Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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The impact of dietary fibers on dendritic cell responses in vitro is dependent on the differential effects of the fibers on intestinal epithelial cells
Bermudez-Brito, M. ; Sahasrabudhe, N.M. ; Rösch, C. ; Schols, H.A. ; Faas, M.M. ; Vos, P. de - \ 2015
Molecular Nutrition & Food Research 59 (2015)4. - ISSN 1613-4125 - p. 698 - 710.
immune function - receptor 2 - health - homeostasis - modulation - mortality - polysaccharides - activation - mechanisms - prebiotics
Scope In the present study, the direct interaction of commonly consumed fibers with epithelial or dendritic cells (DCs) was studied. Methods and results The fibers were characterized for their sugar composition and chain length profile. When in direct contact, fibers activate DCs only mildly. This was different when DCs and fibers were co-cultured together with supernatants from human epithelial cells (Caco spent medium). Caco spent medium enhanced the production of IL-12, IL-1Ra, IL-6, IL-8, TNF-a, MCP-1 (monocyte chemotactic protein), and MIP-1a but this was strongly attenuated by the dietary fibers. This attenuating effect on proinflammatory cytokines was dependent on the interaction of the fibers with Toll-like receptors as it was reduced by Pepinh-myd88. The interaction of galacto-oligosaccharides, chicory inulin, wheat arabinoxylan, barley ß-glucan with epithelial cells and DCs led to changes in the production of the Th1 cytokines in autologous T cells, while chicory inulin, and barley ß-glucan reduced the Th2 cytokine IL-6. The Treg-promoting cytokine IL-10 was induced by galacto-oligosaccharides whereas chicory inulin decreased the IL-10 production. Conclusions Our results suggest that dietary fibers can modulate the host immune system not only by the recognized mechanism of effects on microbiota but also by direct interaction with the consumer's mucosa. This modulation is dietary fiber type dependent.
The effect of molecular composition and crosslinking on adhesion of a bio-inspired adhesive
Yang, J. ; Keijsers, J. ; Heek, M. van; Stuiver, A. ; Cohen Stuart, M.A. ; Kamperman, M.M.G. - \ 2015
Polymer Chemistry 6 (2015). - ISSN 1759-9954 - p. 3121 - 3130.
polychaete phragmatopoma-californica - density-functional theory - mussel - protein - dopa - mechanisms - surfaces - catechol - glue
In this article, catechol-functionalized polymers are synthesized by free radical polymerization of dopamine methacrylamide (DMA) and 2-methoxyethyl methacrylate (MEA) at 60 °C in DMF. By varying the DMA content in the polymer, it is found that during free radical polymerization, the catechol groups in DMA react with the propagating radicals, resulting in the formation of a crosslinked structure. We systematically study the effect of DMA content and crosslinking on the adhesion properties of the polymers. Under both dry and wet conditions, maximum adhesion is obtained for a polymer composed of 5 mol% DMA. This polymer exhibits an optimum balance between the catechol content to strengthen the interface, compliance to ensure good contact formation and cohesive strength to resist separation. An increase in the crosslinking degree of the polymer resulted in reduced dry adhesion.
Species richness, but not phylogenetic diversity, influences community biomass production and temporal stability in a re-examination of 16 grassland biodiversity studies
Venail, P. ; Gross, K. ; Oakley, T.H. ; Narwani, A. ; Allan, E. ; Flombaum, P. ; Isbell, F. ; Reich, P.B. ; Tilman, D. ; Ruijven, J. van; Cardinale, B.J. - \ 2015
Functional Ecology 29 (2015)5. - ISSN 0269-8463 - p. 615 - 626.
water green-algae - functional diversity - ecosystem stability - niche conservatism - current knowledge - plant diversity - ecology - relatedness - environments - mechanisms
1.Hundreds of experiments have now manipulated species richness (SR) of various groups of organisms and examined how this aspect of biological diversity influences ecosystem functioning. Ecologists have recently expanded this field to look at whether phylogenetic diversity (PD) among species, often quantified as the sum of branch lengths on a molecular phylogeny leading to all species in a community, also predicts ecological function. Some have hypothesized that phylogenetic divergence should be a superior predictor of ecological function than SR because evolutionary relatedness represents the degree of ecological and functional differentiation among species. But studies to date have provided mixed support for this hypothesis. 2.Here, we reanalyse data from 16 experiments that have manipulated plant SR in grassland ecosystems and examined the impact on above-ground biomass production over multiple time points. Using a new molecular phylogeny of the plant species used in these experiments, we quantified how the PD of plants impacts average community biomass production as well as the stability of community biomass production through time. 3.Using four complementary analyses, we show that, after statistically controlling for variation in SR, PD (the sum of branches in a molecular phylogenetic tree connecting all species in a community) is neither related to mean community biomass nor to the temporal stability of biomass. These results run counter to past claims. However, after controlling for SR, PD was positively related to variation in community biomass over time due to an increase in the variances of individual species, but this relationship was not strong enough to influence community stability. 4.In contrast to the non-significant relationships between PD, biomass and stability, our analyses show that SR per se tends to increase the mean biomass production of plant communities, after controlling for PD. The relationship between SR and temporal variation in community biomass was either positive, non-significant or negative depending on which analysis was used. However, the increases in community biomass with SR, independently of PD, always led to increased stability. These results suggest that PD is no better as a predictor of ecosystem functioning than SR. 5.Synthesis. Our study on grasslands offers a cautionary tale when trying to relate PD to ecosystem functioning suggesting that there may be ecologically important trait and functional variation among species that is not explained by phylogenetic relatedness. Our results fail to support the hypothesis that the conservation of evolutionarily distinct species would be more effective than the conservation of SR as a way to maintain productive and stable communities under changing environmental conditions.
Biochar application does not improve the soil hydrological function of a sandy soil
Jeffery, S. ; Meinders, M.B.J. ; Stoof, C.R. ; Bezemer, T.M. ; Voorde, T.F.J. van de; Mommer, L. ; Groenigen, J.W. van - \ 2015
Geoderma 251-252 (2015). - ISSN 0016-7061 - p. 47 - 54.
water repellency - contact angles - productivity - mechanisms - retention - pyrolysis - stability - porosity - charcoal - carbon
Biochar application to soil is currently being widely posited as a means to improve soil quality and thereby increase crop yield. Next to beneficial effects on soil nutrient availability and retention, biochar is assumed to improve soil water retention. However, evidence for such an effect in the primary literature remains elusive. Therefore, we studied the effect of biochar on soil hydrological characteristics in two separate field experiments on a sandy soil in The Netherlands. In Experiment I, biochar produced through slowpyrolysis of herbaceous feedstock at two temperatures (400 °C and 600 °C) was applied to soil at a rate of 10 t ha-1. In Experiment II, the 400 °C biochar was applied at rates of 1, 5, 20 and 50 t ha-1. Soils were analysed for soil water retention, aggregate stability and other soil physical parameters after three growing seasons and one growing season for Experiment I and Experiment II, respectively.Wecharacterised the pore structure of the biochar using X-ray computed micro-tomography (XRT) and hydrophobicity using contact angle measurements.We found no significant effects of biochar application on soilwater retention in either experiment. Aggregate stability was also not significantly affected, nor was field saturated hydraulic conductivity. XRT analysis of the biochars showed that they were highly porous, with 48% and 57% porosity for the 400 °C and 600 °C biochar respectively. More than 99% of internal pores of the biochar particles were connected to the surface, suggesting a potential role for biochars in improving soil water retention. However, the biochars were highly hydrophobic. We postulate that this strong hydrophobicity prevented water from infiltrating into the biochar particles, prohibiting an effect on soil water retention. Our results suggest that, in addition to characterising pore space, biochars should be analysed for hydrophobicity when assessing their potential for improving soil physical properties.
Human buccal epithelium acquires microbial hyporesponsiveness at birth, a role for secretory leukocyte protease inhibitor
Menckeberg, C.L. ; Hol, J. ; Simons-Oosterhuis, Y. ; Raatgeep, H.R. ; Ruiter, L.F. de; Lindenbergh-Kortleve, D.J. ; Korteland-van Male, A.M. ; Aidy, S.F. El; Lierop, P.P.E. van; Kleerebezem, M. ; Groeneweg, M. ; Kraal, G. ; Elink-Schuurman, B.E. ; Jongste, J.C. de; Nieuwenhuis, E.E.S. ; Samsom, J.N. - \ 2015
Gut 64 (2015). - ISSN 0017-5749 - p. 884 - 893.
toll-like receptors - negative regulation - intestinal-mucosa - crohn-disease - responses - cells - tolerance - lipopolysaccharide - inflammation - mechanisms
Objective Repetitive interaction with microbial stimuli renders epithelial cells (ECs) hyporesponsive to microbial stimulation. Previously, we have reported that buccal ECs from a subset of paediatric patients with Crohn's disease are not hyporesponsive and spontaneously released chemokines. We now aimed to identify kinetics and mechanisms of acquisition of hyporesponsiveness to microbial stimulation using primary human buccal epithelium. Design Buccal ECs collected directly after birth and in later stages of life were investigated. Chemokine release and regulatory signalling pathways were studied using primary buccal ECs and the buccal EC line TR146. Findings were extended to the intestinal mucosa using murine model systems. Results Directly after birth, primary human buccal ECs spontaneously produced the chemokine CXCL-8 and were responsive to microbial stimuli. Within the first weeks of life, these ECs attained hyporesponsiveness, associated with inactivation of the NF-¿B pathway and upregulation of the novel NF-¿B inhibitor SLPI but no other known NF-¿B inhibitors. SLPI protein was abundant in the cytoplasm and the nucleus of hyporesponsive buccal ECs. Knock-down of SLPI in TR146-buccal ECs induced loss of hyporesponsiveness with increased NF-¿B activation and subsequent chemokine release. This regulatory mechanism extended to the intestine, as colonisation of germfree mice elicited SLPI expression in small intestine and colon. Moreover, SLPI-deficient mice had increased chemokine expression in small intestinal and colonic ECs. Conclusions We identify SLPI as a new player in acquisition of microbial hyporesponsiveness by buccal and intestinal epithelium in the first weeks after microbial colonisation.
Surface properties and phosphate adsorption of binary systems containing goethite and kaolinite
Wei, S.Y. ; Tan, W.F. ; Liu, F. ; Zhao, W. ; Weng, L. - \ 2014
Geoderma 213 (2014). - ISSN 0016-7061 - p. 478 - 484.
iron-oxide - clay-minerals - aqueous-solution - soils - sorption - ferrihydrite - hematite - crystallinity - mechanisms - stability
In soils goethite and kaolinite are often cemented together as a binary association, which has a significant influence on the physical and chemical properties of soils. In this study, the surface properties and phosphate adsorption of goethite, kaolinite, goethite-kaolinite association (GKA) and goethite-kaolinite mixture (GKM) were investigated. Compared to the average simple sum values of goethite and kaolinite, the pore volume and specific surface area (SSA) of GKA increased, and those of GKM remained almost unchanged. Goethite, kaolinite, GKM and GKA have a pH of point of zero charge (PZC) at around 8.2, 4.1, 6.1, and 7.0, respectively; and their surface charge is 0561, -0.092, 0.041, and 0.097 mmol/g at pH 5.0, respectively. The phosphate adsorption data of goethite and kaolinite could be fitted by one-site Langmuir model (R-2 = 0.963 and 0.956, respectively). Two-site Langmuir model described the phosphate adsorption by GKM and GKA well (R-2 = 0.985 and 0.982, respectively); and the Freundlich correlation coefficients of GKM and GKA were 0.967 and 0.924, respectively. This indicated that GKM and GKA possessed the surface with two types of reactive sites, and the surface heterogeneity of GKM was higher than that of GKA. Compared to the average value of goethite and kaolinite, the adsorption capacities of GKM (q(max) = 198.17 and q(t) = 226.11 mmol/g) increased slightly and those of GKA (q(max) = 230.24 and q(t) = 235.96 mmol/g) significantly increased, indicating that GKA was a highly effective adsorbent for phosphate. (C) 2013 Elsevier B.V. All rights reserved.
Small Homologous Blocks in Phytophthora Genomes Do Not Point to an Ancient Whole-Genome Duplication
Hooff, J.J.E. van; Snel, B. ; Seidl, M.F. - \ 2014
Genome Biology and Evolution 6 (2014)5. - ISSN 1759-6653 - p. 1079 - 1085.
pathogen phytophthora - maximum-likelihood - evolution - genes - consequences - mechanisms - adaptation - repertoire - sequences - infestans
Genomes of the plant-pathogenic genus Phytophthora are characterized by small duplicated blocks consisting of two consecutive genes (2HOM blocks) and by an elevated abundance of similarly aged gene duplicates. Both properties, in particular the presence of 2HOM blocks, have been attributed to a whole-genome duplication (WGD) at the last common ancestor of Phytophthora. However, large intraspecies synteny-compelling evidence for a WGD-has not been detected. Here, we revisited the WGD hypothesis by deducing the age of 2HOM blocks. Two independent timing methods reveal that the majority of 2HOM blocks arose after divergence of the Phytophthora lineages. In addition, a large proportion of the 2HOM block copies colocalize on the same scaffold. Therefore, the presence of 2HOM blocks does not support a WGD at the last common ancestor of Phytophthora. Thus, genome evolution of Phytophthora is likely driven by alternative mechanisms, such as bursts of transposon activity.
Salt stress in a membrane bioreactor: Dynamics of sludge properties, membrane fouling and remediation through powdered activated carbon dosing
Temmerman, L. De; Maere, T. ; Temmink, H. ; Zwijnenburg, A. ; Nopens, I. - \ 2014
Water Research 63 (2014). - ISSN 0043-1354 - p. 112 - 124.
waste-water treatment - organic-matter - energy-consumption - high salinity - mbr - filterability - ultrafiltration - flocculation - temperature - mechanisms
Membrane bioreactors are a well-established technology for wastewater treatment. However, their efficiency is adversely impacted by membrane fouling, primarily inciting very conservative operations of installations that makes them less appealing from an economic perspective. This fouling propensity of the activated sludge is closely related to system disturbances. Therefore, improved insight into the impact of fouling is crucial towards increased membrane performance. In this work, the disturbance of a salt shock was investigated with respect to sludge composition and filterability in two parallel lab-scale membrane bioreactors. Several key sludge parameters (soluble microbial products, sludge-bound extracellular polymeric substances, supramicron particle size distributions (PSD), submicron particle concentrations) were intensively monitored prior to, during, and after a disturbance to investigate its impact as well as the potential governing mechanism. Upon salt addition, the supramicron PSD immediately shifted to smaller floc sizes, and the total fouling rate increased. Following a certain delay, an increase in submicron particles, supernatant proteins, and polysaccharides was observed as well as an increase in the irreversible membrane fouling rate. Recovery from the disturbance was evidenced with a simultaneous decrease in the above mentioned quantities. A similar experiment introducing powdered activated carbon (PAC) addition used for remediation resulted in either no or less significant changes in the above mentioned quantities, signifying its potential as a mitigation strategy. (C) 2014 Elsevier Ltd. All rights reserved.
Angiopoietin-like 4 Stimulates STAT3-mediated iNOS Expression and Enhances Angiogenesis to Accelerate Wound Healing in Diabetic Mice
Chong, H.C. ; Goh, C.Q. ; Gounko, N.V. ; Luo, B. ; Wang, X. ; Kersten, A.H. - \ 2014
Molecular Therapy 22 (2014)9. - ISSN 1525-0016 - p. 1593 - 1604.
nitric-oxide synthase - solid human tumors - international consensus - growth-factors - foot ulcers - repair - cells - quantification - methodology - mechanisms
Impaired wound healing is a major source of morbidity in diabetic patients. Poor outcome has, in part, been related to increased inflammation, poor angiogenesis, and deficiencies in extracellular matrix components. Despite the enormous impact of these chronic wounds, effective therapies are lacking. Here, we showed that the topical application of recombinant matricellular protein angiopoietin-like 4 (ANGPTL4) accelerated wound reepithelialization in diabetic mice, in part, by improving angiogenesis. ANGPTL4 expression is markedly elevated upon normal wound injury. In contrast, ANGPTL4 expression remains low throughout the healing period in diabetic wounds. Exogenous ANGPTL4 modulated several regulatory networks involved in cell migration, angiogenesis, and inflammation, as evidenced by an altered gene expression signature. ANGPTL4 influenced the expression profile of endothelial-specific CD31 in diabetic wounds, returning its profile to that observed in wild-type wounds. We showed ANGPTL4-induced nitric oxide production through an integrin/JAK/STAT3-mediated upregulation of inducible nitric oxide synthase (iNOS) expression in wound epithelia, thus revealing a hitherto unknown mechanism by which ANGPTL4 regulated angiogenesis via keratinocyte-to-endothelial-cell communication. These data show that the replacement of ANGPTL4 may be an effective adjunctive or new therapeutic avenue for treating poor healing wounds. The present finding also confirms that therapeutic angiogenesis remains an attractive treatment modality for diabetic wound healing.
Development of a pluripotent stem cell derived neuronal model to identify chemically induced pathway perturbation in relation to neurotoxicity: effects of CREB pathway inhibition
Pistollato, F. ; Louisse, J. ; Scelfo, B. ; Mennecozzi, M. ; Accordi, B. ; Basso, B. ; Gaspar, J.A. ; Zagoura, D. ; Barilari, M. ; Palosaari, T. ; Sachinidis, A. ; Bremer, S. - \ 2014
Toxicology and Applied Pharmacology 280 (2014)2. - ISSN 0041-008X - p. 378 - 388.
c-fos - in-vitro - response element - x-inactivation - mechanisms - expression - toxicity - differentiation - identification - contributes
According to the advocated paradigm shift in toxicology, acquisition of knowledge on the mechanisms underlying the toxicity of chemicals, such as perturbations of biological pathways, is of primary interest. Pluripotent stem cells (PSCs), such as human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs), offer a unique opportunity to derive physiologically relevant human cell types to measure molecular and cellular effects of such pathway modulations. Here we compared the neuronal differentiation propensity of hESCs and hiPSCs with the aim to develop novel hiPSC-based tools for measuring pathway perturbation in relation to molecular and cellular effects in vitro. Among other fundamental pathways, also, the cAMP responsive element binding protein (CREB) pathway was activated in our neuronal models and gave us the opportunity to study time-dependent effects elicited by chemical perturbations of the CREB pathway in relation to cellular effects. We show that the inhibition of the CREB pathway, using 2-naphthol-AS-E-phosphate (KG-501), induced an inhibition of neurite outgrowth and synaptogenesis, as well as a decrease of MAP2+ neuronal cells. These data indicate that a CREB pathway inhibition can be related to molecular and cellular effects that may be relevant for neurotoxicity testing, and, thus, qualify the use of our hiPSC-derived neuronal model for studying chemical-induced neurotoxicity resulting from pathway perturbations.
Identification of species-specific novel transcripts in pig reproductive tissues using RNA-seq
Du, Z. ; Eisley, C.J. ; Onteru, S.K. ; Madsen, O. ; Groenen, M. ; Ross, J.W. ; Rothschild, M.F. - \ 2014
Animal Genetics 45 (2014)2. - ISSN 0268-9146 - p. 198 - 204.
long noncoding rnas - extreme phenotypes - human genome - litter size - disease - mechanisms - evolution - discovery - reveals - mir-675
Although structural properties of the porcine reproductive system are shared by many placental mammals, some combination of these properties is unique to pigs. To explore whether genomic elements specific to pigs could potentially underlie this uniqueness, we made the first step to identify novel transcripts in two representative pig reproductive tissues by the technique of massively parallel sequencing. To automate the whole process, we built a computational pipeline, which can also be easily extended for similar studies in other species. In total, 5516 and 9061 novel transcripts were found, and 159 and 252 novel transcripts appear to be specific to pigs for the placenta and testis respectively. Furthermore, these novel transcripts were found to be enriched in quantitative trait loci (QTL) regions for reproduction traits in pigs. We validated eight of these novel transcripts by quantitative real-time PCR. With respect to their genomic organization and their functional relationship to reproduction, these transcripts need to be further validated and explored in various pig breeds to better comprehend the relevant aspects of pig physiology that contribute to reproductive performance.
Colorectal cancer risk variants on 11q23 and 15q13 are associated with unexplained adenomatous polyposis
Hes, F.J. ; Ruano, D. ; Nieuwenhuis, M. ; Tops, C.M.J. ; Schrumpf, M. ; Nielsen, M. ; Huijts, P.E. ; Wijnen, J. ; Wagner, A. ; Gomet Garcia, E.B. ; Sijmons, R.H. ; Menko, F.H. ; Letteboer, T.G. ; Hoogerbrugge, N. ; Harryvan, J.L. ; Kampman, E. ; Morreau, H. ; Vasen, H.F. ; Wezel, T.G. van - \ 2014
Journal of Medical Genetics 51 (2014)1. - ISSN 0022-2593 - p. 55 - 60.
genome-wide association - susceptibility loci - genetic-variants - apc - mutations - hereditary - families - metaanalysis - mechanisms - phenotype
Background Colorectal adenomatous polyposis is associated with a high risk of colorectal cancer (CRC) and is frequently caused by germline mutations in APC or MUTYH. However, in about 20–30% of patients no underlying gene defect can be identified. In this study, we tested if recently identified CRC risk variants play a role in patients with >10 adenomas. Methods We analysed a total of 16 SNPs with a reported association with CRC in a cohort of 252 genetically unexplained index patients with >10 colorectal adenomas and 745 controls. In addition, we collected detailed clinical information from index patients and their first-degree relatives (FDRs). Results We found a statistically significant association with two of the variants tested: rs3802842 (at chromosome 11q23, OR=1.60, 95% CI 1.3 to 2.0) and rs4779584 (at chromosome 15q13, OR=1.50, 95% CI 1.2 to 1.9). The majority of index patients (84%) had between 10 and 100 adenomas and 15% had >100 adenomas. Only two index patients (1%), both with >100 adenomas, had FDRs with polyposis. Forty-one per cent of the index patients had one or more FDRs with CRC. Conclusions These SNPs are the first common, low-penetrant variants reported to be associated with adenomatous polyposis not caused by a defect in the APC, MUTYH, POLD1 and POLE genes. Even though familial occurrence of polyposis was very rare, CRC was over-represented in FDRs of polyposis patients and, if confirmed, these relatives will therefore benefit from surveillance.
Recycling of Indium From CIGS Photovoltaic Cells: Potential of Combining Acid-Resistant Nanofiltration with Liquid-Liquid Extraction.
Zimmermann, Y.S. ; Niewersch, C. ; Lenz, M. ; Corvini, P.F.X. ; Schäffer, A. ; Wintgens, T. - \ 2014
Environmental Science and Technology 48 (2014)22. - ISSN 0013-936X - p. 13412 - 13418.
electronic waste - nf membranes - recovery - metals - environment - mechanisms - management - rejection - solutes - water
Electronic consumer products such as smartphones, TV, computers, light-emitting diodes, and photovoltaic cells crucially depend on metals and metalloids. So-called “urban mining” considers them as secondary resources since they may contain precious elements at concentrations many times higher than their primary ores. Indium is of foremost interest being widely used, expensive, scarce and prone to supply risk. This study first investigated the capability of different nanofiltration membranes of extracting indium from copper–indium-gallium- selenide photovoltaic cell (CIGS) leachates under low pH conditions and low transmembrane pressure differences (98% by nanofiltration, separating it from parts of the Ag, Sb, Se, and Zn present. LLE using di-(2-ethylhexyl)phosphoric acid (D2EHPA) extracted 97% of the indium from the retentates, separating it from all other elements except for Mo, Al, and Sn. Overall, 95% (2.4 g m–2 CIGS) of the indium could be extracted to the D2EHPA phase. Simultaneously, by nanofiltration the consumption of D2EHPA was reduced by >60% due to the metal concentration in the reduced retentate volume. These results show clearly the potential for efficient scarce metal recovery from secondary resources. Furthermore, since nanofiltration was applicable at very low pH (=0.6), it may be applied in hydrometallurgy typically using acidic conditions.
Cell proliferation and modulation of interaction of estrogen receptors with coregulators induced by ERa and ERB agonists
Evers, N.M. ; Berg, J.H.J. van den; Wang, S. ; Melchers, D. ; Houtman, J. ; Haan, L.H.J. de; Ederveen, A.G.H. ; Groten, J.P. ; Rietjens, I. - \ 2014
Journal of Steroid Biochemistry and Molecular Biology 143 (2014). - ISSN 0960-0760 - p. 376 - 385.
breast-cancer-cells - expression - coactivator - mechanisms - ligands - genes - phytoestrogens - transcription - antagonist - (er)alpha
The aim of the present study was to investigate modulation of the interaction of the ERa and ERß with coregulators in the ligand responses induced by estrogenic compounds. To this end, selective ERa and ERß agonists were characterized for intrinsic relative potency reflected by EC50 and maximal efficacy towards ERa and ERß mediated response in ER selective reporter gene assays, and subsequently tested for induction of cell proliferation in T47D-ERß cells with variable ERa/ERß ratio, and finally for ligand dependent modulation of the interaction of ERa and ERß with coregulators using the MARCoNI assay, with 154 unique nuclear receptor coregulator peptides derived from 66 different coregulators. Results obtained reveal an important influence of the ERa/ERß ratio and receptor selectivity of the compounds tested on induction of cell proliferation. ERa agonists activate cell proliferation whereas ERß suppresses ERa mediated cell proliferation. The responses in the MARCoNI assay reveal that upon ERa or ERß activation by a specific agonist, the modulation of the interaction of the ERs with coregulators is very similar indicating only a limited number of differences upon ERa or ERß activation by a specific ligand. Differences in the modulation of the interaction of the ERs with coregulators between the different agonists were more pronounced. Based on ligand dependent differences in the modulation of the interaction of the ERs with coregulators, the MARCoNI assay was shown to be able to classify the ER agonists discriminating between different agonists for the same receptor, a characteristic not defined by the ER selective reporter gene or proliferation assays. It is concluded that the ultimate effect of the model compounds on proliferation of estrogen responsive cells depends on the intrinsic relative potency of the agonist towards ERa and ERß and the cellular ERa/ERß ratio whereas differences in the modulation of the interaction of the ERa and ERß with coregulators contribute to the ligand dependent responses induced by estrogenic compounds.
Monodominance of Parashorea chinensis on fertile soils in a Chinese tropical rain forest
Velden, N. van der; Slik, J.W.F. ; Hu, Y.H. ; Lan, Q. ; Lin, L. ; Deng, X.B. ; Poorter, L. - \ 2014
Journal of Tropical Ecology 30 (2014)4. - ISSN 0266-4674 - p. 311 - 322.
tree species composition - size distributions - diversity - mexico - xishuangbanna - phosphorus - mechanisms - vegetation - responses - guyana
Monodominance in the tropics is often seen as an unusual phenomenon due to the normally high diversity in tropical rain forests. Here we studied Parashorea chinensis H. Wang (Dipterocarpaceae) in a seasonal tropical forest in south-west China, to elucidate the mechanisms behind its monodominance. Twenty-eight 20 × 20-m plots were established in monodominant and mixed forest in Xishuangbanna, Yunnan province. All individuals =1 cm stem diameter and 16 soil variables were measured. Parashorea chinensis forest had a significantly higher mean tree dbh compared with mixed forest. Diversity did not differ significantly between the two forest types. However, within monodominant patches, all diversity indices decreased with an increase in P. chinensis dominance. Floristic composition of P. chinensis forest did differ significantly from the mixed forest. These differences were associated with more fertile soils (significantly higher pH, Mn, K and lower carbon pools and C:N ratio) in the P. chinensis forest than the mixed forest. In contrast to current paradigms, this monodominant species is not associated with infertile, but with fertile soils. Parashorea chinensis seems to be especially associated with high manganese concentrations which it can tolerate, and with edaphic conditions (water, K) that allow this tall and exposed emergent species to maintain its water balance. This is in contrast with most previous studies on monodominance in the tropics that found either no effect of soil properties, or predict associations with nutrient-poor soils.
Nanoscale cell wall deformation impacts long-range bacterial adhesion forces on surfaces
Chen, Y. ; Harapanahalli, A.K. ; Busscher, H.J. ; Norde, W. ; Mei, H.C. van der - \ 2014
Applied and Environmental Microbiology 80 (2014)2. - ISSN 0099-2240 - p. 637 - 643.
staphylococcus-aureus - microscopy - biofilms - attraction - mechanisms - dlvo - van
Adhesion of bacteria occurs on virtually all natural and synthetic surfaces and is crucial for their survival. Once they are adhering, bacteria start growing and form a biofilm, in which they are protected against environmental attacks. Bacterial adhesion to surfaces is mediated by a combination of different short- and long-range forces. Here we present a new atomic force microscopy (AFM)-based method to derive long-range bacterial adhesion forces from the dependence of bacterial adhesion forces on the loading force, as applied during the use of AFM. The long-range adhesion forces of wild-type Staphylococcus aureus parent strains (0.5 and 0.8 nN) amounted to only one-third of these forces measured for their more deformable isogenic ¿pbp4 mutants that were deficient in peptidoglycan cross-linking. The measured long-range Lifshitz-Van der Waals adhesion forces matched those calculated from published Hamaker constants, provided that a 40% ellipsoidal deformation of the bacterial cell wall was assumed for the ¿pbp4 mutants. Direct imaging of adhering staphylococci using the AFM peak force-quantitative nanomechanical property mapping imaging mode confirmed a height reduction due to deformation in the ¿pbp4 mutants of 100 to 200 nm. Across naturally occurring bacterial strains, long-range forces do not vary to the extent observed here for the ¿pbp4 mutants. Importantly, however, extrapolating from the results of this study, it can be concluded that long-range bacterial adhesion forces are determined not only by the composition and structure of the bacterial cell surface but also by a hitherto neglected, small deformation of the bacterial cell wall, facilitating an increase in contact area and, therewith, in adhesion force.
Negative density dependence of seed dispersal and seedling recruitment in a Neotropical palm
Jansen, P.A. ; Visser, M.D. ; Joseph Wright, S. ; Rutten, G. ; Muller-Landau, H.C. - \ 2014
Ecology Letters 17 (2014)9. - ISSN 1461-023X - p. 1111 - 1120.
scatter-hoarding rodent - tropical tree - spatial-patterns - plant diversity - forest - competition - removal - consequences - mechanisms - herbivores
Negative density dependence (NDD) of recruitment is pervasive in tropical tree species. We tested the hypotheses that seed dispersal is NDD, due to intraspecific competition for dispersers, and that this contributes to NDD of recruitment. We compared dispersal in the palm Attalea butyracea across a wide range of population density on Barro Colorado Island in Panama and assessed its consequences for seed distributions. We found that frugivore visitation, seed removal and dispersal distance all declined with population density of A. butyracea, demonstrating NDD of seed dispersal due to competition for dispersers. Furthermore, as population density increased, the distances of seeds from the nearest adult decreased, conspecific seed crowding increased and seedling recruitment success decreased, all patterns expected under poorer dispersal. Unexpectedly, however, our analyses showed that NDD of dispersal did not contribute substantially to these changes in the quality of the seed distribution; patterns with population density were dominated by effects due solely to increasing adult and seed density.
Expressing the public value of plant genetic resources by organising novel relationships: The contribution of selected participaory plant breeding and market-based arrangements.
Li, Jingsong ; Lammerts Van Bueren, E. ; Leeuwis, C. ; Jiggins, J. - \ 2014
Journal of Rural Studies 36 (2014). - ISSN 0743-0167 - p. 182 - 196.
geographical indications - food system - conservation - farmers - biodiversity - innovation - sustainability - agriculture - mechanisms - management
After more than a decade of successful collaboration in participatory plant breeding (PPB) between farmers and maize breeders in southwest China, and release of new improved varieties and hybrids, it was realised that their conservation objectives could not also be secured unless farmers had incentives to maintain their traditional cultivars in production. This article explores their experience of expressing the public value of farmers' cultivars through organizing novel relationships among public and private actors, by means of PPB programmes and market-based arrangements. The researchers reached beyond common agri-food development practices and theories, to apply concepts used in public administrations studies, in order to consider public and private interest and value in relation to the direct, indirect and option value of the plant genetic resources (PGRs) represented by farmers' cultivars. In this paper, seven organizational options from selected countries are examined in relation to their roles in (i) creating indirect and options values; (ii) sustaining the legitimacy of and support for related practices; and (iii) developing operational capacity of the associated organizations and actors. The three main findings are (a) innovations in breeding and conservation developed through PPB are key factors in the management by smallholders of the indirect and option value of agro-biodiversity; (b) market-based arrangements and the creation of new sets of property rights in the products developed from farmer-bred cultivars legitimize and support PPB and PGRs conservation; and (c), the organization of the indirect and option value of farmer-bred cultivars calls for the integration of the joint efforts of producers, consumers, market actors and public sector agencies in networked governance, that can take a variety of forms. Lessons are drawn from and for China, where legal and regulatory practices in the seed sector are still under development and smallholders still maintain crop and varietal diversity by their agricultural practices.
Human protein status modulates brain reward responses to food cues1–3
Griffioen-Roose, S. ; Smeets, P.A.M. ; Heuvel, E.M. van den; Boesveldt, S. ; Finlayson, G. ; Graaf, C. de - \ 2014
American Journal of Clinical Nutrition 100 (2014)1. - ISSN 0002-9165 - p. 113 - 122.
leverage hypothesis - energy-intake - taste - breakfast - appetite - satiety - carbohydrate - mechanisms - receptors - choice
Background: Protein is indispensable in the human diet, and its intake appears tightly regulated. The role of sensory attributes of foods in protein intake regulation is far from clear. Objective: We investigated the effect of human protein status on neural responses to different food cues with the use of functional magnetic resonance imaging (fMRI). The food cues varied by taste category (sweet compared with savory) and protein content (low compared with high). In addition, food preferences and intakes were measured. Design: We used a randomized crossover design whereby 23 healthy women [mean SD age: 22 +/- 2 y; mean +/- SD body mass index (in kg/m(2)): 22.5 +/- 1.8] followed two 16-d fully controlled dietary interventions involving consumption of either a low-protein diet (0.6 g protein center dot kg body weight(-1) center dot d(-1), similar to 7% of energy derived from protein, approximately half the normal protein intake) or a high-protein diet (2.2 g protein center dot kg body weight(-1) center dot d(-1), similar to 25% of energy, approximately twice the normal intake). On the last day of the interventions, blood oxygen level-dependent (BOLD) responses to odor and visual food cues were measured by using fMRI. The 2 interventions were followed by a 1 -d ad libitum phase, during which a large array of food items was available and preference and intake were measured. Results: When exposed to food cues (relative to the control condition), the BOLD response was higher in reward-related areas (orbitofrontal cortex, striatum) in a low-protein state than in a high-protein state. Specifically, BOLD was higher in the inferior orbitofrontal cortex in response to savory food cues. In contrast, the protein content of the food cues did not modulate the BOLD response. A low protein state also increased preferences for savory food cues and increased protein intake in the ad libitum phase as compared with a high-protein state. Conclusions: Protein status modulates brain responses in reward regions to savory food cues. These novel findings suggest that dietary protein status affects taste category preferences, which could play an important role in the regulation of protein intake in humans. This trial was registered at www.trialregister.nl/trialreg/admin/rctview.asp?TC=3288 as NTR3288.
Faecal microbiota composition and host-microbe cross-talk following gastroenteritis and in postinfectious irritable bowel syndrome
Jalanka-Tuovinen, J. ; Salojärvi, J. ; Salonen, A. ; Immonen, O. ; Garsed, K. ; Kelly, F.M. ; Zaitoun, A. ; Palva, A. ; Spiller, R.C. ; Vos, W.M. de - \ 2014
Gut 63 (2014)11. - ISSN 0017-5749 - p. 1737 - 1745.
gastrointestinal microbiota - phylogenetic microarray - disease - questionnaire - depression - anxiety - inflammation - association - mechanisms - bacterial
Background - About 10% of patients with IBS report the start of the syndrome after infectious enteritis. The clinical features of postinfectious IBS (PI-IBS) resemble those of diarrhoea-predominant IBS (IBS-D). While altered faecal microbiota has been identified in other IBS subtypes, composition of the microbiota in patients with PI-IBS remains uncharacterised. Objective - To characterise the microbial composition of patients with PI-IBS, and to examine the associations between the faecal microbiota and a patient's clinical features. Design - Using a phylogenetic microarray and selected qPCR assays, we analysed differences in the faecal microbiota of 57 subjects from five study groups: patients with diagnosed PI-IBS, patients who 6 months after gastroenteritis had either persisting bowel dysfunction or no IBS symptoms, benchmarked against patients with IBS-D and healthy controls. In addition, the associations between the faecal microbiota and health were investigated by correlating the microbial profiles to immunological markers, quality of life indicators and host gene expression in rectal biopsies. Results - Microbiota analysis revealed a bacterial profile of 27 genus-like groups, providing an Index of Microbial Dysbiosis (IMD), which significantly separated patient groups and controls. Within this profile, several members of Bacteroidetes phylum were increased 12-fold in patients, while healthy controls had 35-fold more uncultured Clostridia. We showed correlations between the IMD and expression of several host gene pathways, including amino acid synthesis, cell junction integrity and inflammatory response, suggesting an impaired epithelial barrier function in IBS. Conclusions - The faecal microbiota of patients with PI-IBS differs from that of healthy controls and resembles that of patients with IBS-D, suggesting a common pathophysiology. Moreover, our analysis suggests a variety of host–microbe associations that may underlie intestinal symptoms, initiated by gastroenteritis
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