Effect of artificial redox mediators on the photoinduced oxygen reduction by photosystem I complexes

The peculiarities of interaction of cyanobacterial photosystem I with redox mediators 2,6-dichlorophenolindophenol (DCPIP) and N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD) were investigated. The higher donor efficiency of the reduced DCPIP form was demonstrated. The oxidized form of DCPIP was shown to be an efficient electron acceptor for terminal iron–sulfur cluster of photosystem I. Likewise methyl viologen, after one-electron reduction, DCPIP transfers an electron to the molecular oxygen. These results were discussed in terms of influence of these interactions on photosystem I reactions with the molecular oxygen and natural electron acceptors.     

The Synthesis and Selective Cytotoxicity of New Mannich Bases,Derivatives of 19- and 28-Alkynyltriterpenoids

New propargylamines were synthesized in 72–75% yields by the interaction of 19-alkynylbetulin and 28-O-propargyl glycinamide of oleanolic acid with N-methylpiperazine under the Mannich reaction conditions. 19-[1-Methyl-4-prop-2-yn-1-yl-piperazine]-20,29,30-trinorbetulin was shown to manifest anticancer activity against one line of leukemia cells and two lines of colon cancer cells, whereas the growth of leukemia cells SR in the presence of 4-(4-methylpiperazin-1-yl)but-2-yn-1-yl-N-(3-hydroxy-28-oxoolean-12-en-28-yl)glycinate was 8%.     

Pathogen‐induced conditioning of the primary xylem vessels – a prerequisite for the formation of bacterial emboli by Pectobacterium atrosepticum

Representatives of Pectobacterium genus are some of the most harmful phytopathogens in the world. In the present study, we have elucidated novel aspects of plant–Pectobacterium atrosepticum interactions. This bacterium was recently demonstrated to form specific ‘multicellular’ structures – bacterial emboli in the xylem vessels of infected plants. In our work, we showed that the process of formation of these structures includes the pathogen‐induced reactions of the plant. The colonisation of the plant by P. atrosepticum is coupled with the release of a pectic polysaccharide, rhamnogalacturonan I, into the vessel lumen from the plant cell wall. This polysaccharide gives rise to a gel that serves as a matrix for bacterial emboli. P. atrosepticum‐caused infection involves an increase of reactive oxygen species (ROS) levels in the vessels, creating the conditions for the scission of polysaccharides and modification of plant cell wall composition. Both the release of rhamnogalacturonan I and the increase in ROS precede colonisation of the vessels by bacteria and occur only in the primary xylem vessels, the same as the subsequent formation of bacterial emboli. Since the appearance of rhamnogalacturonan I and increase in ROS levels do not hamper the bacterial cells and form a basis for the assembly of bacterial emboli, these reactions may be regarded as part of the susceptible response of the plant. Bacterial emboli thus represent the products of host–pathogen integration, since the formation of these structures requires the action of both partners.     

Spectral and acid-base properties of hemolymph plasma and its fractions in the gastropod pulmonate mollusc <Emphasis Type="Italic">Achatina fulica</Emphasis>

A set of normal biochemical indices of the hemolymph plasma in the gastropod pulmonate mollusc Achatina fulica was described in this study. A comparative analysis of the whole plasma and its subfractions enriched with and depleted of the oxygen-carrying protein hemocyanin was carried out using spectrophotometry and spectrofluorimetry. Individual features of the absorption spectra were analyzed using fourth derivatives. An optimal method to estimate the protein concentration was identified. The buffer capacity, equivalence points and pK values of the dominant buffer groups were calculated to characterize the acid-base properties of hemolymph plasma and its subfractions. A major role in maintaining the hemolymph buffer capacity was shown to belong to the bicarbonate buffering system. The results of this study are compared with the data for Helix pomatia available in literature. In the future, the tested indices will be used to devise ecotoxicological criteria for environmental assessment.     

Small molecule compounds that induce cellular senescence

To date, dozens of stress‐induced cellular senescence phenotypes have been reported. These cellular senescence states may differ substantially from each other, as well as from replicative senescence through the presence of specific senescence features. Here, we attempted to catalog virtually all of the cellular senescence‐like states that can be induced by low molecular weight compounds. We summarized biological markers, molecular pathways involved in senescence establishment, and specific traits of cellular senescence states induced by more than fifty small molecule compounds.     

Seasonal changes in the population count of allergenic mites (Acariformes, Pyroglyphidae) in the dust of living quarters in the city of Moscow

The seasonal dynamics of allergenic mite quantity in house dust of three model apartments in Moscow has been observed during three years. Two periods of increase in mites' quantity have been revealed: wintry and summer-autumnal. Mite breeding takes place both in winter and in summer-autumnal period. The quantity variations of allergenic mites are cyclic and have individual traits peculiar to each population of these mites.     

Lymphopoietic characteristics in acute hypobaric hypoxia

10 healthy men were examined, that underwent a 48 hours hypobaric (acute) hypoxia in the climate chamber "Taba?", with conditions corresponding to those at an altitude of 4,000 m. The "ascent" and "descent" were performed correspondingly within 30 minutes. Increased share of dying lymphocytes and frequency of chromosomal aberrations in these were found in addition to an elevated activity of nucleolar organizers and to changed morphological patterns of argentophilic nucleoli. T- and B-lymphocyte contents remained unchanged. The role of the lymphopoietic alterations in autoimmune complications and of hemopoietic disorders in the mountains is discussed.