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51.
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The inhibitory action of sex hormones on the glutamate dehydrogenase activity is due to their binding to the enzyme protein. No binding of sex hormones to glutamate dehydrogenase is observed in the presence of L-amino acids, preventing the enzyme dissociation. Under those conditions the enzyme sensitivity to the inhibitory action of the hormones sharply decreases. 相似文献
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Kh T Nishanov V P Tumanov R I Kaem G P Titova 《Biulleten' eksperimental'no? biologii i meditsiny》1987,104(7):32-35
The work was aimed at the elucidation of mechanisms of pathogenetic prevention of acute experimental pancreatitis induced according to the method of Arai. Pathological and biochemical examinations have shown that the application of PNA synthesis inhibitor 5-FU and cellular and intracellular membrane stabilizer-intralipid, infused at the beginning of the experiment, prevented the development of acute purulent pancreatitis. 相似文献
55.
The expression of the liver cell markers, vimentin, desmin, cytokeratins 7, 18, 19, and stem cell markers CD34 and Bcl-2 in the early stages of the human prenatal development was studied. Desmin was revealed in sinusoidal liver cells between 3.5 and 12 weeks of gestation; in mesenchymal cells of ventral mesentery and hepatoblasts it was detected at the 4–7th weeks of gestation. During the hepatic period of hemopoiesis, desmin-positive sinusoidal cells were located close to blood cells. So-called “cholangio-” cytokeratins 7 and 19 displayed different expression patterns. Cytokeratin 7 was found only in cholangiocytes, and cytokeratin 19 in hepatoblasts until 15–16 weeks of prenatal development. Mesenchymal cells of the ventral mesentery expressed cytokeratins 18 and 19 more than hepatoblasts at the 4–7th weeks of gestation. Bcl-2 was seen in the same period in most sinusoidal and mesenchymal cells of the ventral mesentery. CD34 positive cells were detected in liver sinusoids between the 4th and 9th weeks of gestation but probably they are not progenitors of hepatocytes during embryonic development. Ventral mesentery mesenchyma was negative for CD34. These results let us hypothesize that hepatocytes and cholangiocytes may arise from different embryonic sources: cholangyocytes derive only from duodenal epithelial cells, while hepatoblasts develop most likely with the participation of mesenchymal cells. 相似文献
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An overview of models of stomatal conductance at the leaf level 总被引:4,自引:0,他引:4
GAËLLE DAMOUR THIERRY SIMONNEAU HERVÉ COCHARD LAURENT URBAN 《Plant, cell & environment》2010,33(9):1419-1438
Stomata play a key role in plant adaptation to changing environmental conditions as they control both water losses and CO2 uptake. Particularly, in the context of global change, simulations of the consequences of drought on crop plants are needed to design more efficient and water‐saving cropping systems. However, most of the models of stomatal conductance (gs) developed at the leaf level link gs to environmental factors or net photosynthesis (Anet), but do not include satisfactorily the effects of drought, impairing our capacity to simulate plant functioning in conditions of limited water supply. The objective of this review was to draw an up‐to‐date picture of the gs models, from the empirical to the process‐based ones, along with their mechanistic or deterministic bases. It focuses on models capable to account for multiple environmental influences with emphasis on drought conditions. We examine how models that have been proposed for well‐watered conditions can be combined with those specifically designed to deal with drought conditions. Ideas for future improvements of gs models are discussed: the issue of co‐regulation of gs and Anet; the roles of CO2, absissic acid and H2O2; and finally, how to better address the new challenges arising from the issue of global change. 相似文献
58.
Background
The cell shape and morphology of plant tissues are intimately related to structural modifications in the primary cell wall that are associated with key processes in the regulation of cell growth and differentiation. The primary cell wall is composed mainly of cellulose immersed in a matrix of hemicellulose, pectin, lignin and some structural proteins. Xyloglucan is a hemicellulose polysaccharide present in the cell walls of all land plants (Embryophyta) and is the main hemicellulose in non-graminaceous angiosperms. 相似文献59.
M G Goderdzishvili V V Gosteva N V Klitsunova N V Timakova I V Titova 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1989,(2):8-11
The influence of plasmid RP4 Mucts62, heterologous for B. cereus, on the growth rate of B. cereus strains GA 682 and 319 obtained in our earlier experiments and on changes in the ultrastructure of their cell walls in comparison with B. cereus initial strains GP 7 and DSM 318 has been studied. Plasmid RP4 Mucts62 with a wide spectrum of action has been found not only to determine the functional signs of resistance to antibiotics and thermal sensitivity in the heterologous host, but also to take part in the morphological organization of the cell surface structure, and in particular in the structure of the S-layer. B. cereus strains containing plasmid RP4 Mucts62 are characterized by slower growth rate and cell fragility. 相似文献
60.
Men'shikova EA Podosinnikova LS Sokolenko AV Mironova AV Titova SV 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》2004,(5):106-108
A total of 20 ctx- and 16 ctx+ V. cholerae eltor strains, 20 ctx- and 22 ctx+ V. cholerae O139 strains were under study. Hemolytic activity was tested in modified Greig test with sheep, guinea pig and rabbit red blood cells. The comparative study of the hemolytic properties of V. cholerae O1 and O139 under different conditions of cultivation demonstrated their capacity of lysing sheep red blood cells (SRBC) irrespective of the presence of toxigenic properties. A wider spectrum of lytic activity of ctx- strains in Greig test with respect to red blood cells of different animals and the capacity of lysing SRBC, most resistant to the action of toxin, may be due to a considerably greater content of Hly+ clones in their population. 相似文献