Microbial Population of the Digestive Tract of Click Beetle Larvae (Elateridae, Coleoptera).

The composition and functional structure of the intestinal microflora of three wireworm species (Agriotes obscurus (L.), Selatosomus aeneus (L.), and Ampedus pomorum (Herbst)) with different dietary regimes were studied. The total abundance of the microorganisms was evaluated by fluorescent microscopy, the group composition was assessed by inoculation on a solid glucose-peptone-yeast medium, and the functional diversity was estimated by multisubstrate testing. It was noted that, in the intestine of the larvae, the total number of microorganisms was lower by 1-2 orders of magnitude than in the soil and decaying wood. It was found that the composition of the intestinal microbial communities of wireworms was radically different from that of the substrate: the Bray-Curtis coefficient did not exceed 0.25. It was found that native forms accounted for more than half of the total number of saprotrophic bacteria: in the larvae, gram-positive cocci, enterobacteria, Vibrionaceae, Acinetobacter, and some genera of coryneform bacteria, which were absent in the soil and wood, prevailed. The micromycetes were either absent (Agriotes) or were found in insignificant quantities (Selatosomus, Ampedus). In Selatosomus, apart from the intestinal forms, representatives of Mezorhizobium, No- cardioides, and Erwinia, occurring on plant substrates, were observed.

Functional Diversity of Ant-Associated Bacterial Communities.

It was found that ants significantly affect the physiological activity and functional diversity of soil microbial communities, and redistribution of biophilic elements (C and N) down through the profile occurs in anthills compared to the control soil, as well as their accumulation in the underground part of the ant nests. A high urease activity was revealed in ant nests and ants. Functional dissimilarities of bacterial communities in all studied objects were determined by the miultisubstrate test.

Distribution of polycyclic aromatic hydrocarbons in surface sediments of lower reaches of the Don River (Russia) and their ecotoxicologic assessment by bacterial lux-biosensors.

The lower Don River in the south of the European part of Russia was studied to determine the concentration, spatial distribution, and sources of 19 polycyclic aromatic hydrocarbons (PAHs) in surface sediments. Total PAH concentrations ranged from 14.2 to 529 ng/g-dw. Sedimentary PAH concentrations were higher in the delta of the Don River and in the estuaries of rivers Sal and Aksai compared to the main channel of the Don. Analysis of the PAHs sources showed that PAHs came mostly from pyrogenic sources as a result of incomplete combustion of coal. Bioluminescent bacterial sensors were used for ecotoxicological assessment of surface sediments. The surface sediments of all the investigated stations of lower reaches of the Don River were toxic and genotoxic. The maximum concentration of PAHs and the high genotoxicity effect caused by the presence of genotoxicants were found in the surface sediments of the same stations. Significant correlations between the concentrations of individual PAHs in sediments and the genotoxic effect were found. Correlation between genotoxicity of surface sediments and concentration of phenanthrene and benz(k)fluoranthene was the most significant both with and without application of metabolic activation.

[Effects of the Vital Activity of Soil Insect Larvae on Microbial Processes in the Soil].

The effects of Elateridae larvae (wireworms) on the structure, functional diversity, and tolerance of the soil microbial population in steppe ecosystems have been investigated. The trophic and locomotor activity of wireworms leads to an appreciable increase in bacterial abundance and suppression of fungal activity. The fungal hyphae in the presence of wireworms are significantly damaged, which can be related to the feeding activity of Elateridae. The increase of bacterial abundance on the background of exclusion of the fungal component shifts the microbial succession to the acceleration of organic matter mineralization. The microbial consumption of mono- and oligosaccharides, alcohols, and water-soluble compounds increases in the presence of wireworms (multisubstrate test). The effect of Elateridae larvae on the microorganisms transforming nitrogen compounds is species-specific. Agriotes obscurus activity decreases their consumption of urea and creatinine by 2.1-2.5 times, and Selatosomus aeneus increases it by 1.3 and 2.5 times, respectively. The intensity of actual nitrogen fixation in the soil increases in the presence of wireworms by almost 4 times, but the losses of gaseous nitrogen do not increase because of the decrease in both the denitrification and methanogenesis rates

[Taste perception during clinical symptom complex of gastroesophageal reflux disease].

Taste perception is an important criterion for the state of the oral mucous membrane in patients with gastroesophageal reflux disease. The tongue, as an organ of taste, is characterized by serious changes in the functional state after injury with acid-containing substrates due to reflux. The specific features of taste perception and possibility for their correction were studied in 75 patients with this disorder. The type of changes in activity of tongue taste receptors and taste thresholds in patients before and after therapy were estimated by means of advanced gustometry and functional mobility technique. Specific changes in sensory function of the oral cavity were shown to be associated with acid aggression. Our results illustrate the possibility of taste correction in patients with gastroesophageal reflux disease. Taking into account some features of the general disease, it can be concluded that the introduction of Parodontax-F toothpaste and Emalan into combined therapy is accompanied by the improvement of taste perception. Correction of dysgeusia is an important criterion for the improvement of the quality of life of patients.

[Biological activity of soils in the settlements of southern (Microtus rossiaemeridionalis) and bank (Clethrionomys glareolus) voles].

The effect of southern (Microtus rossiaemeridionalis) and bank (Clethrionomys glareolus) voles on the biological activity of soddy-podzolic soil and culturozem has been studied. To estimate this effect, the activity of nitrogen and carbon transformation in the soil taken from the paths and different chambers of the holes of these rodents, as well as from the control plots where there were no voles, has been determined. The contents of organic carbon and nitrogen in the soil have been found. The parameters of functional diversity of the microbial community of soil have been studied. It has been noted that the effect of voles on the biological activity of the above soils manifested itself in increased intensity of aerobic and anaerobic destruction of organic matter and changes in the parameters of functional diversity of the microbial community of soils.

[Functional features of microbial communities in the digestive tract of field voles (Microtus rossiaemeridionalis and clethrionomys glareolus)].

The nitrogen-fixating and cellobiohydrolase activity, the nitrogen (N) and carbon (C) contents, and the number of microorganisms in the prestomach, cecum, and colon of two vole species were studied: the southern vole (Microtus rossiaemeridionalis) and the bank vole (Clethrionomys glareolus), which is characterized by a mixed type of diet. The nitrogen-fixating activity in the cecum was found to be the highest in the voles compared with the mammals studied earlier. The seasonal dynamics of both nitrogenase and cellobiohydrolase activities was registered in the southern vole. The structure of the microbial complex in the southern vole is more varied and includes microorganisms associated with plant substrates.

[Microbial nitrogen fixation in the gastro-intestinal tract of Kalmykia gerbils (Meriones. tamariscinus and Meriones meridianus)].

The nitrogen-fixing activity, nitrogen (N) and carbon (C) contents, and the number of microorganisms in the forestomach, cecum, and segmented intestine were detected in two gerbil species, granivorous Meriones meridianus and M. tamariscinus, which consume a large amount of green parts of the plants. M. meridianus had higher levels of nitrogen-fixation activity in all investigated parts of the gastro-intestinal tract compared with M. tamariscinus. The highest levels were detected in the colon of M. meridianus. The C/N ratios in the forestomach of M. tamariscinus were higher than in M. meridianus, which is consistent with the greater role of the green parts of plants in its diet. A gradual increase in the nitrogen content from the forestomach to the colon of M. tamariscinus was noted. The amount of microorganisms in the forestomach and intestine of the studied gerbil species was similar.

[Assimilation of biological nitrogen by European beaver].

Nitrogenase activity, the abundance of diazotrophic bacteria, the structure and functional characteristics of the complex of microorganisms, and the content of nitrogen and carbon were determined in the contents of the gastrointestinal tract of the European beaver. A high nitrogen-fixing activity in the large intestine correlated with an increase in nitrogen content in the chyme upon its transfer over the gastrointestinal tract. It is assumed that microbial nitrogen fixation plays a major role in nitrogen nutrition of the European beaver.

[Specific features of nitrogen fixation in the termite Reticulitermes lucifugus].

Nitrogenase activity, abundance of diazotrophic bacteria, and structural and functional parameters have been determined in microbial complexes of three populations of the termite Reticulitermes lucifugus and their nest materials. These data have been used for comparative analysis of nitrogen-fixing micioorganism communities in termite guts and in nest materials from different termite populations. Similarities in the structure and other parameters of these communities have been revealed. The taxonomic composition of microbial communities differs among the populations, but the functional properties of these communities are almost identical. It is concluded that no symbiotic (mutualistic) relationship exists between nitrogen-fixing intestinal bacteria and their host termites.

[Soil biological activity in the Chernye Zemli, Kalmykia, inhabited by gerbils Meriones tamariscinus and M. meridianus].

The influence of tamarisk (Meriones tamariscinus) and midday (M. meridianus) gerbils on soil biological activity in the Chernye Zemli, Kalmykia, was studied. Nitrogen fixation, denitrification, and CO2 emission were measured in soil samples from different parts of gerbil burrows. Functional biodiversity of the microbial community was evaluated using multisubstrate testing and comparison of bacterial group composition in samples from gerbil burrows. The impact of gerbils on soil biological activity was mediated by the changes in the group composition of microorganisms.

[Diazotrophs in the digestive tract of termite Neotermes castaneus].

Normal vital activity of termites Neotermes castaneus requires the presence and continuous replenishment of transient nitrogen-fixing bacteria in their digestive tract, which is realized by coprophagy and repeated utilization of substrate enriched in termite feces. This is the first demonstration of significant changes in the complex of aerobic and facultatively anaerobic nitrogen fixers mediated by an extension of microbial group composition and a shift in dominant taxa in termites that cannot reutilize their feces.

[Spin label study of the structure and conformational properties of fibers from cotton grown from gamma-irradiated seeds]. / Issledovanie metodom spinovykh metok struktury i konformatsionnykh svoistv volokna khlopka, vyrashchennogo iz gamma-obluchennykh semian

According to ESR spectra of the radical - probe I it has been shown that there are two regions in cotton cellulose: ordered and disordered ones, pointing to inhibition and free rotation of the radical. 40 spin-labeled samples of cotton filaments and their mutants by the radicals II-IX chemically bound by the cellulose hydroxyl group were obtained. From ESR spectra strong inhibition of iminoxyl radical was established which was the evidenced of high rigidity of disordered regions of cellulose. Conformational changes of cotton cellulose grown from seeds exposed to different doses of gamma-irradiation.

[Nitrogen fixation--new fenomenon in rodent feeding]. / Azotofiksatsiia--novyi fenomen v pitanii gryzunov.

We have conducted a series of experiments in order to test hypothesis about the possible use of nitrogen fixation by small phytophagous mammals as a way to supplement their nitrogen balance. Two groups of red voles Clethrionomys rutilis were kept on rations with different protein nitrogen content. Three days later, the rate of nitrogen fixation was determined in different regions of the digestive tract. Nitrogen-fixing activity has been detected in the GI tract of all studied voles, specifically in those regions, where symbiocenoses were present; it was particularly high in animals of the experimental group under the conditions of dietary nitrogen limitation. A mixed culture of bacteria capable of nitrogen fixation has been isolated from the digestive tract of red voles.

[Specific features of nitrogen transformation in the soddy-podzolic soil in the areas of habitat of the common vole Microtus arvalis]. / Osobennosti transformatsii azota v dernovo-podzolistoi pochve na uchastkakh, zaselennykh obyknovennoi polevkoi Microtus arvalis.

The influence of common vole Microtus arvalis on processes of nitrogen fixation and denitrification in the soddy-podsolic soil was studied. In the common vole colonies, the level of nitrogen fixation was reliably lower and that of denitrification higher, than in the control soil outside these colonies. Nitrogen-containing excretory products of voles accumulating in the soil are among the main factors that determine the activity of these processes.

[Characteristics of nitrogen fixation and denitrification in Termites Neotermes castaneus, Zootermopsis angusticollis, and Reticulitermes lucifugus]. / Osobennosti azotofiksatsii i denitrifikatsii u termitov Neotermes castaneus, Zootermopsis angusticollis i Reticulitermes lucifugus.

We studied specific features of microbial nitrogen fixation and denitrification in laboratory cultures of the termites Neotermes castaneus, Zootermopsis angusticollis, and Reticulitermes lucifugus, as well as in their nest materials. The nitrogenase activity in the termites was much higher than in the materials of termitarium. Denitrification was found only in the nest materials of termitarium. Studies of the bacterial community of gut nitrogen fixers Neotermes castaneus have shown the predominance of anaerobic and facultatively anaerobic bacteria that amount to up to 60% of the total number of "gut" bacteria. In the materials of termitarium, aerobic cellulose-destroying myxobacteria predominated, which are typical inhabitants of plant substrates, a food for the termite.

[Effect of deficiency of dietary nitrogen on cellulose digestibility and nitrogen-fixing flora activity in the sibling vole Microtus rossiaemeridionalis]. / Vliianie defitsita dietarnogo azota na perevarimost' tselliulozy i aktivnost' azotfiksoruiushchei microflory u vostochnoevropeiskikh polevok Microtus rossiameridianalis.

The effect of food composition on nitrogen-fixing activity of the symbionts living in the digestive tract of the sibling vole Microtus rossiaemeridionalis was experimentally studied. In the control, the rodents were allowed to select any of three food mixes: protein-rich, protein-free with low cellulose content, and protein-free with high cellulose content. The voles consumed the food in a proportion corresponding to 16% of protein and about 6% of cellulose. Exclusion of the protein-rich food considerably increased cellulose consumption (up to 12%) and digestibility (from 35 to 64%). The changes in the consumed food composition were reflected in localization of nitrogenase activity in the digestive tract: the control level of nitrogen-fixing activity in the cecum was three times that in the proventriculus, while an inverse proportion was observed in the experimental groups. In all cases, the colon was the major locus of nitrogen fixation.