Nile red fluorescence demonstrates lipid in the envelope of vesicles from N2-fixing cultures of Frankia

1988 ◽  
Vol 34 (5) ◽  
pp. 656-660 ◽  
Author(s):  
Hayes C. Lamont ◽  
Warwick B. Silvester ◽  
John G. Torrey
Keyword(s):  
Nitrogenase Activity ◽  
Nile Red ◽  
Green Light ◽  
Dark Field ◽  
Free Medium ◽  
Frankia Strain ◽  
Dark Field Microscopy ◽  
Lipid Solvent ◽  
Nile Red Fluorescence ◽  
Fluorescent Stain

Using Nile red as a fluorescent stain for lipid, we investigated the composition of the envelope of vesicles of Frankia strain HFPCcI3 from cultures induced in N-free medium at 1 and 20 kPa O2. Vesicles and nitrogenase activity appeared in the cultures at both pO2; on average, vesicles viewed by dark-field microscopy were larger and had thicker envelopes at 20 kPa O2 than at 1 kPa O2. Envelopes of Nile red-stained vesicles fluoresced red under incident green light. When samples of CcI3 were extracted through a lipid-solvent series and then stained, vesicles still fluoresced red but lacked a distinct peripheral fluorescent ring. These results are consistent with the view that the envelope of Frankia vesicles consists largely of lipid and serves as a barrier to diffusion of O2.

Adaptation of nitrogenase to varying oxygen tension and the role of the vesicle in root nodules of Alnus incana ssp. rugosa

1988 ◽  
Vol 66 (9) ◽  
pp. 1772-1779 ◽  
Author(s):  
Warwick B. Silvester ◽  
Janet K. Silvester ◽  
John G. Torrey
Keyword(s):  
Flow System ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Major Change ◽  
Dark Field ◽  
Alnus Incana ◽  
Major Barrier ◽  
Dark Field Microscopy ◽  
Nodule Morphology

Growth of Alnus incana ssp. rugosa plants with root systems at Po2 levels of 5, 21, and 40 kPa showed no significant differences among treatments over a 6-week period. Nitrogenase activity of attached nodulated foot systems run in an opencuvette continuous-flow system generally was responsive to Po2 over a broad range around the optimum. Plants expressed acetylene-induced and oxygen-induced transient declines in nitrogenase activity, from which they spontaneously recovered. Nitrogenase activity was seldom stable at any one Po2 during assay with apparent adaptation to both above- and below-ambient Po2 Nodule morphology showed quantitative decreases in aeration pathways as ambient Po2 was increased, with air spaces in the cortex and infected tissue being significantly affected. The major change in response to Po2 was the change in vesicle structure. Vesicles from nodules at low Po2 showed a vanishingly thin vesicle envelope under dark-field microscopy, while at high Po2 vesicles appeared very bright and apparently thickened. The results suggest that the major barrier to O2 diffusion in Alnus nodules is the vesicle envelope of the bacterium.

Elastic Scattering in Electron Microscopy

1973 ◽  
Vol 31 ◽  
pp. 252-253
Author(s):  
J. Langmore ◽  
M. Isaacson ◽  
J. Wall ◽  
A. V. Crewe
Keyword(s):  
Electron Microscopy ◽  
Elastic Scattering ◽  
Cross Section ◽  
Quantum Noise ◽  
Dark Field ◽  
Elastic Cross Section ◽  
Biological Molecules ◽  
Dark Field Microscopy ◽  
Field Systems ◽  
Effects Of Radiation

High resolution dark field microscopy is becoming an important tool for the investigation of unstained and specifically stained biological molecules. Of primary consideration to the microscopist is the interpretation of image Intensities and the effects of radiation damage to the specimen. Ignoring inelastic scattering, the image intensity is directly related to the collected elastic scattering cross section, σɳ, which is the product of the total elastic cross section, σ and the eficiency of the microscope system at imaging these electrons, η. The number of potentially bond damaging events resulting from the beam exposure required to reduce the effect of quantum noise in the image to a given level is proportional to 1/η. We wish to compare η in three dark field systems.

Simulated Dark-Field Electron Micrographs of Point Defects and Organometallics

1975 ◽  
Vol 33 ◽  
pp. 200-201
Author(s):  
William Krakow
Keyword(s):  
Electron Micrographs ◽  
Point Defects ◽  
Structure Determination ◽  
Atomic Structure ◽  
Image Interpretation ◽  
Dark Field ◽  
Field Electron ◽  
Dark Field Microscopy ◽  
Dark Field Electron

Tilted beam dark-field microscopy has been applied to atomic structure determination in perfect crystals, several synthesized molecules with heavy atcm markers and in the study of displaced atoms in crystals. Interpretation of this information in terms of atom positions and atom correlations is not straightforward. Therefore, calculated dark-field images can be an invaluable aid in image interpretation.

scholarly journals Multiplexed Plasmonic Nano-Labeling for Bioimaging of Cytological Stained Samples

Cancers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 3509
Author(s):  
Paule Marcoux-Valiquette ◽  
Cécile Darviot ◽  
Lu Wang ◽  
Andrée-Anne Grosset ◽  
Morteza Hasanzadeh Kafshgari ◽  
...  
Keyword(s):  
Accurate Determination ◽  
Cell Types ◽  
Fine Needle Biopsy ◽  
Dark Field ◽  
Imaging Method ◽  
New Methods ◽  
Formalin Fixed Paraffin ◽  
Dark Field Microscopy ◽  
Formalin Fixed Paraffin Embedded

Reliable cytopathological diagnosis requires new methods and approaches for the rapid and accurate determination of all cell types. This is especially important when the number of cells is limited, such as in the cytological samples of fine-needle biopsy. Immunoplasmonic-multiplexed- labeling may be one of the emerging solutions to such problems. However, to be accepted and used by the practicing pathologists, new methods must be compatible and complementary with existing cytopathology approaches where counterstaining is central to the correct interpretation of immunolabeling. In addition, the optical detection and imaging setup for immunoplasmonic-multiplexed-labeling must be implemented on the same cytopathological microscope, not interfere with standard H&E imaging, and operate as a second easy-to-use imaging method. In this article, we present multiplex imaging of four types of nanoplasmonic markers on two types of H&E-stained cytological specimens (formalin-fixed paraffin embedded and non-embedded adherent cancer cells) using a specially designed adapter for SI dark-field microscopy. The obtained results confirm the effectiveness of the proposed optical method for quantitative and multiplex identification of various plasmonic NPs, and the possibility of using immunoplasmonic-multiplexed-labeling for cytopathological diagnostics.

scholarly journals Hyperspectral-enhanced dark field analysis of individual and collective photo-responsive gold–copper sulfide nanoparticles

Nanoscale ◽  
2021 ◽  
Author(s):  
Paula Zamora-Perez ◽  
Beatriz Pelaz ◽  
Dionysia Tsoutsi ◽  
Mahmoud G. Soliman ◽  
Wolfgang J. Parak ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Real Time ◽  
Copper Sulfide ◽  
Dark Field ◽  
Field Analysis ◽  
Dark Field Microscopy

Hyperspectral-enhanced dark field microscopy to correlate Au/CuS NPs’ changes in their physicochemical properties induced by cellular environments with their functionality as photothermal probes by tracking their scattering profile evolution in real time.

scholarly journals Dark-field microscopy enhance visibility of CD31 endothelial staining

2020 ◽  
Vol 64 (3) ◽  
Author(s):  
Eva Jennische ◽  
Stefan Lange ◽  
Ragnar Hultborn
Keyword(s):  
Phase Contrast ◽  
Scattered Light ◽  
Dark Field ◽  
Light Scatter ◽  
Endothelial Lining ◽  
Microscopy Technique ◽  
Dark Field Microscopy ◽  
Dark Field Illumination ◽  
Normal Human ◽  
Intense Light

A simple dark field microscopy technique was used for visualization of blood vessels in normal human renal tissues and carcinoma. Phase contrast condenser ring apt for high power objectives was combined with a 10x objective in order to create a dark field illumination of the specimens examined. The endothelial lining of the vessels had been stained by using CD31 monoclonal antibodies combined with conventional peroxidase immunohistochemistry. The final DAB addition used for this technique induced an intense light scatter in the dark field microscope. This scattered light originating from the endothelial lining made the walls of the bright vessels easily detectable from the dark background.

scholarly journals Risk for infection by Lyme disease cause in green surfaces maintenance workers in Belgrade

2007 ◽  
Vol 64 (5) ◽  
pp. 313-318 ◽  
Author(s):  
Milena Krstic ◽  
Novica Stajkovic
Keyword(s):  
Lyme Disease ◽  
Infection Rate ◽  
Risk Index ◽  
Dark Field ◽  
Elisa Test ◽  
Control Group ◽  
Serum Samples ◽  
Tick Infection ◽  
Dark Field Microscopy ◽  
Tick Infection Rate

Background/Aim. Lyme disease (LD) is a cosmopolitan disease from the group of zoonoses that in humans can affect skins, joints, heart and/or nervous system. Research conducted in endemic areas, shows not only that the population, which lives or works in tick habitats, is in a high risk for getting infected by LD cause, but also that every enviroment itself is specific in regard to both vectors and B. burgdorferi species. In our enviroment, research of seropositivity to B. burgdorferi in persons exposed to vectors of LD have not been conducted. The aim of this study was to determine whether there was a higher risk for getting B. burgdorferi infection in the fieldworks of JKP "Zelenilo Beograd" than in other persons. Methods. Risk for getting LD in the fieldworkers of JKP "Zelenilo Beograd" (park-maintanance company) was determined according to seropositivity, the number and infection rate of LD vectors, and entomological risk index (ERI) value. Serum samples of 34 fieldworkers of JKP "Zelenilo Beograd", and 35 persons of the control group, were tested for the presence of specific IgM and IgG anti-B. burgdorferi antibodies by using ELISA test. In the research localities, the number of ticks was estimated by using the flag hours method, and tick infection rate was determined by dark field microscopy, with magnification rate of 400?. The data were analyzed statistically using ?2 test, and Pearson's correlation analysis. Results. Out of 34 fieldworkes serum samples, 8 (23.5%) were positive on anti-B. burgdorferi antibody presence, while in the control group only one (2.9%) sample was positive (p < 0,05). Seropositivity rate varied from 0-66.6% among localities. Flag hours value among the localities ranged from 8.2-29.9, and tick infection rate ranged from 10.8- 22.3%. ERI value was 0.03-0.15. Correlation between flag hour rate and seropositivity, tick infection rate and seropositivity, and also ERI and seropositivity was established. Conclusion. Frequency of B. burgdorferi seropositivity was significantly higher in green-surface maintenance workers, than in the control group not exposed to these habitats. A significant correlation was found between anti-B. burgdorferi antibodies findings and the number of ticks, tick infection rate, and ERI. The results obtained in our study indicate that there was a significantly higher risk for getting LD cause in the fieldworkers than in the control group. .

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