The role of sulphur in ZDDP-induced reaction films formed in the presence of ZDDP: Contribution of electron spectroscopic imaging technique

The structure of the kinetochore in thin section has been studied in the Indian muntjac by an electron spectroscopic imaging technique. This procedures allows the analysis of the distribution of phosphorus within the layers of the kinetochore. The results indicate that this element is a major component of both the inner and outer plates whereas it is largely absent in the middle plate and fibrous corona. The majority of the phosphorus is localized to a 30-nm fiber(s) that is woven through the layers of the kinetochore. The presence of phosphorus within this fiber, along with its morphological and biochemical features, indicates that it contains DNA. The fiber(s) occupies a major portion of the inner and outer plate where it forms a series of rows. It is rarely observed in the middle layer except where it passes between the inner and outer layers. The absence of structure in the middle plate suggests that it may represent a space rather than a plate that in turn may be related to the function of this region. The distribution of phosphorus within the kinetochore is neither altered by treatment with colcemid nor by the presence of microtubules at the kinetochore. Analysis of conventional micrographs of the kinetochore together with structural information obtained by electron spectroscopic imaging suggests that most microtubules insert and terminate between the rows of kinetochore fibers in the outer plate. However, some microtubules continue through the middle layer and terminate at the lower plate. The insertion of microtubules at different levels of the kinetochore may reflect the existence of functionally distinct microtubule classes. Electron spectroscopic imaging indicates that the microtubules associated with the kinetochore are phosphorylated.

Download Full-text

Electron Spectroscopic Imaging of Magnetotactic Bacteria: Magnetosome Morphology and Diversity

Microscopy and Microanalysis ◽

10.1007/s100050010047 ◽

2000 ◽

Vol 6 (5) ◽

pp. 463-470 ◽

Cited By ~ 8

Author(s):

Ulysses Lins ◽

Flávia Freitas ◽

Carolina N. Keim ◽

Marcos Farina

Keyword(s):

Imaging Technique ◽

Spectroscopic Imaging ◽

Magnetotactic Bacteria ◽

Aquatic Environments ◽

Natural Environments ◽

Electron Spectroscopic Imaging ◽

Multicellular Aggregates ◽

Structural Relationships ◽

Size And Morphology ◽

Uncultured Microorganisms

AbstractMagnetotactic bacteria from aquatic environments were analyzed with the electron spectroscopic imaging technique. Rod-shaped bacteria and cocci were present in most of the samples observed. Magnetotactic multicellular aggregates were also observed at some of the sampling sites. The use of electron spectroscopic imaging allowed the observation of magnetosomes inside magnetotactic microorganisms with exceptional clarity. The number, size, and morphology of magnetosomes, as well as their ultrastructural spatial disposition inside the bacterial cell, could be directly observed and associated with the disposition of flagella of the respective cells.This allowed us to examine the structural relationships between magnetosomes and flagella, which are important components in the mechanisms of magnetotaxis. In disrupted magnetotactic multicellular aggregates, connections between cells were also visualized. We believe this technique will be useful in studying not only magnetotactic bacteria but also other uncultured microorganisms from natural environments.

Download Full-text

The contribution of osmium tetroxide to the image quality and detectability of elements in cells studies by electron spectroscopic imaging

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010016145x ◽

1990 ◽

Vol 48 (3) ◽

pp. 778-779

Author(s):

Rebecca C. Stearns ◽

Cindy L. Hastings ◽

Marshall Katler ◽

John J. Godleski

Keyword(s):

Heavy Metals ◽

Electron Microscope ◽

Osmium Tetroxide ◽

Spectroscopic Imaging ◽

Electron Spectroscopic Imaging ◽

Soluble Ions ◽

The Times ◽

Fe Ions

Osmium tetroxide has been recognized as an excellent fixative which also contributes to the quality of TEM micrographs (1). In the preparation of biological materials for electron spectroscopic imaging (ESI) of 30 run sections with the Zeiss CEM902 electron microscope, OsO4 is usually used in fixation, but poststaining with heavy metals is not needed. However, the extent of the contribution of OsO4, to the images obtained had not been defined clearly, nor was it clear the extent to which the presence of OsO, might obscure detection of elements by ESI or EELS. To establish optimal liquid fixation for the preservation of soluble ions we monitored the loss of Fe ions during preparation. To determine the role of Os4O, in ESI imaging, hamster alveolar macrophages (AMS) were incubated with 0.ImM FeCLo for 15 minutes, then fixed with 2.5% glutaraldehyde in 0.IM K phosphate buffer in 0.01% CaCLo, then grouped into 6 samples varying the times and percentages of OsO, . One sample was not exposed to any OsO4.

Download Full-text

Visualisation of E. coli ribosomal RNA in situ by electron spectroscopic imaging and image averaging

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100122733 ◽

1992 ◽

Vol 50 (1) ◽

pp. 466-467

Author(s):

Daniel Beniac ◽

George Harauz

Keyword(s):

Ribosomal Rna ◽

Three Dimensional ◽

Spectroscopic Imaging ◽

Electron Spectroscopic Imaging ◽

E Coli ◽

Microscopical Technique ◽

Quantitative Image ◽

Dimensional Reconstruction ◽

Image Averaging ◽

Protein Components

The structures of E. coli ribosomes have been extensively probed by electron microscopy of negatively stained and frozen hydrated preparations. Coupled with quantitative image analysis and three dimensional reconstruction, such approaches are worthwhile in defining size, shape, and quaternary organisation. The important question of how the nucleic acid and protein components are arranged with respect to each other remains difficult to answer, however. A microscopical technique that has been proposed to answer this query is electron spectroscopic imaging (ESI), in which scattered electrons with energy losses characteristic of inner shell ionisations are used to form specific elemental maps. Here, we report the use of image sorting and averaging techniques to determine the extent to which a phosphorus map of isolated ribosomal subunits can define the ribosomal RNA (rRNA) distribution within them.

Download Full-text

Transcription factor/DNA interactions visualized by electron spectroscopic imaging

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100122654 ◽

1992 ◽

Vol 50 (1) ◽

pp. 450-451

Author(s):

David P. Bazett-Jones ◽

Mark L. Brown

Keyword(s):

Transcription Factor ◽

Dna Sequences ◽

Transcription Initiation ◽

Molecular Mechanisms ◽

Phosphorus Content ◽

Spectroscopic Imaging ◽

Electron Spectroscopic Imaging ◽

Dna Backbone ◽

Two Parameters ◽

High Level

A multisubunit RNA polymerase enzyme is ultimately responsible for transcription initiation and elongation of RNA, but recognition of the proper start site by the enzyme is regulated by general, temporal and gene-specific trans-factors interacting at promoter and enhancer DNA sequences. To understand the molecular mechanisms which precisely regulate the transcription initiation event, it is crucial to elucidate the structure of the transcription factor/DNA complexes involved. Electron spectroscopic imaging (ESI) provides the opportunity to visualize individual DNA molecules. Enhancement of DNA contrast with ESI is accomplished by imaging with electrons that have interacted with inner shell electrons of phosphorus in the DNA backbone. Phosphorus detection at this intermediately high level of resolution (≈lnm) permits selective imaging of the DNA, to determine whether the protein factors compact, bend or wrap the DNA. Simultaneously, mass analysis and phosphorus content can be measured quantitatively, using adjacent DNA or tobacco mosaic virus (TMV) as mass and phosphorus standards. These two parameters provide stoichiometric information relating the ratios of protein:DNA content.

Download Full-text

Localization of DNA in chromatin using ESI and osmium ammine staining

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100158121 ◽

1990 ◽

Vol 48 (3) ◽

pp. 116-117

Author(s):

C.L. Woodcock ◽

R.A. Horowitz ◽

D. P. Bazett-Jones ◽

A.L. Olins

Keyword(s):

Spectroscopic Imaging ◽

Energy Losses ◽

Electron Spectroscopic Imaging ◽

Feulgen Reaction ◽

Specific Location ◽

Eukaryotic Nucleus ◽

Chromatin Fibers ◽

Patiria Miniata ◽

Model Structures

In the eukaryotic nucleus, DNA is packaged into nucleosomes, and the nucleosome chain folded into ‘30nm’ chromatin fibers. A number of different model structures, each with a specific location of nucleosomal and linker DNA have been proposed for the arrangment of nucleosomes within the fiber. We are exploring two strategies for testing the models by localizing DNA within chromatin: electron spectroscopic imaging (ESI) of phosphorus atoms, and osmium ammine (OSAM) staining, a method based on the DNA-specific Feulgen reaction.Sperm were obtained from Patiria miniata (starfish), fixed in 2% GA in 150mM NaCl, 15mM HEPES pH 8.0, and embedded In Lowiciyl K11M at -55C. For OSAM staining, sections 100nm to 150nm thick were treated as described, and stereo pairs recorded at 40,000x and 100KV using a Philips CM10 TEM. (The new osmium ammine-B stain is available from Polysciences Inc). Uranyl-lead (U-Pb) staining was as described. ESI was carried out on unstained, very thin (<30 nm) beveled sections at 80KV using a Zeiss EM902. Images were recorded at 20,000x and 30,000x with median energy losses of 110eV, 120eV and 160eV, and a window of 20eV.

Download Full-text

Spectroscopic Imaging with an Ultra-Broadband (1–4 THz) Compact Terahertz Difference-Frequency Generation Source

Electronics ◽

10.3390/electronics10030336 ◽

2021 ◽

Vol 10 (3) ◽

pp. 336

Author(s):

Atsushi Nakanishi ◽

Shohei Hayashi ◽

Hiroshi Satozono ◽

Kazuue Fujita

Keyword(s):

Imaging Technique ◽

Spectroscopic Imaging ◽

Difference Frequency Generation ◽

Difference Frequency ◽

Quality Monitoring ◽

Terahertz Emission ◽

Mid Infrared ◽

Quantum Cascade ◽

Frequency Generation ◽

Multi Mode

We demonstrate spectroscopic imaging using a compact ultra-broadband terahertz semiconductor source with a high-power, mid-infrared quantum cascade laser. The electrically pumped monolithic source is based on intra-cavity difference-frequency generation and can be designed to achieve an ultra-broadband multi-mode terahertz emission spectrum extending from 1–4 THz without any external optical setup. Spectroscopic imaging was performed with three frequency bands, 2.0 THz, 2.5 THz and 3.0 THz, and as a result, this imaging technique clearly identified three different tablet components (polyethylene, D-histidine and DL-histidine). This method may be highly suitable for quality monitoring of pharmaceutical materials.

Download Full-text