Staff Publications

Staff Publications

  • external user (warningwarning)
  • Log in as
  • language uk
  • About

    '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.

    We have a manual that explains all the features 

    Records 1 - 20 / 88

    • help
    • print

      Print search results

    • export

      Export search results

    Check title to add to marked list
    Resilience in coastal dune grasslands: pH and soil organic matter effects on P nutrition, plant strategies, and soil communities
    Kooijman, Annemieke ; Morriën, Elly ; Jagers Op Akkerhuis, Gerard ; Missong, Anna ; Bol, Roland ; Klumpp, Erwin ; Hall, Rutger ; Til, Mark van; Kalbitz, Karsten ; Bloem, Jaap - \ 2020
    Ecosphere 11 (2020)5. - ISSN 2150-8925
    Soil organic matter (SOM) and pH are key ecosystem drivers, influencing resilience to environmental change. We tested the separate effects of pH and SOM on nutrient availability, plant strategies, and soil community composition in calcareous and acidic Grey dunes (H2130) with low, intermediate, and/or high SOM, which differ in sensitivity to high atmospheric N deposition. Soil organic matter was mainly important for biomass parameters of plants, microbes, and soil animals, and for microarthropod diversity and network complexity. However, differences in pH led to fundamental differences in P availability and plant strategies, which overruled the normal soil community patterns, and influenced resilience to N deposition. In calcareous dunes with low grass‐encroachment, P availability was low despite high amounts of inorganic P, due to low solubility of calcium phosphates and strong P sorption to Fe oxides at high pH. Calcareous dunes were dominated by low‐competitive arbuscular mycorrhizal (AM) plants, which profit from mycorrhiza especially at low P. In acidic dunes with high grass‐encroachment, P availability increased as calcium phosphates dissolved and P sorption weakened with the shift from Fe oxides to Fe‐OM complexes. Weakly sorbed and colloidal P increased, and at least part of the sorbed P was organic. Acidic dunes were dominated by nonmycorrhizal (NM) plants, which increase P uptake through exudation of carboxylates and phosphatase enzymes, which release weakly sorbed P, and disintegrate labile organic P. The shifts in P availability and plant strategies also changed the soil community. Contrary to expectations, the bacterial pathway was more important in acidic than in calcareous dunes, possibly due to exudation of carboxylates and phosphatases by NM plants, which serve as bacterial food resource. Also, the fungal AM pathway was enhanced in calcareous dunes, and fungal feeders more abundant, due to the presence of AM fungi. The changes in soil communities in turn reduced expected differences in N cycling between calcareous and acidic dunes. Our results show that SOM and pH are important, but separate ecosystem drivers in Grey dunes. Differences in resilience to N deposition are mainly due to pH effects on P availability and plant strategies, which in turn overruled soil community patterns.
    A single day of high-fat diet feeding induces lipid accumulation and insulin resistance in brown adipose tissue in mice
    Kuipers, Eline N. ; Held, Ntsiki M. ; Het Panhuis, Wietse In; Modder, Melanie ; Ruppert, Philip M.M. ; Kersten, Sander ; Kooijman, Sander ; Guigas, Bruno ; Houtkooper, Riekelt H. ; Rensen, Patrick C.N. ; Boon, Mariëtte R. - \ 2019
    American Journal of Physiology. Endocrinology and Metabolism 317 (2019)5. - ISSN 0193-1849 - p. E820 - E830.
    brown adipose tissue - high-fat diet - lipid accumulation - macrophage - mitochondrial dynamics

    Brown adipose tissue (BAT) catabolizes glucose and fatty acids to produce heat and thereby contributes to energy expenditure. Long-term high-fat diet (HFD) feeding results in so-called 'whitening' of BAT characterized by increased lipid deposition, mitochondrial dysfunction, and reduced fat oxidation. The aim of the current study was to unravel the rate and related mechanisms by which HFD induces BAT whitening and insulin resistance. Wild-type mice were fed a HFD for 0, 1, 3, or 7 days. Within 1 day of HFD, BAT weight and lipid content were increased. HFD also immediately reduced insulin-stimulated glucose uptake by BAT, indicating rapid induction of insulin resistance. This was accompanied by a tendency toward a reduced uptake of triglyceride-derived fatty acids by BAT. Mitochondrial mass and Ucp1 expression were unaltered, whereas after 3 days of HFD, markers of mitochondrial dynamics suggested induction of a more fused mitochondrial network. Additionally, HFD also increased macrophage markers in BAT after 3 days of HFD. Counterintuitively, the switch to HFD was accompanied by an acute rise in core body temperature. We showed that a single day of HFD feeding is sufficient to induce the first signs of whitening and insulin resistance in BAT, which reduces the uptake of glucose and triglyceride-derived fatty acids. BAT whitening and insulin resistance are likely sustained by reduced mitochondrial oxidation due to changes in mitochondrial dynamics and macrophage infiltration, respectively. Likely, the switch to HFD swiftly induces thermogenesis in other metabolic organs, which allows attenuation of BAT thermogenesis.

    A Diurnal Rhythm in Brown Adipose Tissue Causes Rapid Clearance and Combustion of Plasma Lipids at Wakening
    Berg, Rosa van den; Kooijman, Sander ; Noordam, Raymond ; Ramkisoensing, Ashna ; Abreu-Vieira, Gustavo ; Tambyrajah, Lauren L. ; Dijk, Wieneke ; Ruppert, Philip ; Mol, Isabel M. ; Kramar, Barbara ; Caputo, Rosanna ; Puig, Laura Sardón ; Ruiter, Evelien M. de; Kroon, Jan ; Hoekstra, Menno ; Sluis, Ronald J. van der; Meijer, Onno C. ; Willems van Dijk, Ko ; Kerkhof, Linda W.M. van; Christodoulides, Constantinos ; Karpe, Fredrik ; Gerhart-Hines, Zachary ; Kersten, Sander ; Meijer, Johanna H. ; Coomans, Claudia P. ; Heemst, Diana van; Biermasz, Nienke R. ; Rensen, Patrick C.N. - \ 2018
    Cell Reports 22 (2018)13. - ISSN 2211-1247 - p. 3521 - 3533.
    angiopoietin-like 4 - APOE3-Leiden.CETP mice - brown adipose tissue - circadian rhythm - diurnal rhythm - fatty acids - lipoprotein lipase - postprandial lipid response - triglycerides
    Many favorable metabolic effects have been attributed to thermogenic activity of brown adipose tissue (BAT). Yet, time of day has rarely been considered in this field of research. Here, we show that a diurnal rhythm in BAT activity regulates plasma lipid metabolism. We observed a high-amplitude rhythm in fatty acid uptake by BAT that synchronized with the light/dark cycle. Highest uptake was found at the onset of the active period, which coincided with high lipoprotein lipase expression and low angiopoietin-like 4 expression by BAT. Diurnal rhythmicity in BAT activity determined the rate at which lipids were cleared from the circulation, thereby imposing the daily rhythm in plasma lipid concentrations. In mice as well as humans, postprandial lipid excursions were nearly absent at waking. We anticipate that diurnal BAT activity is an important factor to consider when studying the therapeutic potential of promoting BAT activity. van den Berg et al. show a strong circadian rhythm in fatty acid uptake by brown adipose tissue that peaks at wakening regardless of the light exposure period. Consequently, postprandial lipid handling by brown adipose tissue is highest at wakening, resulting in the lowest postprandial plasma lipid excursions.
    Alternative strategies for nutrient cycling in acidic and calcareous forests in the Luxembourg cuesta landscape
    Kooijman, A.M. ; Kalbitz, K. ; Smit, A. - \ 2017
    In: The Luxembourg Gutland Landscape Springer International Publishing Switzerland - ISBN 9783319655413 - p. 131 - 151.
    In the forests of the Luxembourg cuesta landscape, nutrient cycling is affected by parent material, but in a different way than usually assumed. We challenge the 'conventional wisdom' that net N-mineralization is higher in calcareous than in acidic soils, due to higher biological activity and gross N-mineralization. In four separate laboratory incubation experiments, net N-mineralization was higher in acidic than in calcareous soil. Experiments with different tree species showed that soil type was even more important than litter quality. In acidic forests, high net N-mineralization may be due to dense organic layers, but also to differences in soil communities, which are dominated by fungi at low pH versus bacteria at high pH. Fungi have lower N-demand than bacteria, and may thus mitigate low activity and gross N-release. Model studies suggested that microbial immobilization was below 20% in acidic soil, and above 80% in calcareous soil, in both organic layer and mineral topsoil. Differences between fungi and bacteria were supported by selective inhibition. Microbial immobilization significantly decreased with the bactericide streptomycin, while respiration increased with the fungicide cycloheximide. This further supports that bacteria and fungi, and with them calcareous and acidic soils, show different strategies for N-nutrition. For P-nutrition, differences between calcareous and acidic soils are also important, as net P-mineralization mainly occurred in the organic layer, due to chemical sorption in the mineral soil. As a result, in the Luxembourg cuesta landscape, availability of both N and P may be higher in acidic than calcareous forests.
    Relationships between forest vegetation, parent material and soil development in the Luxembourg cuesta landscape
    Kooijman, A.M. ; Smit, A. - \ 2017
    In: The Luxembourg Gutland Landscape Springer International Publishing Switzerland - ISBN 9783319655413 - p. 153 - 176.

    In the cuesta landscape, the natural forest vegetation is affected by the clear gradients in parent material. Most forests belong to the alliances Fagion sylvaticae, Luzulo-Fagion and Carpinion betuli. Forest associations show a clear shift in species composition from calcareous to acidic soils. The species-rich Carici-Fagetum and Hordelymo-Fagetum occur on steep slopes on Muschelkalk, with shallow Leptosols and Leptic Regosols, and pH values around 7. Galio-Carpinetum, with many wet-tolerant species, occurs on gentle slopes in Keuper marl, with Luvic Stagnosols and Planosols, pH around 5-6, and perched water tables during part of the year. The relatively species-poor Galio odorati-Fagetum is found on acidic loamy soils, such as the marls of the upper cuesta, Pleistocene river terraces and Loess deposits. Soil types range from Colluvic Regosols to Luvic Stagnosols, with pH values around 4. The species-poor Luzulo-Fagetum is found on plateau and upper cuesta of the Luxembourg sandstone, but also on the oldest river terraces. Soil types range from (Leptic) Arenosols and Podzols to Alic Stagnosols, and pH values are around or below 4. In forests plots on Keuper and Muschelkalk with base-rich, loamy topsoils, parent material was more important to species composition than litter quality. Calcicole species predominated on Muschelkalk, and wet-tolerant species on Keuper, although diversity was lower under beech than under hornbeam. The clear decrease in plant species richness from calcareous to acidic soil is discussed in terms of toxicity, nutrient availability and tolerance to wet conditions, but also in relation to landscape history and regional species pool.

    My idol eats carrots, so do I? The delayed effect of a classroom-based intervention on 4–6-year-old children’s intake of a familiar vegetable
    Zeinstra, G.G. ; Kooijman, V.M. ; Kremer, S. - \ 2017
    Food Quality and Preference 62 (2017). - ISSN 0950-3293 - p. 352 - 359.
    This study aimed to investigate the effect of a role modelling intervention on children’s intake of a familiar vegetable. Ninety nine 4–6-year-old children participated at school in a between-subject experiment with three conditions. Two popular Dutch TV idols acted as enthusiastic role models in a video film that was specifically designed for this study. In the convivial eating (CE) condition, children ate raw carrots while they watched the role modelling video for eight sessions (2x/week). Children in the positive restriction and convivial eating (PR + CE) condition were – prior to eight convivial eating sessions – involved in five sessions where they watched the video without eating carrots themselves. The control group ate carrots twice only, and never watched the role modelling video. The main outcome was vegetable intake. Information on demographics and child eating characteristics was collected via a parental questionnaire. A longer-term follow-up was executed at nine months (N = 93). Children’s average carrot intake was 22 ± 24 g per intervention session. There was no increased intake directly after the intervention, but carrot intake in both intervention groups (CE: 45 g; PR + CE: 52 g) was 20–30 g higher at nine months (p < 0.01), whereas intake remained stable for the control group (p = 0.31). About 40% of all children consistently ate (almost) no carrots; higher fussiness and neophobia, and lower vegetable liking typified these non-eaters. So, although the intervention did not immediately increase children’s vegetable intake, it was associated with a higher intake at follow-up. The high numbers of non-eaters points to the need for tailored interventions that encourage non-eaters to consume relatively familiar – but previously rejected – vegetables.
    Phosphatidic acid binding proteins display differential binding as a function of membrane curvature stress and chemical properties
    Putta, Priya ; Rankenberg, Johanna ; Korver, Ruud A. ; Wijk, Ringo van; Munnik, Teun ; Testerink, Christa ; Kooijman, Edgar E. - \ 2016
    Biochimica et Biophysica Acta. Biomembranes 1858 (2016)11. - ISSN 0005-2736 - p. 2709 - 2716.
    Epsin-like clathrin adaptor (ECA) - Liposome binding assays - Membrane curvature stress - PA target proteins - PA-binding - Phosphatidic acid - Type I and type II lipids

    Phosphatidic acid (PA) is a crucial membrane phospholipid involved in de novo lipid synthesis and numerous intracellular signaling cascades. The signaling function of PA is mediated by peripheral membrane proteins that specifically recognize PA. While numerous PA-binding proteins are known, much less is known about what drives specificity of PA-protein binding. Previously, we have described the ionization properties of PA, summarized in the electrostatic-hydrogen bond switch, as one aspect that drives the specific binding of PA by PA-binding proteins. Here we focus on membrane curvature stress induced by phosphatidylethanolamine and show that many PA-binding proteins display enhanced binding as a function of negative curvature stress. This result is corroborated by the observation that positive curvature stress, induced by lyso phosphatidylcholine, abolishes PA binding of target proteins. We show, for the first time, that a novel plant PA-binding protein, Arabidopsis Epsin-like Clathrin Adaptor 1 (ECA1) displays curvature-dependence in its binding to PA. Other established PA targets examined in this study include, the plant proteins TGD2, and PDK1, the yeast proteins Opi1 and Spo20, and, the mammalian protein Raf-1 kinase and the C2 domain of the mammalian phosphatidylserine binding protein Lact as control. Based on our observations, we propose that liposome binding assays are the preferred method to investigate lipid binding compared to the popular lipid overlay assays where membrane environment is lost. The use of complex lipid mixtures is important to elucidate further aspects of PA binding proteins.

    Dietary supplement for energy and reduced appetite containing the β-agonist isopropyloctopamine leads to heart problems and hospitalisations
    Bovee, Toine F.H. ; Mol, Hans G.J. ; Bienenmann-Ploum, Monique E. ; Heskamp, Henri H. ; Bruchem, Gerard D. van; Ginkel, Leendert A. van; Kooijman, Martin ; Lasaroms, Johan J.P. ; Dam, Ruud van; Hoogenboom, Ron L.A.P. - \ 2016
    Food Additives & Contaminants. Pt. A, Chemistry, Analysis, Control, Exposure & Risk Assessment 33 (2016)5. - ISSN 1944-0049 - p. 749 - 759.
    Biosensor - enforcement - health risks - internet - supplements - web shops

    In 2013 the Dutch authorities issued a warning against a dietary supplement that was linked to 11 reported adverse reactions, including heart problems and in one case even a cardiac arrest. In the UK a 20-year-old woman, said to have overdosed on this supplement, died. Since according to the label the product was a herbal mixture, initial LC-MS/MS analysis focused on the detection of plant toxins. Yohimbe alkaloids, which are not allowed to be present in herbal preparations according to Dutch legislation, were found at relatively high levels (400–900 mg kg–1). However, their presence did not explain the adverse health effects reported. Based on these effects the supplement was screened for the presence of a β-agonist, using three different biosensor assays, i.e. the validated competitive radioligand β2-adrenergic receptor binding assay, a validated β-agonists ELISA and a newly developed multiplex microsphere (bead)-based β-agonist assay with imaging detection (MAGPIX®). The high responses obtained in these three biosensors suggested strongly the presence of a β-agonist. Inspection of the label indicated the presence of N-isopropyloctopamine. A pure standard of this compound was bought and shown to have a strong activity in the three biosensor assays. Analysis by LC-full-scan high-resolution MS confirmed the presence of this ‘unknown known’ β3-agonist N-isopropyloctopamine, reported to lead to heart problems at high doses. A confirmatory quantitative analysis revealed that one dose of the preparation resulted in an intake of 40–60 mg, which is within the therapeutic range of this compound. The case shows the strength of combining bioassays with chemical analytical techniques for identification of illegal pharmacologically active substances in food supplements.

    Differences in activity and N demand between bacteria and fungi in a microcosm incubation experiment with selective inhibition
    Kooijman, A.M. ; Bloem, J. ; Dalen, B.R. van; Kalbitz, K. - \ 2016
    Applied Soil Ecology 99 (2016). - ISSN 0929-1393 - p. 29 - 39.
    Cycloheximide - Immobilization - Lime-poor - Lime-rich - Net N-mineralization - Streptomycin

    Bacteria and fungi are important micro-organisms in the soil, but may differ in their impact on net N-mineralization. The hypothesis was tested that fungi are characterized by low microbial activity, but also low immobilization, and bacteria by high activity and high immobilization. A one-month laboratory incubation experiment with selective inhibition of fungi (cycloheximide) or bacteria (streptomycin) was conducted with samples of organic layer and mineral topsoil (0-10. cm) from neutral, bacteria-dominated and acidic, fungi-dominated Luxembourg beech forests. In the control treatment, respiration was higher in neutral than in acidic soil, but net N-mineralization was lower, due to higher immobilization. In the antibiotic treatments, differences in nitrification suggest that selective inhibition indeed occurred; in all soils and horizons, nitrification was especially limited by bactericide. Besides as inhibitor of the target group, antibiotics may also serve as source of C and N for the non-target group. For both bactericide and fungicide, acidic soils showed higher net recovery of C and N from antibiotics than neutral soil, which suggests that uptake or sorption of antibiotics is higher in the latter. Clear differences between neutral and acidic soils arose when the main micro-organisms were stimulated. In bacteria-dominated neutral soil, application of fungicide led to increased microbial respiration. In fungi-dominated acidic soil, however, application of bactericide did not lead to higher respiration, but to increased net N-mineralization per unit respiration, which supports a lower immobilization. Differences between antibiotics were consistent for organic layer and mineral topsoil, with increase in activity with fungicide, and lower immobilization with bactericide. The results provide correlative and experimental evidence that reduced immobilization by fungi compensates for their lower rates of activity with respect to N-availability to the vegetation.

    Identification and functional characterization of the Arabidopsis Snf1-related protein kinase SnRK2.4 phosphatidic acid-binding domain
    Julkowska, Magdalena M. ; McLoughlin, Fionn ; Galvan-Ampudia, Carlos S. ; Rankenberg, Johanna M. ; Kawa, Dorota ; Klimecka, Maria ; Haring, Michel A. ; Munnik, Teun ; Kooijman, Edgar E. ; Testerink, Christa - \ 2015
    Plant, Cell & Environment 38 (2015)3. - ISSN 0140-7791 - p. 614 - 624.
    phosphatidic acid - phospholipid binding - root system architecture - SnRK2.10

    Phosphatidic acid (PA) is an important signalling lipid involved in various stress-induced signalling cascades. Two SnRK2 protein kinases (SnRK2.4 and SnRK2.10), previously identified as PA-binding proteins, are shown here to prefer binding to PA over other anionic phospholipids and to associate with cellular membranes in response to salt stress in Arabidopsis roots. A 42 amino acid sequence was identified as the primary PA-binding domain (PABD) of SnRK2.4. Unlike the full-length SnRK2.4, neither the PABD-YFP fusion protein nor the SnRK2.10 re-localized into punctate structures upon salt stress treatment, showing that additional domains of the SnRK2.4 protein are required for its re-localization during salt stress. Within the PABD, five basic amino acids, conserved in class 1 SnRK2s, were found to be necessary for PA binding. Remarkably, plants overexpressing the PABD, but not a non-PA-binding mutant version, showed a severe reduction in root growth. Together, this study biochemically characterizes the PA-SnRK2.4 interaction and shows that functionality of the SnRK2.4 PABD affects root development.

    Brown adipose tissue takes up plasma triglycerides mostly after lipolysis
    Khedoe, P.P.S.J. ; Hoeke, Geerte ; Kooijman, Sander ; Dijk, Wieneke ; Buijs, Jeroen T. ; Kersten, Sander ; Havekes, Louis M. ; Hiemstra, Pieter S. ; Berbée, Jimmy F.P. ; Boon, Mariëtte R. ; Rensen, Patrick C.N. - \ 2015
    Journal of Lipid Research 56 (2015)1. - ISSN 0022-2275 - p. 51 - 59.
    Cholesterol - Chylomicrons - Fatty acid metabolism - Lipids - Lipoprotein lipase - Lipoproteins/metabolism

    Brown adipose tissue (BAT) produces heat by burning TGs that are stored within intracellular lipid droplets and need to be replenished by the uptake of TG-derived FA from plasma. It is currently unclear whether BAT takes up FA via uptake of TG-rich lipoproteins (TRLs), after lipolysis-mediated liberation of FA, or via a combination of both. Therefore, we generated glycerol tri[3H]oleate and [14C]cholesteryl oleate double-labeled TRL-mimicking particles with an average diameter of 45, 80, and 150 nm (representing small VLDL to chylomicrons) and injected these intravenously into male C57Bl/6J mice. At room temperature (21°C), the uptake of 3H-activity by BAT, expressed per gram of tissue, was much higher than the uptake of 14C-activity, irrespective of particle size, indicating lipolysis-mediated uptake of TG-derived FA rather than whole particle uptake. Cold exposure (7°C) increased the uptake of FA derived from the differently sized particles by BAT, while retaining the selectivity for uptake of FA over cholesteryl ester (CE). At thermoneutrality (28°C), total FA uptake by BAT was attenuated, but the specificity of uptake of FA over CE was again largely retained. Altogether, we conclude that, in our model, BAT takes up plasma TG preferentially by means of lipolysis-mediated uptake of FA.

    The role of emotions in food choice and liking
    Gutjar, S. ; Graaf, C. de; Kooijman, V.M. ; Wijk, R.A. de; Nys, A. ; Horst, G.J. ter; Jager, G. - \ 2015
    Food Research International 76 (2015)2. - ISSN 0963-9969 - p. 216 - 223.
    Consumer liking ratings of food products often fail to predict market success. In addition to sensory tests, it is thought that food-evoked emotions provide a sensitive measure to describe products in a way that adds to information from liking. In this study two different tools were used to measure emotional responses to foods, PrEmo® and EsSense Profile® to differentiate between similar products from the same product category. Additionally, we investigated the relationship between food-evoked emotions, liking and choice behaviour. Participants (n = 123) tasted seven test products, scored liking, and evaluated each product with PrEmo® and EsSense Profile®. In a separate breakfast session we assessed the participants' actual food choice (their preferred breakfast drink out of seven). The results showed that PrEmo® and EsSense Profile® differentiated successfully between similar groups of breakfast drinks. We also found that liking is only partly associated with the emotion responses to the products. Thus, emotional profiles provide new information not captured by liking scores. Furthermore, food choice was related to mainly positive emotions, suggesting that food-evoked emotions can add to liking ratings in explaining choice behaviour.
    35 years of DEB research
    Meer, J. van der; Klok, T.C. ; Kearney, M.R. ; Wijsman, J.W.M. ; Kooijman, S.A.L.M. - \ 2014
    Journal of Sea Research 94 (2014). - ISSN 1385-1101 - p. 1 - 4.
    energy budget model - covariation method - parameters
    Research on the Dynamic Energy Budget (DEB) theory started 35 years ago. Initially much emphasis was put on the development of a consistent theory. During recent years attention was paid on parameterizing DEB models for a huge collection of species. This enables the search for patterns in parameter values in an ecological and evolutionary context. This special issue presents some of the results of this quest, among other things focusing on the development of metabolic acceleration, combined with various applications of DEB theory in fisheries, aquaculture, climate science and ecotoxicology.
    Stikstofkringloop in kalkrijke en kalkarme duinbodems : en de implicaties daarvan voor de effectiviteit van plaggen
    Kooijman, A.M. ; Bloem, J. ; Cerli, C. ; Jagers Op Akkerhuis, G.A.J.M. ; Kalbitz, K. ; Dimmers, W.J. ; Vos, A. ; Peest, A.K. ; Kemmers, R.H. - \ 2014
    Driebergen : Vereniging van Bos- en Natuurterreineigenaren (OBN rapport 2014/OBN189-DK) - 87
    duingebieden - bodemchemie - stikstof - mineralisatie - ecologisch herstel - plaggen steken - natura 2000 - duneland - soil chemistry - nitrogen - mineralization - ecological restoration - sod cutting - natura 2000
    In dit rapport staat het Natura 2000 habitattype H2130, de Grijze duinen, centraal. In veel duingebieden is de hoge stikstof-depositie een probleem voor een gunstige staat van instandhouding van de Grijze duinen. In de herstelstrategie die binnen de Programmatische Aanpak Stikstof (PAS) is uitgewerkt voor dit habitattype, staat o.a. de maatregel plaggen genoemd. In deze rapportage wordt onderzocht of plaggen de Grijze duinen minder gevoelig maakt voor stikstofdepositie en daarmee of deze maatregel effectief is. Voor het beheer van grijze duinen is het belangrijk meer inzicht te krijgen in de betekenis van N-opslag in de bodem en de rol van het bodemleven daarbij. Het in dit rapport beschreven onderzoek geeft antwoord op de vraag in welke mate micro-organismen en mesofauna, en uiteindelijk de opslag van N in organische stof in de bodem, een rol speelt bij de gevoeligheid van duinen voor N-depositie.
    Predictive brain signals of linguistic development
    Kooijman, V.M. ; Junge, C. ; Johnson, E.K. ; Hagoort, P. ; Cutler, A. - \ 2013
    Frontiers in Psychology 4 (2013). - ISSN 1664-1078
    event-related potentials - word segmentation - language-development - speech-perception - electrophysiological evidence - cerebral specialization - american infants - native-language - 1st year - recognition
    The ability to extract word forms from continuous speech is a prerequisite for constructing a vocabulary and emerges in the first year of life. Electrophysiological (ERR) studies of speech segmentation by 9- to 12-month-old listeners in several languages have found a left-localized negativity linked to word onset as a marker of word detection. We report an ERR study showing significant evidence of speech segmentation in Dutch-learning 7-month-olds. In contrast to the left-localized negative effect reported with older infants, the observed overall mean effect had a positive polarity. Inspection of individual results revealed two participant sub-groups: a majority showing a positive-going response, and a minority showing the left negativity observed in older age groups. We retested participants at age three, on vocabulary comprehension and word and sentence production. On every test, children who at 7 months had shown the negativity associated with segmentation of words from speech outperformed those who had produced positive-going brain responses to the same input. The earlier that infants show the left-localized brain responses typically indicating detection of words in speech, the better their early childhood language skills.
    Damherten in de Amsterdamse Waterleidingduinen. Hun invloed op het duinlandschap en de kwaliteit van enkele habitats
    Haperen, A.M.M. van; Kooijman, A.M. ; Kuiters, A.T. ; Nijssen, M. ; Roon, J.A. van; Schotsman, N. ; Slings, Q.L. - \ 2013
    Waternet - 35 p.
    Levels of lead, arsenic, mercury and cadmium in clays for oral use on the Dutch market and estimation of associated risks
    Reeuwijk, N.M. ; Klerx, W.N.M. ; Kooijman, M. ; Hoogenboom, L.A.P. ; Rietjens, I.M.C.M. ; Martena, M.J. - \ 2013
    Food Additives & Contaminants. Pt. A, Chemistry, Analysis, Control, Exposure & Risk Assessment 30 (2013)9. - ISSN 1944-0049 - p. 1535 - 1545.
    pregnant-women - trace-elements - contaminated soils - geophagy - bioaccessibility - bioavailability - supplementation - nutrition - aluminum - tanzania
    Pregnant women in Africa, Asia and Suriname, and some immigrants in Western societies, traditionally consume clay products known by a variety of names such as mabele, calabash chalk, sikor and pimba. Furthermore, clay is used for health purposes in Western societies. Because certain clays can contain high levels of metals and metalloids, the aim of this study was to determine lead, arsenic, mercury and cadmium in clay products for oral use available on the Dutch market. Traditional clays originating from Africa (n = 10) and Suriname (n = 26), and health clays (n = 27) were sampled from 2004 up to and including 2012. Total metal and metalloid contents were measured by ICP-MS and showed maximum levels of lead, arsenic, mercury and cadmium of 99.7, 45.1, 2.2 and 0.75 mg kg(-1), respectively. In the absence of maximum limits for these type of clays, the potential exposure was estimated from the determined concentration, the estimated daily use level of the clays, and the estimated bioaccessibility of the different metals and arsenic. The intake estimates were compared with existing health-based guidance values. For lead, the use of 34 of the 36 traditional clays and two of the 27 health clays would result in intake levels exceeding the toxicological limit by up to 20-fold. Use of 15 of the 35 traditional clays and 11 of the 27 health clays would result in intake levels exceeding the toxicological limit for inorganic arsenic by up to 19-fold. Although limited bioaccessibility from the clay may limit the exposure and exceedance of the health-based guidance values, it was concluded that lead and arsenic intakes from some clay products could be of concern also because of their use by pregnant women and the potential developmental toxicity. As a result the use of these products, especially by pregnant women, should be discouraged
    The effect of three learning techniques on Dutch children's vegetable consumption
    Zeinstra, G.G. ; Vrijhof, M.N. ; Kooijman, V.M. - \ 2013
    The effect of three learning techniques on Dutch children’s vegetable consumption
    Zeinstra, G.G. ; Vrijhof, M.N. ; Kooijman, V.M. - \ 2013
    voedselconsumptie - kinderen - voeding en gezondheid - groenten - leren - food consumption - children - nutrition and health - vegetables - learning
    Dutch young children consume about 45 grams of vegetables a day, whereas 100-150 grams is recommended. In the Netherlands, vegetables are mainly consumed during dinner. New strategies are needed to encourage children’s vegetable consumption, also during other moments of the day. The objective was to test the effect of three different learning techniques on children’s vegetable consumption.
    Dioxins (polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo-furans) in traditional clay products used during pregnancy
    Reeuwijk, N.M. ; Talidda, A. ; Malisch, R. ; Kotz, A. ; Tritsher, A. ; Fiedler, H. ; Zeilmaker, M.J. ; Kooijman, M. ; Wienk, K.J.H. ; Traag, W.A. ; Hoogenboom, L.A.P. - \ 2013
    Chemosphere 90 (2013)5. - ISSN 0045-6535 - p. 1678 - 1685.
    toxic equivalency factors - ball clay - united-states - geophagy - health - pcbs - contamination - humans - origin - soils
    Geophagy, the practice of consuming clay or soil, is encountered among pregnant women in Africa, Eastern Asia and Latin America, but also in Western societies. However, certain types of clay are known to contain high concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). The aim of this study was to determine the PCDD/F contents of orally consumed clays purchased from Dutch and African markets. Congener patterns were compared with those of pooled human milk samples collected in eight African countries, to investigate a possible relationship with clay consumption. From the Dutch market thirteen clay products were examined, seven of African and six of Suriname origin. From seven African countries, twenty clay products were collected. All 33 clay products were screened with a cell-based bioassay and those showing a high response were analyzed by GC/HRMS. High PCDD/F concentrations were measured in three clay products from the Dutch market, ranging from 66 to 103 pg TEQ g(-1), whereas clay products from African countries were from 24 to 75 pg TEQ g(-1). Patterns and relatively high concentrations of PCDD/Fs in human milk samples from the Democratic Republic of the Congo and Côte d'Ivoire suggest a relationship with the consumption of contaminated clay. Frequent use of PCDD/F contaminated clay products during pregnancy may result in increased exposure of the mother and subsequently the developing fetus and new-born child. The use of these contaminated clays during pregnancy should be carefully considered or even discouraged.
    Check title to add to marked list
    << previous | next >>

    Show 20 50 100 records per page

    Please log in to use this service. Login as Wageningen University & Research user or guest user in upper right hand corner of this page.