenic Pythium spp. by 2,4-DAPG-producing Pseudomonas spp. are discussed.

Boron Nitride Nanotubes: Nanoparticles Functionalization and Junction Fabrication

2007 ◽  
Vol 7 (2) ◽  
pp. 530-534 ◽  
Author(s):  
Chunyi Zhi ◽  
Yoshio Bando ◽  
Guozhen Shen ◽  
Chengchun Tang ◽  
Dmitri Golberg
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Boron Nitride ◽  
Boron Nitride Nanotubes ◽  
X Ray Diffraction ◽  
Carbon Nanostructure ◽  
Wet Chemistry ◽  
X Ray ◽  
Transmission Electron ◽  
First Time

Adopting a wet chemistry method, Au and Fe3O4 nanoparticles were functionalized on boron nitride nanotubes (BNNTs) successfully for the first time. X-ray diffraction pattern and transmission electron microscopy were used to characterize the resultant products. Subsequently, a method was proposed to fabricate heterojunction structures based on the particle-functionalized BNNTs. As a demonstration, BNNT-carbon nanostructure, BNNT-ZnO and BNNT-Ga2O3 junctions were successfully fabricated using the functionalized particles as catalysts.

Characterization of cellular development and fatty acid accumulation in thraustochytrid Aurantiochytrium strains of Taiwan

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Natarajan Velmurugan ◽  
Yesupatham Sathishkumar ◽  
Shashanka Sonowal ◽  
Ka-Lai Pang ◽  
Yang Soo Lee
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Flow Cytometry ◽  
Cell Growth ◽  
Intracellular Lipid ◽  
Fatty Acid Accumulation ◽  
Transmission Electron ◽  
Intracellular Lipid Accumulation ◽  
High Level

Abstract Long-chain saturated and polyunsaturated fatty acids of two new thraustochytrid isolates cultured from Taiwan mangroves, Aurantiochytrium sp. IMB169 and Aurantiochytrium sp. IMB171, were characterized through their cell growth and development in relation to their intracellular lipid accumulation using transmission electron microscopy. Flow cytometry in combination with the lipophilic fluorescent dye BODIPY 505/515 was used to stain and characterize intracellular lipid bodies in the two isolates. The transmission electron microscopy and flow cytometry analyses revealed a progressive accumulation of lipid products in IMB169 and IMB171. Further, selective BODIPY stained cells were successfully separated and enriched using flow cytometry at single cell level. Among the two isolates, IMB169 was found to produce a high level of docosahexaenoic acid. The qualitative and analytical results obtained using electron microscopy and flow cytometry studies were validated by gas chromatography (GC). In addition, a quantitative baseline was established using cell growth, flow cytometry and GC analyses for developing an efficient bioprocessing methodology to selectively enrich thraustochytrids phenotypes with desirable characteristics.

scholarly journals Ionic Liquids-Containing Silica Microcapsules: A Potential Tunable Platform for Shaping-Up Epoxy-Based Composite Materials?

Nanomaterials ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 881
Author(s):  
Ting Shi ◽  
Sébastien Livi ◽  
Jannick Duchet ◽  
Jean-François Gérard
Keyword(s):  
Electron Microscopy ◽  
Sol Gel ◽  
Diameter Distribution ◽  
Excellent Thermal Stability ◽  
Transmission Electron ◽  
Micron Size ◽  
Phosphonium Ionic Liquid ◽  
One Step ◽  
The One ◽  
First Time

In this work, silica microcapsules containing phosphonium ionic liquid (IL), denoted SiO2@IL, were successfully synthesized for the first time using the one step sol-gel method in IL/H20 emulsion. The morphologies of the obtained micron-size microcapsules, including their diameter distribution, were characterized using dynamic light scattering (DLS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The thermal behavior of these microcapsules and the mass fraction of the encapsulated IL in the silica microcapsules were determined using thermogravimetric analysis, showing an excellent thermal stability (up to 220 °C) and highlighting that an amount of 20 wt.% of IL is contained in the silica microcapsules. In a second step, SiO2@IL microcapsules (1 wt.%) were dispersed into epoxy-amine networks to provide proof of concept of the ability of such microcapsules to act as healing agents as microcracks propagate into the epoxy networks.

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