scholarly journals Isolation and Characterization of Chloroplast DNA from the Marine Chromophyte, Olisthodiscus luteus: Electron Microscopic Visualization of Isomeric Molecular Forms

1981 ◽  
Vol 68 (3) ◽  
pp. 641-647 ◽  
Author(s):  
Jane Aldrich ◽  
Rose Ann Cattolico
Keyword(s):  
Chloroplast Dna ◽  
Molecular Forms ◽  
Electron Microscopic ◽  
Isolation And Characterization ◽  
Olisthodiscus Luteus

Human leukocyte interferon: Isolation and characterization of several molecular forms

1981 ◽  
Vol 210 (1) ◽  
pp. 307-318 ◽  
Author(s):  
Menachem Rubinstein ◽  
Warren P. Levy ◽  
John A. Moschera ◽  
Chun-Yen Lai ◽  
Robert D. Hershberg ◽  
...  
Keyword(s):  
Human Leukocyte ◽  
Molecular Forms ◽  
Isolation And Characterization ◽  
Human Leukocyte Interferon

Isolation and characterization of Escherichia coli O157:H7 and shiga toxin-converting bacteriophages from strains of human, bovine and porcine origin

2002 ◽  
Vol 2 (3) ◽  
pp. 29-38 ◽  
Author(s):  
E.E. Müller ◽  
M.B. Taylor ◽  
W.O.K. Grabow ◽  
M.M. Ehlers
Keyword(s):  
Escherichia Coli ◽  
Pcr Analysis ◽  
Sewage Sample ◽  
Natural Environments ◽  
Escherichia Coli O157 ◽  
Electron Microscopic ◽  
E Coli ◽  
Isolation And Characterization ◽  
Faecal Samples

Toxin-converting bacteriophages encoding the Stx2 gene were induced from strains of Escherichia coli O157:H7 isolated from sewage, bovine and porcine faeces. Toxin synthesis can be stimulated by the induction of integrated toxin-converting phages from the host E. coli O157:H7 organism by ultra-violet (UV) exposure. The UV-mediated DNA damage of E. coli O157:H7 triggers a bacterial SOS response resulting in phage release. Free ranging phages outside their E. coli O157:H7 hosts were detected but could not be isolated directly from environmental samples such as sewage and river water. E. coli O157:H7 colonies carrying the genes coding for Stx2 were isolated from 1 sewage sample (0.76% of positive samples), 8 cattle faecal samples (16.67% of positive samples) and 2 pig faecal samples (14.28% of positive samples). Characterization of E. coli O157:H7 was done by repetitive sequence analysis using ERIC-PCR to determine the relationships between the individual E. coli O157:H7 strains. The ERIC-PCR analysis revealed distinct patterns for all E. coli O157:H7 strains with some small differences between the strains. DNA sequencing of some of the E. coli O157:H7 positive isolates carrying the Stx2 genes were performed confirming the amplified DNA nucleotide sequences of Stx2. Electron microscopic analysis revealed, for the first time in South Africa, that Stx2-converting phages induced from E. coli O157:H7 have different morphologies to that of phage lambda which was previously described. The role of the induced integrated Stx2 phages in natural environments such as river and dam water remains unclear. With the induction of Stx2-converting phages from environmental E. coli O157:H7 isolates, it is now possible to determine the potential of these phages to convert non-pathogenic E. coli strains and other enterobacteriaciae into pathogenic strains.

scholarly journals Isolation and characterization of a new type of chlorovirus that infects an endosymbiotic Chlorella strain of the heliozoon Acanthocystis turfacea

2005 ◽  
Vol 86 (10) ◽  
pp. 2871-2877 ◽  
Author(s):  
Julia A. Bubeck ◽  
Artur J. P. Pfitzner
Keyword(s):  
Genome Structure ◽  
Microscopic Analysis ◽  
Host Cells ◽  
Natural Environments ◽  
Electron Microscopic ◽  
Chlorella Virus ◽  
Isolation And Characterization ◽  
The Family ◽  
New Type

A novel virus, named Acanthocystis turfacea Chlorella virus (ATCV), that infects endosymbiotic Chlorella algae of the heliozoon Acanthocystis turfacea was isolated from freshwater samples. Electron microscopic analysis of ATCV revealed that the viral capsid has a distinct icosahedral shape with a diameter of 140–190 nm. Filamentous structures extending from some of the virus vertices, which may aid attachment of the virus to host cells, were also observed. The capsid is made up of one major coat protein of about 50 kDa and contains a large dsDNA genome. ATCV is a member of the genus Chlorovirus, which belongs to the family Phycodnaviridae, a group of large, icosahedral, dsDNA-containing viruses that infect algae and are ubiquitous in natural environments. However, ATCV is clearly distinct from the prototype Chlorovirus, Paramecium bursaria Chlorella virus (PBCV-1), in some aspects of its genome structure and gene content and therefore must be regarded as a member of a new group of Chlorella viruses.

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