284 research outputs found

    Complementarity effects through dietary mixing enhance the performance of a generalist insect herbivore

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    The ontogenetic niche concept predicts that resource use depends on an organism’s developmental stage. This concept has been investigated primarily in animals that show differing resource use strategies as juveniles and as adults, such as amphibians. We studied resource use and performance in the grasshopper Chorthippus parallelus (Orthoptera, Acrididae) provided with food plant mixtures of either one, three or eight plant species throughout their development. C. parallelus survival and fecundity was highest in the food plant mixture with eight plant species and lowest in the treatments where only one single plant species was offered as food. C. parallelus’ consumption throughout its ontogeny depended on sex, and feeding on different plant species was dependent on a grasshopper’s developmental stage. To depict grasshopper foraging in food plant mixtures compared to foraging on single plant species, we introduce the term “relative forage total” (RFT) based on an approach used in biodiversity research by Loreau and Hector (Nature 413:548–274, 2001). RFT of grasshoppers in food plant mixtures was always higher than what would have been expected from foraging in monocultures. The increase in food consumption was due to an overall increase in feeding on plant species in mixtures compared to consumption of the same species offered as a single diet. Thus we argue that grasshopper foraging exhibits complementarity effects. Our results reinforce the necessity to consider development-related changes in insect herbivore feeding. Thorough information on the feeding ontogeny of insect herbivores could not only elucidate their nutritional ecology but also help to shed light on their functional role in plant communities

    Associations between MTHFR 1793G>A and plasma total homocysteine, folate, and vitamin B12 in kidney transplant recipients

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    Associations between MTHFR 1793G>A and plasma total homocysteine, folate, and vitamin B12 in kidney transplant recipients.BackgroundCurrently, no evidence is available on the putative associations between a novel single nucleotide polymorphism of the 5,10-methylenetetrahydrofolate reductase gene MTHFR 1793G>A and plasma levels of vitamin B12, folate, or total homocysteine (tHcy).MethodsIn a cross-sectional study of 730 kidney allograft recipients, patients were categorized by MTHFR 1793G>A genotype. In univariate and multivariate linear regression models that allowed the outcome variables vitamin B12, folate, and tHcy plasma levels to follow a gamma distribution, we tested for possible associations of allelic variants of MTHFR 1793G>A and these three dependent variables. As hypothesized in previous work, we specifically evaluated possible effect modification between the MTHFR 1793G>A and 1298A>C mutations on these outcomes.ResultsThe allele frequency for MTHFR 1793G>A was 0.052. Heterozygosity (N = 72) or homozygosity (N = 2) for MTHFR 1793G>A was not independently associated with plasma levels of vitamin B12 (P = 0.33) or tHcy (P = 0.70), but a borderline association with higher folate concentrations was detected (Δfolate = 1.91 nmol/L) (95% CI -0.03 to 3.86 nmol/L) (P = 0.05). Further, we found strong and significant positive interactions between the MTHFR 1793G>A and 1298A>C mutations on vitamin B12 concentrations.ConclusionHigher folate concentrations in kidney transplant recipients with MTHFR 1793GA or 1793AA and markedly higher concentrations of vitamin B12 in patients with combined MTHFR 1793G>A and 1298A>C mutations may contribute to the survival advantage that has been postulated for such patients showing these genotypes

    Heme oxygenase-1 genotype and restenosis after balloon angioplasty: a novel vascular protective factor

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    AbstractObjectivesWe investigated the association of the heme oxygenase-1 (HO-1) promoter genotype with the inflammatory response and restenosis after balloon angioplasty.BackgroundHeme oxygenase-1, which is induced by balloon angioplasty, can inhibit neointima formation and vascular remodeling. A dinucleotide repeat in the HO-1 gene promoter shows a length polymorphism that modulates HO-1 gene transcription. Short (<25 guanosine thymidine [GT]) repeats are associated with a 10-fold greater up-regulation of HO-1 than are longer repeats.MethodsWe studied 381 consecutive patients who underwent femoropopliteal balloon angioplasty (n = 210) and comparison groups with femoropopliteal stenting (n = 68) and lower limb angiography (n = 103). C-reactive protein (CRP) was measured at baseline, 24, and 48 h. We evaluated patency at six months by duplex sonography and assessed the association of the length of GT repeats in the HO-1 gene promoter with postintervention CRP and restenosis.ResultsRestenosis within six months was found in 74 patients (35%) after balloon angioplasty and in 21 patients (31%) after stenting. After balloon angioplasty, carriers of the short length (<25 GT) dinucleotide repeats had a lower postintervention CRP at 24 h (p = 0.009) and 48 h (p < 0.001) and a reduced risk for restenosis (adjusted relative risk 0.43, 95% confidence interval: 0.24 to 0.71, p < 0.001) compared with patients with longer alleles. After stenting or angiography, we found no association between the HO-1 genotype with CRP or restenosis.ConclusionsThe HO-1 promoter genotype that controls the degree of HO-1 up-regulation in response to stress stimuli is associated with the postintervention inflammatory response and the restenosis risk after balloon angioplasty

    Electron Cloud: Observations with LHC-Type Beams in the SPS

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    In August 1999, strong pressure increases were observed in the SPS in the presence of the new LHC-type beams. This paper reports on observations of the electron cloud phenomenon and the related pressure increase as a function of parameters such as the number of protons per bunch, the number of bunches per batch, the shape of the vacuum chamber and the electron current collected on pick-ups. Results of the observed clean-up, "beam scrubbing" will be presented as well as the consequences of the e-cloud phenomenon on the SPS operation with the LHC nominal beam intensity

    Sektoralisierung als Planungsherausforderung im inklusiven Gemeinwesen

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    2. Hrsg.: Martin F. Reichstein Förderung durch: Forschungsinstitut für gesellschaftliche Weiterentwicklung (FGW)Seit September 2016 führt das Zentrum für Planung und Evaluation Sozialer Dienste (ZPE) der Universität Siegen das Forschungsprojekt „Koordinationspotenziale kommunaler Teilhabepolitik in der Pflege, Behindertenhilfe und Sozialpsychiatrie (KoKoP)“ durch. Das Projekt wird im Rahmen des Programms „Vorbeugende Sozialpolitik“ des nordrheinwestfä- lischen Forschungsinstituts für Gesellschaftliche Weiterentwicklung (FGW) finanziell gefördert. Ziel des Projektes ist es, anhand empirischer Untersuchungen Erkenntnisse darüber zu gewinnen, welche Möglichkeiten für Kommunen bestehen, durch Planung und Koordination die Wirkungen von Teilhabeleistungen in den Leistungsbereichen der Pflege, Behindertenhilfe und Sozialpsychiatrie zu optimieren. Zudem soll der Frage nachgegangen werden, wie professionelle Hilfen stärker mit informellen Ressourcen im Vor- und Umfeld des Leistungsgeschehens verknüpft werden können. Mögliche Problemquellen werden u.a. in einer ausgeprägten Sektoralisierung des Leistungsgeschehens, mangelnder Kooperation sowie in einer geringen Sozialraumorientierung vermutet. Im Rahmen eines eintägigen Expertenworkshops am 14. November 2017 wurden zum einen Zwischenergebnisse bisheriger Untersuchungen vorgestellt und diskutiert. Zum anderen wurden in drei Arbeitsgruppen zentrale Fragestellungen des Projekts erörtert. Der vorliegende Band ist eine Zusammenschau von Beiträgen einzelner Teilnehmer*innen dieses Workshops

    Electron Cloud Effects in the CERN SPS and LHC

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    Electron cloud effects have been recently observed in the CERN SPS in the presence of LHC type proton beams with 25 ns bunch spacing. Above a threshold intensity of about 4 X 10^12 protons in 81 consecutive bunches, corresponding to half of the nomina

    Non-target screening with high-resolution mass spectrometry: critical review using a collaborative trial on water analysis

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    In this article, a dataset from a collaborative nontarget screening trial organised by the NORMAN Association is used to review the state-of-the-art and discuss future perspectives of non-target screening using high-resolution mass spectrometry in water analysis. A total of 18 institutes from 12 European countries analysed an extract of the same water sample collected from the River Danube with either one or both of liquid and gas chromatography coupled with mass spectrometry detection. This article focuses mainly on the use of high resolution screening techniques with target, suspect, and non-target workflows to identify substances in environmental samples. Specific examples are given to emphasise major challenges including isobaric and co-eluting substances, dependence on target and suspect lists, formula assignment, the use of retention information, and the confidence of identification. Approaches and methods applicable to unit resolution data are also discussed. Although most substances were identified using high resolution data with target and suspect-screening approaches, some participants proposed tentative non-target identifications. This comprehensive dataset revealed that nontarget analytical techniques are already substantially harmonised between the participants, but the data processing remains time-consuming. Although the objective of a Bfullyautomated identification workflow^ remains elusive in the short term, important steps in this direction have been taken, exemplified by the growing popularity of suspect screening approaches. Major recommendations to improve non-target screening include better integration and connection of desired features into software packages, the exchange of target and suspect lists, and the contribution of more spectra from standard substances into (openly accessible) databases.This work was supported in part by the SOLUTIONS project, which received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under Grant Agreement No. 603437

    The rotation-coupled sliding of EcoRV

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    It has been proposed that certain type II restriction enzymes (REs), such as EcoRV, track the helical pitch of DNA as they diffuse along DNA, a so-called rotation-coupled sliding. As of yet, there is no direct experimental observation of this phenomenon, but mounting indirect evidence gained from single-molecule imaging of RE–DNA complexes support the hypothesis. We address this issue by conjugating fluorescent labels of varying size (organic dyes, proteins and quantum dots) to EcoRV, and by fusing it to the engineered Rop protein scRM6. Single-molecule imaging of these modified EcoRVs sliding along DNA provides us with their linear diffusion constant (D1), revealing a significant size dependency. To account for the dependence of D1 on the size of the EcoRV label, we have developed four theoretical models describing different types of motion along DNA and find that our experimental results are best described by rotation-coupled sliding of the protein. The similarity of EcoRV to other type II REs and DNA binding proteins suggests that this type of motion could be widely preserved in other biological contexts
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