Closed circular DNA was relaxed with a topoisomerase in the presence of varying concentrations of the intercalating dye, ethidium bromide, to create underwound, planar DNA rings. We directly determined the helical repeat of these DNA molecules by the Gaussian center method and found that it varied as a simple predicted function of the degree of underwinding and the helical repeat of relaxed, dy...

A simple, inexpensive design is presented for the rapid conversion of the popular MD-4 Polaroid land camera to a high quality digital gel documentation system. Images of ethidium bromide stained DNA gels captured using the digital system were compared to images captured on Polaroid instant film. Resolution and sensitivity were enhanced using the digital system. In addition to the low cost and s...

We have studied a number of petite [rho-] mutants of Saccharomyces cerevisiae induced in a wild-type strain of mitochondrial genotype [ome- CHL(R) ERY(S) OLI(S) (1, 2, 3) PAR(S)] by Berenil and ethidium bromide, all of which have retained two mitochondrial genetic markers, [CHL(R)] and [ERY(S)], but have lost all other known markers. Though stable in their ability to retain these markers in the...

A salt-induced cooperative conformational transition of a synthetic DNA, poly(dG-dC), is reversed by addition of ethidium bromide. Binding of the dye at high salt concentrations is highly cooperative. Circular dichroism spectra of the complex and the kinetic data support a model for this cooperative binding that is formally equivalent to the "allosteric" one proposed for oligomeric proteins by ...

A method that provides an easy, rapid, and reproducible way for separating closed circular DNA species from linear DNA and nicked circles is described. The method is based on the difference in mobility of form I (supercoiled) DNA and form II (nicked circles), and the differential mobility of relaxed circular DNA in the presence and absence of ethidium bromide (EtdBr). It can be used for detecti...

The reactions of the EcoRI restriction endonuclease on the covalently closed DNA of plasmid pMB9 were studied in the presence of ethidium bromide. At the concentrations of ethidium bromide tested, which covered the range over which the DNA is changed from negatively to positively supercoiled, the dye caused no alteration to the rate at which this enzyme cleaved the covalently closed DNA to yiel...

It is known that bacteria showing a multi-drug resistance phenotype use several mechanisms to overcome the action of antibiotics. As a result, this phenotype can be a result of several mechanisms or a combination of thereof. The main mechanisms of antibiotic resistance are: mutations in target genes (such as DNA gyrase and topoisomerase IV); over-expression of efflux pumps; changes in the cell ...

Fluoroquinolone-resistant Escherichia coli isolates which overexpressed acrB and had a substitution at amino acid 45 of AcrR were complemented with wild-type acrR. Complementation led to increased sensitivity to ciprofloxacin and to ethidium bromide, suggesting that mutation at amino acid 45 of AcrR contributes to ciprofloxacin resistance.

Herein, we study the nanomechanical characteristics of single DNA molecules in the presence of DNA binders, including intercalating agents (ethidium bromide and doxorubicin), a minor groove binder (netropsin) and a typical alkylating damaging agent (cisplatin). We have used magnetic tweezers manipulation techniques, which allow us to measure the contour and persistence lengths together with the...

Susceptibility testing with a variety of structurally unrelated compounds showed that hefC in Helicobacter pylori is involved in multidrug efflux. This efflux was shown to depend on the proton motive force, as demonstrated by ethidium bromide accumulation experiments. Thus, H. pylori contains an active multidrug efflux mechanism.