Head Size and DNA Content in Bacteriophage T4

1972 ◽  
Vol 30 ◽  
pp. 200-201
Author(s):  
Fred Eiserling ◽  
A. H. Doermann ◽  
Linde Boehner
Keyword(s):  
Electron Microscopy ◽  
Dna Content ◽  
Bacteriophage T4 ◽  
Head Size ◽  
Virus Particles ◽  
Altered Protein ◽  
A Cell ◽  
Bacterial Viruses ◽  
A Site ◽  
Protein Shell

The control of form or shape inheritance can be approached by studying the morphogenesis of bacterial viruses. Shape variants of bacteriophage T4 with altered protein shell (capsid) size and nucleic acid (DNA) content have been found by electron microscopy, and a mutant (E920g in gene 66) controlling head size has been described. This mutant produces short-headed particles which contain 2/3 the normal DNA content and which are non-viable when only one particle infects a cell (Fig. 1).We report here the isolation of a new mutant (191c) which also appears to be in gene 66 but at a site distinct from E920g. The most striking phenotype of the mutant is the production of about 10% of the phage yield as “giant” virus particles, from 3 to 8 times longer than normal phage (Fig. 2).

Aberrant Type C Virus Production in a Cell Line Derived from Balb/3T3

1972 ◽  
Vol 30 ◽  
pp. 286-287
Author(s):  
N. Savage ◽  
A. Hackett
Keyword(s):  
Electron Microscopy ◽  
Cell Line ◽  
Leukemia Virus ◽  
Morphological Characteristics ◽  
Virus Production ◽  
Oncogenic Viruses ◽  
Endogenous Virus ◽  
Virus Particles ◽  
Moloney Leukemia Virus ◽  
A Cell

A cell line, UC1-B, which was derived from Balb/3T3 cells, maintains the same morphological characteristics of the non-transformed parental culture, and shows no evidence of spontaneous virus production. Survey by electron microscopy shows that the cell line consists of spindle-shaped cells with no unusual features and no endogenous virus particles.UC1-B cells respond to Moloney leukemia virus (MLV) infection by a change in morphology and growth pattern which is typical of cells transformed by sarcoma virus. Electron microscopy shows that the cells are now variable in shape (rounded, rhomboid, and spindle), and each cell type has some microvilli. Virtually all (90%) of the cells show virus particles developing at the cell surface and within the cytoplasm. Maturing viruses, typical of the oncogenic viruses, are found along with atypical tubular forms in the same cell.

Detection of Influenza Virus Particles in Throat Washings by Electron Microscopy

1970 ◽  
Vol 28 ◽  
pp. 340-341
Author(s):  
Mahadeo B. Pendharker ◽  
Kenneth A. Siegesmund ◽  
Harold D. Rose ◽  
Frank Piraino ◽  
Ross C. Kory
Keyword(s):  
Electron Microscopy ◽  
Influenza Virus ◽  
Ultrastructural Study ◽  
Filter Paper ◽  
Influenza A ◽  
Laboratory Tests ◽  
Cell Block ◽  
Virus Particles ◽  
Centrifuge Tube ◽  
A Cell

Although the symptomatology of influenza is well known and fairly typical in most cases, the exact diagnosis is often presumptive because of the technical difficulties in performing laboratory tests. We have recently developed a method for concentrating and processing throat washings to provide a cell block which can be sectioned for ultrastructural study. We have used this technique for studying the throat washings from five sero-logically proven patients with Influenza A2 Hong Kong infection. Two ml of throat washings were mixed with 0. 5 ml of a fixative containing 2% acrolein, 3% glutaraldehyde in phosphate buffer at pH 7. 2 in a centrifuge tube. A disc of filter paper (Whatman #41 ashless) 5 mm in diameter was placed in the centrifuge tube, and the samples were centrifuged at 18,000 rpm for one hour.

scholarly journals Cryo-electron Microscopy Structures of Expanded Poliovirus with VHHs Sample the Conformational Repertoire of the Expanded State

2016 ◽  
Vol 91 (3) ◽  
Author(s):  
Mike Strauss ◽  
Lise Schotte ◽  
Krishanthi S. Karunatilaka ◽  
David J. Filman ◽  
James M. Hogle
Keyword(s):  
Electron Microscopy ◽  
Careful Analysis ◽  
Productive Infection ◽  
Altered State ◽  
Virus Structure ◽  
Cryo Electron Microscopy ◽  
A Cell ◽  
Single Domain Antibodies ◽  
A Site ◽  
Polypeptide Chains

ABSTRACT By using cryo-electron microscopy, expanded 80S-like poliovirus virions (poliovirions) were visualized in complexes with four 80S-specific camelid VHHs (Nanobodies). In all four complexes, the VHHs bind to a site on the top surface of the capsid protein VP3, which is hidden in the native virus. Interestingly, although the four VHHs bind to the same site, the structures of the expanded virus differ in detail in each complex, suggesting that each of the Nanobodies has sampled a range of low-energy structures available to the expanded virion. By stabilizing unique structures of expanded virions, VHH binding permitted a more detailed view of the virus structure than was previously possible, leading to a better understanding of the expansion process that is a critical step in infection. It is now clear which polypeptide chains become disordered and which become rearranged. The higher resolution of these structures also revealed well-ordered conformations for the EF loop of VP2, the GH loop of VP3, and the N-terminal extensions of VP1 and VP2, which, in retrospect, were present in lower-resolution structures but not recognized. These structural observations help to explain preexisting mutational data and provide insights into several other stages of the poliovirus life cycle, including the mechanism of receptor-triggered virus expansion. IMPORTANCE When poliovirus infects a cell, it undergoes a change in its structure in order to pass RNA through its protein coat, but this altered state is short-lived and thus poorly understood. The structures of poliovirus bound to single-domain antibodies presented here capture the altered virus in what appear to be intermediate states. A careful analysis of these structures lets us better understand the molecular mechanism of infection and how these changes in the virus lead to productive-infection events.

Recent Applications of High Resolution Electron Microscopy to Crystalline Arrays of Virus Particles

1978 ◽  
Vol 36 (3) ◽  
pp. 470-482 ◽  
Author(s):  
R.W. Horne
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
Analytical Techniques ◽  
Staining Technique ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Full Potential ◽  
Virus Particles ◽  
Resolution Electron ◽  
Wide Range

The technique of surrounding virus particles with a neutralised electron dense stain was described at the Fourth International Congress on Electron Microscopy, Berlin 1958 (see Home & Brenner, 1960, p. 625). For many years the negative staining technique in one form or another, has been applied to a wide range of biological materials. However, the full potential of the method has only recently been explored following the development and applications of optical diffraction and computer image analytical techniques to electron micrographs (cf. De Hosier & Klug, 1968; Markham 1968; Crowther et al., 1970; Home & Markham, 1973; Klug & Berger, 1974; Crowther & Klug, 1975). These image processing procedures have allowed a more precise and quantitative approach to be made concerning the interpretation, measurement and reconstruction of repeating features in certain biological systems.

Uranyl Acetate and Rotary Shadowing to Increase the Contrast of Small Aggregated Virus Particles

1969 ◽  
Vol 27 ◽  
pp. 424-425
Author(s):  
Lee F. Ellis ◽  
Richard M. Van Frank ◽  
Walter J. Kleinschmidt
Keyword(s):  
Electron Microscopy ◽  
Tissue Culture ◽  
Density Gradient ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Uranyl Acetate ◽  
Interferon Inducer ◽  
Virus Particles ◽  
Staining Methods ◽  
Rotary Shadowing

The extract from Penicillum stoliniferum, known as statolon, has been purified by density gradient centrifugation. These centrifuge fractions contained virus particles that are an interferon inducer in mice or in tissue culture. Highly purified preparations of these particles are difficult to enumerate by electron microscopy because of aggregation. Therefore a study of staining methods was undertaken.

Electron Microscope Study of RNA's of Paramyxoviruses

1972 ◽  
Vol 30 ◽  
pp. 196-197
Author(s):  
Ruchama Baum ◽  
J.T. Seto
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Electron Microscope Study ◽  
Sendai Virus ◽  
Sodium Dodecyl ◽  
Rna Molecules ◽  
Virus Particles ◽  
Molecular Weights ◽  
Length Measurements

The ribonucleic acid (RNA) of paramyxoviruses has been characterized by biochemical and physiochemical methods. However, paramyxovirus RNA molecules have not been studied by electron microscopy. The molecular weights of these single-stranded viral RNA molecules are not known as yet. Since electron microscopy has been found to be useful for the characterization of single-stranded RNA, this investigation was initiated to examine the morphology and length measurements of paramyxovirus RNA's.Sendai virus Z strain and Newcastle disease virus (NDV), Milano strain, were used. For these studies it was necessary to develop a method of extracting RNA molecules from purified virus particles. Highly purified Sendai virus was treated with pronase (300 μg/ml) at 37°C for 30 minutes and the RNA extracted by the sodium dodecyl sulfate (SDS)-phenol procedure.

Artifacts caused by dehydration and epoxy embedding in TEM

1991 ◽  
Vol 49 ◽  
pp. 338-339
Author(s):  
Hilton H. Mollenhauer
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Volume Change ◽  
Tissue Damage ◽  
Beam Specimen ◽  
Chemical Fixation ◽  
Resin Impregnation ◽  
Storage Vesicles ◽  
A Cell ◽  
Tissue Shrinkage

Various means have been devised to preserve biological specimens for electron microscopy, the most common being chemical fixation followed by dehydration and resin impregnation. It is intuitive, and has been amply demonstrated, that these manipulations lead to aberrations of many tissue elements. This report deals with three parts of this problem: specimen dehydration, epoxy embedding resins, and electron beam-specimen interactions. However, because of limited space, only a few points can be summarized.Dehydration: Tissue damage, or at least some molecular transitions within the tissue, must occur during passage of a cell or tissue to a nonaqueous state. Most obvious, perhaps, is a loss of lipid, both that which is in the form of storage vesicles and that associated with tissue elements, particularly membranes. Loss of water during dehydration may also lead to tissue shrinkage of 5-70% (volume change) depending on the tissue and dehydrating agent.

Search mode for rapid detection of virus particles

1991 ◽  
Vol 49 ◽  
pp. 286-287
Author(s):  
O. E. Bradfute
Keyword(s):  
Electron Microscopy ◽  
Rapid Detection ◽  
Plant Virus ◽  
Low Dose ◽  
Search Mode ◽  
Virus Diseases ◽  
Virus Particles ◽  
Focus Image ◽  
Time Required ◽  
Rapid Switching

Electron microscopy is frequently used in preliminary diagnosis of plant virus diseases by surveying negatively stained preparations of crude extracts of leaf samples. A major limitation of this method is the time required to survey grids when the concentration of virus particles (VPs) is low. A rapid survey of grids for VPs is reported here; the method employs a low magnification, out-of-focus Search Mode similar to that used for low dose electron microscopy of radiation sensitive specimens. A higher magnification, in-focus Confirm Mode is used to photograph or confirm the detection of VPs. Setting up the Search Mode by obtaining an out-of-focus image of the specimen in diffraction (K. H. Downing and W. Chiu, private communications) and pre-aligning the image in Search Mode with the image in Confirm Mode facilitates rapid switching between Modes.

Identification of Maize Rayado Fino Virus by Immunoelectron Microscopy

1985 ◽  
Vol 43 ◽  
pp. 636-637
Author(s):  
O. E. Bradfute
Keyword(s):  
Electron Microscopy ◽  
Zea Mays ◽  
Costa Rica ◽  
Severe Disease ◽  
Rabbit Serum ◽  
Normal Rabbit Serum ◽  
Virus Particles ◽  
Far North ◽  
Maize Rayado Fino Virus ◽  
Antibody Coating

Maize rayado fino virus (MRFV) causes a severe disease of corn (Zea mays) in many locations throughout the neotropics and as far north as southern U.S. MRFV particles detected by direct electron microscopy of negatively stained sap from infected leaves are not necessarily distinguishable from many other small isometric viruses infecting plants (Fig. 1).Immunosorbent trapping of virus particles on antibody-coated grids and the antibody coating or decoration of trapped virus particles, was used to confirm the identification of MRFV. Antiserum to MRFV was supplied by R. Gamez (Centro de Investigacion en Biologia Celular y Molecular, Universidad de Costa Rica, Ciudad Universitaria, Costa Rica).Virus particles, appearing as a continuous lawn, were trapped on grids coated with MRFV antiserum (Fig. 2-4). In contrast, virus particles were infrequently found on grids not exposed to antiserum or grids coated with normal rabbit serum (similar to Fig. 1). In Fig. 3, the appearance of the virus particles (isometric morphology, 30 nm diameter, stain penetration of some particles, and morphological subunits in other particles) is characteristic of negatively stained MRFV particles. Decoration or coating of these particles with MRFV antiserum confirms their identification as MRFV (Fig. 4).

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