Fast-activating cation channel in barley mesophyll vacuoles. Inhibition by calcium

In contrast to the vacuolar ion channels which are gated open by an increase of cytosolic Ca²⁺ the vacuolar ion currents at resting cytosolic Ca²⁺are poorly explored. Therefore, this study was performed to investigate the properties of the so-called fast-activating vacuolar (FV) current which dominates the electrical characteristics of the tonoplast at physiological free Ca²⁺ concentrations. Patch—clamp measurements were performed on whole barley ( Hordeum vulgare ) mesophyll vacuoles and on excised tonoplast patches. Single ion channels were identified, which, based on their selectivity, activation kinetics, Ca²⁺- and voltage-dependence, carry the whole-vacuole FV current. Reversal potential determinations indicated a K⁺ overs C⁻ permeability ratio of about 30. Both inward and outward whole-vacuole currents as well as the activity of single FV channels were inhibited by an increase of cytosolic Ca²⁺, with a K_d≈ 6 µM. At physiological vacuolar Ca²⁺ activities, the FV channel is an outward-rectifying potassium channel. The FV channel was activated in less than a few milliseconds both by negative and positive potential steps, having a minimal activity that is 40 mV negative of the K⁺ equilibrium potential. It is proposed that transport of K⁺ through this cation channel controls the electrical potential difference across the tonoplast.     

Biological method of identifying antibiotic substances at an early screening stage

A biological method was used in addition to the chemical methods of identification in the screening programme of new antibiotics. The method consists of evaluation of the effect of the crude antibiotic preparations on microbial forms resistant to various antibiotics. The efficiency of the biological method is shown. It provides more complete and rapid characterization of the properties of the new antibiotics and their rough identification at early screening stages.     

Study of the microcirculatory bed by a method of demonstrating lactate dehydrogenase]

The method of detection of lactate dehydrogenase with some modification was used to study the microcirculatory bed in total preparations of serous membranes and plane sections of organs of any square surface. The employment of non-fixed material, the short time (from 15 to 60 min) necessary to obtain preparations of any size and simultaneous determination of the localization and the degree of the activity of the enzyme--are, to the authors opinion, undoubtful advantages of the given method, which can be an addition to the well-known impregnation method of determination of the microcirculatory bed.     

Immobilization of antibiotics on a titanium surface

Immobilization of antibiotics on the surface of electrolytically oxidated titanium was tried. Transfer of the immobilized ampicillin into hardly soluble calcium ampicillate resulted in providing the coating with antimicrobial activity for 5 days. The quantity of the immobilized antibiotic determined polarographically amounted to 6.4.10(-3) mol per 1 m2 of the surface.     

Thermotolerant Methanotrophic Bacteria from Sediments of the River Chernaya,Crimea, and Assessment of Their Growth Characteristics

Microbiology - The technology of single-cell protein production from natural gas is based on using thermotolerant methanotrophic bacteria with high growth rates on methane. So far, the spectrum of...     

Identification of Aerobic Methane-Oxidizing Bacteria in Coastal Sediments of the Crimean Peninsula

Microbiology - Methane oxidation rates and diversity of methane-oxidizing microorganisms in the upper sediment layers of the Crimean Peninsula coastal regions (Black Sea) were investigated....     

Polycyclic Aromatic Hydrocarbons in the Surface Microlayer of Lake Baikal during Wildfires and Naphthalene-degrading Strains from the Bacterioneuston

Microbiology - The summer of 2015 was characterized by a large number of forest fires along the coastline of Lake Baikal. The concentrations of all analyzed polycyclic aromatic hydrocarbons (PAHs)...