Voltage-gated ion channel's gene expression in the myocardium of embryo and adult chickens.

The functioning of the cardiovascular system is critical for embryo survival. Cardiac contractions depend on the sequential activation of different classes of voltage-gated ion channels. Understanding the fundamental features of these interactions is important for identifying the mechanisms of pathologies development in the myocardium. However, at present there is no consensus on which ion channels are involved in the formation of automaticity in the early embryonic stages. The aim of this study was to elucidate the expression of genes encoding various types of ion channels that are involved in the generation of electrical activity chicken heart at different stages of ontogenesis. We analyzed the expression of 14 genes from different families of ion channels. It was revealed that the expression profiles of ion channel genes change depending on the stages of ontogenesis. The HCN4, CACNA1D, SCN1A, SCN5A, KCNA1 genes have maximum expression at the tubular heart stage. In adult, a switch occurs to the higher expression of CACNA1C, KCNH6, RYR and SLC8A1 genes. This data correlated with the results obtained by the microelectrode method. It can be assumed that the automaticity of the tubular heart is mainly due to the mechanism of the «membrane-clock¼ (hyperpolarization-activated current (If), Ca2+-current L-type (ICaL), Na+-current (INa) and the slow component of the delayed rectifier K+-current (IKs)). Whereas in adult birds, the mechanism for generating electrical impulses is determined by both « membrane- clock¼ and «Ca2+-clock¼.

Systematic review of comparative transcriptomic studies of cellular resistance to genotoxic stress.

The development of resistance by tumor cells to various types of therapy is a significant problem that decreases the effectiveness of oncology treatments. For more than two decades, comparative transcriptomic studies of tumor cells with different sensitivities to ionizing radiation and chemotherapeutic agents have been conducted in order to identify the causes and mechanisms underlying this phenomenon. However, the results of such studies have little in common and often contradict each other. We have assumed that a systematic analysis of a large number of such studies will provide new knowledge about the mechanisms of development of therapeutic resistance in tumor cells. Our comparison of 123 differentially expressed gene (DEG) lists published in 98 papers suggests a very low degree of consistency between the study results. Grouping the data by type of genotoxic agent and tumor type did not increase the similarity. The most frequently overexpressed genes were found to be those encoding the transport protein ABCB1 and the antiviral defense protein IFITM1. We put forward a hypothesis that the role played by the overexpression of the latter in the development of resistance may be associated not only with the stimulation of proliferation, but also with the limitation of exosomal communication and, as a result, with a decrease in the bystander effect. Among down regulated DEGs, BNIP3 was observed most frequently. The expression of BNIP3, together with BNIP3L, is often suppressed in cells resistant to non-platinum genotoxic chemotherapeutic agents, whereas it is increased in cells resistant to ionizing radiation. These observations are likely to be mediated by the binary effects of these gene products on survival, and regulation of apoptosis and autophagy. The combined data also show that even such obvious mechanisms as inhibition of apoptosis and increase of proliferation are not universal but show multidirectional changes.

Soil microbiota and microarthropod communities in oil contaminated sites in the European Subarctic.

The present comprehensive study aimed to estimate the aftermath of oil contamination and the efficacy of removing the upper level of polluted soil under the conditions of the extreme northern taiga of northeastern European Russia. Soil samples from three sites were studied. Two sites were contaminated with the contents of a nearby sludge collector five years prior to sampling. The highly contaminated upper soil level was removed from one of them. The other was left for self-restoration. A chemical analysis of the soils was conducted, and changes in the composition of the soil zoocoenosis and bacterial and fungal microbiota were investigated. At both contaminated sites, a decrease in the abundance and taxonomic diversity of indicator groups of soil fauna, oribatid mites and collembolans compared to the background site were found. The pioneer eurytopic species Oppiella nova, Proisotoma minima and Xenyllodes armatus formed the basis of the microarthropod populations in the contaminated soil. A complete change in the composition of dominant taxonomic units was observed in the microbiota, both the bacterial and fungal communities. There was an increase in the proportion of representatives of Proteobacteria and Actinobacteria in polluted soils compared to the background community. Hydrocarbon-degrading bacteria-Alcanivorax, Rhodanobacter ginsengisoli, Acidobacterium capsulatum, and Acidocella-and fungi-Amorphotheca resinae abundances greatly increased in oil-contaminated soil. Moreover, among both bacteria and fungi, a sharp increase in the abundance of uncultivated organisms that deserve additional attention as potential oil degraders or organisms with a high resistance to oil contamination were observed. The removal of the upper soil level was partly effective in terms of decreasing the oil product concentration (from approximately 21 to 2.6 g/kg of soil) and preventing a decrease in taxonomic richness but did not prevent alterations in the composition of the microbiota or zoocoenosis.

New Data on the Expansion of Eurytemora Giesbrecht (Copepoda: Calanoida) in the Russian Arctic Region.

As a result of studying different populations of crustaceans of the genus Eurytemora Giesbrecht from the inland water bodies of the basins of the White Sea, the Pechora Sea, the Lena River delta, and Pacific coast of the United States, the species Eurytemora gracilicauda Akatova 1949 has been found along the entire northern border of the Russian Eurasia, while North American E. americana Williams 1906 has not been registered within these limits. Clear morphological and molecular genetic differences between E. gracilicauda and E. americana are presented.

[The level of DNA damage and DNA reparation rate in cells of earthworms sampled from natural populations for numerous generations inhabited territories with anthropogenically enhanced levels of radionuclides in soil].

Low doses of ionizing radiation and chemical toxic agent effects on biological systems on different organization levels have been studied by numerous researchers. But there is a clear lack of experimental data that allow one to reveal molecular and cellular adaptations of plants and animals from natural populations to adverse effects of environmental factors. The present study was aimed to assess genotoxic effects in earthworms Aporrectodea caliginosa Savigny and Lumbricus rubellus Hoffmeister sampled from the populations that during numerous generations inhabited the territories with a technogeneously enhanced content of natural origin radionuclides and heavy metals in soil. The levels ofthe DNA damage detected with alkaline and neutral versions of Comet-assay in invertebrates from contaminated territories were established not to differ from the spontaneous level found in the animals from the reference population. At the same time the rate of the DNA damage reparation induced in A. caliginosa sampled from the contaminated sites with additional acute γ-irradiation (4 Gy) was found to be considerably higher as compared with earthworms from the reference population.

[Adaptive response comparison of CBA mice splenocyte and Drosophila melanogaster larva neuroblast, developed in conditions of chronic gamma-irradiation influence with low-dose rate].

The level of DNA damage and apoptosis of mice splenocytes, developed in condition of chronic gamma-irradiation with low-doze rate (8 +/- 2 cGy), in response to high-dose irradiation (2 Gy) in the completion of irradiation, as well in 30 minutes after irradiation was analysed. Reaction of neuroblasts of Drosophila melanogaster larvae (4 cGy - priming dose, 3 and 6 Gy--challenging doses) is also investigated. The adaptive response by the level of DNA-damage is shown for both objects. This resistance is presumably connected to increase of DNA-damage repair efficiency in preirradiated objects, as well promotion of sensitivity to apoptosis (in the case of Drosophila larvae neuroblast). It is assumed, that observed changes may be result of selection of cell during development in condition of an chronic irradiation.

[The phenomenon of the single-strand DNA breaks level decrease in blood system cells in first generation chronically irradiated mice].

For the first time has been shown experimentally that chronic low dose-rate gamma-radiation (0.04 mGy/hr) exposure leads to decrease of the single-strand DNA breaks level in spleen cells in 2.3 times (p < 0.001) and blood leukocytes in 6.1 times (p < 0.01), a decrease of the apoptotic cells frequency in 1.3 times (p < 0.05) and an increase in the spleen relative mass ratio B 1.2 times (p < 0.001) in CBA mice offspings (F1) from the chronically irradiated parents and exposed to chronic irradiation during the embryonic and postembryonic periods. A hypothesis about the more compact chromatin structure of blood system cells in the individuals of the first generation from chronically irradiated mice is proposed.