Effect of colchicine on physiological and biochemical properties of Rhodococcus qingshengii.

The genus Rhodococcus includes polymorphic non-spore-forming gram-positive bacteria belonging to the class Actinobacteria. Together with Mycobacterium and Corynebacterium, Rhodococcus belongs to the Mycolata group. Due to their relatively high growth rate and ability to form biof ilms, Rhodococcus are a convenient model for studying the effect of biologically active compounds on pathogenic Mycolata. Colchicine was previously found to reduce biof ilm formation by P. carotovorum VKM B-1247 and R. qingshengii VKM Ac-2784D. To understand the mechanism of action of this alkaloid on the bacterial cell, we have studied the change in the fatty acid composition and microviscosity of the R. qingshengii VKM Ac-2784D membrane. Nystatin, which is known to reduce membrane microviscosity, is used as a positive control. It has been found that colchicine at concentrations of 0.01 and 0.03 g/l and nystatin (0.03 g/l) have no signif icant effect on the survival of R. qingshengii VKM Ac-2784D cultivated in a buffered saline solution with 0.5 % glucose (GBSS). However, colchicine (0.03 g/l) signif icantly inhibits biof ilm formation. Rhodococcus cells cultivated for 24 hours in GBSS with colchicine acquire a rounded shape. Colchicine at 0.01 g/l concentration increases C16:1(n-7), C17:0, C20:1(n-9) and C21:0 fatty acids. The microviscosity of the membrane of individual cells was distributed from the lowest to the highest values of the generalized laurdan f luorescence polarization index (GP), which indicates a variety of adaptive responses to this alkaloid. At a higher concentration of colchicine (0.03 g/l) in the membranes of R. qingshengii VKM Ac-2784D cells, the content of saturated fatty acids increases and the content of branched fatty acids decreases. This contributes to an increase in membrane microviscosity, which is conf irmed by the data on the GP f luorescence of laurdan. All of the above indicates that colchicine induces a rearrangement of the Rhodococcus cell membrane, probably in the direction of increasing its microviscosity. This may be one of the reasons for the negative effect of colchicine on the formation of R. qingshengii VKM Ac-2784D biof ilms.

Investigation of the Presence of DNA of Highly Pathogenic Human Papillomaviruses in Water Bodies of the Lake Baikal Natural Territory.

Human papillomaviruses (HPVs) are extremely widespread throughout the world. There are more than 100 types of HPVs, of which at least 14 types represent high oncogenic risk viruses (World Health Organization, 2020). Numerous attempts were made to analyze various water sources in order to (i) reveal the presence of DNA of pathogenic human papillomaviruses in them and (ii) assess the potential risks of occurrence of epidemics caused by HPV. With time, the necessity to solve these important problems stimulated the formation of a new direction in the world medical and environmental investigations.This paper contains the investigation of the presence of DNA of highly dangerous types of human papillomaviruses (HPV6, HPV11, HPV16 and HPV18) in water bodies of the Baikal natural territory, in particular in the water reservoirs in and near the villages of Listvyanka, Bolshiye Koty, Kultuk and the cities of Baikalsk and Slyudyanka. In course of our work, the conditions good for the study of the biological material obtained from water samples by the PCR technique to reveal the presence of DNA of HPV6, HPV11, HPV16 and HPV18 papillomaviruses were chosen. PCR analysis was conducted with the aid of both the already well-known universal primers GP5 + /6 + and the primers developed by our team to be applied to the conservative domains of nucleotide sequences encoding the main capsid protein L1 of human papillomaviruses HPV6, HPV11 (these types of the virus contribute to the occurrence of anogenital condylomatosis and the development of respiratory papillomatosis) and HPV16, HPV16 (these types of virus contribute to the occurrence of cervical cancer).The analyzes conducted by our team have revealed the presence of DNA of the four types of HPVs (6, 11, 16 and 18) in the samples taken from various water sources of the Baikal natural territory.

Role of Plasmalemma Microdomains (Rafts) in Protection of the Plant Cell Under Osmotic Stress.

Lipid-protein microdomains (presumably rafts) of the plasmalemma isolated from the beetroots subjected to hyperosmotic stress and hypoosmotic stress were studied. In these microdomains, the variations in the composition of total lipids, sterols, and fatty acids were observed. These variations differed under hypo- and hyperosmotic types of stress. We presumed that such variations were bound up with different strategies, which are probably related to protecting the cell from osmotic stress. One of the protection tendencies might be related, in our opinion, to credible growth of the content of such lipids as sterols and sterol esters, which are considered as raft-forming. Under osmotic stress, these lipids can contribute to the formation of both new raft structures and new membrane contacts of plasmalemma with intracellular organelles. Another protection tendency may be bound up with the redistribution of membrane phospholipids and phosphoglycerolipids possibly to stabilize the membrane's lamellar structure, which is ensured by credible growth of the content of such lipids as phosphatidylcholines, phosphatidylinositols, and digalactosyldiacylglycerol. The participation of lipid-protein microdomains in the adaptive mechanisms of plant cells may, in our opinion, also be bound up with the redistribution of membrane sterols, which (redistribution) in a number of variants may provoke credible growth in the content of cholesterol or "anti-stress" sterols (campesterol and stigmasterol). So, according to our results, the variations in the content of the plasmalemma lipid-protein microdomains take place under osmotic stress. These variations may influence the functioning of plasmalemma and take part in the adaptive mechanisms of plant cells.

Growth-Stimulating Activity of Natural Polymer-Based Nanocomposites of Selenium during the Germination of Cultivated Plant Seeds.

The growth-stimulating activity of three selenium nanocomposites (NCs) in various matrices based on arabinogalactan (NC Se/AG, 6.4% Se), starch (NC Se/St, 2% Se), and carrageenan (NC Se/Car, 12% Se) with respect to plants of radish, soybean, and potato was investigated. It was shown that the treatment of plant seeds with NCs stimulated root growth during germination. It was found that the studied NCs affected both the level of lipid peroxidation and the activity of the antioxidant enzyme glutathione peroxidase (GPX). The treatment of radish seeds with NCs stimulated root growth during their germination and reduced the content of diene conjugates (DC) in root tissues. It was shown that soaking seeds in NC Se/AG solution increased the GPX activity in the tissues of the radish root by 40%. Stimulation of soybean root growth under the influence of NC Se/Car may also be associated with the activation of GPX. Furthermore, in potato plants, this NC led to the stimulation of germination; however, this was probably due to the activation of other antioxidant enzymes. The results obtained allow us to consider Se NCs as potential plant growth stimulants.

[PECULIAR PROPERTIES OF SOME COMPONENTS OF MORPHOLOGICAL STRUCTURE IN A PLANT CELL VACUOLE REVEALED BY CONFOCAL MICROSCOPY].

Results of investigations of peculiar properties related to the structure of plant cell vacuolar membranes are discussed. The study was carried out using confocal microscopy, which allowed us in the process of scanning to identify membrane tubes and vesicules in the preparations of isolated vacuoles. Such membrane tubes were found both inside and outside the vacuoles, and, in the case of scanning intermittently at equal time intervals, transition of vesicles with the membrane tube was observed. Furthermore, scanning of isolated vacuoles was conducted at various distances from the glass substrate. Each time, in the upper area of the isolated vacuole lying on the substrate, we observed a large segment of vacuolar membrane and registered the effect of highly intensive fluorescing of some of membrane segments. The distributions of laurdan fluorescence generalized polarization (GP) values for the vacuolar membrane on the whole and for the intensively fluorescing membrane segments have been obtained. We have found that the microviscosity of the intensively fluorescing membrane segments essentially differs from that of the rest part of the membrane.