[Changes in Cell Surface Properties and Biofilm Formation Efficiency in Azospirillum brasilense Sp245 Mutants in the Putative Genes of Lipid Metabolism mmsB1 and fabG1].

The previously obtained insertion mutants ofAzospirillum brasilense Sp245 in the genes mmsBl and fabG1 (strains SK039 and Sp245.1610, respectively) were characterized by impaired flagellation and motility. The putative products of expression of these genes are 3-hydroxyisobutyrate dehydrogenase and 3-oxoacyl-[acyl-carrier protein] reductase, respectively. In the present work, A. brasilense- Sp245 strains SK039 and Sp245.1610 were found to have differences in the content of 3-hydroxyhexadecanoic, hexadecanoic, 3-hydroxytetradecanoic, hexadecenoic, octadecenoic, and nonadecanoic acids in their lipopolysaccharide prepa- rations, as well as in cell hydrophobicity and hemagglutination activity and dynamics of cell aggregation, in biomass amount, and in the relative content of lipopolysaccharide antigens in mature biofilms formed on hydrophilic or hydrophobic surfaces.

[Ligninolytic Activity of Bacteria of the Genera Azospirillum and Niveispirillum].

Capacity of associative soil bacteria of the genera Azospirillum and Niveispirillum for degradation of lignin model compounds was demonstrated. Lignin and Mn-peroxidases were detected in the culture liquid of the type strains of these genera. The data on involvement of nonspecific bacterial peroxidases in lignin degradation were obtained.

[Biosynthesis of gold nanoparticles by Azospirillum brasilense].

Plant-associated nitrogen-fixing soil bacteria Azospirillum brasilense were shown to reduce the gold of chloroauric acid to elemental gold, resulting in formation of gold nanoparicles. Extracellular phenoloxidizing enzymes (laccases and Mn peroxidases) were shown to participate in reduction of Au+3 (HAuCl4) to Au(0). Transmission electron microscopy revealed accumulation of colloidal gold nanoparticles of diverse shape in the culture liquid of A. brasilense strains Sp245 and Sp7. The size of the electron-dense nanospheres was 5 to 50 nm, and the size of nanoprisms varied from 5 to 300 nm. The tentative mechanism responsible for formation of gold nanoparticles is discussed.

Effects of Azospirillum brasilense Sp7 lectin and Phaseolus vulgarus phytohemagglutinin on cytokine activity of lymphocytes in vitro.

We studied the effect of fucose-specific lectin from Azospirillum brasilense Sp7 bacteria and Phaseolus vulgarus phytohemagglutinin (PHA) on activity of IFN-γ, IFN-α, IL-1α, IL-4, IL-8, and TNF-α in human blood in vitro. During the experiment, IFN-γ production increased from 25 pg/ml in controls to 103 and 56 pg/ml under the influence of lectin and PHA, respectively. Agglutinins had similar effects on IFN-α production. Bacterial lectin increased IL-1α level from 2.65±0.08 to 8.45±0.41 pg/ml. PHA also increased IL-1α levels, but this effect was by 1.5-2 times less pronounced. Bacterial lectin and PHA increased production IL-4 by almost 2 times and production of IL-8 by 6 and 5 times, respectively, compared to the control. No differences were found in the effects of bacterial lectin and PHA on TNF-α synthesis. Experiments showed that immunostimulatory and immunomodulatory effects of bacterial lectin are more pronounced than those of PHA.

[The material and technical base of fluorographic units of primary health care facilities and its development promises].

The goal of the study was to assess the status of equipment and the staff potential in the fluorography and X-ray units of primary health care facilities and to define priorities and the volume of investments for their modernization. Two hundred and seventy-two health care facilities were studied through the use of questionnaires. The data were processed using standard statistical methods, such as calculation of the mean, median, and 95% confidence intervals. Prognosis was made for the idling period of equipment during stagnation of measures to improve the material and technical base of fluorography units. Priorities for modernizing the material and technical base and the staff potential were defined for the fluorography units of primary health care facilities. The volume of investments required for the modernization was estimated.

[Role of the carbohydrate-binding center of bacterial lectin in the effect on adipocytes under the influence of increased temperature].

The effect of temperature and lectin from bacteria of the genues Azospirillum with blocked activity on human adipose tissue cells has been studied. The temperature used was 43.5 +/- 0.5 degrees C. Comparative results are given for the effect of lectin with the blocked and active carbohydrate-binding centers on adipocytes during heating, and the time course of the structural changes of adipocytes is described. When lectin with the active carbohydrate-binding centers was used for treatment, the heat-treated cells of a healthy obesity-prone subject died on the average in 55 +/- 5 min, whereas cells treated with lectin with the L-fucose-blocked carbohydrate-binding centers died in 80 +/- 5 min. The heat-treated cells of a diabetic obesity-prone patient died in 150 +/- 10 min on average when exposed to both active and inactive lectin. Consequently, when the lectin center is blocked with L-fucose, the effectiveness of lectin action on adipose cells of healthy obesity-prone persons decreases.

[Impact of bacterial lectin on functional activity of lymphocytes].

Impact of Azospirillum brasilense Sp7 lectin with carbohydrate specificity to L-fucose on T- and B-lymphocytes production, activity of IL-1alpha, and TNF-alpha was studied in vitro and compared with influence of red kidney bean phytohemagglutinin (PHA) on the same parameters. Increase of growth of T- and B-cells subpopulations has been shown that point to stimulatory effect of the bacterial lectin. Bacterial lectin of A. brasilense also increased synthesis of IL-1alpha and TNF-alpha. It has been shown that the bacterial lectin has more pronounced stimulatory effect on functional activity of lymphocytes compared with PHA.

In vitro effect of fucose-specific lectins on rat erythrocyte membranes under normal conditions and during toxic stress.

We studied the effect of various fucose-specific lectins on lipid peroxidation in rat erythrocyte membranes under normal conditions and during exposure to the toxic agent. Under normal conditions parameters of lipid peroxidation in erythrocyte membranes increased after treatment with lectins or cadmium nitrate. Lectins possess biological activity modulated lipid peroxidation in membranes of erythrocytes from experimental animals, which depended on the time of adaptation. Differences were revealed in the effect of bacterial and plant lectins on lipid peroxidation in erythrocytes treated with the test xenobiotic.

[Effect of Azospirillum brasilense lectin on the kinetics of lymph nodes cell populations and cytokine status in experimental animals]. / Vliianie lektina Azospirillum brasilense na kinetiku kletochnykh populiatsii mezenterial'nykh limfaticheskikh uzlov i dinamiku tsitokinovogo statusa éksperimental'nykh zhivotnykh.

The complex study of the influence of A. brasilense Sp 7 lectin with carbohydrate specificity to L-fucose and D-galactose on the dynamics of cell populations in different structural functional zones of the white mice mesentery, as well as on the capacity of immunocompetent cells of mesenterial lymph nodes for synthesizing cytokines (interleukin-1, interleukin-6 and tumor necrosis factor), was carried out. A single oral administration of bacterial lectin in a dose of 4.5 micrograms produced a pronounced immunostimulating effect.

[The role of cell surface bacterial lectins in the aggregation of Azospirilla]. / Uchastie bakterial'nykh lektinov kletochnoi poverkhnosti v agregatsii Azospirill.

The mutant strain Azospirillum brasilense Sp7.2.3 with impaired lectin activity exhibited poorer cell aggregation than its parent strain A. brasilense Sp7(S) both in the exponential and stationary growth phases. The pretreatment of bacterial cells with the specific haptens (L-fucose and D-galactose) of a lectin located at the cell surface of the mutant strain was found to inhibit the aggregation of azospirilla. The specific binding of the A. brasilense Sp7(S) lectin to the extracellular polysaccharide-containing complexes of this strain was revealed by dot immunoblotting on nitrocellulose membrane filters. The interaction of the lectins of A. brasilense 75, A. brasilense Sp7, and A. lipoferum 59b with the polysaccharide-containing complexes that were isolated from these strains was not specific. No interstrain cross-interaction between the exopolysaccharides and lectins of azospirilla was found. A coflocculation of A. brasilense Sp7 cells with Bacillus polymyxa 1460 cells was shown. The involvement of autogenous lectins in the aggregation of bacterial cells is discussed.