UV-inducible repair: Influence on survival, dimer excision, DNA replication and breakdown in Escherichia coli B/r Hcr+ cells

1978 ◽  
Vol 160 (1) ◽  
pp. 81-87 ◽  
Author(s):  
Milena Sedliaková ◽  
Viera Slezáriková ◽  
František Mašek ◽  
Jela Brozmanová
Keyword(s):  
Escherichia Coli ◽  
Dna Replication ◽  
Escherichia Coli B ◽  
Inducible Repair

THE EFFECT OF 3000–4000 Å LIGHT ON THE SYNTHESIS OF β-GALACTOSIDASE AND BACTERIOPHAGES BY ESCHERICHIA COLI B

1967 ◽  
Vol 13 (1) ◽  
pp. 69-79 ◽  
Author(s):  
S. J. Webb ◽  
J. Singh Bhorjee
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Dna Replication ◽  
Glutamic Acid ◽  
Strong Correlation ◽  
Sublethal Doses ◽  
Time Periods ◽  
Escherichia Coli B

The irradiation of Escherichia coli B with sublethal doses of 3000–4000 Å light prevented the microorganisms from manufacturing β-galactosidase and T2 and T7 coliphages. Inhibition occurred only if the cells were irradiated immediately after their contact with the inducer lactose or infection with T2 and T7 phages. If, before irradiation the cells were allowed to incubate for 15 min after the addition of lactose or the coliphages to the cells, little effect of the light was found. The uptake of uracil and amino acids by washed cells was more rapid in the first 15 min than during later time periods while thymine uptake did not begin until the first 15 min had elapsed. The 3000–4000 Å light inhibited the uptake of arginine and thymine but not uracil or glutamic acid. The addition of 5% inositol inhibited the synthesis of β-galactosidase and the uptake of14C-labelled metabolites. Since there was a strong correlation between the degree to which arginine and thymine uptakes were inhibited by the light or inositol, it appears that the production of a protein during the first 15 min is intimately connected with DNA replication and the synthesis of induced enzymes.

scholarly journals The mechanism of sensitivity to phleomycin in growing Escherichia coli cells

1976 ◽  
Vol 155 (1) ◽  
pp. 87-99 ◽  
Author(s):  
M J Sleigh ◽  
G W Grigg
Keyword(s):  
Escherichia Coli ◽  
Dna Replication ◽  
Cell Membrane ◽  
Dna Breakage ◽  
Escherichia Coli Cells ◽  
Low Concentrations ◽  
Cellular Change ◽  
Initiation Of Dna Replication ◽  
Cellular Dna ◽  
Escherichia Coli B

Stationary-phase Escherichia coli B cells transferred to new growth medium are initially resistant to net DNA breakage by low concentrations of phleomycin, and become sensitive as DNA replication commences. From studies with inhibitors of various stages of the DNA replication cycle it is evident that it is not DNA synthesis itself that is required for induction of DNA breakage by phleomycin, but events associated with the initiation of DNA replication. Termination of replication in the absence of further initiaiton results in resistance to phleomycin. The cellular change responsible for changes in sensitivity to phleomycin could be the attachment of the bacterial chromosome to the cell membrane at initiation and detachment on termination of replication, suggesting an alteration in the balance between cellular DNA breakage and repair processes for membrane-associated compared with non-membrane-associated DNA.

SOME OBSERVATIONS CONCERNING DNA AND β-GALACTOSIDASE SYNTHESIS IN ESCHERICHIA COLI B

1967 ◽  
Vol 13 (4) ◽  
pp. 377-388 ◽  
Author(s):  
S. J. Webb ◽  
J. Singh Bhorjee ◽  
Janet L. Walker ◽  
D. A. Rokosh
Keyword(s):  
Escherichia Coli ◽  
Dna Replication ◽  
Enzyme Synthesis ◽  
Induction Medium ◽  
Minute Period ◽  
Rate Characteristic ◽  
Two Stages ◽  
Escherichia Coli B

When starved cells of thymine-requiring Escherichia coli B were placed in a complete induction medium there was an initial lag of 10 minutes before measurable amounts of the enzyme were detected. Cells exposed for 15 minutes to one inducer and then given an alternative inducer continued to manufacture the enzyme for 60 minutes at a rate characteristic of the initial inducer. After this period, enzyme manufacture assumed the characteristics of the second inducer. Glucose or mitomycin was found to inhibit enzyme synthesis only when they were added during the first 10 minutes or 45- to 60-minute periods of induction. Chloramphenicol stopped enzyme synthesis at any stage of induction. The synthesis of DNA was found to occur in two stages and enzyme synthesis was prevented by glucose or mitomycin only if they were added to the cells during a 10-minute period which immediately preceded DNA replication. It is concluded that a gene can express itself only once, and change in expression requires the synthesis of new DNA.

Sites of Adsorption of the Bacteriophages T3 and T5 on the Wall of Escherichia Coli B.

1967 ◽  
Vol 25 ◽  
pp. 96-97
Author(s):  
Manfred E. Bayer
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Electron Microscope ◽  
Uranyl Acetate ◽  
E Coli ◽  
Receptor Sites ◽  
Rigid Cell Wall ◽  
Host Cell Surface ◽  
Bacterial Viruses ◽  
Escherichia Coli B

Bacterial viruses adsorb specifically to receptors on the host cell surface. Although the chemical composition of some of the cell wall receptors for bacteriophages of the T-series has been described and the number of receptor sites has been estimated to be 150 to 300 per E. coli cell, the localization of the sites on the bacterial wall has been unknown.When logarithmically growing cells of E. coli are transferred into a medium containing 20% sucrose, the cells plasmolize: the protoplast shrinks and becomes separated from the somewhat rigid cell wall. When these cells are fixed in 8% Formaldehyde, post-fixed in OsO4/uranyl acetate, embedded in Vestopal W, then cut in an ultramicrotome and observed with the electron microscope, the separation of protoplast and wall becomes clearly visible, (Fig. 1, 2). At a number of locations however, the protoplasmic membrane adheres to the wall even under the considerable pull of the shrinking protoplast. Thus numerous connecting bridges are maintained between protoplast and cell wall. Estimations of the total number of such wall/membrane associations yield a number of about 300 per cell.

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