Polymorphism of Ganglioside-Water Systems: a New Class of Micellar Cubic Phases. Freeze-Fracture Electron Microscopy and X-Ray Scattering Studies

1995 ◽  
Vol 5 (3) ◽  
pp. 445-464 ◽  
Author(s):  
Annette Gulik ◽  
Herv� Delacroix ◽  
G�nther Kirschner ◽  
Vittorio Luzzati
Keyword(s):  
Electron Microscopy ◽  
Freeze Fracture ◽  
Water Systems ◽  
X Ray ◽  
New Class ◽  
X Ray Scattering ◽  
Cubic Phases ◽  
Freeze Fracture Electron Microscopy ◽  
Fracture Electron ◽  
Ray Scattering

scholarly journals Structure of Nanotubes Self-Assembled from a Monoamide Organogelator

2020 ◽  
Vol 21 (14) ◽  
pp. 4960
Author(s):  
Samuel Zapién-Castillo ◽  
Nancy P. Díaz-Zavala ◽  
José A. Melo-Banda ◽  
Duncan Schwaller ◽  
Jean-Philippe Lamps ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Benzoic Acid ◽  
Butyl Ester ◽  
Freeze Fracture ◽  
Mean Value ◽  
Wide Angle ◽  
X Ray ◽  
X Ray Scattering ◽  
Freeze Fracture Electron Microscopy ◽  
Fracture Electron

Some organic compounds are known to self-assemble into nanotubes in solutions, but the packing of the molecules into the walls of the tubes is known only in a very few cases. Herein, we study two compounds forming nanotubes in alkanes. They bear a secondary alkanamide chain linked to a benzoic acid propyl ester (HUB-3) or to a butyl ester (HUB-4). They gel alkanes for concentrations above 0.2 wt.%. The structures of these gels, studied by freeze fracture electron microscopy, exhibit nanotubes: for HUB-3 their external diameters are polydisperse with a mean value of 33.3 nm; for HUB-4, they are less disperse with a mean value of 25.6 nm. The structure of the gel was investigated by small- and wide-angle X-ray scattering. The evolution of the intensities show that the tubes are metastable and transit slowly toward crystals. The intensities of the tubes of HUB-4 feature up to six oscillations. The shape of the intensities proves the tubular structure of the aggregates, and gives a measurement of 20.6 nm for the outer diameters and 11.0 nm for the inner diameters. It also shows that the electron density in the wall of the tubes is heterogeneous and is well described by a model with three layers.

scholarly journals The crystal lattice of Paramecium trichocysts before and after exocytosis by X-ray diffraction and freeze-fracture electron microscopy.

1987 ◽  
Vol 105 (4) ◽  
pp. 1649-1662 ◽  
Author(s):  
L Sperling ◽  
A Tardieu ◽  
T Gulik-Krzywicki
Keyword(s):  
Electron Microscopy ◽  
Freeze Fracture ◽  
X Ray ◽  
Before And After ◽  
Ordered Array ◽  
Extracellular Form ◽  
Freeze Etching ◽  
Freeze Fracture Electron Microscopy ◽  
Genetically Determined ◽  
Fracture Electron

Paramecium trichocysts are unusual secretory organelles in that: (a) their crystalline contents are built up from a family of low molecular mass acidic proteins; (b) they have a precise, genetically determined shape; and (c) the crystalline trichocyst contents expand rapidly upon exocytosis to give a second, extracellular form which is also an ordered array. We report here the first step of our study of trichocyst structure. We have used a combination of x-ray powder diffraction, freeze-etching, and freeze-fracture electron microscopy of isolated, untreated trichocysts, and density measurements to show that trichocyst contents are indeed protein crystals and to determine the elementary unit cell of both the compact intracellular and the extended extracellular form.

scholarly journals Structural states of myelin observed by x-ray diffraction and freeze-fracture electron microscopy.

1979 ◽  
Vol 82 (1) ◽  
pp. 140-149 ◽  
Author(s):  
D A Kirschner ◽  
C J Hollingshead ◽  
C Thaxton ◽  
D L Caspar ◽  
D A Goodenough
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Freeze Fracture ◽  
Intermediate Structure ◽  
X Ray Diffraction ◽  
Membrane Unit ◽  
X Ray ◽  
Critical Measure ◽  
Freeze Fracture Electron Microscopy ◽  
Fracture Electron

Coordinated freeze-fracture electron microscopy and x-ray diffraction were used to visualize the morphological relation between compacted and native period membrane arrays in myelinated nerves treated with dimethylsulfoxide (DMSO). Comparison of x-ray diffraction at room temperature and at low temperature was used as a critical measure of the extent of structural preservation. Our x-ray diffraction patterns show that in the presence of cryoprotective agents, it is possible to preserve with only small changes the myelin structure which exists at room temperature. These changes include a slight increase in packing disorder of the membrane, a small, negative thermal expansion of the membrane unit, and some reorganization in the cytoplasmic half of the bilayer. The freeze-fracture electron microscopy clearly demonstrates continuity of compact and native period phases in DMSO-treated myelin. Finally, the use of freezing to trap the transient, intermediate structure during a structural transition in glycerol is demonstrated.

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