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81.
Adenoviruses use lactoferrin as a bridge for CAR-independent binding to and infection of epithelial cells 下载免费PDF全文
Johansson C Jonsson M Marttila M Persson D Fan XL Skog J Frängsmyr L Wadell G Arnberg N 《Journal of virology》2007,81(2):954-963
Most adenoviruses bind to the coxsackie- and adenovirus receptor (CAR). Surprisingly, CAR is not expressed apically on polarized cells and is thus not easily available to viruses. Consequently, alternative mechanisms for entry of coxsackievirus and adenovirus into cells have been suggested. We have found that tear fluid promotes adenovirus infection, and we have identified human lactoferrin (HLf) as the tear fluid component responsible for this effect. HLf alone was found to promote binding of adenovirus to epithelial cells in a dose-dependent manner and also infection of epithelial cells by adenovirus. HLf was also found to promote gene delivery from an adenovirus-based vector. The mechanism takes place at the binding stage and functions independently of CAR. Thus, we have identified a novel binding mechanism whereby adenovirus hijacks HLf, a component of the innate immune system, and uses it as a bridge for attachment to host cells. 相似文献
82.
Marko J. Spasojevic Susan Harrison Howard W. Day Randal J. Southard 《Ecology letters》2014,17(6):700-709
One important but largely unanswered question about floristic responses to climate change is how interactions such as competition, facilitation and plant–soil feedbacks will influence the ability of species to track shifting climates. In a rugged and moisture‐limited region that has recently warmed by 2° (Siskiyou Mountains, OR, USA), we planted three species into cooler aspects and elevations than those they currently inhabit, with and without removal of neighbouring plants, and tracked them over 2 years. Two species had higher success in cooler topographic locations, and this success was enhanced by neighbouring plants, which appeared to modulate minimum growing season temperatures. One species' success was also facilitated by the higher soil organic matter found in cooler sites. These results are a novel experimental demonstration of two important factors that may buffer climate change impacts on plants: rugged topography and plant–plant facilitation. 相似文献
83.
Burger C Belskii E Eeva T Laaksonen T Mägi M Mänd R Qvarnström A Slagsvold T Veen T Visser ME Wiebe KL Wiley C Wright J Both C 《The Journal of animal ecology》2012,81(4):926-936
1.?Climate warming has led to shifts in the seasonal timing of species. These shifts can differ across trophic levels, and as a result, predator phenology can get out of synchrony with prey phenology. This can have major consequences for predators such as population declines owing to low reproductive success. However, such trophic interactions are likely to differ between habitats, resulting in differential susceptibility of populations to increases in spring temperatures. A mismatch between breeding phenology and food abundance might be mitigated by dietary changes, but few studies have investigated this phenomenon. Here, we present data on nestling diets of nine different populations of pied flycatchers Ficedula hypoleuca, across their breeding range. This species has been shown to adjust its breeding phenology to local climate change, but sometimes insufficiently relative to the phenology of their presumed major prey: Lepidoptera larvae. In spring, such larvae have a pronounced peak in oak habitats, but to a much lesser extent in coniferous and other deciduous habitats. 2.?We found strong seasonal declines in the proportions of caterpillars in the diet only for oak habitats, and not for the other forest types. The seasonal decline in oak habitats was most strongly observed in warmer years, indicating that potential mismatches were stronger in warmer years. However, in coniferous and other habitats, no such effect of spring temperature was found. 3.?Chicks reached somewhat higher weights in broods provided with higher proportions of caterpillars, supporting the notion that caterpillars are an important food source and that the temporal match with the caterpillar peak may represent an important component of reproductive success. 4.?We suggest that pied flycatchers breeding in oak habitats have greater need to adjust timing of breeding to rising spring temperatures, because of the strong seasonality in their food. Such between-habitat differences can have important consequences for population dynamics and should be taken into account in studies on phenotypic plasticity and adaptation to climate change. 相似文献
84.
Seven of the 45 subunits of mitochondrial NADH:ubiquinone oxidoreductase (complex I) are mitochondrially encoded and have been shown to harbor pathogenic mutations. We modeled the human disease-associated mutations A4136G/ND1-Y277C, T4160C/ND1-L285P and C4171A/ND1-L289M in a highly conserved region of the fourth matrix-side loop of the ND1 subunit by mutating homologous amino acids and surrounding conserved residues of the NuoH subunit of Escherichia coli NDH-1. Deamino-NADH dehydrogenase activity, decylubiquinone reduction kinetics, hexammineruthenium (HAR) reductase activity, and the proton pumping efficiency of the enzyme were assayed in cytoplasmic membrane preparations.Among the human disease-associated mutations, a statistically significant 22% decrease in enzyme activity was observed in the NuoH-L289C mutant and a 29% decrease in the double mutant NuoH-L289C/V297P compared with controls. The adjacent mutations NuoH-D295A and NuoH-R293M caused 49% and 39% decreases in enzyme activity, respectively. None of the mutations studied significantly affected the Km value of the enzyme for decylubiquinone or the amount of membrane-associated NDH-1 as estimated from the HAR reductase activity. In spite of the decrease in enzyme activity, all the mutant strains were able to grow on malate, which necessitates sufficient NDH-1 activity. The results show that in ND1/NuoH its fourth matrix-side loop is probably not directly involved in ubiquinone binding or proton pumping but has a role in modifying enzyme activity. 相似文献
85.
Seppo Andersson Yurong Wang Raili P?nni Tuomas H?nninen Marko Mononen Haiqing Ren Ritva Serimaa Pekka Saranp?? 《植物学报(英文版)》2015,(4):388-395
We studied in detail the mean micro fibril angle and the width of cellulose crystals from the pith to the bark of a 15-year-old Maidenhair tree(Ginkgo biloba L.). The orientation of cellulose micro fibrils with respect to the cell axis and the width and length of cellulose crystallites were determined using Xray diffraction. Raman microscopy was used to compare the lignin distribution in the cell wall of normal/opposite and compression wood, which was found near the pith. Ginkgo biloba showed a relatively large mean micro fibril angle,varying between 19° and 39° in the S2 layer, and the average width of cellulose crystallites was 3.1–3.2 nm. Mild compression wood without any intercellular spaces or helical cavities was observed near the pith. Slit-like bordered pit openings and a heavily lignified S2 L layer con firmed the presence of compression wood. Ginkgo biloba showed typical features present in the juvenile wood of conifers. The micro fibril angle remained large over the 14 annual rings. The entire stem disc,with a diameter of 18 cm, was considered to consist of juvenile wood. The properties of juvenile and compression wood as well as the cellulose orientation and crystalline width indicate that the wood formation of G. biloba is similar to that of modern conifers. 相似文献
86.
The centrosome is the principal microtubule organizing center in most animal cells. It consists of a pair of centrioles surrounded by pericentriolar material. The centrosome, like DNA, duplicates exactly once per cell cycle. During interphase duplicated centrosomes remain closely linked by a proteinaceous linker. This centrosomal linker is composed of rootletin filaments that are anchored to the centrioles via the protein C-Nap1. At the onset of mitosis the linker is dissolved by Nek2A kinase to support the formation of the bipolar mitotic spindle. The importance of the centrosomal linker for cell function during interphase awaits characterization. Here we assessed the phenotype of human RPE1 C-Nap1 knockout (KO) cells. The absence of the linker led to a modest increase in the average centrosome separation from 1 to 2.5 μm. This small impact on the degree of separation is indicative of a second level of spatial organization of centrosomes. Microtubule depolymerisation or stabilization in C-Nap1 KO cells dramatically increased the inter-centrosomal separation (> 8 μm). Thus, microtubules position centrosomes relatively close to one another in the absence of linker function. C-Nap1 KO cells had a Golgi organization defect with a two-fold expansion of the area occupied by the Golgi. When the centrosomes of C-Nap1 KO cells showed considerable separation, two spatially distinct Golgi stacks could be observed. Furthermore, migration of C-Nap1 KO cells was slower than their wild type RPE1 counterparts. These data show that the spatial organization of centrosomes is modulated by a combination of centrosomal cohesion and microtubule forces. Furthermore a modest increase in centrosome separation has major impact on Golgi organization and cell migration. 相似文献
87.
Lovro ?ubelj Marko Bajec Biljana Mileva Boshkoska Andrej Kastrin Zoran Levnaji? 《PloS one》2015,10(5)
Science is a social process with far-reaching impact on our modern society. In recent years, for the first time we are able to scientifically study the science itself. This is enabled by massive amounts of data on scientific publications that is increasingly becoming available. The data is contained in several databases such as Web of Science or PubMed, maintained by various public and private entities. Unfortunately, these databases are not always consistent, which considerably hinders this study. Relying on the powerful framework of complex networks, we conduct a systematic analysis of the consistency among six major scientific databases. We found that identifying a single "best" database is far from easy. Nevertheless, our results indicate appreciable differences in mutual consistency of different databases, which we interpret as recipes for future bibliometric studies. 相似文献
88.
Heli Elovaara Teija Huusko Mikael Maksimow Kati Elima Gennady G. Yegutkin Mikael Skurnik Ulrich Dobrindt Anja Siitonen Michael J. McPherson Marko Salmi Sirpa Jalkanen 《PloS one》2015,10(11)
Escherichia coli amine oxidase (ECAO), encoded by the tynA gene, catalyzes the oxidative deamination of aromatic amines into aldehydes through a well-established mechanism, but its exact biological role is unknown. We investigated the role of ECAO by screening environmental and human isolates for tynA and characterizing a tynA-deletion strain using microarray analysis and biochemical studies. The presence of tynA did not correlate with pathogenicity. In tynA+ Escherichia coli strains, ECAO enabled bacterial growth in phenylethylamine, and the resultant H2O2 was released into the growth medium. Some aminoglycoside antibiotics inhibited the enzymatic activity of ECAO, which could affect the growth of tynA+ bacteria. Our results suggest that tynA is a reserve gene used under stringent environmental conditions in which ECAO may, due to its production of H2O2, provide a growth advantage over other bacteria that are unable to manage high levels of this oxidant. In addition, ECAO, which resembles the human homolog hAOC3, is able to process an unknown substrate on human leukocytes. 相似文献
89.
Maria A. Lankinen Kati Hanhineva Marjukka Kolehmainen Marko Lehtonen Seppo Auriola Hannu Mykk?nen Kaisa Poutanen Ursula Schwab Matti Uusitupa 《PloS one》2015,10(4)
Objective
3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF) is a metabolite produced endogenously from dietary sources of furan fatty acids. The richest source of furan fatty acids in human diet is fish. CMPF was recently shown to be elevated in fasting plasma in individuals with gestational diabetes and type 2 diabetes, and mechanistically high level of CMPF was linked to β cell dysfunction. Here we aimed to study the association between plasma CMPF level and glucose metabolism in persons with impaired glucose metabolism.Methods
Plasma CMPF concentration was measured from plasma samples of the study participants in an earlier controlled dietary intervention. All of them had impaired glucose metabolism and two other characteristics of the metabolic syndrome. Altogether 106 men and women were randomized into three groups for 12 weeks with different fish consumption (either three fatty fish meals per week, habitual fish consumption or maximum of one fish meal per week). Associations between concentration of CMPF and various glucose metabolism parameters at an oral glucose tolerance test at baseline and at the end of the study were studied.Results
Fasting plasma CMPF concentration was significantly increased after a 12-week consumption of fatty fish three times per week, but the concentration remained much lower compared to concentrations reported in diabetic patients. Increases of plasma CMPF concentrations mostly due to increased fish consumption were not associated with impaired glucose metabolism in this study. Instead, elevated plasma CMPF concentration was associated with decreased 2-hour insulin concentration in OGTT.Conclusions
Moderately elevated concentration of CMPF in plasma resulting from increased intake of fish is not harmful to glucose metabolism. Further studies are needed to fully explore the role of CMPF in the pathogenesis of impaired glucose metabolism.Trial Registration
ClinicalTrials.gov NCT00573781 相似文献90.
Markus Fehr Simone Baechler Christopher Kropat Christian Mielke Fritz Boege Gudrun Pahlke Doris Marko 《Mycotoxin Research》2010,26(4):247-256
Alternariol (AOH) was reported recently to act as a topoisomerase poison. To underline the relevance of topoisomerase targeting for the genotoxic properties of AOH, we addressed the question whether human tyrosyl-DNA phosphodiesterase 1 (TDP1), an enzyme vital to the repair of covalent DNA-topoisomerase adducts, affects AOH-mediated genotoxicity. The relevance of TDP1 activity on AOH-induced genotoxicity was investigated by the comet assay in human cells overexpressing GFP chimera of TDP1 or the inactive mutant TDP1H263A as well as in cells subjected to siRNA-mediated knock-down of endogenous TDP1. Cells overexpressing TDP1 exhibited significantly less DNA damage after treatment with AOH in comparison to cells expressing the inactive mutant TDP1H263A. In accordance with these results, levels of AOH inducing DNA strand breaks were increased in TDP1-suppressed cells in comparison to cells transfected with control siRNA. The specific topoisomerase poisons camptothecin and etoposide caused comparable effects, underlining that TDP1 plays an important role in the repair of topoisomerase-mediated DNA damage. In summary, the repair enzyme TDP1 was identified as a factor for the modulation of AOH-mediated DNA damage in human cells. 相似文献