Flattening and shrinkage of bacteriophage T7 after preparation for electron microscopy by negative staining

1977 ◽  
Vol 58 (3) ◽  
pp. 235-243 ◽  
Author(s):  
Philip Serwer
Keyword(s):  
Electron Microscopy ◽  
Negative Staining ◽  
Bacteriophage T7

Observation of Fast Sedimenting, Replicating Bacteriophage T7 DNA by Negative Staining

1980 ◽  
Vol 38 ◽  
pp. 538-539
Author(s):  
P. Serwer
Keyword(s):  
Electron Microscopy ◽  
Cytochrome C ◽  
Dna Packaging ◽  
Negative Staining ◽  
Bacteriophage T7 ◽  
Dna Complexes ◽  
Sufficient Detail ◽  
Protein Monolayer

To package the DNA of bacteriophage T7, a preformed, DNA-free capsid (capsid I) with an envelope thicker than the envelope of bacteriophage T7:(a) binds DNA, (b) converts to a capsid (capsid II) with a bacteriophage-like envelope prior to packaging DNA and (c) draws in DNA (1). During attempts to understand T7 DNA packaging, complexes of capsids with mature T7 DNA and complexes of capsids with longer than mature, linear T7 DNA have been isolated (2). Objects with capsid-like dimensions were observed on a fast sedimenting, replicating complex of T7 DNA (100S+ DNA) prepared for electron microscopy using a protein monolayer-shadowing technique (3). This procedure for preparation of specimens does not, however, reveal sufficient detail to rigorously identify an object as a capsid. To better visualize objects bound to 100S+ T7 DNA, this DNA has been prepared for electron microscopy using the aqueous technique for the negative staining of capsid-DNA complexes more recently described (4) (the DNA is coated with cytochrome c and is revealed in an extended configuration).

Electron Microscopy of Bacteriophage T7 Internal Head Proteins

1975 ◽  
Vol 33 ◽  
pp. 638-639
Author(s):  
P. Serwer
Keyword(s):  
Electron Microscopy ◽  
Bacteriophage T7 ◽  
Specimen Preparation ◽  
Dna Molecule ◽  
The Core ◽  
Internal Core ◽  
Phage T7 ◽  
T7 Phage ◽  
Preparation Techniques ◽  
Internal Head

The genome of bacteriophage T7 is a duplex DNA molecule packaged in a space whose volume has been measured to be 2.2 x the volume of the B form of T7 DNA. To help determine the mechanism for packaging this DNA, the configuration of proteins inside the phage head has been investigated by electron microscopy. A core which is roughly cylindrical in outline has been observed inside the head of phage T7 using three different specimen preparation techniques.When T7 phage are treated with glutaraldehyde, DNA is ejected from the head often revealing an internal core (dark arrows in Fig. 1). When both the core and tail are present in a particle, the core appears to be coaxial with the tail. Core-tail complexes sometimes dislodge from their normal location and appear attached to the outside of a phage head (light arrow in Fig. 1).

The fine structure and the protein composition of γ phage of Bacillus anthracis

1975 ◽  
Vol 21 (11) ◽  
pp. 1889-1892 ◽  
Author(s):  
Takashi Watanabe ◽  
Akinori Morimoto ◽  
Toshiro Shiomi
Keyword(s):  
Electron Microscopy ◽  
Fine Structure ◽  
Bacillus Anthracis ◽  
Protein Composition ◽  
Staining Technique ◽  
Negative Staining ◽  
Polyacrylamide Gels ◽  
Long Tail

The fine structure of γ phage of Bacillus anthracis was studied by electron microscopy with a negative-staining technique. The phage has a hexagonal head and a long tail without a sheath. By electrophoresis on polyacrylamide gels, the proteins of the phage particles are separate into 10 polypeptides with moleclar weights ranging from 140 000 to 12 000.

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