scholarly journals Enumerating Viruses by Using Fluorescence and the Nature of the Nonviral Background Fraction

2012 ◽  
Vol 78 (18) ◽  
pp. 6615-6618 ◽  
Author(s):  
Peter C. Pollard
Keyword(s):  
Size Fraction ◽  
Epifluorescence Microscopy ◽  
Fluorescence Excitation ◽  
Filtration Method ◽  
Microscopy Technique ◽  
Fluorescence Measurements ◽  
Transmission Electron ◽  
Sybr Gold ◽  
High Fluorescence ◽  
Differential Filtration

ABSTRACTBulk fluorescence measurements could be a faster and cheaper way of enumerating viruses than epifluorescence microscopy, flow cytometry, or transmission electron microscopy (TEM). However, since viruses are not imaged, the background fluorescence compromises the signal, and we know little about its nature. In this paper the size ranges of nucleotides that fluoresce in the presence of SYBR gold were determined for wastewater and a range of freshwater samples using a differential filtration method. Fluorescence excitation-emission matrices (FEEMs) showed that >70% of the SYBR fluorescence was in the <10-nm size fraction (background) and was not associated with intact viruses. This was confirmed using TEM. The use of FEEMs to develop a fluorescence-based method for counting viruses is an approach that is fundamentally different from the epifluorescence microscopy technique used for enumerating viruses. This high fluorescence background is currently overlooked, yet it has had a most pervasive influence on the development of a simple fluorescence-based method for quantifying viral abundance in water.

Synthesis and characterization of a sulfur-containing phthalocyanine-gold nanoparticle hybrid

2015 ◽  
Vol 19 (01-03) ◽  
pp. 335-343 ◽  
Author(s):  
Vicente M. Blas-Ferrando ◽  
Javier Ortiz ◽  
Fernando Fernández-Lázaro ◽  
Ángela Sastre-Santos
Keyword(s):  
Gold Nanoparticle ◽  
Lipoic Acid ◽  
Zinc Phthalocyanine ◽  
Synthesis And Characterization ◽  
Ligand Exchange Reaction ◽  
H Nmr ◽  
Fluorescence Measurements ◽  
Transmission Electron ◽  
Yield Values

This work reports on the synthesis and characterization of a new gold nanoparticle-zinc phthalocyanine system, AuNP - S (t Bu )3 ZnPc , prepared by a ligand exchange reaction of tetraoctylammonium bromide with a novel unsymmetrically substituted zinc phthalocyanine which contains one thioester group in the peripheral position [ AcS (t Bu )3 ZnPc ]. The AuNP - S (t Bu )3 ZnPc hybrid was characterized using UV-vis and 1 H NMR spectroscopies. Transmission electron microscopy allowed the estimation of the size, which was calculated to be ~5 nm. AuNPs - S (t Bu )3 ZnPc conjugate showed much lower fluorescence quantum yield values than the AcS (t Bu )3 ZnPc demonstrating either an energy or electron transfer from the ZnPc to the AuNP . The AuNP - S (t Bu )3 ZnPc hybrid has been anchored to a TiO 2 semiconducting layer using lipoic acid. A solid configuration of TiO 2-lipoic acid- AuNP - S (t Bu )3 ZnPc has been prepared by anchoring lipoic acid to the TiO 2 ( TiO 2-LA) and introducing later the TiO 2-LA with free thiol groups in a toluene solution of AuNP - S (t Bu )3 ZnPc . We have also observed by UV-vis and fluorescence measurements the importance of the ZnPc in avoiding AuNP aggregation on the TiO 2 surface.

scholarly journals Transformations of the Microstructure and Phase Compositions of Titanium Alloys during Ultrasonic Impact Treatment. Part I. Commercially Pure Titanium

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 562
Author(s):  
Alexey Panin ◽  
Andrey Dmitriev ◽  
Anton Nikonov ◽  
Marina Kazachenok ◽  
Olga Perevalova ◽  
...  
Keyword(s):  
Surface Layer ◽  
Phase Transformations ◽  
Pure Titanium ◽  
Surface Plastic ◽  
Commercially Pure Titanium ◽  
Ultrasonic Impact Treatment ◽  
Coordination Numbers ◽  
Microscopy Technique ◽  
Transmission Electron ◽  
Treated Sample

Experimental and theoretical studies helped to reveal patterns of surface roughening and the microstructure refinement in the surface layer of commercial pure titanium during ultrasonic impact treatment. Applying transmission electron microscopy technique, a gradient microstructure in the surface layer of the ultrasonically treated sample, where the grain size is varied from nano- to micrometers was revealed. It was shown that the surface plastic strains of the titanium sample proceeded according to the plastic ploughing mechanism, which was accompanied by dislocation sliding, twinning, and the transformations of the microstructure and phase composition. The molecular dynamics method was applied to demonstrate the mechanism of the phase transformations associated with the formation of stacking faults, as well as the reversible displacement of atoms from their sites in the hcp lattice, causing a change in coordination numbers. The role of the electronic subsystem in the development of the strain-induced phase transformations during ultrasonic impact treatment was discussed.

Soil Colloids and Soil Organic Matter Associativity - the Basis of Soil Structure

2001 ◽  
Vol 7 (S2) ◽  
pp. 534-535
Author(s):  
G. Vrdoljak ◽  
G. Sposito
Keyword(s):  
Electron Microscopy ◽  
Nmr Spectroscopy ◽  
Soil Structure ◽  
Size Fraction ◽  
Research Station ◽  
Forest Site ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Highly Weathered Soils

In the hierarchical model of soil structure, the lowest scale of structure is the combination of clays < 0.2 um diameter to form 2 um domains. to investigate the basis for soil structure, two highly weathered soils from Brazil (Oxisols) were selected and the < 2 um size fraction extracted by sedimentation for analysis. The first soil used in this study, classified as Xanthic Hapludox, was collected in 1991 at an EMBRAPA research station outside of Manaus, Brazil from a tropical forest site collected from the 0-8 cm depth. The second soil (0-20 cm depth) was sampled from a topographically flat area inside the Brasilia National Park, Brasilia D.F. Brazil by Dr. Flavio Vasconcelos.The samples were analyzed by NMR spectroscopy, transmission electron microscopy, atomic force microscopy, and scanning electron microscopy. NMR spectroscopy revealed the organic materials within this size fraction consisted predominantly of polysaccharides.

Increase In Intracellular Sodium Evoked by Glutamate Transporter Activation In Cortical Astrocytes: A Fluorescence Microscopy Analysis

1999 ◽  
Vol 5 (S2) ◽  
pp. 1046-1047
Author(s):  
J.-Y. Chatton ◽  
P. Marquet ◽  
P.J. Magistretti
Keyword(s):  
Primary Cultures ◽  
Glutamate Transporter ◽  
Specific Inhibitor ◽  
Ccd Camera ◽  
Light Level ◽  
Epifluorescence Microscopy ◽  
Fluorescence Excitation ◽  
Microscopy Imaging ◽  
Excitatory Neurotransmitter ◽  
Cortical Astrocytes

Primary cultures of mouse cortical astrocytes were used to investigate the changes in intracellular Na+ concentration ([Na+]i) following exposure to the excitatory neurotransmitter glutamate. The fluorescent probe sodium-binding benzofuran isophthalate (SBFI) was used to measure [Na+]i by epifluorescence microscopy imaging. Detection of the low light level fluorescent signal was accomplished using a Gen III+ intensified CCD camera. Fluorescence excitation ratio images of dye-loaded cells were obtained after sequential illumination at 340nnm and 380nm, with an emission observed at >520nm. Ratio images were proportional in intensity to [Na+]i. In situ calibration of the fluorescent signals was obtained for each experiment and each cell under study by equilibrating [Na+]i with external Na+ after treatment with the cation ionophores monensin and gramicidin, and with ouabain, a specific inhibitor of the Na+/K+ ATPase. Cells on glass coverslips were perfused at 35°C in a closed microscope chamber using solutions buffered with 25 mM bicarbonate/5%CO2.

scholarly journals Laser-induced fluorescence of organic matter from a Brazilian Oxisol under sewage-sludge applications

2006 ◽  
Vol 63 (3) ◽  
pp. 269-275 ◽  
Author(s):  
Martha González Pérez ◽  
Débora Marcondes Bastos Pereira Milori ◽  
Ladislau Martin-Neto ◽  
Luiz Alberto Colnago ◽  
Otávio Antonio de Camargo ◽  
...  
Keyword(s):  
Organic Matter ◽  
Sewage Sludge ◽  
Agricultural Soils ◽  
Size Fraction ◽  
Laser Induced Fluorescence ◽  
Natural Ecosystem ◽  
Mineral Matrix ◽  
High Fluorescence ◽  
Lif Spectroscopy ◽  
Pi System

Sludge applications have been used to maintain fertility of agricultural soils without damaging the natural ecosystem. The aim of this study was evaluating the influence of sewage-sludge addition on the quality of organic matter (OM) of a Brazilian Oxisol by Laser Induced Fluorescence (LIF). LIF was used to analyze OM of whole soil and different soil fractions separated by chemical and physical methods. The high fluorescence contribution of humin fraction to the fluorescence of whole soils was shown, stressing the importance of studying OM associated to mineral matrix of soil. Spectra with different shapes were obtained for every particle size fraction, indicating differences in organic compounds bounded to them. The fraction with the higher carbon content was the 2-20 µm, that contains ~5% C and represents only 10% in soil, but stores 34-39 % of total C and shows the highest fluorescence intensity. The spectrum of this fraction shows its heterogeneity and a higher concentration of compounds which fluorescence is centered at 510 nm. This indicates a higher concentration of unsaturated bond systems capable of high degree of resonance, increased conjugation of the electron pi system, and higher aromaticity comparing with other fractions. No differences were detected for treatments of sewage-sludge applications. LIF spectroscopy is a promising technique for OM studies in whole soils, allowing to study spatial distribution of OM within the soil's mineral matrix, including Oxisols.

Various dictyostelids from the environment can produce multilamellar bodies

2020 ◽  
Vol 66 (12) ◽  
pp. 679-688
Author(s):  
Alicia F. Durocher ◽  
Cynthia Gagné-Thivierge ◽  
Steve J. Charette
Keyword(s):  
Cell Communication ◽  
Laboratory Strain ◽  
Food Storage ◽  
Epifluorescence Microscopy ◽  
Free Living ◽  
Multicellular Development ◽  
Multilamellar Bodies ◽  
Transmission Electron ◽  
Axenic Conditions ◽  
Social Amoebae

Multilamellar bodies (MLBs), structures composed of concentric membrane layers, are known to be produced by different protozoa, including species of ciliates, free-living amoebae, and Dictyostelium discoideum social amoebae. Initially believed to be metabolic waste, potential roles like cell communication and food storage have been suggested for D. discoideum MLBs, which could be useful for the multicellular development of social amoebae and as a food source. However, among dictyostelids, this phenomenon has only been observed with D. discoideum, and mainly with laboratory strains grown in axenic conditions. It was thought that other social amoebae may also produce MLBs. Four environmental social amoeba isolates were characterized. All strains belong to the Dictyostelium genus, including some likely to be Dictyostelium giganteum. They have distinctive phenotypes comprising their growth rate on Klebsiella aerogenes lawns and the morphology of their fruiting bodies. They all produce MLBs like those produced by a D. discoideum laboratory strain when grown on K. aerogenes lawns, as revealed by analysis using the H36 antibody in epifluorescence microscopy as well as by transmission electron microscopy. Consequently, this study shows that MLBs are produced by various dictyostelid species, which further supports a role for MLBs in the lifestyle of amoebae.

scholarly journals Application of Digital Image Analysis and Flow Cytometry To Enumerate Marine Viruses Stained with SYBR Gold

2001 ◽  
Vol 67 (2) ◽  
pp. 539-545 ◽  
Author(s):  
Feng Chen ◽  
Jing-rang Lu ◽  
Brian J. Binder ◽  
Ying-chun Liu ◽  
Robert E. Hodson
Keyword(s):  
Flow Cytometry ◽  
Image Analysis ◽  
Digital Image ◽  
Digital Image Analysis ◽  
Flow Cytometric Analysis ◽  
Epifluorescence Microscopy ◽  
Flow Cytometric ◽  
Viral Particles ◽  
Sybr Gold ◽  
Nucleic Acid Stain

ABSTRACT A novel nucleic acid stain, SYBR Gold, was used to stain marine viral particles in various types of samples. Viral particles stained with SYBR Gold yielded bright and stable fluorescent signals that could be detected by a cooled charge-coupled device camera or by flow cytometry. The fluorescent signal strength of SYBR Gold-stained viruses was about twice that of SYBR Green I-stained viruses. Digital images of SYBR Gold-stained viral particles were processed to enumerate the concentration of viral particles by using digital image analysis software. Estimates of viral concentration based on digitized images were 1.3 times higher than those based on direct counting by epifluorescence microscopy. Direct epifluorescence counts of SYBR Gold-stained viral particles were in turn about 1.34 times higher than those estimated by the transmission electron microscope method. Bacteriophage lysates stained with SYBR Gold formed a distinct population in flow cytometric signatures. Flow cytometric analysis revealed at least four viral subpopulations for a Lake Erie sample and two subpopulations for a Georgia coastal sample. Flow cytometry-based viral counts for various types of samples averaged 1.1 times higher than direct epifluorescence microscopic counts. The potential application of digital image analysis and flow cytometry for rapid and accurate measurement of viral abundance in aquatic environments is discussed.

Sign in / Sign up

Export Citation Format

Share Document