Dose-response analysis can be carried out using multi-purpose commercial statistical software, but except for a few special cases the analysis easily becomes cumbersome as relevant, non-standard output requires manual programming. The extension package drc for the statistical environment R provides a flexible and versatile infrastructure for dose-response analyses in general. The present versio...

hopA mutants, which have been suggested to be defective in mini-F plasmid partitioning (H. Niki, C. Ichinose, T. Ogura, H. Mori, M. Morita, M. Hasegawa, N. Kusukawa, and S. Hiraga, J. Bacteriol. 170:5272-5278, 1988), were found to carry mutations in the gyrB gene, coding for the B subunit of DNA gyrase. In gyrB(HopA) mutants, relaxation of the superhelicity of plasmids, increased IncG incompati...

Two enzymes which phosphorylate neomycin and kanamycin have been detected in Escherichia coli strains carrying R factors. Neomycin-kanamycin phosphotransferase I can phosphorylate neomycin and kanamycin, but not butirosin. Neomycin-kanamycin phosphotransferase II can phosphorylate all three antibiotics. The enzymes also differ in their response to certain inhibitors of phosphorylation. Neomycin...

Introduction: Radiation therapy is an important procedure for treatment of more than half of tumors. One way to increase the efficiency of radiation therapy is application of radiosensitizer at the site of tumor. gold nanoparticles (GNPs) have several characteristics that make them attractive for using with radiation therapy including small size (1–100 nm), biocompatibility, pr...

Restriction-modification (RM) systems represent a minimal and ubiquitous biological system of self/non-self discrimination in prokaryotes [1], which protects hosts from exogenous DNA [2]. The mechanism is based on the balance between methyltransferase (M) and cognate restriction endonuclease (R). M tags endogenous DNA as self by methylating short specific DNA sequences called restriction sites,...