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101.
Novel role for Netrins in regulating epithelial behavior during lung branching morphogenesis 总被引:1,自引:0,他引:1
Liu Y Stein E Oliver T Li Y Brunken WJ Koch M Tessier-Lavigne M Hogan BL 《Current biology : CB》2004,14(10):897-905
The development of many organs, including the lung, depends upon a process known as branching morphogenesis, in which a simple epithelial bud gives rise to a complex tree-like system of tubes specialized for the transport of gas or fluids. Previous studies on lung development have highlighted a role for fibroblast growth factors (FGFs), made by the mesodermal cells, in promoting the proliferation, budding, and chemotaxis of the epithelial endoderm. Here, by using a three-dimensional culture system, we provide evidence for a novel role for Netrins, best known as axonal guidance molecules, in modulating the morphogenetic response of lung endoderm to exogenous FGFs. This effect involves inhibition of localized changes in cell shape and phosphorylation of the intracellular mitogen-activated protein kinase(s) (ERK1/2, for extracellular signal-regulated kinase-1 and -2), elicited by exogenous FGFs. The temporal and spatial expression of netrin 1, netrin 4, and Unc5b genes and the localization of Netrin-4 protein in vivo suggest a model in which Netrins in the basal lamina locally modulate and fine-tune the outgrowth and shape of emergent epithelial buds. 相似文献
102.
Setting up standards and a reference map for the alkaline proteome of the Gram-positive bacterium Lactococcus lactis 总被引:2,自引:0,他引:2
Despite the fact that almost 39% of the theoretical expressed proteins of Lactococcus lactis have a predicted isoelectric point above 7, these proteins have not been studied in previous proteome analyses. In the present study, we set up a reference map of alkaline lactococcal proteins by using immobilized pH gradients (IPG) spanning pH 6 to 12 and 9 to 12, and protein identification by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). Different electrophoresis systems for isoelectric focusing were evaluated to optimize the first dimension. Best results were obtained by sample application using cup-loading at the anodic side and increasing the final voltage up to 8000 V for IPGs, using N,N-dimethylacrylamide as monomer. After two-dimensional gel electrophoresis of extracts obtained from exponentially growing cells, about 200 protein spots were selected for identification by peptide mass fingerprinting. With MALDI-TOF MS, 153 proteins were identified that were the products of 85 different genes. Their predicted isoelectric points range from as high as 11.31 to as low as 6.34. Ribosomal proteins, hypothetical proteins and proteins with unknown function represent the largest groups of identified proteins. For further classification, the codon adaptation index (CAI) and grand average of hydropathicity (GRAVY) for each lactococcal protein were calculated. The protein with the lowest CAI identified in this study is the manganese ABC transporter ATP-binding protein. Less than 10% of the alkaline lactococcal proteins have a smaller CAI. The highest GRAVY for an identified protein is 0.26. The complete in silico data of Lactococcus lactis as well as clickable reference maps are available at www.wzw.tum.de/proteomik/lactis. 相似文献
103.
Wober J Möller F Richter T Unger C Weigt C Jandausch A Zierau O Rettenberger R Kaszkin-Bettag M Vollmer G 《The Journal of steroid biochemistry and molecular biology》2007,107(3-5):191-201
The special extract ERr 731® from the roots of Rheum rhaponticum is the major constituent of Phytoestrol® N which is used for the treatment of climacteric symptoms in menopausal women. However, the molecular mode of action of ERr 731® was unknown. For the first time, ERr 731® and its aglycones trans-rhapontigenin and desoxyrhapontigenin were investigated with regard to the activation of the estrogen receptor- or estrogen receptor-β (ER, ERβ). The related hydroxystilbenes cis-rhapontigenin, resveratrol and piceatannol were studied as comparators. As controls, 17β-estradiol or the selective ER-(propylpyrazoltriol) or ERβ-agonists (diarylpropionitril) were used. Neither in ER-expressing yeast cells, in the ER-responsive Ishikawa cells, nor in human endometrial HEC-1B cells transiently transfected with the ER an activation of ER by ERr 731® or the other single compounds was detected. Furthermore, an antiestrogenic effect was not observed. In contrast in human endometrial HEC-1B cells transiently transfected with the ERβ, 100 ng/ml ERr 731® and the single compounds significantly induced the ERβ-coupled luciferase activity in a range comparable to 10−8 M 17β-estradiol. All effects were abolished with the pure ER antagonist ICI 182780, indicating an ER-specific effect. The ERβ agonistic activity by ERr 731® could be of importance for its clinical use, as central functions relevant to climacteric complaints are proposed to be mediated via ERβ activation. 相似文献
104.
The absolute configuration of three 4‐aryl‐3,4‐dihydro‐2(1H)‐pyrimidones (Biginelli compounds, DHPMs) was established by comparison of the typical circular dichroism (CD) spectra of individual enantiomers with reference samples of known absolute configuration. The enantiomers were obtained by semipreparative separation of racemic mixtures on a Chiralcel OD‐H chiral stationary phase. The method was used to establish the enantiopreference of various lipases in biocatalytic kinetic resolution experiments employing activated DHPM esters. Chirality 11:659–662, 1999. © 1999 Wiley‐Liss, Inc. 相似文献
105.
Influence of Protoplasmic Water Loss on the Control of Protein Synthesis in the Desiccation-Tolerant Moss Tortula ruralis: Ramifications for a Repair-Based Mechanism of Desiccation Tolerance 总被引:8,自引:1,他引:8 下载免费PDF全文
Oliver MJ 《Plant physiology》1991,97(4):1501-1511
Desiccation tolerance of the moss Tortula ruralis is characterized by a desiccation-induced change in gene expression that becomes evident upon rehydration. As reported earlier, this change in gene expression is apparently brought about by a change in the control of translation and does not include a major shift in mRNA abundance. A full qualitative and quantitative analysis of the alteration in gene expression, which is characterized by the loss of (or greater than fivefold decrease in) the synthesis of 25 hydration (h) proteins and initiation (or greater than fivefold increase) of the synthesis of 74 rehydration (r) proteins, is given in this report. Exposure to a desiccating atmosphere, for times that result in varying levels of water loss, enabled the determination that the control of synthesis of r proteins is different from the control of synthesis of h proteins. The r and h protein synthesis responses are internally coordinate, however. Similarly, the return to normal levels of h protein synthesis differs from that of the r proteins. The return to normal synthetic levels for all h proteins is synchronous, but the rate of loss of r protein synthesis varies with each individual r protein. Run-off translation of polysomes isolated from gametophytes during the drying phase demonstrates that there are no novel mRNAs recruited and no particular mRNA is favored for translation during desiccation. These findings add credence to the argument that translational control is the major component of the desiccation-induced alteration in gene expression in this plant, as discussed. Aspects of the response of protein synthesis to desiccation are consistent with the hypothesis that T. ruralis exhibits a repair-based mechanism of desiccation tolerance. 相似文献
106.
Christian Beyer Georg Schett Steffen Gay Oliver Distler Jörg HW Distler 《Arthritis research & therapy》2009,11(2):220-9
Autoimmunity, microangiopathy and tissue fibrosis are hallmarks of systemic sclerosis (SSc). Vascular alterations and reduced
capillary density decrease blood flow and impair tissue oxygenation in SSc. Oxygen supply is further reduced by accumulation
of extracellular matrix (ECM), which increases diffusion distances from blood vessels to cells. Therefore, severe hypoxia
is a characteristic feature of SSc and might contribute directly to the progression of the disease. Hypoxia stimulates the
production of ECM proteins by SSc fibroblasts in a transforming growth factor-β-dependent manner. The induction of ECM proteins
by hypoxia is mediated via hypoxia-inducible factor-1α-dependent and -independent pathways. Hypoxia may also aggravate vascular
disease in SSc by perturbing vascular endothelial growth factor (VEGF) receptor signalling. Hypoxia is a potent inducer of
VEGF and may cause chronic VEGF over-expression in SSc. Uncontrolled over-expression of VEGF has been shown to have deleterious
effects on angiogenesis because it leads to the formation of chaotic vessels with decreased blood flow. Altogether, hypoxia
might play a central role in pathogenesis of SSc by augmenting vascular disease and tissue fibrosis. 相似文献
107.
Laeyendecker O Church JD Oliver AE Mwatha A Owen SM Donnell D Brookmeyer R Musoke P Jackson JB Guay L Nakabiito C Quinn TC Eshleman SH 《PloS one》2010,5(10):e13259
Background
Accurate incidence estimates are needed for surveillance of the HIV epidemic. HIV surveillance occurs at maternal-child health clinics, but it is not known if pregnancy affects HIV incidence testing.Methods
We used the BED capture immunoassay (BED) and an antibody avidity assay to test longitudinal samples from 51 HIV-infected Ugandan women infected with subtype A, C, D and intersubtype recombinant HIV who were enrolled in the HIVNET 012 trial (37 baseline samples collected near the time of delivery and 135 follow-up samples collected 3, 4 or 5 years later). Nineteen of 51 women were also pregnant at the time of one or more of the follow-up visits. The BED assay was performed according to the manufacturer''s instructions. The avidity assay was performed using a Genetic Systems HIV-1/HIV-2 + O EIA using 0.1M diethylamine as the chaotropic agent.Results
During the HIVNET 012 follow-up study, there was no difference in normalized optical density values (OD-n) obtained with the BED assay or in the avidity test results (%) when women were pregnant (n = 20 results) compared to those obtained when women were not pregnant (n = 115; for BED: p = 0.9, generalized estimating equations model; for avidity: p = 0.7, Wilcoxon rank sum). In addition, BED and avidity results were almost exactly the same in longitudinal samples from the 18 women who were pregnant at only one study visit during the follow-up study (p = 0.6, paired t-test).Conclusions
These results from 51 Ugandan women suggest that any changes in the antibody response to HIV infection that occur during pregnancy are not sufficient to alter results obtained with the BED and avidity assays. Confirmation with larger studies and with other HIV subtypes is needed. 相似文献108.
Nadine Flinner Lars Ellenrieder Sebastian B. Stiller Thomas Becker Enrico Schleiff Oliver Mirus 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》2013,1833(12):3314-3325
Mitochondrial β-barrel proteins fulfill central functions in the outer membrane like metabolite exchange catalyzed by the voltage-dependent anion channel (VDAC) and protein biogenesis by the central components of the preprotein translocase of the outer membrane (Tom40) or of the sorting and assembly machinery (Sam50). The mitochondrial division and morphology protein Mdm10 is another essential outer membrane protein with proposed β-barrel fold, which has so far only been found in Fungi. Mdm10 is part of the endoplasmic reticulum mitochondria encounter structure (ERMES), which tethers the ER to mitochondria and associates with the SAM complex. In here, we provide evidence that Mdm10 phylogenetically belongs to the VDAC/Tom40 superfamily. Contrary to Tom40 and VDAC, Mdm10 exposes long loops towards both sides of the membrane. Analyses of single loop deletion mutants of Mdm10 in the yeast Saccharomyces cerevisiae reveal that the loops are dispensable for Mdm10 function. Sequences similar to fungal Mdm10 can be found in species from Excavates to Fungi, but neither in Metazoa nor in plants. Strikingly, the presence of Mdm10 coincides with the appearance of the other ERMES components. Mdm10's presence in both unikonts and bikonts indicates an introduction at an early time point in eukaryotic evolution. 相似文献
109.
Oliver Robertson Martine Maron Yvonne Buckley Alan House Clive McAlpine 《Austral ecology》2014,39(3):255-266
Many passerine bird populations, particularly those that have open‐cup nests, are in decline in agricultural landscapes. Current theory suggests that an increase in habitat generalist predators in response to landscape change is partially responsible for these declines. However, empirical tests have failed to reach a consensus on how and through what mechanisms landscape change affects nest predation. We tested one hypothesis, the Additive Predation Model, with an artificial nest experiment in fragmented landscapes in southern Queensland, Australia. We employed structural equation modelling of the influence of the relative density of woodland and habitat generalist predators and landscape features at the nest, site, patch and landscape scales on the probability of nest predation. We found little support for the Additive Predation Model, with no significant influence of the density of woodland predators on the probability of nest predation, although landscape features at different spatial scales were important. Within woodlands fragmented by agriculture in eastern Australia, the presence of noisy miner colonies appears to influence ecological processes important for nest predation such that the Additive Predation Model does not hold. In the absence of colonies of the aggressive native bird, the noisy miner, the influence of woodland predators on the risk of artificial nest predation was low compared with that of habitat generalist predators. Outside noisy miner colonies, we found significant edge effects with greater predation rates for artificial nests within woodland patches located closer to the agricultural matrix. Furthermore, the density of habitat generalist predators increased with the extent of irrigated land‐use, suggesting that in the absence of noisy miner colonies, nest predation increases with land‐use intensity at the landscape scale. 相似文献
110.
Jeannine Günther Angela Kill Mike Oliver Becker Harald Heidecke Judith Rademacher Elise Siegert Mislav Radi? Gerd-Rüdiger Burmester Duska Dragun Gabriela Riemekasten 《Arthritis research & therapy》2014,16(2):R65