Interpretation of Structural Detail in Viruses of the Polyoma Group*

2015 ◽  
pp. 95-124 ◽  
Author(s):  
June D. Almeida ◽  
A. P. Waterson ◽  
E. W. L. Fletcher
Keyword(s):  
Structural Detail

scholarly journals Discrimination of patterns of N-acetylation in chitooligosaccharides by gas phase IR spectroscopy integrated to mass spectrometry

2017 ◽  
Vol 89 (9) ◽  
pp. 1349-1357 ◽  
Author(s):  
Jasper Wattjes ◽  
Baptiste Schindler ◽  
Stéphane Trombotto ◽  
Laurent David ◽  
Bruno M. Moerschbacher ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Ir Spectroscopy ◽  
Gas Phase ◽  
Dimensional Analysis ◽  
Unique Combination ◽  
Structural Detail ◽  
Chitosan Oligosaccharides ◽  
Infra Red ◽  
Rapid Discrimination ◽  
Gas Phase Spectroscopy

AbstractWe propose a novel, bi-dimensional analysis of partially N-acetylated chitosan oligosaccharides based on gas phase Infra-Red spectroscopy integrated to mass spectrometry (MS). By providing simultaneously MS and IR fingerprints, this approach combines the advantages of MS with the refined structural detail offered by gas phase spectroscopy and provides robust signatures for the rapid discrimination of the patterns of N-acetylation. Four mono-N-deacetylated and two doubly-N-deacetylated chitosan tetramer standards with well-defined patterns of acetylation were produced and analyzed by IR integrated to MS. We show that each sequence displays a unique combination of MS and IR fingerprints, thus offering a rapid diagnostic for the pattern of acetylation without the need for reducing end labeling.

Ultrastructure of the cell envelope and septation process in Caryophanon latum as revealed by thin section and freeze-etching techniques

1974 ◽  
Vol 20 (10) ◽  
pp. 1435-1442 ◽  
Author(s):  
W. C. Trentini ◽  
H. E. Gilleland Jr.
Keyword(s):  
Cytoplasmic Membrane ◽  
External Surface ◽  
Cell Envelope ◽  
Optimal Conditions ◽  
Structural Detail ◽  
Cross Sectional ◽  
External Wall ◽  
Thin Sectioning ◽  
Freeze Etching ◽  
Peptidoglycan Layer

With optimal conditions of thin-sectioning and freeze-etching, the cell wall of Caryophanon latum was composed of a thick peptidoglycan layer plus two external wall layers. The freeze-etched appearance of the external surface of the outer layer was smooth and lacked structural detail. The numerous cross septa within a trichome were formed by the symmetrical and concurrent ingrowth of the cytoplasmic membrane and the peptidoglycan layer. The site of septum initiation was identifiable by a dart-shaped ingrowth of the peptidoglycan layer rather than by the presence of a mesosome. However, small simple mesosomes were occasionally seen associated with the developing septum. The peptidoglycan in the septum had thickened to at least double the thickness of the wall peptidoglycan layer by the time of septum completion. The external wall layers did not participate in septum formation but did participate in trichome separation. The separation of the septal peptidoglycan was completed during the early ingrowth of the external wall layers. A unique cross-sectional view of a developing septum closing like an iris diaphragm as seen in a freeze-etched preparation was observed.

scholarly journals PHOTORECEPTOR STRUCTURES

1957 ◽  
Vol 3 (3) ◽  
pp. 441-448 ◽  
Author(s):  
J. J. Wolken ◽  
J. Capenos ◽  
A. Turano
Keyword(s):  
Electron Microscopy ◽  
Polarized Light ◽  
Plant Cells ◽  
House Fly ◽  
Structural Detail ◽  
Thin Sections ◽  
Retinal Rods ◽  
Single Structure ◽  
Vertebrate Eye ◽  
Insect Eye

The eyes of three eye mutants of Drosophila melanogaster were fixed and thin sections studied for its structural detail in the electron microscope. Each ommatidium was found to have seven retinula cells with an equal number of rhabdomeres (visual units). The rhabdomeres average 1.2 µ in diameter and 60 µ in length. Each rhabdomere consists of osmium-fixed dense bands averaging 120 A in thickness, and with less dense interspaces 200 to 400 A. There is an average of 23 dense bands or 46 interfaces per micron within the rhabdomere. The rhabdomere as we have presented it is a single structure of packed rods or tubes. The "fine structure" within the rhabdomere is similar to that observed by electron microscopy for the retinula of the house fly, and to the retinal rods of the vertebrate eye, and to the chloroplasts of plant cells in a variety of animal and plant photoreceptor structures. In addition, the radial arrangements within the ommatidium of radially unsymmetrical units, the rhabdomeres, is probably related to the analysis of polarized light in the insect eye.

The Application of S-N Curves Considering Mismatch of Stress Concentration Between Test Specimen and Structure

1998 ◽  
Vol 42 (01) ◽  
pp. 68-78
Author(s):  
Sergei V. Petinov ◽  
Anil K. Thayamballi
Keyword(s):  
Test Specimen ◽  
Local Strain ◽  
Statistical Correlation ◽  
Life Assessment ◽  
Structural Detail ◽  
Numerical Examples ◽  
Fatigue Life Assessment ◽  
Allowable Stresses ◽  
Structural Details ◽  
Conventional Manner

This paper presents a procedure for the adjustment of S-N diagrams for noncontinuous welded joints in the fatigue analysis of structural details. The adjustment takes into account the effects of differences in geometry between the test specimen underlying the S-N curve and the hull structural detail it is applied to, considering the inelastic response of material at the anticipated crack origin, multiple modes of loading, and their statistical correlation. The basis of the approach is a comparison of relative fatigue lives for the structural detail of interest and the corresponding baseline specimen, using the local strain approach to fatigue, with extensions to the high-cycle regime. An S-N diagram so corrected is used in the conventional manner to predict fatigue damage or to establish related allowable stresses. The procedure developed is thus entirely compatible with present fatigue life assessment methods. The developed procedure is illustrated through numerical examples.

Enhancement of Differential Interference Contrast Images of Live Cells Obtained With Digital Cameras

1999 ◽  
Vol 5 (S2) ◽  
pp. 1112-1113
Author(s):  
M.V. Parthasarathy
Keyword(s):  
High Resolution ◽  
Contrast Enhancement ◽  
Dynamic Range ◽  
Ccd Camera ◽  
Video Camera ◽  
Live Cells ◽  
Photographic Emulsion ◽  
Digital Cameras ◽  
Structural Detail ◽  
Ccd Cameras

The usefulness of Differential Contrast Interference (DIC) light microscopy for observing fine details within transparent specimens is well known. However, when viewed by the eye or by recording with photographic emulsion, fine structural detail at the limit of resolution is often not visible because of lack of contrast. To overcome this problem, electronic contrast enhancement capabilities of video cameras have been used to enhance structural details that would otherwise be invisible. The technique, commonly referred to as VE-DIC (Video Enhanced DIC), uses first analog contrast enhancement of the image with a video camera followed by a real-time digital image processor to further enhance the image with. We are exploring the feasibility of achieving fine structural detail of live cells by directly acquiring digital images of them with a high resolution CCD camera.High resolution cooled slow-scan 12-bit CCD cameras are well suited for DIC microscopy because of their greater dynamic range than video CCD cameras that are normally 8-bits or lower.

scholarly journals Structural basis for inhibition of the type I-F CRISPR–Cas surveillance complex by AcrIF4, AcrIF7 and AcrIF14

2020 ◽  
Author(s):  
Clinton Gabel ◽  
Zhuang Li ◽  
Heng Zhang ◽  
Leifu Chang
Keyword(s):  
Genome Editing ◽  
Conformational Changes ◽  
Structural Basis ◽  
Type I ◽  
Structural Detail ◽  
Immune Systems ◽  
Helical Bundle ◽  
Adaptive Immune ◽  
Target Dna ◽  
Adaptive Immune Systems

Abstract CRISPR–Cas systems are adaptive immune systems in bacteria and archaea to defend against mobile genetic elements (MGEs) and have been repurposed as genome editing tools. Anti-CRISPR (Acr) proteins are produced by MGEs to counteract CRISPR–Cas systems and can be used to regulate genome editing by CRISPR techniques. Here, we report the cryo-EM structures of three type I-F Acr proteins, AcrIF4, AcrIF7 and AcrIF14, bound to the type I-F CRISPR–Cas surveillance complex (the Csy complex) from Pseudomonas aeruginosa. AcrIF4 binds to an unprecedented site on the C-terminal helical bundle of Cas8f subunit, precluding conformational changes required for activation of the Csy complex. AcrIF7 mimics the PAM duplex of target DNA and is bound to the N-terminal DNA vise of Cas8f. Two copies of AcrIF14 bind to the thumb domains of Cas7.4f and Cas7.6f, preventing hybridization between target DNA and the crRNA. Our results reveal structural detail of three AcrIF proteins, each binding to a different site on the Csy complex for inhibiting degradation of MGEs.

A Comparison of the Surface Extrapolation and Battelle Structural Stress Methodologies as Applied to a Spectral Fatigue Analysis of a Representative FPSO Structural Detail

2007 ◽  
Author(s):  
Brian E. Healy
Keyword(s):  
Fatigue Damage ◽  
Fatigue Analysis ◽  
Structural Stress ◽  
Structural Detail ◽  
First Time ◽  
Side Shell

A spectral fatigue analysis using both the surface extrapolation and Battelle structural stress methodologies has been performed on a side shell connection detail typical of a representative FPSO or tanker vessel. This marks the first time the Battelle method has been adapted to spectral fatigue and details of the implementation are presented for narrow banded applications. Fatigue damage at the toe along a number of weld lines is computed for a variety of surface extrapolation strategies and Battelle method options. Results are reported and compared. Recommendations regarding the application of the Battelle method to spectral fatigue are made.

On some Arthropod Remains from the Rhynie Chert (Old Red Sandstone)

1926 ◽  
Vol 63 (2) ◽  
pp. 69-71 ◽  
Author(s):  
Stanley Hirst ◽  
S. Maulik
Keyword(s):  
Structural Detail ◽  
Camera Lucida ◽  
First Report ◽  
Red Sandstone ◽  
Rhynie Chert

Since writing the first report on the arthropods of the Rhynie Chert beds (see Ann. Mag. Nat. Hist. (9), xii, pp. 455–74, 5 pls., and 13 text-figs.) some additional specimens of Palaeocharinus have been collected. A few examples are fairly complete and well preserved, showing a considerable amount of structural detail, such as the chaetotaxy, claws of the legs, ornamentation of the chitin, eyes, etc. An account of the lateral eyes is given below. We also include notes on a supposed insect and another fossil arthropod which we refer with doubt to the aquatic Merostoma. All the illustrations in this little paper have been drawn by Miss Violet Borrow, A.R.C.A., with the aid of a camera lucida under our personal supervision.

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