scholarly journals Increased Mutation Rate of E. coli K12λ Cultures Maintained in Continuous Logarithmic Growth

1966 ◽  
Vol 50 (2) ◽  
pp. 369-377 ◽  
Author(s):  
John H. Northrop
Keyword(s):  
Mutation Rate ◽  
Direct Determination ◽  
Growth Curves ◽  
Culture Cell ◽  
Mutation Rates ◽  
E Coli ◽  
Fraction Method ◽  
Logarithmic Growth ◽  
Resistant Cells

Continuous logarithmic growth of E. coli K12λ in an automatic culture cell resulted in marked increases in the proportion of several mutants. The P1 phage-resistant cells increased 10 to 3000 times, the T2 phage-resistant cells 1 to 1000 times, the neomycin-resistant cells 1 to 10 times, and the virus-producing cells 30 to 70 times. No change occurred in the penicillin-resistant cells. Calculation of the growth curves and direct determination of the mutation rates by the null fraction method showed that the increases in the proportion of mutants were due to increases in the mutation rates.

Photophysical and Direct Determination of Binding Constants of Ethidium Bromide Complexed to E. Coli DNA

2002 ◽  
Vol 56 (3) ◽  
pp. 362-369 ◽  
Author(s):  
Eva M. Talavera ◽  
Pablo Guerrero ◽  
Francisco Ocana ◽  
Jose M. Alvarez-Pez
Keyword(s):  
Ethidium Bromide ◽  
Direct Determination ◽  
Binding Constants ◽  
E Coli

GROWTH STUDIES ON BACILLUS STEAROTHERMOPHILUS

1959 ◽  
Vol 5 (3) ◽  
pp. 293-297 ◽  
Author(s):  
Nora E. Neilson ◽  
Mary F. MacQuillan ◽  
J. J. R. Campbell
Keyword(s):  
Bacillus Stearothermophilus ◽  
Growth Curves ◽  
E Coli ◽  
Growth Studies ◽  
Generation Times ◽  
Second Period ◽  
Logarithmic Growth

Growth curves for B. slearothermophilus were established for temperatures between 45 °C and 70 °C. Generation times as short as 10 minutes were obtained. At 65 °C initial logarithmic growth was followed by autolysis of over 90% of the ceils and subsequently by initiation of a second period of logarithmic growth. The effects of temperatures from 45 °C to 64 °C on the characteristics of the growth curves are almost identical with changes reported for E. coli between 22 °C and 42 °C.

scholarly journals Direct determination of the point mutation rate of a murine retrovirus.

1992 ◽  
Vol 66 (6) ◽  
pp. 3683-3689 ◽  
Author(s):  
R J Monk ◽  
F G Malik ◽  
D Stokesberry ◽  
L H Evans
Keyword(s):  
Point Mutation ◽  
Mutation Rate ◽  
Direct Determination

scholarly journals Direct Determination of the Mutation Rate in the Bumblebee Reveals Evidence for Weak Recombination-Associated Mutation and an Approximate Rate Constancy in Insects

2016 ◽  
Vol 34 (1) ◽  
pp. 119-130 ◽  
Author(s):  
Haoxuan Liu ◽  
Yanxiao Jia ◽  
Xiaoguang Sun ◽  
Dacheng Tian ◽  
Laurence D. Hurst ◽  
...  
Keyword(s):  
Mutation Rate ◽  
Direct Determination ◽  
Approximate Rate

scholarly journals The response of Escherichia coli to exposure to the biocide polyhexamethylene biguanide

Microbiology ◽  
2006 ◽  
Vol 152 (4) ◽  
pp. 989-1000 ◽  
Author(s):  
Michael J. Allen ◽  
Graham F. White ◽  
Andrew P. Morby
Keyword(s):  
Escherichia Coli ◽  
Nucleic Acids ◽  
Transcriptional Profiling ◽  
Direct Determination ◽  
Open Reading Frames ◽  
E Coli ◽  
Polyhexamethylene Biguanide ◽  
Wide Range ◽  
Derivatives Of

The global response of Escherichia coli to the broad-spectrum biocide polyhexamethylene biguanide (PHMB) was investigated using transcriptional profiling. The transcriptional analyses were validated by direct determination of the PHMB-tolerance phenotypes of derivatives of E. coli MG1655 carrying either insertionally inactivated genes and/or plasmids expressing the cognate open reading frames from a heterologous promoter in the corresponding chromosomally inactivated strains. The results showed that a wide range of genes was altered in transcriptional activity and that all of the corresponding knockout strains subsequently challenged with biocide were altered in tolerance. Of particular interest was the induction of the rhs genes and the implication of enzymes involved in the repair/binding of nucleic acids in the generation of tolerance, suggesting a novel dimension in the mechanism of action of PHMB based on its interaction with nucleic acids.

Concentration determination of chromatin in unstained resin-embedded sections by means of Z-contrast in STEM

1990 ◽  
Vol 48 (2) ◽  
pp. 186-187
Author(s):  
M. Haider ◽  
B. Bohrmann
Keyword(s):  
Energy Loss ◽  
Freeze Substitution ◽  
Biological Macromolecules ◽  
Local Concentration ◽  
E Coli ◽  
Concentration Determination ◽  
Phosphorous Content ◽  
Z Contrast ◽  
Electron Energy Loss

The technique of Z-contrast in STEM offers the possibility to determine the local concentration of macromolecules like lipids, proteins or DNA. Contrast formation depends on the atomic composition of the particular structure. In the case of DNA, its phosphorous content discriminates it from other biological macromolecules. In our studies, sections of E. coli, the dinoflagellate Amphidinium carterae and Euglena spec. cells were used which were obtained by cryofixation followed by freeze-substitution into acetone with 3% glutaraldehyde. The samples were then embedded either in Lowicryl HM20 at low temperature or in Epon at high temperature. Sections were coated on both sides with 30Å carbon.The DF- and the inelastic image have been recorded simultaneously with a Cryo-STEM. This Cryo-STEM is equipped with a highly dispersive Electron Energy Loss Spectrometer. With this instrument pure Z-contrast can be achieved either with a Filtered DF-image divided by the inelastic image or, as is used in this paper, by dividing the conventional DF-image by an inelastic image which has been recorded with an inelastic detector whose response is dependent on the total energy loss of the inelastically scattered electrons.

The Direct Determination of I131 in Heterogeneous Fecal Specimens

1961 ◽  
Vol 41 (4) ◽  
pp. 380-384 ◽  
Author(s):  
Arthur F. Dratz ◽  
James C. Coberly
Keyword(s):  
Direct Determination
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