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11.
Bréhin AC Mouriès J Frenkiel MP Dadaglio G Desprès P Lafon M Couderc T 《Journal of immunology (Baltimore, Md. : 1950)》2008,180(10):6760-6767
West Nile virus (WNV) is an emerging neurotropic flavivirus. We investigated the dynamics of immune cell recruitment in peripheral tissues and in the CNS during WNV encephalitis in an immunocompetent mouse model. In the periphery, immune cell expansion can successfully limit viremia and lymphoid tissue infection. However, viral clearance in the periphery is too late to prevent viral invasion of the CNS. In the CNS, innate immune cells, including microglia/macrophages, NK cells, and plasmacytoid dendritic cells, greatly expand as the virus invades the brain, whereas B and T cells are recruited after viral invasion, and fail to control the spread of the virus. Thus, the onset of WNV encephalitis was correlated both with CNS viral infection and with a large local increase of innate immune cells. Interestingly, we identify a new immune cell type: CD19(+)B220(-) BST-2(+), which we name G8-ICs. These cells appear during peripheral infection and enter the CNS. G8-ICs express high levels of MHC class II, stain for viral Ag, and are localized in the paracortical zone of lymph nodes, strongly suggesting they are previously unidentified APCs that appear in response to viral infection. 相似文献
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Population Dynamics and Diversity of Viruses,Bacteria and Phytoplankton in a Shallow Eutrophic Lake 总被引:3,自引:0,他引:3
Tijdens M Hoogveld HL Kamst-van Agterveld MP Simis SG Baudoux AC Laanbroek HJ Gons HJ 《Microbial ecology》2008,56(1):29-42
We have studied the temporal variation in viral abundances and community assemblage in the eutrophic Lake Loosdrecht through epifluorescence microscopy and pulsed field gel electrophoresis (PFGE). The virioplankton community was a dynamic component of the aquatic community, with abundances ranging between 5.5 x 10(7) and 1.3 x 10(8) virus-like particles ml(-1) and viral genome sizes ranging between 30 and 200 kb. Both viral abundances and community composition followed a distinct seasonal cycle, with high viral abundances observed during spring and summer. Due to the selective and parasitic nature of viral infection, it was expected that viral and host community dynamics would covary both in abundances and community composition. The temporal dynamics of the bacterial and cyanobacterial communities, as potential viral hosts, were studied in addition to a range of environmental parameters to relate these to viral community dynamics. Cyanobacterial and bacterial communities were studied applying epifluorescence microscopy, flow cytometry, and denaturing gradient gel electrophoresis (DGGE). Both bacterial and cyanobacterial communities followed a clear seasonal cycle. Contrary to expectations, viral abundances were neither correlated to abundances of the most dominant plankton groups in Lake Loosdrecht, the bacteria and the filamentous cyanobacteria, nor could we detect a correlation between the assemblage of viral and bacterial or cyanobacterial communities during the overall period. Only during short periods of strong fluctuations in microbial communities could we detect viral community assemblages to covary with cyanobacterial and bacterial communities. Methods with a higher specificity and resolution are probably needed to detect the more subtle virus-host interactions. Viral abundances did however relate to cyanobacterial community assemblage and showed a significant positive correlation to Chl-a as well as prochlorophytes, suggesting that a significant proportion of the viruses in Lake Loosdrecht may be phytoplankton and more specific cyanobacterial viruses. Temporal changes in bacterial abundances were significantly related to viral community assemblage, and vice versa, suggesting an interaction between viral and bacterial communities in Lake Loosdrecht. 相似文献
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MAP kinase activation by hypoosmotic stress of tobacco cell suspensions: towards the oxidative burst response? 总被引:9,自引:3,他引:6
Anne-Claire Cazalé Marie-Jo Droillard Cathal Wilson Erwin Heberle-Bors Hélène Barbier-Brygoo Christiane Laurière 《The Plant journal : for cell and molecular biology》1999,19(3):297-307
Hypoosmotic stress activates a phosphorylation-dependent oxidative burst. In-gel kinase assays were performed to characterize the protein kinases that could be implicated in osmoregulation and in the activation of the oxidative burst. Hypoosmotic stress activated several kinases among which 50 and 46 kDa proteins displayed mitogen-activated protein kinase (MAP kinase) properties. They phosphorylated myelin basic protein in the absence of calcium, were recognized by antibodies directed against human MAP kinases, and were phosphorylated on tyrosine. Immunoprecipitation with an antibody directed against the tobacco MAP kinase Ntf4 showed that at least one of the activated kinases would be Ntf4-like. Apigenin, a MAP kinase and cyclin-dependent kinase inhibitor which prevents the hypoosmotically induced oxidative burst ( Cazaléet al. 1998 ; Plant Physiol. 116, 659–669), inhibited these kinases in vitro suggesting that they may play a role in the activation of the oxidative burst. Like the oxidative response, activation of the kinases depended on extracellular calcium influx and protein kinases sensitive to staurosporine and 6-DMAP. However, kinase activation did not depend on effluxes through anion channels or on the oxidative burst. Two-dimensional in-gel kinase assays revealed the presence of three protein kinases with an apparent molecular mass of 50 kDa and one of 46 kDa, all four being activated by hypoosmotic stress. The same kinases were also activated by oligogalacturonides and salicylic acid, underlying the importance of these MAP kinases as common components of different signaling pathways triggered by different extracellular stimuli. 相似文献
15.
Tabopda TK Ngoupayo J Liu J Mitaine-Offer AC Tanoli SA Khan SN Ali MS Ngadjui BT Tsamo E Lacaille-Dubois MA Luu B 《Phytochemistry》2008,69(8):1726-1731
Four alkaloids named piperumbellactams A-D (1-4) were isolated from branches of Piper umbellatum together with known N-hydroxyaristolam II (5), N-p-coumaroyl tyramine (6), 4-nerolidylcatechol (7), N-trans-feruloyltyramine, E-3-(3,4-dihydroxyphenyl)-N-2-[4-hydroxyphenylethyl]-2-propenamide, beta-amyrin, friedelin, apigenin 8-C-neohesperidoside, acacetin 6-C-beta-d-glucopyranoside, beta-sitosterol, its 3-O-beta-d-glucopyranoside and its 3-O-beta-d-[6'-dodecanoyl]-glucopyranoside. Glycosidase inhibition, antioxidant and antifungal activities of these compounds were evaluated. Compounds 1-3 showed moderate alpha-glucosidase enzyme inhibition with IC50 values 98.07+/-0.44, 43.80+/-0.56 and 29.64+/-0.46, respectively. In DPPH radical scavenging assay, compounds 2, 3 and 6 showed potent inhibitory activity while compounds 4, 5 and 7 showed potent antifungal activity. 相似文献
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The aim of this review is to give updated results on the chemistry and biological activities of Polygalaceae saponins from
literature data and from authors’ studies. During the last decade the improvement of isolation and structure elucidation techniques
allowed the characterization of about 150 complex triterpene saponins from Polygalaceae having mainly preatroxigenin, medicagenic
acid and presenegenin as aglycone. The sequence 3-O-(β-d-glucopyranosyl)-presenegenin 28-[O-α-L-rhamnopyranosyl-(1→2)-β-d-fucopyranosyl] ester with additional acylations with p-methoxy-, di- or trimethoxycinnamoyl groups at the position 4 of the fucopyranosyl moiety often encountered in the genera
Polygala, Muraltia, Carpolobia, and Securidaca may represent a chemotaxonomic marker for the Polygalaceae family. The biological and pharmacological properties of some
Polygalaceae species such as in vitro activity on the central nervous system, the hypoglycemic, cytotoxic, immunomodulatory activities and in vivo immunoadjuvant properties are highlighted. 相似文献
17.
Thierry Normand Bettina Husen Frauke Leenders Hlne Pelczar Jean-Luc Baert Agns Begue Anne-Claire Flourens Jerzy Adamski Yvan de Launoit 《The Journal of steroid biochemistry and molecular biology》1995,55(5-6):541-548
17β-hydroxysteroid dehydrogenases (17β-HSD) catalyze the conversion of estrogens and androgens at the C17 position. The 17β-HSD type I, II, III and IV share less than 25% amino acid similarity. The human and porcine 17β-HSD IV reveal a three-domain structure unknown among other dehydrogenases. The N-terminal domains resemble the short chain alcohol dehydrogenase family while the central parts are related to the C-terminal parts of enzymes involved in peroxisomal β-oxidation of fatty acids and the C-terminal domains are similar to sterol carrier protein 2. We describe the cloning of the mouse 17β-HSD IV cDNA and the expression of its mRNA. A probe derived from the human 17β-HSD IV was used to isolate a 2.5 kb mouse cDNA encoding for a protein of 735 amino acids showing 85 and 81% similarity with human and porcine 17β-HSD IV, respectively. The calculated molecular mass of the mouse enzyme amounts to 79,524 Da. The mRNA for 17β-HSD IV is a single species of about 3 kb, present in a multitude of tissues and expressed at high levels in liver and kidney, and at low levels in brain and spleen. The cloning and molecular characterization of murine, human and porcine 17β-HSD IV adds to the complexity of steroid synthesis and metabolism. The multitude of enzymes acting at C17 might be necessary for a precise control of hormone levels. 相似文献
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Gayet L Picault N Cazalé AC Beyly A Lucas P Jacquet H Suso HP Vavasseur A Peltier G Forestier C 《FEBS letters》2006,580(30):6891-6897
ABC transporters from the multidrug resistance-associated protein (MRP) subfamily are glutathione S-conjugate pumps exhibiting a broad substrate specificity illustrated by numerous xenobiotics, such as anticancer drugs, herbicides, pesticides and heavy metals. The engineering of MRP transporters into plants might be interesting either to reduce the quantity of xenobiotics taken up by the plant in the context of “safe-food” strategies or, conversely, in the development of phytoremediation strategies in which xenobiotics are sequestered in the vacuolar compartment. In this report, we obtained Arabidopsis transgenic plants overexpressing human MRP1. In these plants, expression of MRP1 did not increase plant resistance to antimony salts (Sb(III)), a classical glutathione-conjugate substrate of MRP1. However, the transporter was fully translated in roots and shoots, and targeted to the plasma membrane. In order to investigate the functionality of MRP1 in Arabidopsis, mesophyll cell protoplasts (MCPs) were isolated from transgenic plants and transport activities were measured by using calcein or Sb(III) as substrates. Expression of MRP1 at the plasma membrane was correlated with an increase in the MCPs resistance to Sb(III) and a limitation of the metalloid content in the protoplasts due to an improvement in Sb(III) efflux. Moreover, Sb(III) transport was sensitive to classical inhibitors of the human MRP1, such as MK571 or glibenclamide. These results demonstrate that a human ABC transporter can be functionally introduced in Arabidopsis, which might be useful, with the help of stronger promoters, to reduce the accumulation of xenobiotics in plants, such as heavy metals from multi-contaminated soils. 相似文献
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Anne-Claire Cazalé Marie-Aude Rouet-Mayer Hélène Barbier-Brygoo Yves Mathieu Christiane Laurière 《Plant physiology》1998,116(2):659-669
Oxidative burst constitutes an early response in plant defense reactions toward pathogens, but active oxygen production may also be induced by other stimuli. The oxidative response of suspension-cultured tobacco (Nicotiana tabacum cv Xanthi) cells to hypoosmotic and mechanical stresses was characterized. The oxidase involved in the hypoosmotic stress response showed similarities by its NADPH dependence and its inhibition by iodonium diphenyl with the neutrophil NADPH oxidase. Activation of the oxidative response by hypoosmotic stress needed protein phosphorylation and anion effluxes, as well as opening of Ca2+ channels. Inhibition of the oxidative response impaired Cl− efflux, K+ efflux, and extracellular alkalinization, suggesting that the oxidative burst may play a role in ionic flux regulation. Active oxygen species also induced the cross-linking of a cell wall protein, homologous to a soybean (Glycine max L.) extensin, that may act as part of cell volume and turgor regulation through modification of the physical properties of the cell wall. 相似文献