Izvestiia Akademii nauk. Seriia biologicheskaia最新文献

The summarized experimental data on ombrophilic bacteria isolated from dystrophic waters formed by a mycobacterial community during the process of spruce wood decomposition are presented. It was demonstrated that the ombrophilic microbial community was characterized by wide phylogenetic diversity at the initial stage of spruce wood decomposition by xylotrophic fungi under low mineralization conditions. It was noted that bacteria were able to grow under acidic and ultrafresh conditions and most of them were referred to oligotrophs. It was determined that all isolated ombrophilic bacteria divided into three groups depending on the substrate specifity: saccharolytic, acidotrophic bacteria, and bacteria, which used C1-compounds as the substrate. The position of the ombrophilic bacteria in the trophic chain was determined.

An ecological scenario of the origin of the plague microbe that is interpreted in the light of modern Darwinism (synthetic theory of evolution) is presented. It is shown that the plague microbe emerged from a clone of the psychrophilic saprozoonotic pseudotuberculosis microbe Yersinia pseudotuberculosis O:1b in the mountain steppe landscapes of Central Asia in the Sartan time, 22000-15000 years ago, in the monohostal Mongolian marmot (Marmota sibirica)-flea (Oropsylla silantiewi) host-parasite system. It was noted that the evolutionary process described corresponds to the sympatric form of speciation by transition ofthe clone of migrant founders to a new, already-existing ecological niche. It was established that monohostal specialization of the plague microbe was made possible due to heterothermia (5-37 degrees C) of marmots in the hibernation period. The factors of the speciation process--isolation, the struggle for existence, and natural selection--were analyzed.

An analysis of the phylogenetic position of the Olkhon mountain vole (Alticolaolchonensis Litvinov 1960) using the sequences of four nuclear (BRCA, GHR, LCAT, and IRBP) and one mitochondrial (cyt. b) genes was undertaken. It was noted that, until recently, multiple studies of the systematic position of this vole had been based exclusively on morphological data, while the major taxonomic traits contained contradictory information regarding both the subgeneric status of this species and its genus. It was established that the molecular data and morphology data allow us to attribute the Lake Baikal vole unambiguously to the nominative subgenus Alticola instead of Aschizomys.

Flora similarity was assessed using complete floristic lists of five ecotopes in each of four mounds along the transect from meadow steppes to desert steppes. It was found that the circumapical similitude of floras is more significant than the expositional similitude. Soil analysis in separate ecotopes showed that regular changes in the biogeochemical features are manifested along the topographic gradient and under the effect of the insolation exposure of slopes in local (mound) ecosystems. It was noted that the slopes are characterized by the most abundant steppe vegetation classes in the phytosociological spectrum of mound ecotopes.

The activity and spectrum of proteinases in the intestines of host fishes change upon infestation with cestodes. Serine proteinases are found to make a greater contribution to the total proteolytic activity. The reduction of proteolytic activity is associated with adsorption of the enzymes of the host on the surface of cestodes, and the increase in the activity is caused by the injury of the intestinal mucosa by the attachment apparatuses of cestodes. The inhibition of proteainase activity indicates the possible participation of microbiota enzymes in protein hydrolyses.

Screening of nodule bacteria (rhizobia) forming symbiotic relationships with legumes has been performed in order to isolate strains resistant to cadmium ions in a wide range of concentrations (6-132 mg/kg). The effect ofcadmium salts (6, 12, 24 mg/kg) on the legume-rhizobium symbiosis ofthe pea Pisum sativum L. with Rhizobium leguminosarum and of the fodder galega Galega orientalis Lam. with Rhizobium galegae has been studied under experimental laboratory conditions. No statistically significant differences have been revealed in the growth and biomass of plants with regard to the control in the range of concentrations given above. However, it was found that cadmium inhibited nodulation in P. sativum and stimulated it in G. orientalis.

The lipid composition and content were analyzed in lettuce Lactica sativa L. (variety Stone head) leaves grown in a weak horizontal permanent magnetic field (PMF) produced by Helmholtz coils of 400 A/m strength under controlled conditions of illumination and temperature in phytothrone. Control plants were grown under the same conditions in a geomagnetic field. PMF decreased the total lipid content by 40% due to a significant decrease in polar and neutral lipids. Among polar lipids, the fractions of glycolipids and phospholipids diminished. Among glycolipids, the content of monogalactosyldiacylglycerols was lower by 25-52%. The content of phospholipids decreased, too, namely phosphatidylglycerols were lower by 17-51%, phosphatidylcholines by 21-24%, phosphatidylethanolamines by 12-20%, and phosphatidylinositols by 12-41%. Therefore, weak PMF reduced the content of lipids in membranes, including the chloroplast, mitochondrial, and cytoplasmic membranes.

A cellular automata computer model for the interactions between two plant species of different growth forms--the lime hairgrass Deschampsia caespitosa (L.) P. Beauv., a sod cereal, and the moneywort Lysimachia nummularia L., a ground creeping perennial herb--is considered. Computer experiments on the self-maintenance of the populations of each species against the background of a gradual increase in the share of randomly eliminated individuals, coexistence of the populations of two species, and the effect of the phytogenous field have been conducted. As has been shown, all the studied factors determine the number of individuals and self-sustainability of the simulated populations by the degree of their impact. The limits of action have been determined for individual factors; within these limits, the specific features in plant reproduction and dispersal provide sustainable coexistence of the simulated populations. It has been demonstrated that the constructed model allows for studying the long-term developmental dynamics of the plants belonging to the selected growth forms.

The content of thyroid and sex steroid hormones is determined in fish-farm juveniles of Black Sea trout 5.5 months old, from the bottom and pelagic spatial groups differing in the probability of future selection of the resident or anadromous life strategies, respectively. Differences in the concentration of the aforementioned hormones are found in young-of-the-year corresponding to those in the migratory and resident forms of yearlings of trout. In the juveniles from the pelagic group at the age 0+, the level of triiodothyronine, thyroxine, and testosterone is higher than in specimens from the bottom group. Prolonged starvation results in a higher content of triiodthyronine, thyroxine, and testosterone in the blood of juveniles from both spatial groups. The concentration of estradiol-17β increases in pelagic specimens and decreases in bottom specimens.

A dynamic mass-balance model has been presented for the biotic energy flux in the ecosystem of the Boguchanskoe Reservoir (Angara River, Irkutsk oblast). It has been revealed that this model is controlled by the small number of input parameters and is intended for prediction of the biomass and annual production of primary producers, reducers, and consumers from various orders, including fish. The model algorithm has been described.