Antibiotic resistance is a global problem of modern medicine. A harbinger of the onset of the post-antibiotic era is the complexity and high cost of developing new antibiotics, as well as their inefficiency due to the rapidly developing resistance of bacteria. The cornerstone of bacterial protection against antibiotics are multidrug resistance pumps (MDR), which are involved in the formation of resistance to xenobiotics, the export of toxins, the maintenance of cellular homeostasis, the formation of biofilms and persistent cells. MDR pumps are the basis for the nonspecific protection of bacteria, while modification of the drug target, inactivation of the drug, switching of the target or sequestration of the target is the second, specific line of their protection. Thus, the nonspecific protection of bacteria formed by MDR pumps is a barrier that prevents the penetration of antibacterial substances into the cell, which is the main factor determining the resistance of bacteria. Understanding the mechanisms of MDR pumps and a balanced assessment of their contribution to overall resistance, as well as to antibiotic sensitivity, will either seriously delay the onset of the post-antibiotic era, or prevent its onset in the foreseeable future.

Non-random mating plays a key role in speciation and impacts the individual life history. Body size is one of the most important traits by which the mate choice is carried out. Various patterns of body size preference are known in fish, but this component of reproductive strategy has been studied in a limited number of species. Although the climbing perch (Anabas testudineus) is widespread and well-known, few descriptions of its spawning have been published, only in captivity and in most cases artificially induced with hormonal agents. This paper describes the main features of natural spawning of the climbing perch in aquarium compared to induced spawning. A positive size-assortative mating has been revealed. The mating system of these fish has been shown to be flexible, presumably ranging from monogamy to polygamy. The results are discussed in the context of the general issue of the adequacy of fish behaviour research methods.

The study of the functioning of various body systems in different vertebrates is one of the key tasks of comparative physiology. Teleost fish are a large group of vertebrates, however, the mechanisms of functioning of their digestive tract have been studied little and mainly only for such a model object as Danio rerio. The aim of this work was to characterize the participation of various subtypes of M-cholinergic receptors and the enzyme Rho-kinase in the cholinergic contraction of the intestinal smooth muscles of the White Sea cod Gadus morhua marisalbi (Gadidae). A longitudinal strip was excised from the proximal cod intestine and placed in an apparatus for recording contractile responses in the isometric mode. Contractile responses to acetylcholine were completely blocked by atropine. Blockade of M3 cholinergic receptors with 4-DAMP resulted in a decrease in acetylcholine-induced contraction compared with the control response. Blockade of M1 receptors with pirenzepine led to a weakening of contraction, less pronounced than with blockade of M3 cholinergic receptors. Blockade of M2-cholinergic receptors with methoctramine did not affect the magnitude of the contractile response. Incubation of preparations with the Rho-kinase inhibitor fasudil was accompanied by a significant decrease in contractile responses compared with the control, as well as a faster decrease in the contraction force after reaching the “peak” of the reaction. Thus, acetylcholine causes contraction of cod intestinal smooth muscle by activating M3- and M1- but not M2-cholinergic receptors. The activity of the Rho-kinase enzyme contributes to the development and maintenance of cod intestinal smooth muscle contraction under the action of acetylcholine. The results obtained are of interest for comparative physiology, may be important for understanding the mechanisms of the damaging effect of environmental factors on the bony fish’ body, as well as for the use of fish as objects of preclinical studies of drugs.

Previous studies revealed the inhibitory effect of single-stranded breaks in a non-template DNA strand (NT-SSB) on RNA polymerase transcription through the nucleosome. The observed effect was explained within the model of chromatin transcription mechanism with the formation of intranucleosomal DNA loops (i-loops) – intermediates in which the enzyme is locked in the DNA loop on the histone octamer. According to the model, NT-SSBs reduce the tension in the DNA structure caused by transcription and hinders the opening of the i-loop with the enzyme and further elongation. In this work, the boundaries of such i-loops are determined. Nucleosomes with NT-SSBs were transcribed. It was determined that the formation of contacts between DNA and histones behind RNAP occurs at a distance of more than 17 base pairs from the active center of the enzyme.

The accumulated knowledge about the role of the CXCL12 chemokine in the initiation and development of liver fibrosis is insignificant and does not allow us to assess the potential of using the CXCL12 mRNA level as an independent marker of fibrogenesis and processes associated with fibrosis and cirrhosis. Thioacetamide modeling of liver fibrosis and cirrhosis in male Wistar rats showed a low level of CXCL12 mRNA expression (p = 0.0000) at all stages of fibrosis progression. At the beginning of the experiment (3 weeks), a decrease in the level of CXCL12 mRNA by 2.93 times (p = 0.0000) compared with the control group was revealed. After 3, 7 and 9 weeks, the level of gene expression decreased gradually (p = 0.0000). During the reorganization of the parenchyma of the organ and the formation of false hepatic nodules (11, 13 and 15 weeks), a certain stabilization of the level of gene expression was noted. Against the background of the total formation of pseudohepatic nodules and a pronounced diffuse proliferation of connective tissue (17 weeks), the level of CXCL12 mRNA expression increased, but did not reach the level of control values. Based on our results, the level of CXCL12 mRNA is associated with the processes of fibrosis/cirrhosis and can act as an independent marker of fibrogenesis, but not cirrhosis of the liver against the background of toxic damage to it by thioacetamide. When conducting fundamental and preclinical studies to evaluate the effectiveness of drugs using this experimental model, the minimum allowable number of control points is considered to be three, namely: portal fibrosis (3 weeks), bridging fibrosis (5 weeks), the beginning of the process of transformation of liver fibrosis into cirrhosis (9 weeks).

The phenological responses of plants to changing weather conditions are very strong and can serve as an indicator of global climate change. If we understand how individual species respond to changing conditions, we can represent how ecosystems will change. The aim of this study was to analyze the exposure of climatic factors (air temperature and precipitation) on the flowering duration of the wild vascular plants species in the Karadag Nature Reserve (Crimea). In general, 152 species were taken into account with a number of phenological observations from 5 to 8 years. Correlation analysis between the flowering duration and the climatic parameters revealed a significant response in 89 (58.6%) species. Moreover, the climatic factors of the current vegetative season impacted 71 species flowering, previous vegetative season impacted 4 species flowering, and both vegetative seasons impacted 14 species flowering. Air temperature and precipitation equally impacted the flowering duration: air temperature impacted 35 (41.2%) species flowering; precipitation impacted 32 (37.7%) species flowering; both factors impacted 18 (21.1%) species flowering. The flowering duration mostly was negatively correlated with air temperature values and positively with precipitation amount. Mesophytes and the forest community species were the most sensitive to the climatic factors; euxerophytes and the steppe community species were the least sensitive to the climatic factors.

The taxonomic composition and spatial localization of yeast and bacteria in kefir grains (KG) obtained for study from different regions of the planet were investigated. The diversity of their microbiome has been demonstrated by high-throughput sequencing of bacterial 16S rRNA genes and the ITS1 region of the 18S-ITS1-5.8S-ITS2-28S complex of yeast rRNA. It has been established that the main representatives of the complex community of KG from different regions are lactic acid bacteria (LAB; lactobacilli, lactococci and Leuconostoc spp. in different ratios), and different types of yeast of the genus Kazachstania (family Saccharomycetaceae). Acetic acid bacteria and a small percentage of yeast Kluyveromyces marxianus were detected in the KG from Tibet, and yeast Pichia kluyveri was detected in the KG from Ossetia

The author’s point of view is presented, according to which, formulated back in the 80s of the last century by Yu.M. Lopukhin et al., the cholesterol theory of aging and death is now often misunderstood by many biologists and physicians. It is emphasized that this theory prioritized not the well-known role of cholesterol (CS) in metabolic processes, but its structural role in the plasma membrane of the cell. It was assumed that an increase in the microviscosity of the cell membrane due to the accumulation of CS in it leads to a deterioration in the transfer of external signals and nutrients to the cell, as well as to a decrease in the activity of membrane enzymes. This, according to the authors, triggers the occurrence of “senile” changes in cells, tissues and organs, and then in the entire multicellular organism, which ultimately leds to an increase in the probability of its death, that is, to aging. At the same time, the content of CS (mainly, of considered to be especially “bad” CS of low density lipoproteins) in serum was assigned only a minor role, because its increase is not at all necessary, according to the authors of the concept, leads to adverse changes in the body. This paper briefly discusses the evolution of ideas about the possible role of CS in aging and the development of various age-related pathologies, mainly cardiovascular diseases and mental disorders. Experimental data on the effect of liposomes containing both normal and oxidized CS on the proliferative activity of cultured cells are analyzed. The data of longitudinal studies are considered, suggesting that, paradoxically, it is people with elevated levels of CS in the blood plasma who live to an advanced age. At the same time, the consumption of large amounts of food rich in CS may not affect the health of some patients. It is noted that a number of studies indicate the absence of a causal relationship between the level of CS in serum and the occurrence of atherosclerotic changes. It is emphasized that CS is a very important compound for our body, without which cell proliferation and, as a result, normal regeneration are impossible. It is noted that there is a continuously increasing amount of data on the negative role of statins in the formation of age-related pathology, especially in people of older age groups. It is concluded that at present it becomes obvious that there is a need for a significant reappraisal (using the systems approach) of ideas about the possible role of CS in aging, the development of atherosclerosis and other age-related diseases, as well as dementias due to various causes, including Alzheimer’s disease.