Reconstruction of Chitin-Protein Complexes Using Correlation Averaging Methods: Ovipositor of the Ichneumon Fly Megarhyssa

1980 ◽  
Vol 38 ◽  
pp. 38-39
Author(s):  
L. T. Germinario ◽  
J. Blackwell ◽  
J. Frank
Keyword(s):  
Protein Complexes ◽  
Hexagonal Lattice ◽  
Uranyl Acetate ◽  
Optical Diffraction ◽  
Insect Cuticle ◽  
High Dose ◽  
Wide Angle ◽  
X Ray ◽  
Averaging Methods ◽  
Digital Correlation

This report describes the use of digital correlation and averaging methods 1,2 for the reconstruction of high dose electron micrographs of the chitin-protein complex from Megarhyssa ovipositor. Electron microscopy of uranyl acetate stained insect cuticle has demonstrated a hexagonal array of unstained chitin monofibrils, 2.4−3.0 nm in diameter, in a stained protein matrix3,4. Optical diffraction Indicated a hexagonal lattice with a = 5.1-8.3 nm3 A particularly well ordered complex is found in the ovipositor of the ichneumon fly Megarhyssa: the small angle x-ray data gives a = 7.25 nm, and the wide angle pattern shows that the protein consists of subunits arranged in a 61 helix, with an axial repeat of 3.06 nm5.

Crystalline order to a resolution of 4.7 A in the sheath of Methanospirilium hungatii: A cross-beta structure

1984 ◽  
Vol 42 ◽  
pp. 214-215
Author(s):  
Murray Stewart ◽  
T.J. Beveridge ◽  
D. Sprott
Keyword(s):  
Cell Wall ◽  
Single Layer ◽  
Uranyl Acetate ◽  
Optical Diffraction ◽  
Tube Axis ◽  
Basic Subunit ◽  
Beta Structure ◽  
Diffraction Patterns ◽  
Protein Treatment ◽  
General Appearance

The archaebacterium Methanospirillum hungatii has a sheath as part of its cell wall which is composed mainly of protein. Treatment with dithiothreitol or NaOH released the intact sheaths and electron micrographs of this material negatively stained with uranyl acetate showed flattened hollow tubes, about 0.5 μm diameter and several microns long, in which the patterns from the top and bottom were superimposed. Single layers, derived from broken tubes, were also seen and were more simply analysed. Figure 1 shows the general appearance of a single layer. There was a faint axial periodicity at 28.5 A, which was stronger at irregular multiples of 28.5 A (3 and 4 times were most common), and fine striations were also seen at about 3° to the tube axis. Low angle electron diffraction patterns (not shown) and optical diffraction patterns (Fig. 2) from these layers showed a complex meridian (as a result of the irregular nature of the repeat along the tube axis) which showed a clear maximum at 28.5 A, consistent with the basic subunit spacing.

Microprobe analysis of inclusion bodies related to two benzofuran derivatives

1987 ◽  
Vol 45 ◽  
pp. 672-673
Author(s):  
T. L. Benning ◽  
P. Ingram ◽  
J. D. Shelburne
Keyword(s):  
Inclusion Bodies ◽  
Uranyl Acetate ◽  
Multiple Organ ◽  
High Dose ◽  
En Bloc ◽  
Tissue Samples ◽  
Transmission Electron ◽  
Organ Systems ◽  
Dense Inclusion ◽  
Melanin Complex

Two benzofuran derivatives, chlorpromazine and amiodarone, are known to produce inclusion bodies in human tissues. Prolonged high dose chlorpromazine therapy causes hyperpigmentation of the skin with electron-dense inclusion bodies present in dermal histiocytes and endothelial cells ultrastructurally. The nature of the deposits is not known although a drug-melanin complex has been hypothesized. Amiodarone may also cause cutaneous hyperpigmentation and lamellar lysosomal inclusion bodies have been demonstrated within the cells of multiple organ systems. These lamellar bodies are believed to be the product of an amiodarone-induced phospholipid storage disorder. We performed transmission electron microscopy (TEM) and energy dispersive x-ray microanalysis (EDXA) on tissue samples from patients treated with these drugs, attempting to detect the sulfur atom of chlorpromazine and the iodine atom of amiodarone within their respective inclusion bodies.A skin biopsy from a patient with hyperpigmentation due to prolonged chlorpromazine therapy was fixed in 4% glutaraldehyde and processed without osmium tetroxide or en bloc uranyl acetate for Epon embedding.

Electron Microscope study of commensurate-incommensurate phase transition in BaZnGeO4

1990 ◽  
Vol 48 (4) ◽  
pp. 172-173
Author(s):  
Naoki Yamamoto ◽  
Makoto Kikuchi ◽  
Tooru Atake ◽  
Akihiro Hamano ◽  
Yasutoshi Saito
Keyword(s):  
Phase Transition ◽  
Electron Microscope Study ◽  
Room Temperature ◽  
Hexagonal Lattice ◽  
Ferroelectric Materials ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Periodic Arrays ◽  
Modulation Wave Vector

BaZnGeO4 undergoes many phase transitions from I to V phase. The highest temperature phase I has a BaAl2O4 type structure with a hexagonal lattice. Recent X-ray diffraction study showed that the incommensurate (IC) lattice modulation appears along the c axis in the III and IV phases with a period of about 4c, and a commensurate (C) phase with a modulated period of 4c exists between the III and IV phases in the narrow temperature region (—58°C to —47°C on cooling), called the III' phase. The modulations in the IC phases are considered displacive type, but the detailed structures have not been studied. It is also not clear whether the modulation changes into periodic arrays of discommensurations (DC’s) near the III-III' and IV-V phase transition temperature as found in the ferroelectric materials such as Rb2ZnCl4.At room temperature (III phase) satellite reflections were seen around the fundamental reflections in a diffraction pattern (Fig.1) and they aligned along a certain direction deviated from the c* direction, which indicates that the modulation wave vector q tilts from the c* axis. The tilt angle is about 2 degree at room temperature and depends on temperature.

A Revised O2 Reduction Model in Li-O2 Batteries as Revealed by in Situ Small Angle X-Ray Scattering

2019 ◽  
Author(s):  
Christian Prehal ◽  
Aleksej Samojlov ◽  
Manfred Nachtnebel ◽  
Manfred Kriechbaum ◽  
Heinz Amenitsch ◽  
...  
Keyword(s):  
Small Angle ◽  
Wide Angle ◽  
Reduction Mechanism ◽  
Reduction Model ◽  
X Ray ◽  
X Ray Scattering ◽  
O2 Reduction ◽  
Ray Scattering

<b>Here we use in situ small and wide angle X-ray scattering to elucidate unexpected mechanistic insights of the O2 reduction mechanism in Li-O2 batteries.<br></b>

scholarly journals High-resolution cryo-EM structure of photosystem II reveals damage from high-dose electron beams

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Koji Kato ◽  
Naoyuki Miyazaki ◽  
Tasuku Hamaguchi ◽  
Yoshiki Nakajima ◽  
Fusamichi Akita ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Physiological State ◽  
High Dose ◽  
Final State ◽  
X Ray ◽  
Redox States ◽  
X Ray Crystallography ◽  
Cryo Electron Microscopy ◽  
Redox Active ◽  
Beam Damage

AbstractPhotosystem II (PSII) plays a key role in water-splitting and oxygen evolution. X-ray crystallography has revealed its atomic structure and some intermediate structures. However, these structures are in the crystalline state and its final state structure has not been solved. Here we analyzed the structure of PSII in solution at 1.95 Å resolution by single-particle cryo-electron microscopy (cryo-EM). The structure obtained is similar to the crystal structure, but a PsbY subunit was visible in the cryo-EM structure, indicating that it represents its physiological state more closely. Electron beam damage was observed at a high-dose in the regions that were easily affected by redox states, and reducing the beam dosage by reducing frames from 50 to 2 yielded a similar resolution but reduced the damage remarkably. This study will serve as a good indicator for determining damage-free cryo-EM structures of not only PSII but also all biological samples, especially redox-active metalloproteins.

Strukturvarianten des MgCu2-Typs: Die Verbindungen Mg2Ni3P und Mg2Ni3As / Variants of the MgCu2 Type: The Compounds Mg2Ni3P and Mg2Ni3As

1992 ◽  
Vol 47 (10) ◽  
pp. 1351-1354 ◽  
Author(s):  
Viktor Keimes ◽  
Albrecht Mewis
Keyword(s):  
Single Crystal ◽  
Homogeneity Range ◽  
Hexagonal Lattice ◽  
Structure Type ◽  
Type Structure ◽  
X Ray ◽  
Lattice Constants ◽  
Metal Atoms ◽  
Rhombohedral Symmetry

The compounds Mg2Ni3P and Mg2Ni3As were prepared by heating the elements. Their structures have been determined from single-crystal X-ray data. The structure of the phosphide is a rhombohedral ternary variant of the cubic Laves structure type MgCu2 (R 3̄ m; hexagonal lattice constants: a = 4.971(0) Å, c = 10.961(2) Å). The ordered substitution of one quarter of the metal atoms by phosphorus and the resulting shorter distances are responsible for the rhombohedral symmetry.The arsenide crystallizes in the MgCu2 type structure (Fd 3 m; a = 6.891(1)A, composition Mg2Ni3As) with a statistic distribution of the Ni and As atoms; the relevant homogeneity range extends from Mg2Ni2.9As1.1 to Mg2Ni3.5As0.5.

scholarly journals On the amorphous layer in bone mineral and biomimetic apatite: A combined small- and wide-angle X-ray scattering analysis.

2020 ◽  
Author(s):  
Federica Bertolotti ◽  
Francisco J. Carmona ◽  
Gregorio Dal Sasso ◽  
Gloria B. Ramírez-Rodríguez ◽  
José Manuel Delgado-López ◽  
...  
Keyword(s):  
Bone Mineral ◽  
Amorphous Layer ◽  
Wide Angle ◽  
X Ray ◽  
X Ray Scattering ◽  
Biomimetic Apatite ◽  
Ray Scattering
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