scholarly journals Ultrastructural Analysis of DNA Complexes During Transfection and Intracellular Transport

2003 ◽  
Vol 51 (9) ◽  
pp. 1237-1240 ◽  
Author(s):  
Régis Cartier ◽  
Maria Velinova ◽  
Cathleen Lehman ◽  
Bettina Erdmann ◽  
Regina Reszka
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Intracellular Transport ◽  
Ultrastructural Analysis ◽  
Cell Entry ◽  
Dna Complexes ◽  
Simple Method ◽  
Transmission Electron ◽  
Internalization Process ◽  
Entry Mechanism

We present a simple method based on transmission electron microscopy that allows investigation of the early steps of polyplex-mediated transfection without the use of labeled DNA. The ultrastructural analysis showed internalization of 0.2–1-μm aggregates composed of 30–50-nm subunits. In addition, new details of the internalization process were revealed, suggesting an unspecific cell entry mechanism of large DNA aggregates.

scholarly journals Ultrastructural analysis of selected Cretaceous megaspores from Argentina

1988 ◽  
Vol 7 (1) ◽  
pp. 73-87 ◽  
Author(s):  
Wilson A. Taylor ◽  
Thomas N. Taylor
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Lower Cretaceous ◽  
Ultrastructural Analysis ◽  
Biological Information ◽  
Evolutionary Significance ◽  
Additional Information ◽  
Transmission Electron ◽  
Extant Species ◽  
Wall Construction

Abstract. Detailed ultrastructural analysis of an assemblage of Lower Cretaceous megaspores from the Baqueró Formation of Argentina allows a complete description of two new taxa as well as additional information on the structure of several previously described types. Erlansonisporites sparassis displays a complex wall stratification, a separable surface reticulum, and attached microspores. Horstisporites iridodea sp. nov. possesses an elaborately patterned wall like that seen in several extant species of the modern lycopod genus Selaginella. On the basis of developmental information from modern heterosporous lycopod megaspores, the mesospore bearing Bacutriletes triangulatus sp. nov. is recognised as an aborted product of a meiotic tetrad. Also reported from this locality are Hughesisporites patagonicus, Bacutriletes sp. A, and an additional loosely defined megaspore type with characteristic clavae. Transmission electron microscopy provides the opportunity to infer previously unattainable biological information from dispersed spores. Such studies provide new insights as a foundation for the further elucidation of the developmental and evolutionary significance of wall construction in heterosporous pteridophytes.

A Simple Method to Self-Assemble Two-dimensional and Three-dimensional Superlattices of Gold Nanoparticles

2007 ◽  
Vol 1056 ◽  
Author(s):  
Tao Fu ◽  
Hai-Yan Qin ◽  
Wen-Jiang Li ◽  
Sailing He
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Gold Nanoparticles ◽  
Particle Dispersion ◽  
Diameter Distribution ◽  
Chloroauric Acid ◽  
Two Dimensional ◽  
Visible Absorption ◽  
Simple Method ◽  
Transmission Electron

ABSTRACTCitrate-capped gold nanoparticles with narrow diameter distribution were prepared by the reduction of chloroauric acid with borohydride. After the gold nanoparticles were transferred to toluene solution through ligand conformation change, close-packed two-dimensional nanocrystal lattices were obtained on transmission electron microscopy (TEM) copper grids by evaporating approximately 10 μL of concentrated particle dispersion. The formation of the thiolate gold nanoparticles was investigated by UV-visible absorption spectroscopy and FTIR spectra. The 2D Fourier transform power spectra of the monolayer confirmed the supperlattices' hexagonal symmetry. Furthermore, long-range-ordered bilayer superlattices, of which the nanoparticles in the top layer piled on the ones in the bottom layer, could also be observed by transmission electron microscopy.

Novel Method for Preparing Transmission Electron Microscopy Samples of Micrometer-Sized Powder Particles by Using Focused Ion Beam

2017 ◽  
Vol 23 (5) ◽  
pp. 1055-1060 ◽  
Author(s):  
Tae-Hoon Kim ◽  
Min-Chul Kang ◽  
Ga-Bin Jung ◽  
Dong Soo Kim ◽  
Cheol-Woong Yang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Focused Ion Beam ◽  
Size Range ◽  
Ion Beam ◽  
Preparation Technique ◽  
Simple Method ◽  
Transmission Electron ◽  
Powder Particles ◽  
Novel Method

AbstractThe preparation of transmission electron microscopy (TEM) samples from powders is quite difficult and challenging. For powders with particles in the 1–5 μm size range, it is especially difficult to select an adequate sample preparation technique. Epoxy is commonly used to bind powder, but drawbacks, such as differential milling originating from unequal milling rates between the epoxy and powder, remain. We propose a new, simple method for preparing TEM samples. This method is especially useful for powders with particles in the 1–5 μm size range that are vulnerable to oxidation. The method uses solder as an embedding agent together with focused ion beam (FIB) milling. The powder was embedded in low-temperature solder using a conventional hot-mounting instrument. Subsequently, FIB was used to fabricate thin TEM samples via the lift-out technique. The solder proved to be more effective than epoxy in producing thin TEM samples with large areas. The problem of differential milling was mitigated, and the solder binder was more stable than epoxy under an electron beam. This methodology can be applied for preparing TEM samples from various powders that are either vulnerable to oxidation or composed of high atomic number elements.

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