The ability of yeast cells to retain potassium and to form colonies was studied after exposure to pressures ranging from 2 to 143 atmospheres of oxygen. The investigations allow comparison of these responses with those found after x-ray exposure. Exposure to 2 to 8 atmospheres of oxygen for 2, 20, and 40 hours showed decreased potassium leakage as measured by an elution technique. Further exper...

We report a previously undescribed quorum-sensing mechanism for triggering multicellularity in Bacillus subtilis. B. subtilis forms communities of cells known as biofilms in response to an unknown signal. We discovered that biofilm formation is stimulated by a variety of small molecules produced by bacteria--including the B. subtilis nonribosomal peptide surfactin--that share the ability to ind...

Isolated axons from the squid, Dosidicus gigas, were internally perfused with potassium fluoride solutions. Membrane currents were measured following step changes of membrane potential in a voltage-clamp arrangement with external isosmotic solution changes in the order: potassium-free artificial seawater; potassium chloride; potassium chloride containing 10, 25, 40 or 50, mM calcium or magnesiu...

Amphotericin B (AmB) and filipin effects on L and HeLa cells were compared by monitoring drug-induced potassium leakage from cells, changes in radioactive uridine incorporation into cellular ribonucleic acid, protein leakage from cells, and cell viability. L cells were much more susceptible to both AmB and filipin than were HeLa cells, but the overall dose response was similar. For AmB, the var...

The flux ratio (influx/efflux) of K(+) across the plasmalemma of beet cells at an external potassium concentration of 0.6 mm does not respond to changes of membrane potential in the manner expected for the free diffusion of ions. The K(+) efflux is affected by the presence of adsorbed Ca(2+), but is apparently unrelated to the electrical potential or to the net uptake of potassium. The K(+) eff...

In order to evaluate the effects of potassium nitrate nutrition on some low temperature tolerance indices in Citrus aurantium seedlings a factorial experiment was conducted based on a completely randomized design with four replications at the Institute of Citrus Research in Ramsar. Treatments were potassium nitrate nutrition at four levels (0, 2.5, 5, and 10 mM) and temperature at four levels (...