Ultrastructural changes in the erythrocyte plasma membranes of chickens in the early stages of interaction with the influenza virus

Using freeze-fracture method it is shown that at the early stages of interaction with chicken erythrocytes the influenza virus induces generalized changes in the physical state of erythrocyte plasma membranes resulted from local disturbances of the cell surface in adsorption sites of virions. Ultrastructural changes seen in the membranes reach their maximum 5 minutes after infection which corresponds to the moment of maximum pinocytotic cell activity in relation to the viruses.     

Some characteristics of using polyalcohols as cryoprotectors in preserving Actinomyces noursei LIA-0471]

Freezing of Act. noursei cell suspensions at a rate of 0.5 degrees per minute in the presence of various substances showed that 5 per cent concentrations of glycerol, ethylen-, diethylen-, propylenglycol and polyethylenglycols had a cryoprotective effect. Polyethylenglycols with a molecular weight of 1500-20 000 had the highest protective effect on the actinomycetous cells from the damaging action of repeated freezing and thawing. The method of repeated freezing and thawing is recommended for studying the cryoprotective effect of various compounds.     

Comparative study of beta-adrenoreceptors of rat brain synaptic membranes

Affinity of beta-adrenoreceptors in the rat brain synaptic membranes to agonists isoproterenol and norepinephrine, as well as to antagonist 125I-hydroxybenzylpindolol is lower in young (1 month) and old (24--26 months) than in mature (8--12 months) rats. Desensitization toward isoproterenol is expressed in the young ones only. In the old but not in other groups simultaneous action of isoproterenol and N-ethylmaleimide decreases the following binding of the antagonist while the same agents added separately produced no effect. It is suggested that beta-adrenoreceptors undergo age-related changes in their conformational state due to modification of the membrane environment.     

Effect of UV-light on formation of fluorescent products of lipid peroxidation

The rate of fluorescent product formation during the peroxidation of polyunsaturated linolenic acid or egg phosphatidylethanolamine and also during the oxidation of linolenic acid together with a phenylalanine and synthetic phosphatidylethanolamine 1,5--3 times more intensive after previous UV-irradiation of the unsaturated fatty acid. Schiff bases are fluorescent products in amine containing systems which are produced in the reaction of the malonaldehyde with amines. It is possible that fluorochromes produced during the only unsaturated acid oxidation are the result of the radical recombination. Accumulation of the oxidated products determined by TBA-reactive substances does not inevitably correlate with the fluorescent intensity in explored systems.     

Cyclic GMP-induced structural transitions of photoreceptor membranes

The influence of cyclic GMP on the structural state of photoreceptor membranes was studied. The spin probe technique was used to obtain the dependences of microviscosity of lipid domains of membranes on cGMP concentration. It was shown that microviscosity of 5-doxylsteraric acid environment in rod outer segment, disc and plasma mambranes changed at concentrations of 2.10(7); 5.10(-6) and 6.10(-6). Non-cyclic GMP was ineffective. The ultrasound treatment of membraneous samples resulted on disappearance of the structural changes.     

Characteristics of the heterogeneity of the physical properties of the lipid phase of synaptic membranes from the rat brain using the fluorescent probe pyrene

A theoretical analysis of the dependence of pyrene excimerization on its concentration in biological membranes was carried out. It was shown that in synaptic membranes the concentration dependencies of pyrene excimerization parameter upon direct stimulation appear as nonlinear, thus being reflective of the heterogeneity of physical properties of the lipid phase. Upon pyrene excitation at the expense of the energy transfer from tryptophanyl residues the dependence is linear, which points to the homogeneity of the anular lipid pool. It was assumed that a comparison of microviscosity of the anular and bilayer lipids requires independent measurements of the coefficient of the probe distribution between the lipids or of the anular lipid content in the membrane.