IRIS Explorer Software for Radial-Depth Cueing Reovirus Particles and Other Macromolecular Structures Determined by Cryoelectron Microscopy and Image Reconstruction

1997 ◽  
Vol 120 (1) ◽  
pp. 11-21 ◽  
Author(s):  
Stephan M Spencer ◽  
Jean-Yves Sgro ◽  
Kelly A Dryden ◽  
Timothy S Baker ◽  
Max L Nibert
Keyword(s):  
Image Reconstruction ◽  
Cryoelectron Microscopy ◽  
Radial Depth ◽  
Depth Cueing

scholarly journals Structures of bovine and human papillomaviruses. Analysis by cryoelectron microscopy and three-dimensional image reconstruction

1991 ◽  
Vol 60 (6) ◽  
pp. 1445-1456 ◽  
Author(s):  
T.S. Baker ◽  
W.W. Newcomb ◽  
N.H. Olson ◽  
L.M. Cowsert ◽  
C. Olson ◽  
...  
Keyword(s):  
Image Reconstruction ◽  
Three Dimensional ◽  
Human Papillomaviruses ◽  
Cryoelectron Microscopy ◽  
Dimensional Image

scholarly journals Image Reconstructions of Microtubules Decorated with Monomeric and Dimeric Kinesins: Comparison with X-Ray Structure and Implications for Motility

1998 ◽  
Vol 141 (2) ◽  
pp. 419-430 ◽  
Author(s):  
A. Hoenger ◽  
S. Sack ◽  
M. Thormählen ◽  
A. Marx ◽  
J. Müller ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Image Reconstruction ◽  
Three Dimensional ◽  
Coiled Coil ◽  
Cryoelectron Microscopy ◽  
Short Neck ◽  
X Ray ◽  
Dimensional Image ◽  
Tubulin Subunit ◽  
Image Reconstructions

We have decorated microtubules with monomeric and dimeric kinesin constructs, studied their structure by cryoelectron microscopy and three-dimensional image reconstruction, and compared the results with the x-ray crystal structure of monomeric and dimeric kinesin. A monomeric kinesin construct (rK354, containing only a short neck helix insufficient for coiled-coil formation) decorates microtubules with a stoichiometry of one kinesin head per tubulin subunit (α–β-heterodimer). The orientation of the kinesin head (an anterograde motor) on the microtubule surface is similar to that of ncd (a retrograde motor). A longer kinesin construct (rK379) forms a dimer because of the longer neck helix forming a coiled-coil. Unexpectedly, this construct also decorates the microtubule with a stoichiometry of one head per tubulin subunit, and the orientation is similar to that of the monomeric construct. This means that the interaction with microtubules causes the two heads of a kinesin dimer to separate sufficiently so that they can bind to two different tubulin subunits. This result is in contrast to recent models and can be explained by assuming that the tubulin–kinesin interaction is antagonistic to the coiled-coil interaction within a kinesin dimer.

scholarly journals Cryoelectron-Microscopy Image Reconstruction of Symmetry Mismatches in Bacteriophage φ29

2001 ◽  
Vol 135 (1) ◽  
pp. 38-46 ◽  
Author(s):  
Marc C. Morais ◽  
Yizhi Tao ◽  
Norman H. Olson ◽  
Shelley Grimes ◽  
Paul J. Jardine ◽  
...  
Keyword(s):  
Image Reconstruction ◽  
Cryoelectron Microscopy ◽  
Microscopy Image

scholarly journals Early steps in reovirus infection are associated with dramatic changes in supramolecular structure and protein conformation: analysis of virions and subviral particles by cryoelectron microscopy and image reconstruction

1993 ◽  
Vol 122 (5) ◽  
pp. 1023-1041 ◽  
Author(s):  
KA Dryden ◽  
G Wang ◽  
M Yeager ◽  
ML Nibert ◽  
KM Coombs ◽  
...  
Keyword(s):  
Image Reconstruction ◽  
Conformational Change ◽  
Protein Conformation ◽  
Cell Attachment ◽  
Environmental Stability ◽  
Cryoelectron Microscopy ◽  
Reovirus Infection ◽  
Sigma 1 ◽  
Outer Capsid ◽  
Subviral Particles

Three structural forms of type 1 Lang reovirus (virions, intermediate subviral particles [ISVPs], and cores) have been examined by cryoelectron microscopy (cryoEM) and image reconstruction at 27 to 32-A resolution. Analysis of the three-dimensional maps and known biochemical composition allows determination of capsid protein location, globular shape, stoichiometry, quaternary organization, and interactions with adjacent capsid proteins. Comparisons of the virion, ISVP and core structures and examination of difference maps reveal dramatic changes in supra-molecular structure and protein conformation that are related to the early steps of reovirus infection. The intact virion (approximately 850-A diam) is designed for environmental stability in which the dsRNA genome is protected not only by tight sigma 3-mu 1, lambda 2-sigma 3, and lambda 2-mu 1 interactions in the outer capsid but also by a densely packed core shell formed primarily by lambda 1 and sigma 2. The segmented genome appears to be packed in a liquid crystalline fashion at radii < 240 A. Depending on viral growth conditions, virions undergo cleavage by enteric or endosomal/lysosomal proteases, to generate the activated ISVP (approximately 800-A diam). This transition involves the release of an outer capsid layer spanning radii from 360 to 427 A that is formed by 60 tetrameric and 60 hexameric clusters of ellipsoidal subunits of sigma 3. The vertex-associated cell attachment protein, sigma 1, also undergoes a striking change from a poorly visualized, more compact form, to an extended, flexible fiber. This conformational change may maximize interactions of sigma 1 with cell surface receptors. Transcription of viral mRNAs is mediated by the core particle (approximately 600-A diam), generated from the ISVP after penetration and uncoating. The transition from ISVP to core involves release of the 12 sigma 1 fibers and the remaining outer capsid layer formed by 200 trimers of rod-shaped mu 1 subunits that span radii from 306 to 395 A. In the virion and ISVP, flower-shaped pentamers of the lambda 2 protein are centered at the vertices. In the ISVP-to-core transition, domains of the lambda 2 subunits rotate and swing upward and outward to form a turret-like structure extending from radii 305 to 400 A, with a diameter of 184 A, and a central channel 84 A wide. This novel conformational change allows the potential diffusion of substrates for transcription and exit of newly synthesized mRNA segments.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Three-dimensional structure of the acetylcholine receptor by cryoelectron microscopy and helical image reconstruction.

1990 ◽  
Vol 111 (6) ◽  
pp. 2623-2635 ◽  
Author(s):  
C Toyoshima ◽  
N Unwin
Keyword(s):  
Thin Films ◽  
Image Reconstruction ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Cryoelectron Microscopy ◽  
Data Sets ◽  
Alpha Subunits ◽  
Constant Diameter ◽  
C And N ◽  
Preliminary Study

Long tubular vesicles have been grown from isolated Torpedo postsynaptic membranes, in which the receptors are arranged helically on the vesicle surface. The structures of these tubes have been analyzed by cryoelectron microscopy of specimens embedded in thin films of ice, combined with helical image reconstruction. Complete data sets from tubes belonging to several helical families have been obtained to a resolution of 17 A in all directions. Confirming a preliminary study (Toyoshima, C., and N. Unwin. 1988. Nature (Lond.). 336:247-250), the central ion channel has an almost constant diameter throughout the molecule except for the portion extending through the hydrophobic part of the lipid bilayer, where the pore is too small to be resolved. However, the density on the pseudo fivefold axis running through the pore is consistently highest in the cytoplasmic half of the bilayer, suggesting the gate is located in that region. The path followed by each subunit has been identified throughout the length of the receptor. The two alpha subunits follow equivalent paths. All subunits have similar features which change in character at the same level relative to the membrane.

scholarly journals Comparison of the Native CCMV Virion within VitroAssembled CCMV Virions by Cryoelectron Microscopy and Image Reconstruction

Virology ◽  
1998 ◽  
Vol 244 (1) ◽  
pp. 212-218 ◽  
Author(s):  
James M. Fox ◽  
Guoji Wang ◽  
Jeffrey A. Speir ◽  
Norm H. Olson ◽  
John E. Johnson ◽  
...  
Keyword(s):  
Image Reconstruction ◽  
Cryoelectron Microscopy

Criteria and Methods for Reliable Three-Dimensional Image Reconstruction

1974 ◽  
Vol 32 ◽  
pp. 330-331
Author(s):  
R. A. Crowther
Keyword(s):  
Image Reconstruction ◽  
Finite Number ◽  
Density Distribution ◽  
Electron Micrographs ◽  
Mathematical Problem ◽  
Three Dimensional ◽  
Ideal Case ◽  
Dimensional Image ◽  
General Object ◽  
The Ideal

The reconstruction of a three-dimensional image of a specimen from a set of electron micrographs reduces, under certain assumptions about the imaging process in the microscope, to the mathematical problem of reconstructing a density distribution from a set of its plane projections.In the absence of noise we can formulate a purely geometrical criterion, which, for a general object, fixes the resolution attainable from a given finite number of views in terms of the size of the object. For simplicity we take the ideal case of projections collected by a series of m equally spaced tilts about a single axis.

Cryosectioning plant roots prepared by high-pressure freezing

1987 ◽  
Vol 45 ◽  
pp. 662-663
Author(s):  
R.E. Crang ◽  
M. Mueller ◽  
K. Zierold
Keyword(s):  
High Pressure ◽  
Cell Walls ◽  
Plant Tissues ◽  
Ice Crystal ◽  
High Pressure Freezing ◽  
Vitreous State ◽  
Radial Depth ◽  
Irregular Topography ◽  
Considerable Depth ◽  
Conventional Freezing

Obtaining frozen-hydrated sections of plant tissues for electron microscopy and microanalysis has been considered difficult, if not impossible, due primarily to the considerable depth of effective freezing in the tissues which would be required. The greatest depth of vitreous freezing is generally considered to be only 15-20 μm in animal specimens. Plant cells are often much larger in diameter and, if several cells are required to be intact, ice crystal damage can be expected to be so severe as to prevent successful cryoultramicrotomy. The very nature of cell walls, intercellular air spaces, irregular topography, and large vacuoles often make it impractical to use immersion, metal-mirror, or jet freezing techniques for botanical material.However, it has been proposed that high-pressure freezing (HPF) may offer an alternative to the more conventional freezing techniques, inasmuch as non-cryoprotected specimens may be frozen in a vitreous, or near-vitreous state, to a radial depth of at least 0.5 mm.

Three dimensional deblurring of transmitted-light brightfield micrographs

1993 ◽  
Vol 51 ◽  
pp. 564-565
Author(s):  
Santosh Bhattacharyya
Keyword(s):  
Image Reconstruction ◽  
Three Dimensional ◽  
Transmitted Light ◽  
Reconstruction Algorithms ◽  
3D Image Reconstruction ◽  
Structural Details ◽  
Spread Function ◽  
Early Testing ◽  
Linearized Model ◽  
Image Reconstruction Algorithms

Three dimensional microscopic structures play an important role in the understanding of various biological and physiological phenomena. Structural details of neurons, such as the density, caliber and volumes of dendrites, are important in understanding physiological and pathological functioning of nervous systems. Even so, many of the widely used stains in biology and neurophysiology are absorbing stains, such as horseradish peroxidase (HRP), and yet most of the iterative, constrained 3D optical image reconstruction research has concentrated on fluorescence microscopy. It is clear that iterative, constrained 3D image reconstruction methodologies are needed for transmitted light brightfield (TLB) imaging as well. One of the difficulties in doing so, in the past, has been in determining the point spread function of the system.We have been developing several variations of iterative, constrained image reconstruction algorithms for TLB imaging. Some of our early testing with one of them was reported previously. These algorithms are based on a linearized model of TLB imaging.

Ordered subset expectation maximization algorithm for image reconstruction applied to zero-flow or low-flow mimicking brain phantom

2005 ◽  
Vol 25 (1_suppl) ◽  
pp. S678-S678
Author(s):  
Yasuhiro Akazawa ◽  
Yasuhiro Katsura ◽  
Ryohei Matsuura ◽  
Piao Rishu ◽  
Ansar M D Ashik ◽  
...  
Keyword(s):  
Image Reconstruction ◽  
Expectation Maximization ◽  
Expectation Maximization Algorithm ◽  
Low Flow ◽  
Brain Phantom ◽  
Zero Flow
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