Ex vivo EPR investigation of metabolic changes in mice treated with radiotoxins

The effect of radiotoxins (RT), obtained from gamma-irradiated potato tubers, on mice have been investigated using ex vivo EPR. Parts of liver, lung, spleen, heart and kidney were used for investigation. The amount of the preparations injected was 0.2 ml, RT concentration varying from 0.1 to 1 LD100 (LD100 = 100 mg/kg). An intraperitoneal injection of RT in dose of 0.1 LD100 resulted in metabolic changes only in spleen. During 8 hours after injection a gradual depression of enzyme ribonucleotide reductase activity in spleen has been observed. After the treatment of mice with a lethal dose of RT signals from nitrosyl complexes have been appeared in spectra from all tissue investigated. The intensities of lines depend both on a time passed after treatment and a sensitivity of tissue to RT action. One of the main reasons of the lethal outcome of mice treated with RT may be the breaking of the compensatory adaptive response due to enhanced hypoxic state resulting from the high concentration of nitrosyl complexes generated in the tissue.     

Stability of the beta-sheet of the WW domain: A molecular dynamics simulation study.

The WW domain consists of approximately 40 residues, has no disulfide bridges, and forms a three-stranded antiparallel beta-sheet that is monomeric in solution. It thus provides a model system for studying beta-sheet stability in native proteins. We performed molecular dynamics simulations of two WW domains, YAP65 and FBP28, with very different stability characteristics, in order to explore the initial unfolding of the beta-sheet. The less stable YAP domain is much more sensitive to simulation conditions than the FBP domain. Under standard simulation conditions in water (with or without charge-balancing counterions) at 300 K, the beta-sheet of the YAP WW domain disintegrated at early stages of the simulations. Disintegration commenced with the breakage of a hydrogen bond between the second and third strands of the beta-sheet due to an anticorrelated transition of the Tyr-28 psi and Phe-29 phi angles. Electrostatic interactions play a role in this event, and the YAP WW domain structure is more stable when simulated with a complete explicit model of the surrounding ionic strength. Other factors affecting stability of the beta-sheet are side-chain packing, the conformational entropy of the flexible chain termini, and the binding of cognate peptide.     

Biologically Active Oligosaccharides from Pectins of Pisum sativum L. Seedlings Affecting Root Generation

Two physiologically active oligosaccharide fractions were isolated from pectin of Pisum sativum L. cell wall after its partial acid hydrolysis. These fractions displayed stimulating and inhibiting effects on root formation in thin-layer explants. The subsequent separation of these fractions by gel permeation and anion-exchange chromatography resulted in fractions with effective concentrations two orders of magnitude lower than the concentrations of the initial fractions. The resulting oligosaccharides displayed their effect on the earliest stage of the rhizogenesis associated with formation of root primordias. The rhizogenesis-inhibiting fraction suppressed cell division by 30-50%. The stimulating fraction mainly contained fragments of xyloglucan and galactan, and the inhibiting fraction contained fragments of xyloglucan, galactan, and arabinan. The polymerization degrees of the stimulating and of the inhibiting oligosaccharides were 10-11 and 5-6, respectively.     

Effect of selenium-containing biocomposites based on <Emphasis Type="Italic">Ganoderma</Emphasis> mushroom isolates grown in the presence of oxopropyl-4-hydroxycoumarins,on bacterial phytopathogens

Effect of selenium-containing biocomposites obtained from submerged cultures of macrobasidiomycetes Ganoderma applantum, G. cattienensis, G. colossus G. lucidum, G. neojaponicum, and G. valesiacum, on plant pathogenic bacteria Clavibacter michiganensis ssp. sepedonicus (Cms), Micrococcus luteus, Pectobacterium atrosepticum, Pectobacterium carotovorum subsp. carotovorum, Pseudomonas fluorescens, Pseudomonas viridiflava, and Xanthomonas campestris was studied. Oxopropyl-4-hydroxychromenones were used as components of the fungal nutrient media. The bacteriostatic and bactericidal activity of the Se-containing and Se-free substances of fungal origin against plant pathogenic bacteria was determined using colony-forming units count, the agar well diffusion method, and by turbidity measurements of bacterial suspensions. The composites produced from the extracellular metabolites of G. cattienensis SIE1302 with 4-hydroxy-3-(3-oxo-1,3-diphenyl propyl)-chromen-2-one (S(45)), and of G. lucidum SIE1303 with 4-hydroxy-3-(3-oxo-1-(3-nitrophenyl)-3-phenylpropyl)-chromen-2-one (S(NO₂)) possessed the most pronounced antibacterial action against Cms. The composites produced from the isolates of G. valesiacum 120702 with S(NO₂) showed the maximal antibacterial activity against Xanthomonas campestris B-610. High antimicrobial effect of G. lucidum 1315 with S(NO₂) against Xanthomonas campestris B-610 and of G. colossus SIE1301 against Pseudomonas fluorescens EL-2.1 was revealed. The pioneering information on the biological activity of coumarin series compounds in their application for producing the substances of fungal origin was obtained.     

Reconstruction of the history of a thermokarst lake in the Mid-Holocene based on an analysis of subfossil Cladocera (Siberia,Central Yakutia)

This paper presents the results of a cladoceran analysis of a sediment core with a lenght of 382 cm collected from a pingo in alas Khara Bulgunnyakh located in Central Yakutia. Based on the Cladocera analysis results, the formation of the lake had started during the Holocene climatic optimum ~6600 cal. yrs. BP. The analysis of changes in the species composition of subfossil cladoceran communities made it possible to identify, on the basis of cluster analysis, four statistically significant ecological zones. The period of optimal conditions for the Cladocera community is defined by a complex evened community structure and numerous cladoceran remains in the sediments accumulated between 6500 and 6000 cal. yrs. BP. The history of the thermokarst water body development and existence reconstructed on the basis of the subfossil cladoceran analysis was rapid and short.     

Transient permeability induced by alkyl derivatives of amphotericin B in lipid membranes

Individual ionic channels were shown to be formed in the brain cholesterol containing phospholipid membranes by two-sided addition of the amphotericin B alkyl derivatives. At concentrations between 10⁻⁸ and 10⁻⁷ M, the resulting conductance appeared to be transient. Existence of different antibiotic assemblies was justified by the kinetic analysis of the membrane conductance decline following the antibiotic washing out. In order to account for the transient characteristics of the induced conductance, it was proposed that the antibiotic oligomers incorporate into the membrane from the aqueous phase, form channels aggregating with cholesterol, and then dissociate in the bilayer into non-active degraded oligomeric or monomeric forms.     

Aspen Tension Wood Fibers Contain β-(1→4)-Galactans and Acidic Arabinogalactans Retained by Cellulose Microfibrils in Gelatinous Walls

Contractile cell walls are found in various plant organs and tissues such as tendrils, contractile roots, and tension wood. The tension-generating mechanism is not known but is thought to involve special cell wall architecture. We previously postulated that tension could result from the entrapment of certain matrix polymers within cellulose microfibrils. As reported here, this hypothesis was corroborated by sequential extraction and analysis of cell wall polymers that are retained by cellulose microfibrils in tension wood and normal wood of hybrid aspen (Populus tremula × Populus tremuloides). β-(1→4)-Galactan and type II arabinogalactan were the main large matrix polymers retained by cellulose microfibrils that were specifically found in tension wood. Xyloglucan was detected mostly in oligomeric form in the alkali-labile fraction and was enriched in tension wood. β-(1→4)-Galactan and rhamnogalacturonan I backbone epitopes were localized in the gelatinous cell wall layer. Type II arabinogalactans retained by cellulose microfibrils had a higher content of (methyl)glucuronic acid and galactose in tension wood than in normal wood. Thus, β-(1→4)-galactan and a specialized form of type II arabinogalactan are trapped by cellulose microfibrils specifically in tension wood and, thus, are the main candidate polymers for the generation of tensional stresses by the entrapment mechanism. We also found high β-galactosidase activity accompanying tension wood differentiation and propose a testable hypothesis that such activity might regulate galactan entrapment and, thus, mechanical properties of cell walls in tension wood.Contractile cell walls found in plant organs and tissues such as tendrils, contractile roots, and tension wood (TW) have remarkable functions and properties. Their traits have been most intensely studied in TW of hardwoods, where they provide negative gravitropic response capacities to stems with secondary growth, as recently reviewed by Mellerowicz and Gorshkova (2012). These properties are conferred by TW fibers, which in many species contain a so-called gelatinous cell wall layer (G-layer; Norberg and Meier, 1966; Clair et al., 2008). G-layers are formed following the deposition of xylan-type secondary cell wall layer(s) and, thus, can be considered tertiary layers (Wardrop and Dadswell, 1948). They are almost or completely devoid of xylan and lignin and have very high cellulose contents (up to 85%). However, several other polymers appear to be present in TW G-layers, according to recent chemical analyses of isolated G-layers (Nishikubo et al., 2007; Kaku et al., 2009) and immunohistochemical labeling of TW sections (Arend, 2008; Bowling and Vaughn, 2008). Notably, xyloglucan (XG) has been found in G-layers of poplar (Populus spp.) TW (Nishikubo et al., 2007) and at the boundary between secondary cell wall layers (S-layers) and G-layers (Baba et al., 2009; Sandquist et al., 2010). It is also important for tension creation (Baba et al., 2009). However, it is not detectable in mature G-layers by monoclonal antibodies or XG-binding modules (Nishikubo et al., 2007; Baba et al., 2009; Sandquist et al., 2010).Structurally similar G-layers have been also identified in phloem fibers in many fibrous crops, such as flax (Linum usitatissimum), hemp (Cannabis sativa), and ramie (Boehmeria nivea; Gorshkova et al., 2012). These fibers occur in bundles that can be isolated for biochemical analysis. G-layers in fibers from diverse sources have a very similar structure, being largely composed of cellulose (with axial microfibril orientation, high degrees of crystallinity, and large crystallite sizes) lacking xylan and lignin (Mellerowicz et al., 2001; Pilate et al., 2004; Gorshkova et al., 2010, 2012) and having high water contents (Schreiber et al., 2010). In phloem fibers, the G-layers become very prominent, reaching thicknesses up to 15 µm and occupying over 90% of the cell wall’s total cross-sectional areas (Crônier et al., 2005). Pectic β-(1→4)-galactan with complex structures has been shown to be the major matrix polysaccharide of isolated phloem fibers in flax (Gorshkova et al., 2004; Gorshkova and Morvan, 2006; Gurjanov et al., 2007). Some of it is so strongly retained within cellulose that it cannot be extracted by concentrated alkali and can only be obtained after cellulose dissolution (Gurjanov et al., 2008). Such galactan, therefore, is a prime candidate for a polymer entrapped by cellulose microfibrils during crystallization that could substantially contribute to the contractile properties of cellulose in G-layers, according to recently formulated models (Mellerowicz et al., 2008; Mellerowicz and Gorshkova 2012). Furthermore, Roach et al. (2011) have shown that trimming of β-(1→4)-galactan by β-galactosidase is important for final cellulose crystallization, the formation of G-layer structure, and, hence, the stem’s mechanical properties.There is also immunocytochemical evidence for the presence of β-(1→4)-galactan and type II arabinogalactan (AG-II) in G-layers of TW fibers (Arend, 2008; Bowling and Vaughn, 2008). In addition, high-M_r branched galactans have been isolated from TW of Fagus sylvestris (Meier, 1962) and Fagus grandifolia (Kuo and Timell, 1969), with estimated degrees of polymerization (DP) of approximately 300 and complex structure, probably including both β-(1→4) and β-(1→6) linkages, although their exact nature remains unknown. Furthermore, Gal has been identified as one of the major sugars after Glc and Xyl in hydrolysates of isolated Populus spp. G-layers (Furuya et al., 1970; Nishikubo et al., 2007), and the Gal content of cell walls is a proposed indicator of the extent of TW development in beech (Fagus spp.; Ruel and Barnoud, 1978). However, subsequent linkage analyses identified only 2- and 3,6-linked Gal in poplar TW G-layers (Nishikubo et al., 2007), while in flax fibers, 4-linked Gal is the main component (Gorshkova et al., 1996, 2004; Gurjanov et al., 2007, 2008). Thus, the type(s) of galactans present in poplar TW remains unclear, and the galactans have not been shown previously either to have a rhamnogalacturonan-I (RG-I) backbone or to be strongly retained by cellulose microfibrils, as demonstrated for flax gelatinous fibers.To improve our understanding of cell wall properties in TW and their contraction mechanism, in the study presented here, we tested aspects of the recently proposed entrapment model (Mellerowicz et al., 2008; Mellerowicz and Gorshkova, 2012). According to this model, contraction is driven by the formation of larger cellulose structures, sometimes called macrofibrils, via interactions of cellulose microfibrils in the G-layer with each other and forming inclusions containing matrix polymers. This would induce tension within cellulose through the stretching of microfibrils required to surround the inclusions. The model is compatible with available data on the structure and action of gelatinous walls, but the main assumption, that polymers are trapped inside crystalline cellulose, such as that found in flax, has not been tested previously. Therefore, we compared matrix polymers retained by cellulose microfibrils in normal wood (NW) and TW of the model hardwood species hybrid aspen (Populus tremula × Populus tremuloides) that forms TW with gelatinous fibers. For this purpose, we used a combination of sequential cell wall extractions, similar to those used previously to characterize flax gelatinous fibers (Gurjanov et al., 2008), followed by fractionation of polymers by size-exclusion chromatography, immunological analyses, and oligosaccharide profiling by polysaccharide analysis using carbohydrate gel electrophoresis (PACE). The results reveal the main polymers of cellulose-retained fractions and key differences between NW and TW. Comparison of our results and previous findings also indicates that there are both similarities and differences in the constitution of gelatinous fibers in aspen and flax. An updated model of the contractile G-layer of TW fibers based on the data is presented.     

Biophysical and medical and biological aspects of use of polyene antibiotics in combination with dimethylsulfoxide

Modern conceptions of the physicochemical properties of dimethylsulfoxide and polyene antibiotics are reviewed. The results of investigations of independent and mutual effects of polyene antibiotics and dimethylsulfoxide on membrane permeability were analysed. The own experimental data of radioprotective and antitumour action of complex dimethylsulfoxide-polyene antibiotics are presented, and the perspectives of their use in medicine are described.     

Coenzyme Q10-containing composition (Immugen) protects against occupational and environmental stress in workers of the gas and oil industry

The manual workers of the gas-and-oil extraction industry are exposed to hostile environmental and occupational conditions, resulting in elevated mortality and disability, due to chronic neurological and cardiovascular diseases. We evaluated the degree of oxidative stress, often associated with these pathological features, in the blood of manual and office employees of Russian Siberian extraction plants, and their psycho-physiological conditions. Results showed increased levels of spontaneous (p < 0.05) and PMA-activated (p < 0.01) luminol-dependent chemiluminescence (LDCL) in the white blood cells (WBC), and decreased peroxynitrite levels (p < 0.05) in the group of manual workers, and less markedly in the clerks and technicians working on spot, vs. a control group of city clerks. Superoxide release by WBC, and plasma/WBC membrane ubiquinol levels did not display major differences in the three groups. A relevant percentage of manual/office workers of extraction platforms presented impaired cardiovascular and neurological functions. The short term administration of a nutraceutical formulation based on coenzyme10, vitamin E, selenium, methionine and phospholipids led to significant improvement of cardiovascular parameters and psycho-emotional status, consistent with the normalization of LDCL and peroxynitrite production by WBC, with a good compliance to treatment confirmed by the increased blood levels of ubiquinol.