Том 44, № 5 (2017)

The effects of hypoxanthine (HX) at low concentrations on the ability of bovine oocyte to mature to metaphase 2 (M2) and to fertilize in vitro have been studied. It is proved that exogenous HX even at a low concentration, which was introduced into the HX-free and protein-free alpha-MEM medium supplemented with 1 μg/mL follicle-stimulating hormone, can significantly decrease the proportions of both the oocytes the matured to stage M2 and the penetrated and normally fertilized oocytes. It is indicated that the data may be used in order to develop commercial media for in vitro maturation of oocytes of mammalia, including humans.

It was shown that in the conditions of organotrophic growth of colorless sulfur-reducing bacteria Sphaerotilus natans there was only one form of succinate dehydrogenase (SDH) and there were two in the mixotrophic type of nutrition. Three isoforms of SDH from S. natans with different nutrition types were obtained in an electrophoretic homogeneous substance. A quaternary structure of all isoforms was represented by heterotetramer. It was noted that the catalytic and regulatory characteristics of the isoforms involved in the tricarboxylic acid cycle had similar values. The thermodynamic characteristics of the isoforms of SDH and their thermal stability were determined.

Microsatellite primers designed for American and European populations of the white campion and Nottingham catchfly were tested on white campion samples from six Ural populations. It was noted that the loci studied are represented by 2–43 alleles and the average observed heterozygosity varied from 11 to 100%. It was established that 2 of the 14 loci studied can be considered as markers for radiobiological studies.

It was shown that analysis of cellular fatty acids using gas chromatography-mass-spectrometry and application of the gene encoding β-subunit of DNA gyrase (gyrB) as an alternative phylogenetic marker supplemented the taxonomic description of the biotechnologically valuable strain Ochrobactrum sp. IB DT-5.3/2 but were ineffective for species identification of the bacterium. However, based on the results of the matrixassisted laser desorption-ionization time of flight mass spectrometry of the protein fractions and our previous studies of the cultural–morphological and biochemical features, as well as sequencing of the 16S rRNA gene, we can conclude that the strain Ochrobactrum sp. IB DT-5.3/2 refers to the species O. intermedium.

The structure and dynamics of vegetation of the zonal central Russian meadow steppes have been studied with the example of the Privolzhskaya Forest–Steppe State Nature Reserve. Under the influence of a completely protected mode, the vegetation of the studied meadow steppes on the watershed surfaces was subjected to varying degrees and mesophytization and sylvatization. It was noted that these processes occur more intensively in the meadow steppe landscapes of secondary moraine plains (Poperechenskaya steppe and Ostrovtsovskaya forest–steppe) than in the meadow steppes of erosion-denudation plains (Kuncherovskaya forest–steppe).

This study demonstrates that the number of stem cells in mushroom bodies of the ground beetle Pterostichus niger increases already in the first half of embryogenesis and that this timing allows for an intensive increase of the number of neurons that compose the mushroom bodies during the second half of embryonic development. The degree of development of the mushroom bodies in new-born P. niger larvae was shown to be higher than that in new-born larvae of any other holometabolous insect investigated previously.

The functional activity of P-glycoprotein (Pgp) was studied in Chinchilla rabbits after orchiectomy and administration of testosterone undecanoate after surgery. The functional activity of Pgp was determined by the pharmacokinetics of fexofenadine, its marker substrate. In addition, the localization of the transport protein was assessed in the liver, kidney, and jejunum by the immunohistochemistry. It was found that a decrease in the serum testosterone concentration after orchiectomy leads to an increase in Pgp activity on the 14th and 21st days after the surgery, which is accompanied by an increase in the staining intensity of Pgp-positive epithelium membranes of the proximal and distal renal tubules. It was found that the administration of testosterone at a dose of 6 mg/kg body weight in the period after the surgery neutralizes these changes.

The results of laboratory experiments on studying the characteristics of feeding of natural populations of Daphnia galeata from the freshwater Curonian Lagoon on cyanobacteria using the counting and radioisotope methods are discussed. The consumption and assimilation of the cyanobacterium Aphanizomenon flos-aquae by Daphnia have been revealed, as has the inhibition of feeding in Daphnia by species of the genus Microcystis. The results of PCR analysis of the total DNA of plankton from the Curonian Lagoon and enzyme-linked immunosorbent assay have proved the ability of Microcystis populations to produce microcystins, while no genes involved in the synthesis of cyanotoxins have been found in A. flos-aquae.

According to observations from 1987 to 2010 on a constant sampling plot, using spatial statistics, we have shown dynamics of the horizontal structure of all-aged stands of a pristine spruce herb–bilberry forest. We note that the trees forming it provide a continual change of generations and, therefore, random community structure and its spatial stability. We determined that small-leaved arboreal plants, which represent part of the tree stand, tend to grouping at distances from 4 m. It was discovered that the mutual arrangement of trees of different sizes and species do not differ from a random occurrence.