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.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Selective separation of flavour-active compounds from strip gas using frictional diffusion
    Ammari, Ali ; Schroën, Karin G.P.H. ; Boom, Remko M. - \ 2020
    Separation and Purification Technology 251 (2020). - ISSN 1383-5866
    Beer - Flavour separation - Frictional diffusion - Gas-phase

    Attaining constant flavour composition in products that are produced batch-wise, such as beer, is not trivial given the inherent variability in fermentation. CO2 stripping is feasible but unselective. Condensation of the flavour is possible but energy intensive. We here propose the use of frictional diffusion (also called FricDiff), which is based on differences in diffusion rates in a sweep or carrier gas such as CO2 through an inert porous medium. Application of a slight counter-flow of the sweep gas can be used to adapt the selectivity between different flavours. It is shown that from a difference in diffusion rate of 25%, a selectivity of more than 10 can be obtained between ethyl acetate and isoamyl acetate, albeit at the cost of the flavour flux through the porous barrier.

    Exocyst subunit Sec6 is positioned by microtubule overlaps in the moss phragmoplast prior to cell plate membrane arrival
    Tang, Han ; Keijzer, Jeroen de; Overdijk, Elysa J.R. ; Sweep, Els ; Steentjes, Maikel ; Vermeer, Joop E.M. ; Janson, Marcel E. ; Ketelaar, Tijs - \ 2019
    Journal of Cell Science 132 (2019)3. - ISSN 0021-9533
    Cell plate - Exocyst - MAP65 - Microtubule - Phragmoplast - Physcomitrella patens

    During plant cytokinesis a radially expanding membrane-enclosed cell plate is formed from fusing vesicles that compartmentalizes the cell in two. How fusion is spatially restricted to the site of cell plate formation is unknown. Aggregation of cell-plate membrane starts near regions of microtubule overlap within the bipolar phragmoplast apparatus of the moss Physcomitrella patens Since vesicle fusion generally requires coordination of vesicle tethering and subsequent fusion activity, we analyzed the subcellular localization of several subunits of the exocyst, a tethering complex active during plant cytokinesis. We found that the exocyst complex subunit Sec6 but not the Sec3 or Sec5 subunits localized to microtubule overlap regions in advance of cell plate construction in moss. Moreover, Sec6 exhibited a conserved physical interaction with an ortholog of the Sec1/Munc18 protein KEULE, an important regulator for cell-plate membrane vesicle fusion in Arabidopsis Recruitment of the P. patens protein KEULE and vesicles to the early cell plate was delayed upon Sec6 gene silencing. Our findings, thus, suggest that vesicle-vesicle fusion is, in part, enabled by a pool of exocyst subunits at microtubule overlaps, which is recruited independently of vesicle delivery.

    National climate change mitigation legislation, strategy and targets: a global update
    Tudorica-Iacobuta, G. ; Dubash, Navroz K. ; Upadhyaya, Prabhat ; Deribe, Mekdelawit ; Hoehne, N.E. - \ 2018
    Wageningen University & Research
    national policies - domestic policy instruments - climate policy - energy efficiency - renewable energy policy
    Global climate change governance has changed substantially in the last decade, with a shift in focus from negotiating globally agreed greenhouse gas (GHG) reduction targets to nationally determined contributions, as enshrined in the 2015 Paris Agreement. This paper analyses trends in adoption of national climate legislation and strategies, GHG targets, and renewable and energy efficiency targets in almost all UNFCCC Parties, focusing on the period from 2007 to 2017. The uniqueness and added value of this paper reside in its broad sweep of countries, the more than decade-long coverage and the use of objective metrics rather than normative judgements. Key results show that national climate legislation and strategies witnessed a strong increase in the first half of the assessed decade, likely due to the political lead up to the Copenhagen Climate Conference in 2009, but have somewhat stagnated in recent years, currently covering 69% of global GHG emissions (almost 50% of countries). In comparison, the coverage of GHG targets increased considerably in the run up to adoption of the Paris Agreement and 93% of global GHG emissions are currently covered by such targets. Renewable energy targets saw a steady spread, with 79% of the global GHG emissions covered in 2017 compared to 45% in 2007, with a steep increase in developing countries. Key policy insightsThe number of countries that have national legislation and strategies in place increased strongly up to 2012, but the increase has levelled off in recent years, now covering 69% of global emissions by 2017 (49% of countries and 76% of global population).Economy-wide GHG reduction targets witnessed a strong increase in the build up to 2015 and are adopted by countries covering 93% of global GHG emissions (81% not counting USA) and 91% of global population (86% not counting USA) in 2017.Renewable energy targets saw a steady increase throughout the last decade with coverage of countries in 2017 comparable to that of GHG targets.Key shifts in national measures coincide with landmark international events – an increase in legislation and strategy in the build-up to the Copenhagen Climate Conference and an increase in targets around the Paris Agreement – emphasizing the importance of the international process to maintaining national momentum.
    Madeiran Arabidopsis thaliana reveals ancient long-range colonization and clarifies demography in Eurasia
    Fulgione, Andrea ; Koornneef, Maarten ; Roux, Fabrice ; Hermisson, Joachim ; Hancock, Angela M. - \ 2018
    Molecular Biology and Evolution 35 (2018)3. - ISSN 0737-4038 - p. 564 - 574.
    Admixture - Arabidopsis thaliana - Demography - Island - Population genetics - Relict

    The study of model organisms on islands may shed light on rare long-range dispersal events, uncover signatures of local evolutionary processes, and inform demographic inference on the mainland. Here, we sequenced the genomes of Arabidopsis thaliana samples from the oceanic island of Madeira. These samples include the most diverged worldwide, likely a result of long isolation on the island. We infer that colonization of Madeira happened between 70 and 85 ka, consistent with a propagule dispersal model (of size 10), or with an ecological window of opportunity. This represents a clear example of a natural long-range dispersal event in A. thaliana. Long-term effective population size on the island, rather than the founder effect, had the greatest impact on levels of diversity, and rates of coalescence. Our results uncover a selective sweep signature on the ancestral haplotype of a known translocation in Eurasia, as well as the possible importance of the low phosphorous availability in volcanic soils, and altitude, in shaping early adaptations to the island conditions. Madeiran genomes, sheltered from the complexities of continental demography, help illuminate ancient demographic events in Eurasia. Our data support a model in which two separate lineages of A. thaliana, one originating in Africa and the other from the Caucasus expanded and met in Iberia, resulting in a secondary contact zone there. Although previous studies inferred that the westward expansion of A. thaliana coincided with the spread of human agriculture, our results suggest that it happened much earlier (20-40 ka).

    National climate change mitigation legislation, strategy and targets : a global update
    Iacobuta, Gabriela ; Dubash, Navroz K. ; Upadhyaya, Prabhat ; Deribe, Mekdelawit ; Höhne, Niklas - \ 2018
    Climate Policy 18 (2018)9. - ISSN 1469-3062 - p. 1114 - 1132.
    climate policy - domestic policy instruments - energy efficiency - National policies - renewable energy policy

    Global climate change governance has changed substantially in the last decade, with a shift in focus from negotiating globally agreed greenhouse gas (GHG) reduction targets to nationally determined contributions, as enshrined in the 2015 Paris Agreement. This paper analyses trends in adoption of national climate legislation and strategies, GHG targets, and renewable and energy efficiency targets in almost all UNFCCC Parties, focusing on the period from 2007 to 2017. The uniqueness and added value of this paper reside in its broad sweep of countries, the more than decade-long coverage and the use of objective metrics rather than normative judgements. Key results show that national climate legislation and strategies witnessed a strong increase in the first half of the assessed decade, likely due to the political lead up to the Copenhagen Climate Conference in 2009, but have somewhat stagnated in recent years, currently covering 69% of global GHG emissions (almost 50% of countries). In comparison, the coverage of GHG targets increased considerably in the run up to adoption of the Paris Agreement and 93% of global GHG emissions are currently covered by such targets. Renewable energy targets saw a steady spread, with 79% of the global GHG emissions covered in 2017 compared to 45% in 2007, with a steep increase in developing countries. Key policy insightsThe number of countries that have national legislation and strategies in place increased strongly up to 2012, but the increase has levelled off in recent years, now covering 69% of global emissions by 2017 (49% of countries and 76% of global population).Economy-wide GHG reduction targets witnessed a strong increase in the build up to 2015 and are adopted by countries covering 93% of global GHG emissions (81% not counting USA) and 91% of global population (86% not counting USA) in 2017.Renewable energy targets saw a steady increase throughout the last decade with coverage of countries in 2017 comparable to that of GHG targets.Key shifts in national measures coincide with landmark international events – an increase in legislation and strategy in the build-up to the Copenhagen Climate Conference and an increase in targets around the Paris Agreement – emphasizing the importance of the international process to maintaining national momentum.

    A survey of functional genomic variation in domesticated chickens
    Derks, Martijn F.L. ; Megens, Hendrik Jan ; Bosse, Mirte ; Visscher, Jeroen ; Peeters, Katrijn ; Bink, Marco C.A.M. ; Vereijken, Addie ; Gross, Christian ; Ridder, Dick De; Reinders, Marcel J.T. ; Groenen, Martien A.M. - \ 2018
    Genetics, Selection, Evolution 50 (2018)1. - ISSN 0999-193X
    Background: Deleterious genetic variation can increase in frequency as a result of mutations, genetic drift, and genetic hitchhiking. Although individual effects are often small, the cumulative effect of deleterious genetic variation can impact population fitness substantially. In this study, we examined the genome of commercial purebred chicken lines for deleterious and functional variations, combining genotype and whole-genome sequence data. Results: We analysed over 22,000 animals that were genotyped on a 60 K SNP chip from four purebred lines (two white egg and two brown egg layer lines) and two crossbred lines. We identified 79 haplotypes that showed a significant deficit in homozygous carriers. This deficit was assumed to stem from haplotypes that potentially harbour lethal recessive variations. To identify potentially deleterious mutations, a catalogue of over 10 million variants was derived from 250 whole-genome sequenced animals from three purebred white-egg layer lines. Out of 4219 putative deleterious variants, 152 mutations were identified that likely induce embryonic lethality in the homozygous state. Inferred deleterious variation showed evidence of purifying selection and deleterious alleles were generally overrepresented in regions of low recombination. Finally, we found evidence that mutations, which were inferred to be evolutionally intolerant, likely have positive effects in commercial chicken populations. Conclusions: We present a comprehensive genomic perspective on deleterious and functional genetic variation in egg layer breeding lines, which are under intensive selection and characterized by a small effective population size. We show that deleterious variation is subject to purifying selection and that there is a positive relationship between recombination rate and purging efficiency. In addition, multiple putative functional coding variants were discovered in selective sweep regions, which are likely under positive selection. Together, this study provides a unique molecular perspective on functional and deleterious variation in commercial egg-laying chickens, which can enhance current genomic breeding practices to lower the frequency of undesirable variants in the population.
    Host and Environmental Factors Influencing Individual Human Cytokine Responses
    Horst, Rob ter; Jaeger, Martin ; Smeekens, Sanne P. ; Oosting, Marije ; Swertz, Morris A. ; Li, Yang ; Kumar, Vinod ; Diavatopoulos, Dimitri A. ; Jansen, Anne F.M. ; Lemmers, Heidi ; Toenhake-Dijkstra, Helga ; Herwaarden, Antonius E. van; Janssen, Matthijs ; Molen, Renate G. van der; Joosten, Irma ; Sweep, Fred C.G.J. ; Smit, Johannes W. ; Netea-Maier, Romana T. ; Koenders, Mieke M.J.F. ; Xavier, Ramnik J. ; Meer, Jos W.M. van der; Dinarello, Charles A. ; Pavelka, Norman ; Wijmenga, Cisca ; Notebaart, Richard A. ; Joosten, Leo A.B. ; Netea, Mihai G. - \ 2016
    Cell 167 (2016)4. - ISSN 0092-8674 - p. 1111 - 1124.e13.
    age - alpha-1-antitrypsin - cytokines - environment - gender - genetics - host - microbiome - season - vitamin D

    Differences in susceptibility to immune-mediated diseases are determined by variability in immune responses. In three studies within the Human Functional Genomics Project, we assessed the effect of environmental and non-genetic host factors of the genetic make-up of the host and of the intestinal microbiome on the cytokine responses in humans. We analyzed the association of these factors with circulating mediators and with six cytokines after stimulation with 19 bacterial, fungal, viral, and non-microbial metabolic stimuli in 534 healthy subjects. In this first study, we show a strong impact of non-genetic host factors (e.g., age and gender) on cytokine production and circulating mediators. Additionally, annual seasonality is found to be an important environmental factor influencing cytokine production. Alpha-1-antitrypsin concentrations partially mediate the seasonality of cytokine responses, whereas the effect of vitamin D levels is limited. The complete dataset has been made publicly available as a comprehensive resource for future studies. PaperClip

    Colonization of Enteroaggregative Escherichia coli and Shiga toxin-producing Escherichia coli in chickens and humans in southern Vietnam
    Trung, Nguyen Vinh ; Nhung, Hoang Ngoc ; Carrique-Mas, Juan J. ; Mai, Ho Huynh ; Tuyen, Ha Thanh ; Campbell, James ; Nhung, Nguyen Thi ; Minh, Pham Van; Wagenaar, Jaap A. ; Mai, Nguyen Thi Nhu ; Hieu, Thai Quoc ; Schultsz, Constance ; Hoa, Ngo Thi - \ 2016
    BMC Microbiology 16 (2016)1. - ISSN 1471-2180
    Chicken - E. coli - EAEC - Humans - STEC - Vietnam

    Background: Enteroaggregative (EAEC) and Shiga-toxin producing Escherichia coli (STEC) are a major cause of diarrhea worldwide. E. coli carrying both virulence factors characteristic for EAEC and STEC and producing extended-spectrum beta-lactamase caused severe and protracted disease during an outbreak of E. coli O104:H4 in Europe in 2011. We assessed the opportunities for E. coli carrying the aggR and stx genes to emerge in 'backyard' farms in south-east Asia. Results: Faecal samples collected from 204 chicken farms; 204 farmers and 306 age- and gender-matched individuals not exposed to poultry farming were plated on MacConkey agar plates with and without antimicrobials being supplemented. Sweep samples obtained from MacConkey agar plates without supplemented antimicrobials were screened by multiplex PCR for the detection of the stx1, stx2 and aggR genes. One chicken farm sample each (0.5 %) contained the stx1 and the aggR gene. Eleven (2.4 %) human faecal samples contained the stx1 gene, 2 samples (0.4 %) contained stx2 gene, and 31 (6.8 %) contained the aggR gene. From 46 PCR-positive samples, 205 E. coli isolates were tested for the presence of stx1, stx2, aggR, wzx O104 and fliC H4 genes. None of the isolates simultaneously contained the four genetic markers associated with E. coli O104:H4 epidemic strain (aggR, stx2, wzx O104 and fliC H4 ). Of 34 EAEC, 64.7 % were resistant to 3rd-generation cephalosporins. Conclusion: These results indicate that in southern Vietnam, the human population is a more likely reservoir of aggR and stx gene carrying E. coli than the chicken population. However, conditions for transmission of isolates and/or genes between human and animal reservoirs resulting in the emergence of highly virulent E. coli strains are still favorable, given the nature of'backyard' farms in Vietnam.

    Cathodic biofilm activates electrode surface and achieves efficient autotrophic sulfate reduction
    Pozo, Guillermo ; Jourdin, Ludovic ; Lu, Yang ; Keller, Jürg ; Ledezma, Pablo ; Freguia, Stefano - \ 2016
    Electrochimica Acta 213 (2016). - ISSN 0013-4686 - p. 66 - 74.

    Recent evidence suggests that autotrophic sulfate reduction could be driven by direct and indirect electron transfer mechanisms in bioelectrochemical systems. However, much uncertainty still exists about the electron fluxes from the electrode to the final electron acceptor sulfate during autotrophic sulfate reduction. In this study, linear sweep voltammetry and chronamperometry coupled to off-gas measurement demonstrates that autotrophic sulfate reduction (0.9 ± 0.1 mol SO4 2−-S m2 d−1) is driven by electron fluxes from the cathode to sulfate via hydrogen as intermediate, with 95 ± 0.04% Coulombic efficiency towards sulfide production. Moreover, the biofilm-forming sulfate-reducing bacteria (SRBs) enriched on the cathode showed the remarkable ability to consume hydrogen at a rate of 3.9 ± 0.5 mol H2 m−2 d−1, outcompeting methanogens and homoacetogens for the hydrogen without the need to add chemical inhibitors. Furthermore, quantitative DAIME-FISH of the microbial communities in z-stack images confirmed that SRBs were more abundant (46.1 ± 3.9%) across the 16 ± 2 μm-thick biofilm than Methanobacteriales (13.9 ± 1.8%) and other bacteria (24.8 ± 2.6%) were. Finally, exposing the biofilm to biocidal conditions (pH 3.0, air drying and autoclaving) led to a 27% reduction of the hydrogen production rate, which was nevertheless 5.3 times higher than a bare electrode. Energy dispersive x-ray spectroscopy (EDS) and protein electrode surface analyses revealed the presence of metallic and proteinaceous materials deposited on the surface after biocidal conditions, suggesting that the biofilm was able to modify the electrode surface towards more efficient hydrogen evolution reaction (HER).

    Whole-Genome Hitchhiking on an Organelle Mutation
    Flood, Pádraic J. ; Heerwaarden, Joost van; Becker, Frank ; Snoo, C.B. de; Harbinson, Jeremy ; Aarts, Mark G.M. - \ 2016
    Current Biology (2016). - ISSN 0960-9822 - p. 1306 - 1311.

    Strong selection on a beneficial mutation can cause a selective sweep, which fixes the mutation in the population and reduces the genetic variation in the region flanking the mutation [1-3]. These flanking regions have increased in frequency due to their physical association with the selected loci, a phenomenon called "genetic hitchhiking" [4]. Theoretically, selection could extend the hitchhiking to unlinked parts of the genome, to the point that selection on organelles affects nuclear genome diversity. Such indirect selective sweeps have never been observed in nature. Here we show that strong selection on a chloroplast gene in the wild plant species Arabidopsis thaliana has caused widespread and lasting hitchhiking of the whole nuclear genome. The selected allele spread more than 400 km along the British railway network, reshaping the genetic composition of local populations. This demonstrates that selection on organelle genomes can significantly reduce nuclear genetic diversity in natural populations. We expect that organelle-mediated genetic draft is a more common occurrence than previously realized and needs to be considered when studying genome evolution. Flood et al. discover that strong selection on a chloroplast gene has extended to the nuclear genome, which has hitched a ride along with the selected chloroplast. This is the first description of organelle-mediated genetic draft and shows that selection on organelles can directly impact nuclear genetic diversity.

    Domestication selected for deceleration of the circadian clock in cultivated tomato
    Müller, Niels A. ; Wijnen, Cris L. ; Srinivasan, Arunkumar ; Ryngajllo, M. ; Ofner, I. ; Lin, Tao ; Ranjan, Aashish ; West, Donelly ; Maloof, J.N. ; Sinha, Neelima R. ; Huang, Sanwen ; Zamir, Dani ; Jimenez-Gomez, J.M. - \ 2016
    Nature Genetics 48 (2016). - ISSN 1061-4036 - p. 89 - 93.
    Plant breeding - Plant genetics - Transcriptomics
    The circadian clock is a critical regulator of plant physiology and development, controlling key agricultural traits in crop plants1. In addition, natural variation in circadian rhythms is important for local adaptation2, 3, 4. However, quantitative modulation of circadian rhythms due to artificial selection has not yet been reported. Here we show that the circadian clock of cultivated tomato (Solanum lycopersicum) has slowed during domestication. Allelic variation of the tomato homolog of the Arabidopsis gene EID1 is responsible for a phase delay. Notably, the genomic region harboring EID1 shows signatures of a selective sweep. We find that the EID1 allele in cultivated tomatoes enhances plant performance specifically under long day photoperiods, suggesting that humans selected slower circadian rhythms to adapt the cultivated species to the long summer days it encountered as it was moved away from the equator.
    Limited attractant range of the black-light suction trap for the capture of Culicoides biting midges (Dipetera: Ceratopogonidae)
    Elbers, A.R.W. ; Meiswinkel, R. - \ 2016
    Journal of Applied Entomology 140 (2016)5. - ISSN 0931-2048 - p. 386 - 394.
    The suction light trap (LT) is a standard tool used to capture Culicoides biting midges, when estimating abundances, and mapping species ranges. The exact range of attraction of the LT is in dispute, however, with several studies indicating the range to vary widely, between 4 and 50 m. In this study, the attractant range of a LT, set at various distances (0, 1, 2, 3, 5 and 8 m) from a cow tethered at pasture, is assessed in two trials conducted on a dairy farm in the Netherlands in 2013 and 2014. In the first trial, sweep-netting and light-trapping was performed concurrently. Although a Spearman Rank correlation of 0.89 (P = 0.03) showed the two sets of abundance results to be highly correlated, species prevalence differed significantly according to the method used: the Culicoides obsoletus complex dominated the LT observations, whereas Culicoides chiopterus and Culicoides dewulfi were more abundant in those obtained by sweep-net, due to the former taxon being largely nocturnal, the latter diurnal. There is a distinct negative logarithmic relationship between Culicoides abundance and distance from the vertebrate host, with midge abundance, in the LT, increasing significantly only when it is placed very close to the bait animal, at a distance of 0–1 m. The sharp decay function in the number of Culicoides caught with increasing distance from the LT, limits the comparison of LT surveillance data obtained under various settings, even from within a climatically homogeneous geographical region such as north-western Europe.
    LAOS: The strain softening/strain hardening paradox
    Mermet-Guyennet, M.R.B. ; Gianfelice De Castro, J. ; Habibi, M. ; Martzel, N. ; Denn, M.M. ; Bonn, D. - \ 2015
    Journal of Rheology 59 (2015)1. - ISSN 0148-6055 - p. 21 - 32.

    Numerous materials, from biopolymers to filled rubbers, exhibit strain softening at high strain amplitudes during a strain sweep in oscillatory rheology: The modulus decreases with increasing deformation. On the other hand, if the nonlinear elastic response is analyzed within a single oscillation cycle (described by a Lissajous curve), these systems are often reported to exhibit strain hardening. We compare strain sweeps and single cycle LAOS (large amplitude oscillatory shear) analyses of stress vs strain on three very different materials. We conclude that the reported strain hardening is due to the use of a tangent modulus in the LAOS analysis, and that the overall rheology remains strain softening. To show that this conclusion is robust, we demonstrate a rescaling of the modulus that collapses the data from all the oscillatory measurements onto a single master curve that clearly exhibits the correct strain softening behavior.

    The effect of fire on the habitat use of the Black-eared Miner Manorina melanotis
    Raap, T. ; Schoote, G. van; Dieren, M. van; Hedger, C. ; Kuipers, H. ; Weterings, M.J.A. - \ 2015
    Ardea 103 (2015)1. - ISSN 0373-2266 - p. 79 - 90.
    In 2006, a widespread fire in the Bookmark Biosphere Reserve, South Australia, consumed over one-third of the old growth mallee considered to be the prime habitat of the endangered Black-eared Miner Manorina melanotis. Since 2008, the species has been observed foraging and breeding in the fire-altered area. To verify whether food resources can explain the Black-eared Miners’ presence in habitat consisting of early seral stages, we examined if a link could be found between the foraging behaviour of the Black-eared Miner and its invertebrate food resources. Foraging behaviour of Black-eared Miners was sampled opportunistically using focal observations. All potential invertebrate food resources were sampled using micro-pitfalls, malaise traps, beating trays, sweep nets and active searches. Black-eared Miners devoted significantly more time to foraging in long unburned (hereafter referred to as unburned) rather than in recently burned habitat. No differences in invertebrate abundance, species richness or diversity were found between burned and unburned habitats. However, differences in community composition between habitats were found. Lerp, which is a sugary protective covering of particular insect larvae, is an important food source for the Black-eared Miners, and was found more in the unburned natural habitat. We found that Black-eared miners may be more adaptable than previously thought when it comes to utilization of burned habitat. Still, this study reaffirms the importance of unburned habitat for Black-eared Miners.
    Robot & Weiden : Vijf concepten voor automatisch melden en weiden
    Philipsen, A.P. ; Derks, T. ; Hoog, B. van der; Leeuw, S. de; Sweep, B. ; Cornelissen, J. - \ 2015
    Wageningen : Stichting Weidegang / Wageningen UR Livestock Research - 16
    melkveehouderij - begrazing - begrazingsbeheer - melkrobots - automatisering - machinaal melken - dairy farming - grazing - grazing management - milking robots - automation - machine milking
    Ons motto is 'Robot & Weiden: dat kan!' Het is een kwestie van de juiste werkwijze vinden, eentje die past bij jouw bedrijf, ambities en voorkeuren. In Robot & Weiden heeft een groep van 50 weidende melkveehouders met een AMS en een team van weidegang-experts de koppen bij elkaar gestoken om van elkaar te leren hoe je automatisch melken en weiden kunt combineren. Daarbij stond de vraag centraal wat werkt wel en wat werkt niet? Zij hebben deze ervaringen omgezet tot vijf Robot & Weiden concepten.
    From induced resistance to defence in plant-insect interactions
    Poelman, E.H. - \ 2015
    Entomologia Experimentalis et Applicata 157 (2015)1. - ISSN 0013-8703 - p. 11 - 17.
    Plant–insect interactions typically take place in complex settings of interactions among multiple trophic levels as well as multiple species in each trophic level. The complex interaction network may strongly impact on extrapolations of resistance traits to have a defensive function. For example, the induced response plants express to their current attacker often enhances resistance to that attacker, but may make a plant more susceptible to attack by another herbivore. Hence, the defensive function or plant fitness benefit of the response to a single attacker may be misinterpreted from pairwise interactions. Moreover, plant physiological responses to a first stress by herbivory may hamper the response to a second stress and lead to conclusions of maladaptation in plant defence responses. In light of the entire community of attackers and beneficial organisms the plant interacts with, the susceptibility to some attackers may be a consequence of adaptations that reduce fitness costs of herbivory when considering the full sweep of species that affect plant fitness. A similar argumentation may apply for indirect resistance in which predators or parasitoids dampen the effect of herbivores on plants. Plant volatiles that attract third trophic level organisms such as parasitoids may at the same time attract enemies of the parasitoids in the fourth trophic level, hyperparasitoids, which again dampen the effect of parasitoids on herbivores. In addition, the effectiveness of predators and parasitoids may be dependent on habitat complexity. Here, I plea for studies on the full plant-associated community to understand the fitness outcome of an (induced) plant trait and hence coin it induced direct or indirect plant defence.
    West Nile Virus: High Transmission Rate in North-Western European Mosquitoes Indicates Its Epidemic Potential and Warrants Increased Surveillance
    Fros, J.J. ; Geertsema, C. ; Vogels, C.B.F. ; Roosjen, P.P.J. ; Failloux, A.B. ; Vlak, J.M. ; Koenraadt, C.J.M. ; Takken, W. ; Pijlman, G.P. - \ 2015
    PLoS Neglected Tropical Diseases 9 (2015)7. - ISSN 1935-2727
    united-states - differential virulence - experimental-infection - vector competence - lineage 1 - outbreak - circulation - strains - disease - encephalitis
    West Nile virus (WNV) is on the rise in Europe, with increasing numbers of human cases of neurological disease and death since 2010. However, it is currently unknown whether or not WNV will continue to spread to north-western Europe (NWE), in a fashion similar to the WNV epidemic sweep in the United States (1999–2004). The presence of competent mosquitoes is a strict requirement for WNV transmission, but no laboratory studies have been conducted with the new European lineage 2 WNV outbreak strain. Our study is the first to investigate transmissibility in NWE Culex pipiens for lineage 2 WNV in a systematic, direct comparison with North American Culex pipiens and with the lineage 1 WNV strain. We demonstrate that European mosquitoes are highly competent for both WNV lineages, which underscores the epidemic potential ofWNV in Europe. However, the transmission rate for lineage 2 WNV was significantly lower in North American mosquitoes, which indicates different risk levels between both continents for lineage 2 but not lineage 1 WNV. Based on our result, we propose that WNV surveillance in mosquitoes and birds must be intensified in Europe to allow early detection, timely intervention strategies and prevent outbreaks of WNV neurological disease.
    Fibril Formation from Pea Protein and Sesequent Gel Formation
    Munialo, C.D. ; Martin, A.H. ; Linden, E. van der; Jongh, H.H.J. de - \ 2014
    Journal of Agricultural and Food Chemistry 62 (2014)11. - ISSN 0021-8561 - p. 2418 - 2427.
    beta-lactoglobulin gels - amyloid fibrils - ph 2.0 - electrostatic interactions - functional-properties - circular-dichroism - globular-proteins - heat - gelation - behavior
    The objective of this study was to characterize fibrillar aggregates made using pea proteins, to assemble formed fibrils into protein-based gels, and to study the rheological behavior of these gels. Micrometer-long fibrillar aggregates were observed after pea protein solutions had been heated for 20 h at pH 2.0. Following heating of pea proteins, it was observed that all of the proteins were hydrolyzed into peptides and that 50% of these peptides were assembled into fibrils. Changes on a structural level in pea proteins were studied using circular dichroism, transmission electron microscopy, and particle size analysis. During the fibril assembly process, an increase in aggregate size was observed, which coincided with an increase in thioflavin T binding, indicating the presence of ß-sheet aggregates. Fibrils made using pea proteins were more branched and curly. Gel formation of preformed fibrils was induced by slow acidification from pH 7.0 to a final pH of around pH 5.0. The ability of pea protein-based fibrillar gels to fracture during an amplitude sweep was comparable to those of soy protein and whey protein-based fibrillar gels, although gels prepared from fibrils made using pea protein and soy protein were weaker than those of whey protein. The findings show that fibrils can be prepared from pea protein, which can be incorporated into protein-based fibrillar gels.
    Surface Temperature and Surface-Layer Turbulence in a Convective Boundary Layer
    Garai, A. ; Pardyjak, E. ; Steeneveld, G.J. ; Kleissl, J. - \ 2013
    Boundary-Layer Meteorology 148 (2013)1. - ISSN 0006-8314 - p. 51 - 72.
    sensible heat-flux - energy balance algorithm - renewal analysis - model - grass - flow - environment - similarity - canopies - density
    Previous laboratory and atmospheric experiments have shown that turbulence influences the surface temperature in a convective boundary layer. The main objective of this study is to examine land-atmosphere coupled heat transport mechanism for different stability conditions. High frequency infrared imagery and sonic anemometer measurements were obtained during the boundary layer late afternoon and sunset turbulence (BLLAST) experimental campaign. Temporal turbulence data in the surface-layer are then analyzed jointly with spatial surface-temperature imagery. The surface-temperature structures (identified using surface-temperature fluctuations) are strongly linked to atmospheric turbulence as manifested in several findings. The surface-temperature coherent structures move at an advection speed similar to the upper surface-layer or mixed-layer wind speed, with a decreasing trend with increase in stability. Also, with increasing instability the streamwise surface-temperature structure size decreases and the structures become more circular. The sequencing of surface- and air-temperature patterns is further examined through conditional averaging. Surface heating causes the initiation of warm ejection events followed by cold sweep events that result in surface cooling. The ejection events occur about 25 % of the time, but account for 60–70 % of the total sensible heat flux and cause fluctuations of up to 30 % in the ground heat flux. Cross-correlation analysis between air and surface temperature confirms the validity of a scalar footprint model.
    Wageningen University Porcine re-sequencing Phase 1
    Groenen, M. ; Megens, H.J.W.C. ; Frantz, L.A.F. ; Bosse, M. ; Crooijmans, R.P.M.A. ; Dibbits, B.W. ; Madsen, O. ; Paudel, Y. - \ 2012
    Wageningen University
    PRJEB1683 - ERP001813 - PRJEB1683
    Wageningen University Porcine re-sequencing Phase 1 For 10,000 years pigs and humans have shared a close and complex relationship. From domestication to modern breeding practices, humans have shaped the genomes of domestic pigs. Here we present the assembly and analysis of the genome sequence of a female domestic Duroc pig (Sus scrofa) and a comparison with the genomes of wild and domestic pigs from Europe and Asia. Wild pigs emerged in South East Asia and subsequently spread across Eurasia. Our results reveal a deep phylogenetic split between European and Asian wild boars ~1 million years ago, and a selective sweep analysis indicates selection on genes involved in RNA processing and regulation. Genes associated with immune response and olfaction exhibit fast evolution. Pigs have the largest repertoire of functional olfactory receptor genes, reflecting the importance of smell in this scavenging animal. The pig genome sequence provides an important resource for further improvements of this important livestock species, and our identification of many putative disease-causing variants extends the potential of the pig as a biomedical model.
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