A reflection on partial coherence in electron microscopy

Fertig, J.; Rose, H.

doi:10.1016/s0304-3991(76)91589-8

Cited by 33 publications

(13 citation statements)

References 7 publications

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“…Low spatial frequencies are imaged with full contrast, while higher frequencies are somewhat attenuated (54). Furthermore, when this STEM annular detector is used the signal is said to be "incoherent" in the sense that each atom in the probe makes its own contribution to the signal independently of its relationship to its neighbors (18). Thus, the intensity of the large-angle annular detector signal is directly proportional to the number of atoms in the beam at any given time (weighted by their atomic number) and is essentially independent of their spatial arrangement.…”

Section: Electron Opticsmentioning

confidence: 99%

Mass Mapping With the Scanning Transmission Electron Microscope

Wall¹,

Hainfeld²

1986

Annu. Rev. Biophys. Biophys. Chem.

251

156

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Section: Electron Opticsmentioning

confidence: 99%

Mass Mapping With the Scanning Transmission Electron Microscope

Wall¹,

Hainfeld²

1986

Annu. Rev. Biophys. Biophys. Chem.

251

156

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“…These images are recorded directly in digital form. As the finely focused STEM electron beam scans the specimen, the dark-field signal recorded from each image element is, to a close approximation, proportional to the mass ofelectron scattering material present in the sampled portion of specimen (18). Consequently, such data may be used to perform molecular mass calculations for individual particles (19)(20)(21), and we have made a large number ofmeasurements of linear mass density for both native and reassembled IF.…”

mentioning

confidence: 99%

Structure of fibroblastic intermediate filaments: analysis of scanning transmission electron microscopy.

Steven¹,

Wall²,

Hainfeld³

et al. 1982

Proc. Natl. Acad. Sci. U.S.A.

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The structure of fibroblastic intermediate filaments from Chinese hamster ovary cells has been investigated by scanning transmission electron microscopy. Freshly extracted (native) filaments were compared with filaments reassembled in vitro from purified decamin. From digital micrographs of unstained specimens, direct measurements of linear mass density were performed on many individual filaments. Native filaments beyond a certain minimal length constitute a homogeneous population, averaging 38 ± 4 kilodaltons (kDal)/nm. A minor but distinct polymorphic variant (23 ± 4 kDal/nm) was also present as very short filaments or end-segments; these may represent breakdown products or assembly intermediates. Analysis of reassembled filaments demonstrates that the in vitro assembly reaction is-in the main-faithful, although the distribution of their mass measurements is appreciably broader than that of the native data. In addition to the predominant type at 37 ± 4 kDal/nm and a minor component at 26 ± 4 kDal/nm, small amounts of a third, more massive, polymorphic variant at 52 ± 5 kDal/nm were also present. Micrographs of negatively stained specimens clearly demonstrate that the filaments are composed of bundles of protofilaments-each 2-3 nm in diameter-and also reveal an axial periodicity of about 46 nm. The implications of these findings are discussed for three classes of model previously proposed for the structure of intermediate filaments.Reassembly in vitro of supramolecular structures from purified constituents is an experimental approach that has contributed greatly to the understanding of how such entities are formed and regulated in the living cell. In such cases as viruses or multimeric enzymes, the success of a reassembly experiment may be demonstrated by a functional assay based on infectivity or catalytic activity. However, with systems whose functional properties are either lacking or undefined, evidence for faithful reassembly is based primarily on structural criteria determined by physical techniques such as electron microscopy and x-ray diffraction.Intermediate filaments (IF) are long fibrous protein polymers that are ubiquitous cytoskeletal constituents of eukaryotic cells (1-3). Five major subclasses ofIF have been distinguished (4), their proteins have been isolated and characterized, and conditions under which they may be induced to self-assemble in vitro have been determined (5). The principal criterion of faithful reassembly has been morphology as defined by electron microscopy. For certain subclasses of native and reassembled IF, x-ray diffraction has also been used to demonstrate the presence ofcoiled-coil a-helices in approximate alignment with the filament axis (6-11). However, quantitative correspondence of a-helical content has not been established and the mode of packing of protein subunits in either reassembled or native IF has yet to be determined.To obtain more rigorous structural information, we have examined fibroblastic IF by scanning transmission electron microscopy (STEM). Bo...

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“…0 , Uranyl sulphate, dose= 1.7 x lo4 el/(nm)2; 0, uranyl sulphate, dose= 9 . 6~ lo4 el/(nm)2; x uranyl acetate, dose=O.75x lo4 el/(nrn)2; 3 ) uranyl acetate, dose=10.7x lo4 el/(nm)2. detector (Fertig & Rose, 1977;Ohtsuki et al, 1979). Therefore measurements with this detector signal can be interpreted as reflecting variation in mass thickness rather than 'phase grain'.…”

Section: Stem Resultsmentioning

confidence: 99%

Uranyl sulphate: A new negative stain for electron microscopy

Estis

Haschemeyer

Wall

1981

Journal of Microscopy

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SUMMARY Uranyl sulphate is a negative stain of high quality for electron microscopy of macromolecules below their isoelectric point. The stain results in good contrast and high resolution as demonstrated by optical diffraction of periodic structure. Analysis of scanning transmission electron microscopic data reveals that uranyl sulphate is lower in background noise level than uranyl acetate and is dramatically more resistant toward granularization upon continued exposure to electron irradiation. Electron microscopic images of most macromolecules contrasted with uranyl sulphate were indistinguishable from those obtained with uranyl acetate. However, electron microscopic images of Reo virus contrasted with uranyl sulphate are always readily distinguished from those obtained with uranyl acetate.

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A reflection on partial coherence in electron microscopy

Cited by 33 publications

References 7 publications

Mass Mapping With the Scanning Transmission Electron Microscope

Mass Mapping With the Scanning Transmission Electron Microscope

Structure of fibroblastic intermediate filaments: analysis of scanning transmission electron microscopy.

Uranyl sulphate: A new negative stain for electron microscopy

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