Ultrastructure of wilt syndrome caused by Verticillium dahliae. VII. Correlated light and transmission electron microscope identification of vessel coatings and tyloses

1979 ◽  
Vol 57 (7) ◽  
pp. 822-834 ◽  
Author(s):  
Jane Robb ◽  
J. D. Brisson ◽  
Lloyd Busch ◽  
B. C. Lu

Thin cross sections of petioles from wilted leaves of chrysanthemums infected with Verticillium dahliae were fixed in glutaraldehyde + FeCl3 and embedded for electron microscopy. Alternate thick (LM) and thin (TEM) sections were cut. The thick sections were stained with (1) the Prussian blue reaction, (2) Sudan black B, (3) toluidine blue O, or (4) Schiff s reagent. Correlated LM and TEM of exactly the same vessels showed that tylosis walls, smooth coating, fibrillar coating, and bubbly coating stained differentially. The tyloses are more abundant than formerly anticipated but are restricted to the primary vessels; fungal cells and coating on vessel walls are confined to smaller secondary vessels.

2009 ◽  
Vol 1184 ◽  
Author(s):  
Helge Heinrich ◽  
Biao Yuan ◽  
Haritha Nukala ◽  
Bo Yao

AbstractIn Scanning Transmission Electron Microscopy (STEM) the High-Angle Annular Dark-Field (HAADF) signal increases with atomic number and sample thickness, while dynamic scattering effects and sample orientation have little influence on the contrast. The sensitivity of the HAADF detector for a FEI F30 transmission electron microscope has been calibrated. Additionally, a nearly linear relationship of the HAADF signal with the incident electron current is confirmed. Cross sections of multilayered samples for contrast calibration were obtained by focused ion-beam (FIB) preparation. These cross sections contained several layers with known composition. A database with several pure elements and compounds has been compiled, containing experimental data on the fraction of electrons scattered onto the HAADF detector for each nanometer of sample thickness. Contrast simulations are based on the multi-slice formalism and confirm the differences in HAADF-scattering contrast for the elements and compounds. TEM offers high lateral resolution, but contains little or no information on the thickness of samples. Thickness maps in energy-filtered transmission electron microscopy, convergent-beam electron diffraction and tilt series are so far the only methods to determine thicknesses of particles in a transmission electron microscope. We show that the calibrated HAADF contrast can be used to determine the thicknesses of individual nanoparticles deposited on carbon films. With this information the volumes of nanoparticles with known composition were determined.


Author(s):  
M.A. O’Keefe ◽  
J. Taylor ◽  
D. Owen ◽  
B. Crowley ◽  
K.H. Westmacott ◽  
...  

Remote on-line electron microscopy is rapidly becoming more available as improvements continue to be developed in the software and hardware of interfaces and networks. Scanning electron microscopes have been driven remotely across both wide and local area networks. Initial implementations with transmission electron microscopes have targeted unique facilities like an advanced analytical electron microscope, a biological 3-D IVEM and a HVEM capable of in situ materials science applications. As implementations of on-line transmission electron microscopy become more widespread, it is essential that suitable standards be developed and followed. Two such standards have been proposed for a high-level protocol language for on-line access, and we have proposed a rational graphical user interface. The user interface we present here is based on experience gained with a full-function materials science application providing users of the National Center for Electron Microscopy with remote on-line access to a 1.5MeV Kratos EM-1500 in situ high-voltage transmission electron microscope via existing wide area networks. We have developed and implemented, and are continuing to refine, a set of tools, protocols, and interfaces to run the Kratos EM-1500 on-line for collaborative research. Computer tools for capturing and manipulating real-time video signals are integrated into a standardized user interface that may be used for remote access to any transmission electron microscope equipped with a suitable control computer.


2020 ◽  
Vol 10 (14) ◽  
pp. 4946
Author(s):  
Nguyen Thi Thu Trang ◽  
Jungshan Chang ◽  
Wei-An Chen ◽  
Chih-Chun Chen ◽  
Hui-Min Chen ◽  
...  

Ultrastructural observation of biological specimens or nanogranules usually requires the use of electron microscopy. Electron microscopy takes a lot of time, requires many steps, and uses many chemicals, which may affect the native state of biological specimens. A novel microchip (K-kit) was used as a specimen kit for in situ imaging of human platelet granules in an aqueous solution using a transmission electron microscope. This microchip enabled us to observe the native human platelet granules very quickly and easily. The protocols included blood collection, platelet purification, platelet granule isolation, sample loading into this microchip, and then observation by a transmission electron microscope. In addition, these granules could still remain in aqueous solution, and only a very small amount of the sample was required for observation and analysis. We used this microchip to identify the native platelet granules by negative staining. Furthermore, we used this microchip to perform immunoelectron microscopy and successfully label α-granules of platelets with the anti-P-selectin antibody. These results demonstrate that the novel microchip can provide researchers with faster and better choices when using a transmission electron microscope to examine nanogranules of biological specimens in aqueous conditions.


1985 ◽  
Vol 54 ◽  
Author(s):  
Taeil Kim ◽  
D.D.L. Chung

ABSTRACTThe structure of 500 Å Au/500 A Ge/500 Å Au/GaAs (100) was studied by transmission electron microscopy after annealing at 350 – 500°C. Annealing at 350 – 450°C caused the formation of AuGeAs with a (110) texture, but this phase disappeared after annealing at 500°C. The hexagonal a-AuGa (or AuGa) was formed after annealing at 400°C, such that (111)Au // (0001)a, and [110]AU // [1120]a and there was perfect lattice match between Au (i.e., Au-rich solid solution) and a-AuGa. After annealing at 450°C or above, a phase tentatively identified as the hexagonal Au3Ga was formed and Ge (i.e., Ge-rich solid solution) became epitaxial to (100) GaAs. Annealing at 400°C caused Au to change from no texture to a (110) texture.


1998 ◽  
Vol 6 (9) ◽  
pp. 18-21
Author(s):  
Alwyn Eades

The world of electron microscopy is in a period of transition from acquiring images on film to acquiring images digitally, using CCD cameras, for example. It would be useful to knew how much information there is on a piece of film, in order to know how film compares with digital methods and to be able to make good judgements on the optimum moment to change from one technology to the other.This is an attempt to use simple arguments to estimate just how much information there is in an image exposed on film in the transmission electron microscope, the main reason for addressing this issue Is that, while many people are affected by it there seems to be little agreement on the answer.


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