RESUMEN
A series of promising luminescent materials, nonlinear optical crystals, and physiologically active compounds - aryl(oxy)(sulfanyl)(sulfonyl)acetates of guanidine (A) of unknown type was synthesized. Various functional groups present in (A) were identified using FTIR spectroscopy. 1H and 13C NMR spectral studies further confirm the molecular structure (A). Crystals of guanidinium 4-chlorophenyl(sulfanyl)acetate (1) and guanidinium 4-chlorophenyl(sulfonyl)acetate (2) were successfully grown. They belong to the same lowest symmetry category, but to different crystal systems: monoclinic (1) and orthorhombic (2). It has been established that intrinsic optical absorption begins at a wavelength of â¼ 290 nm for crystalline compound (1) and â¼ 335 nm for crystal (2). The intrinsic luminescence spectrum of crystal (1) includes two bands with maxima at 300 and 515 nm. In the intrinsic luminescence spectrum of crystal (2), only one band is observed with a maximum at 350 nm. Such luminescence in both crystals is excited in the intrinsic absorption bands, as well as by X-ray radiation. In addition, in the near ultraviolet and throughout the visible region, where optical absorption is not detected (it is very weak), low-inertia (less than 10 ns) rather intense luminescence of uncontrolled impurity-defect centers is excited. The spectral bands of optical absorption, photo- and X-ray luminescence discovered in experiments were systematized using a diagram of energy levels and quantum transitions in crystals and defect centers of the compounds under study.
RESUMEN
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.
RESUMEN
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.