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531.
Gu W Weihrauch D Tanaka K Tessmer JP Pagel PS Kersten JR Chilian WM Warltier DC 《American journal of physiology. Heart and circulatory physiology》2003,285(4):H1582-H1589
Recent evidence suggests that reactive oxygen species (ROS) promote proliferation and migration of vascular smooth muscle (VSMC) and endothelial cells (EC). We tested the hypothesis that ROS serve as crucial messengers during coronary collateral development. Dogs were subjected to brief (2 min), repetitive coronary artery occlusions (1/h, 8/day, 21 day duration) in the absence (occlusion, n = 8) or presence of N-acetylcysteine (NAC) (occlusion + NAC, n = 8). A sham group (n = 8) was instrumented identically but received no occlusions. In separate experiments, ROS generation after a single 2-min coronary artery occlusion was assessed with dihydroethidium fluorescence. Coronary collateral blood flow (expressed as a percentage of normal zone flow) was significantly increased (71 +/- 7%) in occlusion dogs after 21 days but remained unchanged (13 +/- 3%) in sham dogs. Treatment with NAC attenuated increases in collateral blood flow (28 +/- 8%). Brief coronary artery occlusion and reperfusion caused ROS production (256 +/- 33% of baseline values), which was abolished with NAC (104 +/- 12%). Myocardial interstitial fluid produced tube formation and proliferation of VSMC and EC in occlusion but not in NAC-treated or sham dogs. The results indicate that ROS are critical for the development of the coronary collateral circulation. 相似文献
532.
533.
Retroviral vectors pseudotyped with severe acute respiratory syndrome coronavirus S protein 总被引:10,自引:0,他引:10
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Giroglou T Cinatl J Rabenau H Drosten C Schwalbe H Doerr HW von Laer D 《Journal of virology》2004,78(17):9007-9015
The worldwide outbreak of severe acute respiratory syndrome (SARS) was shown to be associated with a novel coronavirus (CoV) now called SARS CoV. We report here the generation of SARS CoV S protein-pseudotyped murine leukemia virus (MLV) vector particles. The wild-type S protein pseudotyped MLV vectors, although at a low efficiency. Partial deletion of the cytoplasmic tail of S dramatically increased infectivity of pseudotypes, with titers only two- to threefold lower than those of pseudotypes generated in parallel with the vesicular stomatitis virus G protein. S-pseudotyped MLV particles were used to analyze viral tropism. MLV(SARS) pseudotypes and wild-type SARS CoV displayed similar cell types and tissue and host restrictions, indicating that the expression of a functional receptor is the major restraint in permissiveness to SARS CoV infection. Efficient gene transfer could be detected in Vero and CaCo2 cells, whereas the level of gene marking of 293T, HeLa, and HepG2 cells was only slightly above background levels. A cat cell line and a dog cell line were not susceptible. Interestingly, PK-15, a porcine kidney cell line, and primary porcine kidney cells were also highly permissive for SARS S pseudotypes and wild-type SARS CoV. This finding suggests that swine may be susceptible to SARS infection and may be a source for infection of humans. Taken together, these results indicate that MLV(SARS) pseudotypes are highly valuable for functional studies of viral tropism and entry and, in addition, can be a powerful tool for the development of therapeutic entry inhibitors without posing a biohazard to human beings. 相似文献
534.
Background
Modification of leaf traits in sugar beet requires a strong leaf specific promoter. With such a promoter, expression in taproots can be avoided which may otherwise take away available energy resources for sugar accumulation. 相似文献535.
The interleukin-10 (IL-10) cytokine family consists of several viral and human homologs that exhibit distinct receptor binding specificities. In the present study, the complex between interleukin-19 (IL-19) and its physiological receptor—the interleukin-20 receptor -chain (IL-20R1)—was modeled.The most prominent feature of this complex is an extended binding interface formed by a long loop of IL-20R1 and a bulge region of IL-19. The two regions exhibit complementary charges and have no structural counterparts in the IL-10/IL-10R1 complex but show some resemblance to the complex between interferon- (IFN-) and its receptor.Sequence comparison of the three cytokines (IL-19, IL-20, IL-24) that bind the IL-20R1 reveals a considerable conservation of the length of the interacting loops. One residue suggested to play a key role in receptor binding specificity is a conserved glutamate. The binding interface of IL-20R1 is rich in aromatic residues while the interfaces of its cytokine ligands are mainly formed by more flexible aliphatic amino acids. This structural feature might play an important role for the specific recognition of a single receptor chain by three different cytokines.
Figure Comparison of the ligand/receptor interfaces in the a IL-10/IL-10R1, b IL-19/IL-20R1 and c IFN-/receptor complexes. The translucent Connolly surfaces of the receptor and the ligand are shown in yellow and white, respectively. The backbone of the receptor and ligand are highlighted by a red and blue/green tube, respectively. For clarity, only one domain of the intertwined dimes is shown for IL-10 and IFN-. Arrows denote the location of helix B and the corresponding structural elements in IL-19 and IFN- as well as the location of receptor loop L2. As evident from b and c an extended interaction surface is created in the IL-19/IL-20R1 and IFN-/receptor complexes by the interaction of this structural element with a long loop of the respective receptor 相似文献
536.
Kerstin Jentschel Dorothee Thiel Frank Rehn Jutta Ludwig-Müller 《Physiologia plantarum》2007,129(2):320-333
Plant hormones, including auxins, might be signals during the establishment of an arbuscular mycorrhizal (AM) symbiosis. Here, we report on the concentrations of three auxins native to nasturtium ( Tropaeolum majus L.) during early AM development. Indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), and phenylacetic acid (PAA) were previously identified as endogenous compounds in this species by full-scan gas chromatography–mass spectrometry. All auxinic compounds were influenced by AM colonization but showed completely different patterns. At very early stage, free IAA and IBA were lower in infected than in control roots, whereas PAA concentration was higher in infected roots than in controls. At later stages, PAA was reduced in colonized roots, whereas, especially, IBA was increased in colonized roots compared with controls. Measurement of total auxins confirmed a complex regulation pattern for the three compounds. In hyphae of Glomus intraradices , none of the auxins was detectable. Biosynthesis of the three auxins was measured using heavy labeled isotopes as precursors in control and AM-inoculated roots. While not much difference was found in the IAA labeling pattern between controls and AM-inoculated roots at both time points, IBA synthesis was slightly higher in AM-inoculated roots. Double labeling experiments showed that two distinct pathways, a tryptophan-dependent and a tryptophan-independent biosynthetic pathway contribute to the synthesis of IAA in T. majus roots. Because T. majus is difficult to genetically manipulate, we have used tobacco plants transformed with the auxin-inducible promoter GH3 fused to the β-glucuronidase (GUS) reporter gene to investigate whether AM structures would co-localize to cells harboring the auxin-inducible promoter. Although the GUS activity increased significantly in AM-inoculated roots, there was no obvious correlation between GH3::GUS expression and fungal structures. 相似文献
537.
Stefanie Döll Markus Kuhlmann Twan Rutten Michael F. Mette Sarah Scharfenberg Antonios Petridis Dorothee‐Carina Berreth Hans‐Peter Mock 《The Plant journal : for cell and molecular biology》2018,93(3):431-444
Secondary metabolites are involved in the plant stress response. Among these are scopolin and its active form scopoletin, which are coumarin derivatives associated with reactive oxygen species scavenging and pathogen defence. Here we show that scopolin accumulation can be induced in the root by osmotic stress and in the leaf by low‐temperature stress in Arabidopsis thaliana. A genetic screen for altered scopolin levels in A. thaliana revealed a mutant compromised in scopolin accumulation in response to stress; the lesion was present in a homologue of THO1 coding for a subunit of the THO/TREX complex. The THO/TREX complex contributes to RNA silencing, supposedly by trafficking precursors of small RNAs. Mutants defective in THO, AGO1, SDS3 and RDR6 were impaired with respect to scopolin accumulation in response to stress, suggesting a mechanism based on RNA silencing such as the trans‐acting small interfering RNA pathway, which requires THO/TREX function. 相似文献
538.
539.
Spatial Variability of Plant Litter Decomposition in Stream Networks: from Litter Bags to Watersheds
The decomposition of plant litter plays a fundamental role in the cycling of carbon and nutrients and is driven by complex interactions of biological and physical controls, yet little is known about its variability and controls across spatial scales. Here we address the indirect effects of riparian canopy cover on litter decomposition and decomposers and their variability within a set of hierarchical scales (watershed, stream segments and reaches) controlling for confounding factors that could co-vary with canopy cover (for example, temperature and nutrients), in high-altitude subtropical streams. Total, microbial and invertebrate-driven decomposition rates were approximately 1.4–6.6 times higher in closed-canopy than in open-canopy watersheds. Riparian canopy cover accounted for 62–69% of total variability of decomposition rates and indirectly (via light availability and litter inputs) promoted fungal facilitation of shredders through leaf litter conditioning. In contrast to what we expected, much of the spatial variability in the decomposition occurred at smaller scale (4–20% of total variability among reaches versus <1% among watersheds) and coincided with the greatest variability in shredder abundance and fungal biomass (70 and 17% among reaches, respectively). We conclude that riparian canopy cover may be an important control of natural variability of litter decomposition at the watershed scale through its effects on fungal decomposers and shredder consumption. We also provide evidence of higher reach and minor watershed variability of litter decomposition in stream networks. Our results point to the importance of identifying the sources of natural variability of decomposition and how they interact within and among spatial scales. 相似文献
540.
Lena Dorothee Schütte Stefan Baumeister Benjamin Weis Christoph Hudemann Eva-Maria Hanschmann Christopher Horst Lillig 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013