Identification of Ca(2+)-activated Mg(2+)-dependent ATP-hydrolase activity of membrane microsomal fraction of loach embryo (Misgurnus fossilis L.)

The functional confirmation of availability of Ca2+ transport initially-active systems in the embryo cells of loach Misgurnus fossilis L. has been obtained. Using thapsigargin, the specific inhibitor of endoplasmic reticulum of Ca2+, Mg(2+)-ATPase, this enzyme activity was divided into thapsigargin-sensitive (actually endoplasmic reticulum Ca2+, Mg(2+)-ATPase) and thapsigargin-insensitive (plasma membrane Ca2+, Mg(2+)-ATPase) constituents. The Ca(2+)-independent Mg(2+)-dependent ATPase activity makes above 39.7% of the common Ca2+, Mg(2+)-ATPase activity of embryo loach. The periodic changes of Ca2+, Mg(2+)-ATPase activity (except for the changes of plasma membrane Ca2+, Mg(2+)-ATPase activity) were found out, which coincide with periodic [Ca2+]i oscillations during the synchronous divisions of loach blastomers embryos.     

Increase of the heart arrhythmogenic resistance and decrease of the myocardial necrosis zone during activation of cannabinoid receptors

We have found that intravenous administration of cannabinoid receptor (CB) agonist HU-210 (0.05 mg/kg), increases cardiac resistance against arrhythmogenic effect of epinephrine, aconitine, coronary artery occlusion and reperfusion in rats. Pretreatment with CB2-receptor antagonist, SR144528 (1 mg/kg), completely abolished the antiarrhythmic effect of HU-210. However this effect of HU-210 was not attenuated by pretreatment with CB1-receptor antagonist, SR141716A (3 mg/kg). We also found that HU-210 (0.05 mg/kg) decreased the relationship between infarction size and area of ischemia. It is concluded that CB2 receptor stimulation promotes an increase in the cardiac resistance against arrhythmogenic influences and probably increases myocardial tolerance of both ischemic and reperfusion damages in rats.     

Degradation of hydrocarbons and their derivatives by a microbial association based on Canadian pondweed

The degrading action of an aquatic plant-microbial association on the base of Canadian pondweed (Elodea canadensis) and its components (sterilized plant and two periphytonic strains, Pseudomonas fluorescens E1-2.1 and Brevundimonas diminuta E1-3.1) on crude oil, the water-soluble crude oil fraction, and individual test compounds (phenol, toluene, benzene, decalin, and naphthalene) was studied. It was found that the native association had a wider range and higher degree of degrading activity than individual species. Bacterial strains were significantly more active only towards naphthalene. The ability of the sterilized plant to degrade crude oil and phenol was no less than that of microorganisms and much more for toluene. Enzymatic activity towards the pollutants studied was found in E. canadensis exudates and buffer extracts of its cells.     

Molecular dynamics simulations of migration of ions and molecules through the acetylcholine receptor channel

A dynamic model of the channel of an acetylcholine receptor in a closed state has been proposed. The channel is formed by five a-helices of subunit M2 and stabilized by the cyclic hydrocarbon (CH2)105. The migration of charged and unchanged van der Waals particles with a diameter of 7.72 A equivalent to the diameter of a hydrated sodium ion has been studied. The migration occurred by the action of external force applied to the complex along the channel axis. In the closed state, the inhibition of ions is due to two components: electrostatic interaction and steric constraints. The van der Waals channel gate is formed by residues 13'-A-Val255, B-Val261, C-Val269, D-Val255, and E-Ile264, and the negatively changed residues occurring in the upper part of the channel have a great effect on ion selectivity.     

S-nitrosoglutathione induced nitrosative stress in yeast: modifying role of catalases

Possible role of catalases in modification of yeast Saccharomyces cerevisiae response to nitrosative stress was studied in the work. Yeast cell of a wild strain and catalase-defective strains were treated with nitric oxide donor S-nitrosoglutathione, then the cell survival rate, and the levels of protein carbonyls and oxidized glutathione were measured. It was shown that S-nitrosoglutathione decreased cells viability of wild and catalase-defective strains. Unexpected, yeast cells defective by both catalases survived successfully as compared with the cells of the wild strain. The intensity of stress was evaluated by measures of oxidative protein modifications and glutathione oxidation. Treatment with S-nitrosoglutathione did not affect the level of protein carbonyls and was lower by about 14 i 22 % in the cells of double mutant strains after treatments with S-nitrosoglutathione in concentrations of 10 and 20 mM. S-nitrosoglutathione induced a strong increase of the level of oxidized glutathione in yeast cells of the wild strain. This stress slightly increased the level of oxidized glutathione in the yeast cells defective by peroxisomal or both catalases. It is interesting, that an increase of oxidized glutathione level was not observed in the yeast cells defective by cytosolic catalase. The obtained results prove that catalases can modify yeast cell response to the nitrosative stress.     

Temperature impact on localization of "free" phenolic compounds in the root tissues and deformation of root hairs in pea seedlings inoculated by Rhizobium

The study was focused on localization of "free" phenolic compounds in pea Pisum sativum L. seedling roots grown at 22 and 8 degrees C 24 h after their inoculation with Rhizobium leguminosarum bv. viceae bacteria. A comparison of phenolic compound distribution along the root in root tissues, and results of observation of root hair development on the root surface, response of root hairs to inoculation, manifesting itself in various deformation degree (bends, twists, ect.) enabled us to reveal differences between roots grown at different temperatures. These differences are basically referred to a sector localized 0-5 mm away from the root tip containing meristematic and extending cells. A distribution of phenolic compounds in sectors with root hairs responding to inoculation by various degrees of contortion practically did not depend on the temperature of plant growth. The evidence provided in the course of this work enabled us to suggest that inhibition of pea root infection at low temperature is caused by decelerated growth processes characteristic of both the root itself and root hairs, as well by a slow increase in the root hair zone.     

Strains of Vibrio cholerae serogroups O1 and O139 that produce the basic protective antigens

To find out stable and effective producers of major protective antigens intended for use as components of cholera chemical vaccine against V. cholerae strains of serogroups O and O139, the comparative analysis of the production of cholera toxin, toxin-coregulated pili (TCP), antigens O1 and O139, polysaccharide capsule and outer membrane protein OmpU in different V. cholerae strains groups O1 and O139 has been made. V. cholerae strain KM68, serogroup O1, has been found capable of the production of antigen O1, serovar Ogawa, protein OmpU at a sufficiently high level and the hyperproduction of cholera toxin and TCP, and thus suitable for use in the manufacture of cholera bivalent vaccine as the source of these antigens. Specially selected alysogenic noncapsular strain KM137 of serogroup O139, characterized by a high and stable level of the biosynthesis of this somatic antigen when grown in both laboratory and production conditions, may serve as the produces of antigen O139.