J C Jésior

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Profiles of negatively stained gap junctions have been measured by grid sectioning. After normal levels of electron irradiation, the membrane thickness shrinks to about half that of unirradiated controls, but no shrinkage occurs in the hexagonal lattice plane. Even under low irradiation conditions, there is significant thinning of the membranes. Edge views,(More)
The parameters which might play a role in the compression of plastic-embedded objects are studied. The compression is measured on spherical polystyrene latex particles, used as markers in the grid sectioning technique. By changing independently the hardness of the latex particles through a controlled electron irradiation and the hardness of the embedding(More)
Low-angle diamond knives, one of them with an angle as low as 14.6 degrees, have been tested to measure compression induced during the sectioning of polystyrene latex spheres embedded in epoxy resins. Compression diminishes roughly proportional to the sectioning angle (sum of knife and clearance angles). The beneficial application of low-angle diamond(More)
The thickness of negatively stained 2D crystalline arrays of the bladder membrane does not vary significantly during air drying and exposure to high vacuum. High-dose electron irradiation reduces the thickness to about 60% of the native value. These results, together with the fact that the same behaviour has been observed on another 2D system (gap(More)
A real space method allowing the reconstruction of negatively stained crystalline objects from a limited number of projections is presented. The method is based on the assumption that only two density levels are required to describe an ideally negatively stained object (that of the volume occupied by the object and that of the volume occupied by the stain).(More)
Biological molecules often form micro-crystals that are in a size range that is unsuited for study either by X-ray crystallography or by electron microscopy. The method described here allows the use of most of these crystals. It consists of cutting sections through the crystal deposited on a grid after a preliminary observation in the electron microscope to(More)
Yeast aspartyl-tRNA synthetase, a dimer of molecular weight 125,000, and two molecules of its cognate tRNA (Mr = 24160) cocrystallize in the cubic space group I432 (a = 354 A). The crystal structure was solved to low resolution using neutron and X-ray diffraction data. Neutron single crystal diffraction data were collected in five solvents differing by(More)
A device for the precise localization (better than 0.5 micron) of an object on a grid has been developed and connected to the translation system of an electron microscope. Applied to biological thin sections, this device enables to easily find and to observe a selected microcrystal projection obtained by the grid sectioning technique. Moreover, low dose(More)
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