scholarly journals The Isolation and Oharacterization of An Rna Bacteriophage

1964 ◽  
Vol 17 (3) ◽  
pp. 719 ◽  
Author(s):  
CI Davern
Keyword(s):  
Escherichia Coli ◽  
Dna Synthesis ◽  
Culture Medium ◽  
Buoyant Density ◽  
Sedimentation Coefficient ◽  
Caesium Chloride ◽  
Specific Phage ◽  
K 12 ◽  
Male Specific ◽  
Rna Phage

An enrichment procedure for the isolation of RNA bacteriophage is described. The method involves the inoculation of sewage samples into cultures of Escherichia coli K-12 Hfr under conditions where DNA synthesis is restricted by the addition of 5-fiuorodeoxyuridine to the culture medium. Six phage isolates were made and all of them were shown to be male-specific. One of the male-specific phage was further characterized as an RNA phage, having very similar properties to RNA phage already isolated in other parts oftha world. This RNA phage has a buoyant density of 1�42 g/cm3 in caesium chloride. and has a sedimentation coefficient of 79'5 Sin O'Ol:M Tria-HOI buffer, pH 7� 4, at 20�0.

scholarly journals The inhibitory action of transfer factors on lysis ofEscherichia coliK 12 by phages μ 2 and Φ 2

1970 ◽  
Vol 16 (2) ◽  
pp. 215-224 ◽  
Author(s):  
J. S. Pitton ◽  
E. S. Anderson
Keyword(s):  
Transfer Factors ◽  
Resistance Factors ◽  
Specific Phage ◽  
Agar Layer ◽  
K 12 ◽  
Female Specific ◽  
Male Specific ◽  
R Factors ◽  
Selection Of

SUMMARYA selection offi+resistance factors and transfer factors, when introduced into K 12F+, showed a range of inhibitory activity of lysis by the male-specific phage μ 2. This range can be used to subdivide thefi+factors intofi+1,fi+2,fi+3andfi+4classes, according to the degree of inhibition of μ 2 lysis. To this subdivision can be added restriction of the ‘female-specific’ phage φ 2.Introduction of all thefi+factors tested into K 12 HfrH totally inhibited lysis by μ 2 in spot tests, but with twofi+1and onefi+2factors visible lysis was obtained in agar-layer tests. These three factors caused least inhibition of transfer ofproby HfrH. It can be assumed that both tests reflect lower inhibition of sex fimbrial formation by thesefi+factors than by the remainder.Thefi−factors, when introduced into K 12, can be subdivided on the basis of restrictive effects on phage φ 2.These effects can be added to phage restriction in the salmonellae for the purposes of further classification of the transfer factors and R-factors.

Die Bildung von RNS-Doppelstrang zur Vermehrung eines RNS enthaltenden Bakteriophagen

1964 ◽  
Vol 19 (7) ◽  
pp. 593-604 ◽  
Author(s):  
Hans Christian Kaerner ◽  
Hartmut Hoffmann-Berling
Keyword(s):  
Molecular Weight ◽  
Buoyant Density ◽  
Sedimentation Coefficient ◽  
Radioactive Material ◽  
Double Stranded Rna ◽  
Infected Cells ◽  
Rna Phage ◽  
Denaturation Profile ◽  
Molecular Weight Form ◽  
Latent Phase

The RNA phage fr induces in Escherichia coli cells the production of double stranded RNA, which is identified by its thermal denaturation profile ( Tm 101 °C in 0,2-m. Na⊕ ), by its nonreactivity with formaldehyde and by its buoyant density in Cs2SO4 (1,609 g cm-3 , compared to that of fr-RNA = 1,634 g cm-3 ). Unless denatured the double strand is resistant to RNase. In its high molecular weight form the double stranded R N A has twice the weight of fr-RNA, as estimated from the sedimentation coefficient (s20 = 14,5). The base ratios are those expected for a double stranded replicative from of fr-RNA. By melting and annealing one of the strands of the non-radioactive material can be exchanged for 32P-fr-RNA from phage particles. Infectiosity of the doublestranded RNAhas not yet been shown. Extracts from infected cells contain double strand bound to the 30 - 50 s fraction; there is also double strand in the supernatant, apparently in the form of relatively low molecular weight fragments. The double stranded RNA, isolated at the height of infection, accounts for 3 - 8% of the cellular RNA. Cells infected with 32P-fr show a surprisingly large part of the infecting RNA bound to ribosomes quite late in the latent phase. The meaning of this result is discussed.

scholarly journals Global Expression of Prophage Genes in Escherichia coli O157:H7 Strain EDL933 in Response to Norfloxacin

2005 ◽  
Vol 49 (3) ◽  
pp. 931-944 ◽  
Author(s):  
Sylvia Herold ◽  
Jutta Siebert ◽  
Andrea Huber ◽  
Herbert Schmidt
Keyword(s):  
Escherichia Coli ◽  
Primary Metabolism ◽  
Low Concentration ◽  
E Coli ◽  
Specific Phage ◽  
Stress Functions ◽  
Enterocyte Effacement ◽  
K 12 ◽  
Upregulated Genes ◽  
Production Cell

ABSTRACT We investigated the influence of a low concentration of the gyrase inhibitor norfloxacin on the transcriptome of enterohemorrhagic Escherichia coli O157:H7 strain EDL933. For this purpose, we used a commercial DNA microarray containing oligonucleotides specific for E. coli O157:H7 strains EDL933 and RIMD0509952 and E. coli K-12 strain MG1655. Under the conditions applied, 5,963 spots (94% of all spots) could be analyzed. Among these, 118 spots (P < 0.05) indicated transcriptional upregulation and 122 spots (P < 0.05) indicated transcriptional downregulation of the E. coli genes present on the array. Eighty-five upregulated EDL933 genes were phage borne. Fifty-two of them could be ascribed to the Shiga toxin-encoding phages (Stx phages) BP-933W and CP-933V; the other 33 genes belonged to non-Stx prophage elements in the EDL933 genome. Genes present in the BP-933W prophage genome were induced most strongly up to 158-fold in the case of stxA2 upon induction with norfloxacin. Twenty-two additional upregulated genes appeared to be E. coli O157:H7 strain RIMD0509952-specific phage elements, and the remaining 11 genes were related mainly to recombination and stress functions. Downregulation was indicated predominantly for genes responsible for bacterial primary metabolism, such as energy production, cell division, and amino acid biosynthesis. Interestingly, some genes present in the locus of enterocyte effacement appeared to be downregulated. The results of the study have shown that a low concentration of norfloxacin has profound effects on the transcriptome of E. coli O157:H7.

Buoyant density of Escherichia coli is determined solely by the osmolarity of the culture medium

1995 ◽  
Vol 164 (2) ◽  
pp. 155-157 ◽  
Author(s):  
W. W. Baldwin ◽  
Richard Myer ◽  
Erika Anderson ◽  
Arthur L. Koch
Keyword(s):  
Escherichia Coli ◽  
Culture Medium ◽  
Buoyant Density

scholarly journals The number of sex-factors per chromosome in Escherichia coli

1971 ◽  
Vol 121 (1) ◽  
pp. 93-103 ◽  
Author(s):  
R. Frame ◽  
J. O. Bishop
Keyword(s):  
Escherichia Coli ◽  
Buoyant Density ◽  
E Coli ◽  
Caesium Chloride ◽  
Genetic Complexity ◽  
Total Dna ◽  
Gal Genes ◽  
Episomal Dna ◽  
Equilibrium Centrifugation

A substituted sex-factor of Escherichia coli, F′8 gal, was transferred to Proteus mirabilis by conjugation. The DNA of the episome was partially purified from Proteus DNA by preparative equilibrium centrifugation in caesium chloride, and by a bulk method using hydroxyapatite. The buoyant density of the episomal DNA is 1.707, corresponding to a (G+C) content of 47%. By optical renaturation the genetic complexity of the episomal DNA was found to be 76×106 daltons. RNA was synthesized in vitro by using the episomal DNA as template. By hybridizing this RNA with DNA extracted from E. coli carrying F′8 gal, it is shown that the number of copies of the episome per replicating chromosome is close to two during exponential growth. The episome makes up about 4.4% of the total DNA of the growing cells. The activities of galactokinase and galactose 1-phosphate uridylyl-transferase in cells with and without episomal and chromosomal gal genes were found to be proportional to the number of gal genes present, when the cells were induced with d-fucose, but not when they were induced with d-galactose.

scholarly journals A study of pili onPseudomonas aeruginosa

1972 ◽  
Vol 19 (1) ◽  
pp. 39-51 ◽  
Author(s):  
David E. Bradley
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Current Knowledge ◽  
Genetic Material ◽  
Filamentous Phage ◽  
Supporting Evidence ◽  
Bacterial Strains ◽  
Structural Comparison ◽  
Male Specific ◽  
Rna Phage

SUMMARYPseudomonas aeruginosacarries polar pili which act as receptors for RNA-containing bacteriophages. In order to confirm, that these pili were not involved in the transfer of the sex factor FP 2, eleven bacterial strains, both FP 2+and FP 2−, were examined in the electron microscope for the presence of pili and tested for sensitivity to the RNA phage PP7. Pili were found on all strains save one which was resistant to phage PP7. It was also found by electron microscopy that about 25 times more pili per cell were present after PP7 adsorption than before it. This result is discussed with reference to the pilus retraction theory, providing further evidence that some kinds of pili retract instead of acting as simple tubes for the transfer of genetic material. The strong supporting evidence provided by the infective processes of male-specific coliphages is discussed and compared to current knowledge ofP. aeruginosaRNA phages.It was also found that pili were present on the host strain for theP. aeruginosafilamentous phage Pf. Although similar in appearance to RNA phage pili, these differed in that they did not adsorb phage PP7. However, it seemed likely that they were receptors for Pf. A structural comparison is made betweenP. aeruginosapili andEscherichia coliF-pili. It is possible thatP. aeruginosapili could be coded for by a plasmid other than FP 2.

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