Vol 46, No 4 (2019)

A theoretical study of population dynamic modes in a biological community including one of the species the abundance of which periodically changes due to causes not related to interspecific interactions in the community was studied. It is shown that these fluctuations may lead to reorganization of the dynamic modes of other community members, which synchronously adapt to the regular change in the abundance of this species. It is noted that asynchronous intrinsic regular and chaotic fluctuations in the abundance of other species may also occur, especially if these species have a high reproductive potential. It is found that the amplitude of fluctuations depends on intrapopulational factors and may significantly exceed the scope of changes in the abundance of the key species.

The opportunity to create a chemically defined system for bovine sperm in vitro capacitation has been performed. 100 µM dibutyryl cyclic adenosine monophosphate (dbcAMP) used as a capacitating agent instead of heparin 10 µg/mL solution was administered in a Tyrode’s protein-free medium for fertilization. In addition, the fertilization medium did not contain glucose or any sperm-activating additives. It has been proven for the first time that spermatozoa capacitated in the in vitro protein-free medium with the use of dbcAMP only are capable of highly efficient in vitro fertilization of the bovine oocytes, which were matured outside the body in a protein-free medium as well. Embryos developed to the 4- to 8-cell stage are chosen as criteria for normal fertilization.

By means of time-lapse imaging, consistent patterns of nuclei movement in GV oocytes of SN and NSN types, differing in the chromatin configuration and the initial position of the nucleus, were established. Two types of movement specific for the GV oocyte nuclei were shown: directed motion from the periphery to the central region of the oocyte and oscillatory displacements in the central or peripheral region of the oocyte. It was noted that the nuclei of the NSN type oocytes with the initial position at the periphery hardly changed their position and oocytes died 3.5–4 h after the filming started.

The long-term effect of the injection of a synthetic analogue of gonadotropin releasing hormone—Surfagon—on the reproductive system of juvenile brown trout Salmo trutta has been studied. The concentration of thyroid hormones in the blood, the rate of gametogenesis, and physiological adaptation of individuals to external conditions increased over five months after injection. The changes identified predetermine the formation of a predominantly resident fish of the brown trout population. Based on the patterns found, the interrelation of the hormonal status, puberty, and the formation of life strategies in salmon species has been analyzed.

A comparative analysis of the variability of morphobiological and genetic characteristics in samples from the largest stocks of Atlantic cod in waters of the Northeast and Northwest Atlantic was conducted. Using the results of pairwise assessment of genetic differentiation for the studied microsatellite loci, it was established that the dataset from waters of the New England shelf differed significantly from Iceland–Greenland and Lofoten–Barents Sea cod stocks. It was noted that samples of cod from the waters of East and West Greenland and cod from the waters of the Norwegian and Barents seas, despite significant geographical separation, showed a high level of identity. Special features of application of the model for isolation by distance to studying the formation mechanisms of the population structure were reviewed.

Wheat is the major cereal crop. It is grown to meet the demand of food in developing countries but salinity is the serious problem in some countries which are based on agriculture. In the present study fourteen transgenic lines expressing phytase gene were selected using PCR and BASTA leaf paint assay. Different morphological and biochemical analysis that include plant growth, number of spikes, length of spikes, chlorophyll, soluble protein, soluble sugar and proline content were carried out from the leaf of the plants under different stress level of salt. Results showed mostly significant reduction in all the morphological parameters and chlorophyll content with increase in salt concentration while on the other hand in all other parameters, most of them showed significant increment. The result showed that some lines have ability to resist salt stress.

Plant and soil mechanisms of barley plant resistance to Cd toxicity as influenced by the plant growth-promoting rhizobacterium P. fluorescens 21 were studied in a series of pot experiments on artificially Cd-contaminated gray forest soil. It has been established that the application of the bacterium improved the growth of plants and eliminated the toxicity of the heavy metal due to enhancing barrier functions of the plant root system and barrier functions of the soil.

The intraspecific relations of two species of the subgenus Sumeriomys have been studied: the social vole Microtus socialis and the paradox vole M. paradoxus. The relationships between animals same-sex individuals in the experimental groups, are generally amicable, but the cohabitation of two or more females suppresses reproduction. Groups formed from unfamiliar individuals were characterized by increased aggressiveness, which led to high mortality. The paradox vole was diffed from social vole by higher motor and social activity and greater aggressiveness towards unfamiliar individuals. The vocal behavior of individuals of both species is similar. 30% of contacts between individuals are accompanied by squeaks; males sing in intersex interactions, but this behavior is rare (less than 1% of contacts).

Studies of phyto- and zooplankton were performed in summer 2002 and 2016 in the mountain Shebety Lake (Zabaikalskii krai, Russia). According to the hydrochemical composition, the lake waters belong to the hydrocarbonate–calcium type with a total mineralization of 30 mg/L. The littoral plankton biocenosis is characterized by higher species diversity and quantitative parameters in comparison with the pelagic plankton biocenosis. According to the principal component analysis, the hydrochemical composition of lake waters (pH, nutrient, and organic matter concentrations) is the main abiotic factor influencing the structural organization of the plankton community in the pelagic zone; in the littoral zone, these factors are the chemical features of the waters (pH, nutrient content, and cationic composition) and hydrophysical parameters (depth and water temperature). It was found that a combination of abiotic and biotic factors causes a different qualitative distribution of aquatic organisms in different zones of the lake. In the coastal zone, there is a great integration of the community; in the pelagic zone, the community exhibits a multicomponent nature.