Yersinia pestis Surface Antigens in Reception of Specific Bacteriophages.

The significance of Yersinia pestis surface antigens in adhesiveness to specific bacteriophages has been studied with the use of two methodological approaches. It was shown that Ail protein immobilized on the surface of polystyrene microspheres (but not in the solution), can bind both the Pokrovskaya phage and pseudotuberculous diagnostic phage. YapF autotransporter interacted with both phages in a water-soluble form, but YapF bound to polystyrene microspheres interacted only with the Pokrovskaya phage.

Evaluation of intermolecular forces between lipopolysaccharides and monoclonal antibodies using atomic force microscopy.

Understanding of interactions between a bacterium and an immune or non-immune host organism at the cellular and subcellular level is important in order to improve new and existing immunobiological tools for the treatment of bacterial infections (including pseudotuberculosis). The aim of this work was to quantify the interaction force between Yersinia pseudotuberculosis and monoclonal antibodies (mAbs) in the model system "lipopolysaccharide (LPS) - mAbs" by atomic force microscopy (AFM). Our research findings provided the methodical approaches to force measurements between an AFM probe, which was functionalized with Y.

Force interactions between Yersiniae lipopolysaccharides and monoclonal antibodies: An optical tweezers study.

This article reports the force spectroscopy investigation of interactions between lipopolysaccharides (LPSs) of two species from Yersinia genus and complementary (or heterologous) monoclonal antibodies (mAbs). We have obtained the experimental data by optical trapping on the "sensitized polystyrene microsphere - sensitized glass substrate" model system at its approach - retraction in vertical plane. We detected non-specific interactions in low-amplitude areas on histograms mainly due to physicochemical properties of abiotic surface and specific interactions in complementary pairs "antigen - antibodies" in high-amplitude areas (100-120 pN) on histograms.

Influence of Specific Bacteriophage on the Level of Vesicle Formation and Morphology of Cells of Yersinia pseudotuberculosis.

Incubation of Yersinia pseudotuberculosis cells grown on a solid medium with pseudotuberculous diagnostic bacteriophage for 20 min at 37oC led to a significant decrease in the concentration of both components of the system. This effect was absent when the bacteria were grown in a fluid medium. At the same time, this incubation regimen promoted vesicle formation and typical morphological changes in bacteria grown in both surface and suspension cultures.

Immunochemical Nature of Receptors of Pseudotuberculosis Diagnostic Bacteriophage.

The effect of treatment of Yersinia pseudotuberculosis cells with antibodies of various specificities on adhesiveness of pseudotuberculosis bacteriophage was analyzed by competitive inhibition technique. Bacteriophage adsorption to bacteria was sterically inhibited by monoclonal antibodies to protein epitopes of Y. pseudotuberculosis outer membrane.

[IMMUNOCHEMICAL ACTIVITY OF YERSINIA PSEUDOTUBERCULOSIS B-ANTIGEN].

A hybridoma panel producing monoclonal antibodies to immunochemically non-identical antigenic epitopes of the protein nature located in outer membrane of Yersinia pseudotuberculosis was obtained. It was revealed that the previously identified B-antigen protecting laboratory animals from experimental plague was detected using both monoclonal antibodies against mentioned protein determinants and the determinants of lipopolysaccharide O-side chains. The B-antigen is a component of the Y.

[Study of Yersinia pseudotuberculosis surface antigen epitopes using monoclonal antibodies].

A study of the influence of exogenous factors on the immunochemical activity of the bacterium Yersinia pseudotuberculosis and lipopolysaccharide preparations isolated from bacteria was performed using monoclonal antibodies. It was shown that the hybridomas that were obtained in this work produce antibodies against different and, most likely, species-specific epitopes associated with lipopolysaccharide O side chains. The antibody concentrations produced increased with a decrease in the temperature, at which the bacteria were cultivated.

Human antral follicles: oocyte nucleus and the karyosphere formation (electron microscopic and autoradiographic data).

The functional organization of the nucleus in the oocytes from human antral follicles was examined by morphological and autoradiographic analysis methods at the light and electron microscopic level. According to the position of the nucleus, the level of its transcriptional activity, and the pattern of distribution of structures in it, oocytes fall into two groups. In the first one, the oocytes with the nucleus in the central position are characterized by the distribution of numerous structures all over the nucleus or by a different extent of aggregation of chromatin around the nucleolus.

[Nuclear ultrastructure of the oocytes from human antral follicles. Formation of the karyosphere].

The organization of the nucleus in the oocytes from human antral follicles was examined at the electron microscopic level. At this time all the chromosomes are aggregated around an inactivated nucleolus forming a karyosphere 5-7 micron in diameter. The nucleolus bears no granular component and consists of densely packed delicate fibrillar material.

[Mechanism of Hansenula polymorpha reaction to the pulsed addition of a limiting substrate].

As was shown in experiments with a Hansenula polymorpha culture, a temporary drop in the pH of the medium in response to a pulse addition of a limiting substrate (organic or mineral) is not related to NH4+ uptake from the medium. The response is similar in media with NH4+ and in distilled water without NH4+. The pH drop caused by a pulse addition of certain substrates appears to result from the extrusion of H+ ions in the process of antiport: K+/H+ and Mg2+/H+.

[Methanol dehydrogenase activity of Hansenula polymorpha in chemostat cultivation].

The activity of methanol dehydrogenase in the yeast Hansenula polymorpha was studied in chemostat; it did not depend on the concentration of oxygen within the range of low and high pO2 values, on temperature at 37 and 30 degrees C, or on pH from 4.5 to 5.0.

[Relationship between continuous cultivation conditions and the lipid composition of Hansenual polymorpha].

The effect of temperature, pH, and specific growth rate on the composition of fatty acids and lipid classes was studied in the thermotolerant yeast Hansenula polymorpha grown in the chemostat in a medium with methanol. The fatty acid composition of lipids was found to change depending on the conditions of cultivation: the degree of unsaturation of fatty acids increased when the growth temperature decreased; the proportion of linoleic acid in the lipids increased with the specific growth rate of the yeast and with the pH of the medium. The composition of lipid classes also depended on the cultivation conditions.

[Identification of the limiting component of the medium during microbial continuous cultivation].

The paper presents a method allowing a rapid identification of the growth limiting component of the medium. This is done with respect to the fast change in the low inertial parameter of fermentation (rate of titration or oxygen consumption) in response to an insignificant variation of the concentration of the growth limiting nutrient component in the fermentation medium.

[Induced methanol dehydrogenase in the yeast Hansenula polymorphia DL-1].

The yeast Hansenula polymorpha DL-I showed NAD-specific dehydrogenase activity involved in the methanol primary oxidation. This enzyme was found to be induced during periodic and continuous H. polymorpha cultivation, using methanol as the sole source of carbon and energy.