How the COVID-19 pandemic highlights the necessity of animal research
Genzel, Lisa ; Adan, Roger ; Berns, Anton ; Beucken, Jeroen van den; Blokland, Arjan ; Boddeke, Erik H.W.G.M. ; Bogers, Willy M. ; Bontrop, Ronald ; Bulthuis, R. ; Bousema, Teun ; Clevers, Hans ; Coenen, Tineke C.J.J. ; Dam, Anne Marie van; Deen, Peter M.T. ; Dijk, K.W. van; Eggen, Bart J.L. ; Elgersma, Ype ; Erdogan, Izel ; Englitz, Bernard ; Fentener van Vlissingen, J.M. ; Fleur, Susanne la; Fouchier, Ron ; Fitzsimons, Carlos P. ; Frieling, Wilbert ; Haagmans, Bart ; Heesters, Balthasar A. ; Henckens, Marloes ; Herfst, Sander ; Hol, Elly ; Hove, Daniel van den; Jonge, Marien I. de; Jonkers, Jos ; Joosten, Leo A.B. ; Kalsbeek, Andries ; Kamermans, Maarten ; Kampinga, Harm H. ; Kas, Martien J. ; Keijer, J. ; Kersten, Sander ; Kiliaan, Amanda J. ; Kooij, Taco W.A. ; Kooijman, Sander ; Koopman, Werner J.H. ; Korosi, Aniko ; Krugers, Harm J. ; Kuiken, Thijs ; Kushner, Steven A. ; Langermans, Jan A.M. ; Lesscher, Heidi ; Lucassen, Paul J. ; Lutgens, Esther ; Netea, Mihai G. ; Noldus, Lucas P.J.J. ; Meer, Jos W.M. van der; Meye, Frank J. ; Mul, Joram D. ; Oers, Kees van; Olivier, Jocelien D.A. ; Pasterkamp, R.J. ; Philippens, Ingrid H.C.H.M. ; Prickaerts, Jos ; Pullox, Bart J.A. ; Rensen, Patrick C.N. ; Rheenen, Jacco van; Rij, Ronald P. van; Ritsma, Laila ; Rockx, Barry H.G. ; Roozendaal, Benno ; Schothorst, Evert M. van; Stittelaar, K. ; Stockhofe, Norbert ; Swaab, Dick F. ; Swart, Rik L. de; Vanderschuren, Louk J.M.J. ; Vries, Taco de; Vrij, Femke de; Wezel, Richard van; Wierenga, Corette J. ; Wiesmann, Maximilian ; Willuhn, Ingo ; Zeeuw, Chris I. de; Homberg, Judith R. - \ 2020
Current Biology 30 (2020)18. - ISSN 0960-9822 - p. R1014 - R1018.
Recently, a petition was offered to the European Commission calling for an immediate ban on animal testing. Although a Europe-wide moratorium on the use of animals in science is not yet possible, there has been a push by the non-scientific community and politicians for a rapid transition to animal-free innovations. Although there are benefits for both animal welfare and researchers, advances on alternative methods have not progressed enough to be able to replace animal research in the foreseeable future. This trend has led first and foremost to a substantial increase in the administrative burden and hurdles required to make timely advances in research and treatments for human and animal diseases. The current COVID-19 pandemic clearly highlights how much we actually rely on animal research. COVID-19 affects several organs and systems, and the various animal-free alternatives currently available do not come close to this complexity. In this Essay, we therefore argue that the use of animals is essential for the advancement of human and veterinary health. In this Essay, Genzel et al. make the case for animal research in light of the COVID-19 pandemic.
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.
Effect of geomorphology and nitrogen deposition on rate of vegetation succession in inland drift sands
Sparrius, L.B. ; Kooijman, A.M. ; Riksen, M.J.P.M. ; Sevink, J. - \ 2013
Applied Vegetation Science 16 (2013)3. - ISSN 1402-2001 - p. 379 - 389.
campylopus-introflexus - soil development - organic-matter - coastal dunes - netherlands - dry - erosion - wind - moss
Questions (1) At what rate does succession take place in active and more stabilized drift sands in regions with low and high N deposition in the Netherlands? (2) What is the present composition of pioneer vegetation in active and more stabilized drift san
The physical chemistry of the enigmatic phospholipid diacylglycerol pyrophosphate
Strawn, Liza ; Babb, Amy ; Testerink, Christa ; Kooijman, Edgar Eduard - \ 2012
Frontiers in Plant Science 3 (2012). - ISSN 1664-462X
Dgpp - Diacylglycerol pyrophosphate - Effective lipid shape - Electrostatic hydrogen bond switch - Ionization - Lipid second messenger - Phosphatidic acid - Phospholipid signaling
Phosphatidic acid (PA) is a lipid second messenger that is formed transiently in plants in response to different stress conditions, and plays a role in recruiting protein targets, ultimately enabling an adequate response. Intriguingly, this increase in PA concentration in plants is generally followed by an increase in the phospholipid diacylglycerolpyrophosphate (DGPP), via turnover of PA. Although DGPP has been shown to induce stress-related responses in plants, it is unclear to date what its molecular function is and how it exerts its effect. Here, we describe the physicochemical properties, i.e., effective molecular shape and charge, of DGPP. We find that unlike PA, which imparts a negative curvature stress to a (phospho)lipid bilayer, DGPP stabilizes the bilayer phase of phosphatidylethanolamine (PE), similar to the effect of phosphatidylcholine (PC). DGPP thus has zero curvature. The pKa2 of the phosphomonoester of DGPP is 7.44 ± 0.02 in a PC bilayer, compared to a pKa2 of 7.9 for PA. Replacement of half of the PC with PE decreases the pKa2 of DGPP to 6.71 ± 0.02, similar to the behavior previously described for PA and summarized in the electrostatic-hydrogen bond switch model. Implications for the potential function of DGPP in biomembranes are discussed.
Rapid recognition at 10 months as a predictor of language development
Junge, C. ; Kooijman, V.M. ; Hagoort, P. ; Cutler, A. - \ 2012
Developmental Science 15 (2012)4. - ISSN 1363-755X - p. 463 - 473.
event-related potentials - word segmentation - continuous speech - phonotactic knowledge - sound patterns - infants - brain - acquisition - nonsense - memory
Infants' ability to recognize words in continuous speech is vital for building a vocabulary. We here examined the amount and type of exposure needed for 10-month-olds to recognize words. Infants first heard a word, either embedded within an utterance or in isolation, then recognition was assessed by comparing event-related potentials to this word versus a word that they had not heard directly before. Although all 10-month-olds showed recognition responses to words first heard in isolation, not all infants showed such responses to words they had first heard within an utterance. Those that did succeed in the latter, harder, task, however, understood more words and utterances when re-tested at 12 months, and understood more words and produced more words at 24 months, compared with those who had shown no such recognition response at 10 months. The ability to rapidly recognize the words in continuous utterances is clearly linked to future language development.
Autonomic nervous system responses on and facial expressions to the sight, smell and taste of liked and disliked foods
Wijk, R.A. de; Kooijman, V.M. ; Verhoeven, R.H.G. ; Holthuysen, N.T.E. ; Graaf, C. de - \ 2012
Food Quality and Preference 26 (2012)2. - ISSN 0950-3293 - p. 196 - 203.
Abstract Traditional sensory and consumer tests predict long term consumer acceptance of new products rather poorly, as evidenced by the high failure rates of new market introductions. These tests typical reflect conscious processes whereas consumer acceptance may also be based on unconscious processes, which may be measured by implicit physiological and behavioral measures. This study with 16 children (aged 8–10 years) and 15 young adults (mean age 22 years) explored the use of selected physiological and behavioral measures of the autonomic nervous system (ANS) in the study of foods. Three liked and three disliked foods were selected for each participant and their responses were measured during the first sight of each food and when they received the instruction to either visually inspect, smell or taste the foods. The first sight of disliked foods compared to liked foods resulted in increased skin conductance responses (p = 0.05) and increased facial expressions of sadness, disgust, and angriness (p = 0.05). Skin conductance responses (SCRs) varied significantly with the type of instruction (p <0.001), with relatively small SCRs when participants were instructed to visually inspect the foods and larger SCRs when they are instructed to taste or smell the foods. When instructed to taste the foods, children showed increased SCRs for disliked foods while young adults showed decreased SCRs (p = 0.02). Heart rate varied with instruction and age group (p = 0.03). Children showed increased heart rate when instructed to visual inspect or taste the foods and reduced heart rate they were instructed to smell them. In contrast, young adults showed reduced heart rate when instructed to visual inspect and increased heart rate with instructed to taste or smell. Finger temperature was higher for liked foods than for disliked foods, irrespective of instruction and age group (p <0.01). It is concluded that implicit ANS and behavioral responses provide detailed information on food preferences in relation to specific food properties and phases of food sampling that may not be provided by other more explicit tests.
Youth, Nutrition and Behaviour
Voordouw, J. ; Snoek, H.M. ; Broek, E. van den; Reinders, M.J. ; Meeusen, M.J.G. ; Veggel, R.J.F.M. van; Kooijman, V.M. ; Stijnen, D.A.J.M. ; Trentelman, I. - \ 2012
Den Haag : LEI, onderdeel van Wageningen UR - 9
voeding en gezondheid - jeugd - schoollunches - gedrag - kinderen - schoolmaaltijden - schoolkinderen - schoolontbijten - nutrition and health - youth - school lunches - behaviour - children - school meals - school children - school breakfasts
Healthy nutrition is widely assumed to have a beneficial influence on educational performance and social behaviour. Yet research in developed countries about the effects of food intake on children's behaviour and school performance is limited. We propose a randomised controlled field experiment to study the effects of a school lunch programme in the Netherlands, based on an overview of studies by LEI and Food and Biobased Research, both part of Wageningen UR.
Effects of Visual Priming on Taste-Odor Interaction
Beilen, M. van; Bult, J.H.F. ; Renken, R. ; Stieger, M.A. ; Thumfart, S. ; Cornelissen, F. ; Kooijman, V.M. - \ 2011
PLoS ONE 6 (2011)9. - ISSN 1932-6203 - 9 p.
olfactory perception - sucrose solutions - perceived flavor - color - sweetness - discrimination - intensity - mixtures - texture - vision
Little is known about the influence of visual characteristics other than colour on flavor perception, and the complex interactions between more than two sensory modalities. This study focused on the effects of recognizability of visual (texture) information on flavor perception of odorized sweet beverages. Participants rated the perceived sweetness of odorized sucrose solutions in the presence or absence of either a congruent or incongruent visual context. Odors were qualitatively reminiscent of sweet foods (strawberry and caramel) or not (savoury). Visual context was either an image of the same sweet foods (figurative context) or a visual texture derived from this product (non-figurative context). Textures were created using a texture synthesis method that preserved perceived food qualities while removing object information. Odor-taste combinations were rated sweeter within a figurative than a non-figurative context. This behaviour was exhibited for all odor-taste combinations, even in trials without images, indicating sustained priming by figurative visual context. A non-figurative context showed a transient sweetening effect. Sweetness was generally enhanced most by the strawberry odor. We conclude that the degree of recognizability of visual information (figurative versus non-figurative), influences flavor perception differently. Our results suggest that this visual context priming is mediated by separate sustained and transient processes that are differently evoked by figurative and non-figurative visual contexts. These components operate independent of the congruency of the image-odor-taste combinations.
The "covariation method" for estimating the parameters of the standard Dynamic energy Budget model I: Philosophy and apporach
Lika, K. ; Kearney, M.R. ; Freitas, V. ; Veer, H.W. van der; Meer, J. van der; Wijsman, J.W.M. ; Pecquerie, L. ; Kooijman, S.A.L.M. - \ 2011
Journal of Sea Research 66 (2011)4. - ISSN 1385-1101 - p. 270 - 277.
multiple end-points - life-cycle - deb theory - toxicity - biology
The Dynamic Energy Budget (DEB) theory for metabolic organisation captures the processes of development, growth, maintenance, reproduction and ageing for any kind of organism throughout its life-cycle. However, the application of DEB theory is challenging because the state variables and parameters are abstract quantities that are not directly observable. We here present a new approach of parameter estimation, the covariation method, that permits all parameters of the standard Dynamic Energy Budget (DEB) model to be estimated from standard empirical datasets. Parameter estimates are based on the simultaneous minimization of a weighted sum of squared deviations between a number of data sets and model predictions or the minimisation of the negative log likelihood function, both in a single-step procedure. The structure of DEB theory permits the unusual situation of using single data-points (such as the maximum reproduction rate), which we call “zero-variate” data, for estimating parameters. We also introduce the concept of “pseudo-data”, exploiting the rules for the covariation of parameter values among species that are implied by the standard DEB model. This allows us to introduce the concept of a generalised animal, which has specified parameter values. We here outline the philosophy behind the approach and its technical implementation. In a companion paper, we assess the behaviour of the estimation procedure and present preliminary findings of emerging patterns in parameter values across diverse taxa.
Inland dunes in The Netherlands: soil, vegetation, nitrogen deposition and invasive species
Sparrius, L.B. - \ 2011
University of Amsterdam (UvA). Promotor(en): J. Sevink; Leo Stroosnijder, co-promotor(en): A.M. Kooijman. - Amsterdam :
eolisch zand - stikstof - vegetatie - invasieve soorten - bodemchemie - nederland - aeolian sands - nitrogen - vegetation - invasive species - soil chemistry - netherlands
Zandverstuivingen, zoals het Kootwijkerzand en de Loonse en Drunense Duinen, ontstonden door overbegrazing en het gebruik van heideplaggen voor het bemesten van akkerland. Door de industriële revolutie veranderde het landgebruik en zijn er nu nog maar enkele zandverstuivingen over. Vanwege de bijzondere planten en dieren en de cultuurhistorische achtergrond zijn veel van deze natuurgebieden nu Europees beschermd. Zandverstuivingen verdwijnen zonder gericht beheer. Laurens Sparrius onderzocht acht zandverstuivingen en vond dat het oppervlak aan kaal zand sinds 1950 is gehalveerd. Ook bleek dat stikstof uit de landbouw het dichtgroeien versnelt. In provincies met weinig luchtvervuiling, zoals Friesland en Drenthe, bleken zandverstuivingen over de laatste vijftig jaar stabieler dan op de Veluwe, met meer intensieve veehouderij. Verder neemt door stikstof de kwaliteit van de begroeiing van stuifzandgebieden af en verdwijnt de oorspronkelijke korstmossenbegroeiing. In plaats hiervan komen dikke tapijten van het invasieve mos Grijs kronkelsteeltje, een uitheemse plantensoort die rond 1960 naar Nederland is gekomen. Het verdwijnen van zandverstuivingen kan volgens Sparrius worden tegengegaan door het verminderen van de stikstofdepositie, uitbreiden van zandverstuivingen door naaldbos te kappen en verwijderen van jonge bomen in stuifzanden.
|Vegetation succession in eight inland drift sands to geomorphology and nitrogen deposition
Sparrius, L.B. ; Kooijman, A.M. ; Riksen, M.J.P.M. ; Sevink, J. - \ 2011
In: Inland dunes in the Netherlands: soil, vegetation, nitrogen deposition and invasive species / Sparrius, L.B., Amsterdam : Universiteit van Amsterdam - p. 30 - 49.
Phosphatidic acid: An electrostatic/ hydrogen-bond switch?
Kooijman, Edgar Eduard ; Testerink, Christa - \ 2010
In: Lipid Signaling in Plants / Munnik, Teun, Springer (Plant Cell Monographs ) - ISBN 9783642038723 - p. 203 - 222.
Phosphatidic acid (PA) has been shown to be an important bioactive lipid that is specifically recognized by various proteins. As such, it plays a crucial role in cellular signaling in all eukaryotes. An important determinant for PA's role in its diverse functions is its anionic headgroup that resides very close to the hydrophobic interior of the lipid bilayer. In this chapter, we describe a new model, the electrostatic/ hydrogen-bond switch that describes PA's ionization properties and its specific interaction with proteins. Furthermore, we will allude to the broader implications of the model for all phosphomonoester moieties found in biological compounds. Recent data in support of the model, as well as biological predictions arising from it, are also discussed.
Editorial for the Special Food Summit 2008 Issue of Chemosensory Perception
Kooijman, V.M. ; Stafleu, A. ; Stieger, M.A. ; Hamer, R.H. ; Graaf, C. de - \ 2010
Chemosensory Perception 3 (2010)1. - ISSN 1936-5802
Extrapolating toxic effects on individuals to the population level: the role of dynamic energy budgets
Jager, T. ; Klok, T.C. - \ 2010
Philosophical Transactions of the Royal Society B. Biological sciences 365 (2010)12. - ISSN 0962-8436 - p. 3531 - 3540.
earthworm dendrobaena-octaedra - multiple end-points - lumbricus-rubellus - intrinsic rate - growth rate - life-cycle - models - reproduction - copper - tests
The interest of environmental management is in the long-term health of populations and ecosystems. However, toxicity is usually assessed in short-term experiments with individuals. Modelling based on dynamic energy budget (DEB) theory aids the extraction of mechanistic information from the data, which in turn supports educated extrapolation to the population level. To illustrate the use of DEB models in this extrapolation, we analyse a dataset for life cycle toxicity of copper in the earthworm Dendrobaena octaedra. We compare four approaches for the analysis of the toxicity data: no model, a simple DEB model without reserves and maturation (the Kooijman–Metz formulation), a more complex one with static reserves and simplified maturation (as used in the DEBtox software) and a full-scale DEB model (DEB3) with explicit calculation of reserves and maturation. For the population prediction, we compare two simple demographic approaches (discrete time matrix model and continuous time Euler–Lotka equation). In our case, the difference between DEB approaches and population models turned out to be small. However, differences between DEB models increased when extrapolating to more field-relevant conditions. The DEB3 model allows for a completely consistent assessment of toxic effects and therefore greater confidence in extrapolating, but poses greater demands on the available data.
Preadvies mossen en korstmossen.
Bijlsma, R.J. ; Aptroot, A. ; Dort, K.W. van; Haveman, R. ; Herk, C.M. van; Kooijman, A.M. ; Sparrius, L.B. ; Weeda, E.J. - \ 2009
Ede : Directie Kennis, Ministerie van Landbouw, Natuur en Voedselkwaliteit (Rapport DK nr. 2009/dk104-O ) - 255
mossen - bryophyta - korstmossen - soorten - bedreigde soorten - landschap - milieubeheer - nederland - natuurbeheer - natura 2000 - mosses - bryophyta - lichens - species - endangered species - landscape - environmental management - netherlands - nature management - natura 2000
Binnen het in OBN-kader uitgevoerd onderzoek was tot nu toe vaak aandacht voor de ruim 580 soorten mossen (inclusief variëteiten) en 800 soorten korstmossen die in Nederland voorkomen. Uit de Rode Lijsten blijkt dat er alle aanleiding is om meer aandacht te geven aan deze groepen. De achteruitgang van mossen en korstmossen speelt landelijk en in alle landschappen. Het Deskundigenteam Heuvellandschap heeft het preadvies begeleid namens alle deskundigenteams (droog zandlandschap, nat zandlandschap en beekdallandschap; rivierenlandschap; laagveenlandschap; zeekleilandschap; duin- en kustlandschap). Bij dit onderwerp zijn betrokken geweest: Universiteit Utrecht, Universiteit van Amsterdam, B ware (Radboud Universiteit), BLWG, Forestfun ecologisch advies en onderzoek, Alterra
Paradoxical differences in N-dynamics between Luxembourg soils: litter quality or parent material?
Kooijman, A.M. ; Smit, A. - \ 2009
European Journal of Forest Research 128 (2009)6. - ISSN 1612-4669 - p. 555 - 565.
gross nitrogen transformations - organic-matter - beech forests - terrestrial ecosystems - humus forms - mineralization - decomposition - availability - patterns - earthworms
To explore whether litter quality could alter differences in N-dynamics between soil types, we compared spruce and beech growing on soils with parent material sandstone and limestone, and beech and hornbeam on acid marl and limestone. We measured pH, organic matter content, C:N ratio, soil respiration and net N-mineralization of the organic layer and the mineral topsoil in a laboratory incubation experiment and estimated gross N-mineralization and immobilization with a simulation model. Species effects were restricted to the organic layer, but higher mass for low-degradable species was compensated by higher process rates for high-degradable ones, so N-dynamics per square metre did not differ. Also, the mineral topsoil was not affected by litter quality, which may have been overruled by soil conditions. Forest soils formed from different parent materials, however, clearly differed in N-dynamics, although different from expectations for net N-mineralization. Sandstone showed low respiration and gross N-mineralization, but net N-mineralization was higher than expected, probably due to low microbial N-demand. In contrast, limestone, and to some extent acid marl, showed high respiration and gross N-release, but lower net N-mineralization than expected, because microbial immobilization was also high. Simulated gross N-mineralization even showed a negative instead of positive correlation with net N-mineralization, probably due to the strong increase in immobilization when gross N-mineralization is high. The shift in microbial N-demand may in turn be related to a more general shift from bacteria to fungi over pH-gradients.
|Onderzoek naar effectgerichte maatregelen voor het herstel en beheer van stuifzanden
Sparrius, L.B. ; Kooijman, A. ; Nijssen, M. ; Esselink, H. ; Burg, A. Van den; Riksen, M. ; Kuiters, A.T. ; Bijlsma, R.J. ; Waal, R.W. de; Dobben, H.F. van; Ketner-Oostra, R. ; Jongerius, P. ; Turnhout, C. van; Swaay, C. van - \ 2008
Amsterdam, Nijmegen, Wageningen : Stichting Bargerveen, Universiteit van Amsterdam, Radboud Universiteit, Alterra, Wageningen Universiteit (Tweede tussenrapport, februari 2008 ) - 86 p.
|Geoloketten leert: hanteerbaarheid voor de gebruiker is grootste knelpunt
Hoogerwerf, M.R. ; Kuyper, M.C. ; Kooijman, J. ; Vermeij, B. ; Bulens, J.D. - \ 2008
VI Matrix 16 (2008)3. - ISSN 0929-6107 - p. 22 - 25.
informatiesystemen - geoinformatie - information systems - geoinformation
Het project GeoLoketten wil geo-informatie in Nederland optimaal toegankelijk maken via webservices. In het kader van het innovatieprogramma Ruimte voor Geo-informatie worden daarvoor methoden en technieken ontwikkeld. Innoveren moet je leren, maar dit leertraject bleek bijzonder dynamisch. Al is de geosector nog zo snel, de ict-wereld achterhaalt haar wel
Ureidobenzotriazine Multiple H-Bonding Arrays: The Importance of Geometrical Details on the Stability of H-Bonds
Ligthart, G.B.W.L. ; Guo, D. ; Spek, A.L. ; Kooijman, H. ; Zuilhof, H. ; Sijbesma, R.P. - \ 2008
Journal of Organic Chemistry 73 (2008)1. - ISSN 0022-3263 - p. 111 - 117.
3-amino-1,2,4-benzotriazine 1,4-dioxide tirapazamine - donor-acceptor interaction - pyridine n-oxides - hydrogen-bonds - heterocyclic ureas - molecular recognition - guanine-cytosine - guanidine base - complexes - polymers
A 3-ureidobenzo-1,2,4-triazine 1-N-oxide (1) was synthesized successfully. The derivative displays an acceptor-donor-acceptor-acceptor (ADAA) hydrogen-bonding motif in CDCl3 and DMSO-d6 solution as well as in the solid state. Although moderately strong association of 1 was observed with DAD motifs, nonspecific binding is observed with ureidopyridines featuring a complementary DADD array. Density functional calculations of conformations 1a and 1b together with two complexes revealed the clearly nonplanar geometry of the multiply hydrogen-bonded complex, in which some bonds are significantly longer (3.2 Å) than is optimal for H-bonds. As a result, only very small free energies of association were calculated, in line with the experimentally observed absence of specific assembly of the components.
An electrostatic/hydrogen bond switch as the basis for the specific interaction of phosphatidic acid with proteins
Kooijman, Edgar E. ; Tieleman, D.P. ; Testerink, Christa ; Munnik, Teun ; Rijkers, Dirk T.S. ; Burger, Koert N.J. ; Kruijff, Ben De - \ 2007
Journal of Biological Chemistry 282 (2007)15. - ISSN 0021-9258 - p. 11356 - 11364.
Phosphatidic acid (PA) is a minor but important phospholipid that, through specific interactions with proteins, plays a central role in several key cellular processes. The simple yet unique structure of PA, carrying just a phosphomonoester head group, suggests an important role for interactions with the positively charged essential residues in these proteins. We analyzed by solid-state magic angle spinning 31P NMR and molecular dynamics simulations the interaction of low concentrations of PA in model membranes with positively charged side chains of membrane-interacting peptides. Surprisingly, lysine and arginine residues increase the charge of PA, predominantly by forming hydrogen bonds with the phosphate of PA, thereby stabilizing the protein-lipid interaction. Our results demonstrate that this electrostatic/hydrogen bond switch turns the phosphate of PA into an effective and preferred docking site for lysine and arginine residues. In combination with the special packing properties of PA, PA may well be nature's preferred membrane lipid for interfacial insertion of positively charged membrane protein domains.
A new class of non-linear stochastic population models with mass conservation
Kooijman, S.A.L.M. ; Grasman, J. ; Kooi, B.W. - \ 2007
Mathematical Biosciences 210 (2007)2. - ISSN 0025-5564 - p. 378 - 394.
dynamics - ecosystems - quality - time
We study the effects of random feeding, growing and dying in a closed nutrient-limited producer/consumer system, in which nutrient is fully conserved, not only in the mean, but, most importantly, also across random events. More specifically, we relate these random effects to the closest deterministic models, and evaluate the importance of the various times scales that are involved. These stochastic models differ from deterministic ones not only in stochasticity, but they also have more details that involve shorter times scales. We tried to separate the effects of more detail from that of stochasticity. The producers have (nutrient) reserve and (body) structure, and so a variable chemical composition. The consumers have only structure. so a constant chemical composition. The conversion efficiency from producer to consumer, therefore, varies. The consumers use reserve and structure of the producers as complementary compounds, following the rules of Dynamic Energy Budget theory. Consumers die at constant specific rate and decompose instantaneously. Stochasticity is incorporated in the behaviour of the consumers, where the switches to handling and searching, as well as dying are Poissonian point events. We show that the stochastic model has one parameter more than the deterministic formulation without time scale separation for conversions between searching and handling consumers, which itself has one parameter more than the deterministic formulation with time scale separation for these conversions. These extra parameters are the contributions of a single individual producer and consumer to their densities, and the ratio of the two, respectively. The tendency to oscillate increases with the number of parameters. The focus bifurcation point has more relevance for the asymptotic behaviour of the stochastic model than the Hopf bifurcation point, since a randomly perturbed damped oscillation exhibits a behaviour similar to that of the stochastic limit cycle particularly near this bifurcation point. For total nutrient values below the focus bifurcation point, the system gradually becomes more confined to the direct neighbourhood of the isocline for which the producers do not change. (C) 2007 Elsevier Inc. All rights reserved.
Material flows in a social context : a Vietnamese case study combining the materials flow analysis and action-in-context frameworks
Hobbes, M. ; Stalpers, S.I.P. ; Kooijman, J. - \ 2007
Journal of Industrial Ecology 11 (2007)1. - ISSN 1088-1980 - p. 141 - 159.
Materials flow analysis (MFA) is one of the central achievements of industrial ecology. One direction in which one can move MFA beyond mere accounting is by putting the material flows in their social context. This "socially extended MFA" may be carried out at various levels of aggregation. In this article, specific material flows will be linked to concrete actors and mechanisms that cause these flows¿using the action-in-context (AiC) framework, which contains, inter alia, both proximate and indirect actors and factors. The case study site is of Tat hamlet in Vietnam, set in a landscape of paddy fields on valley floors surrounded by steep, previously forested slopes. Out of the aggregate MFA of Tat, the study focuses on material flows associated with basic needs and sustainability. The most important actors causing these material flows are farming households, politicians, traders, and agribusiness firms¿of which local politicians turned out to be pivotal. The study shows the value of combining MFA with actor-based social analysis. MFA achieves the balanced quantification of the physical system, thus helping to pinpoint key processes. Actor-based analysis adds the causal understanding of what drives these key processes, leading to improved scenarios of the future and the effective identification of target groups and instruments for policy making.
Kooijman, H. ; Saraber, F.C.E. ; Groot, Æ. de; Spek, A.L. - \ 2005
Acta Crystallographica Section E 61 (2005)11. - ISSN 1600-5368 - p. O3921 - O3922.
In the crystal structure of the title compound, C20H30O3, there is an intramolecular hydrogen bond between the hydroxyl and acetyl groups [O...O = 2.722 (3) A]
Kooijman, H. ; Saraber, F.C.E. ; Groot, Æ. de; Spek, A.L. - \ 2005
Acta Crystallographica Section E 61 (2005)11. - ISSN 1600-5368 - p. O3908 - O3909.
The steroid ring B of the title compound, C22H32O, is in a half-chair conformation. The five-membered ring is in an intermediate form between the envelope and half-chair conformations
Responses to stress of Caenorhabditis elegans populations with different reproductive strategies
Alda Alvarez, O. ; Jager, T. ; Kooijman, S.A.L.M. ; Kammenga, J.E. - \ 2005
Functional Ecology 19 (2005)4. - ISSN 0269-8463 - p. 656 - 664.
sperm competition - toxicity tests - life-cycle - sex - fertilization - recombination - longevity - genetics - cadmium - growth
Hermaphroditic and gonochoric reproduction are essentially different reproductive strategies that may lead to diverging population responses to adverse environmental conditions. Each strategy implies different physiological mechanisms, which affect life-history traits and represent different ways of dealing with stress. We studied the performance of hermaphroditic vs gonochoric strains in the nematode Caenorhabditis elegans exposed to cadmium stress at the individual and population level. Under control conditions, the gonochoric strain started reproduction earlier than the hermaphroditic strain at a smaller size. This was due to an earlier switch from sperm to oocyte production triggered by male sperm availability. Under cadmium stress hermaphrodites showed a decrease in the size at onset of reproduction, presumably as a strategy to maintain a high population growth rate. In contrast the body size of gonochoric nematodes was not affected. A process-based model (DEBtox) was used as a tool for analysing life-history data and calculating population growth rates. The model fitted the data well using physiologically relevant parameters such as ageing, survival or reproduction related parameters. The simultaneous fit of all life-history traits was used to obtain populations growth rate estimates. The differences between the two C. elegans strains were reflected at the population level. Lower population growth rates, as calculated by DEBtox, were found in the gonochoric strain, largely determined by the proportion of males in the offspring. From the overall results we suggest that the differences found between both populations are due to the reproductive strategy. Under control conditions, CB strain (with gonochoric reproduction) does not favour population growth rates in the short term due to faster ageing and copulation costs on survival. Furthermore, in response to stress this strain also showed lower performance than the N2 hermaphroditic strain, mainly due to a higher sensitivity of survival to the stressor
Modelling nematode life cycles using dynamic energy budgets
Jager, T. ; Alda Alvarez, O. ; Kammenga, J.E. ; Kooijman, S.A.L.M. - \ 2005
Functional Ecology 19 (2005)1. - ISSN 0269-8463 - p. 136 - 144.
caenorhabditis-elegans - toxicity tests - daphnia-magna - c-elegans - growth - reproduction - briggsae - strategy
1. To understand the life cycle of an organism, it is important to understand the underlying physiological mechanisms of their life histories. We here use the theory of dynamic energy budgets (DEB) to investigate the close relationships between growth, reproduction and respiration in nematodes. 2. Using a set of simplified equations based on DEB theory, we are able to accurately describe life-cycle data from the literature for the free-living bacterivorous nematodes Caenorhabditis elegans, C. briggsae and Acrobeloides nanus, under different temperature or food regimes. 3. Nematodes apparently differ from other animals, as the initial growth is slower than expected. We explain this phenomenon by food limitation in the larvae, which is supported by more detailed physiological studies. 4. Food density and temperature are shown to have predictable effects on the growth curves (temperature affects only growth rate, whereas food density also affects ultimate size), although the reproduction patterns reveal some deviations from model predictions. 5. The presented model integrates the different aspects of the life cycle into a single framework, and can be applied as such to interpret the effects of various stressors
|Voorkomen en bestrijden van Pitrus-dominantie in natte schraallanden : onderzoeksvoorstel deskundigenteam natte schraallanden overlevingsplan bos en natuur
Kemmers, R.H. ; Beltman, B. ; Grootjans, A.P. ; Jansen, A.J.M. ; Kooijman, G. ; Schipper, P. - \ 2004
Wageningen : Alterra (Alterra-rapport pitrus ) - 57
graslanden - landbouwgrond - juncus effusus - ecologisch herstel - bodemchemie - vegetatiebeheer - grasslands - agricultural land - juncus effusus - ecological restoration - soil chemistry - vegetation management
|From laboratory tests to population effects using process-based modelling
Jager, T. ; Alda Alvarez, O. ; Kooijman, B. ; Kammenga, J.E. - \ 2004
In: Abstracts, Environmental science solutions: a pan-European perspective, Setac Europe 14th Annual Meeting, Praque, 18-22 April 2004. - Praag : SETAC - p. 79 - 80.
Behoud van natuurwaarden in droge, voedselarme bossen: hoe effectief zijn effectgerichte maatregelen?
Kuyper, T.W. ; Bartelink, H.H. ; Dobben, H.F. van; Klap, J.M. ; Weersink, H. - \ 2004
In: Duurzaam natuurherstel voor behoud van biodiversiteit / van Duinen, Gert Jan, Bobbink, Roland, van Dam, Chantal, Esselink, Hans, Hendriks, Rob, Klein, Mariette, Kooijman, Annemieke, Roelofs, Jan, Siebel, Henk, Ede : Expertisecentrum LNV (Rapport EC- LNV 2004/305) - ISBN 9789075789140 - p. 15 - 31.
bossen - bodemchemie - verzuring - herstel - ecosystemen - herstelbeheer - forests - ecosystems - soil chemistry - acidification - rehabilitation - restoration management
Samenvatting Eutrofienng en verzuring hebben geleid tot een groot aantal veranderingen in de Nederlandse bossen gedurende de laatste decennia Droge voedselarnie bossen behorende tot onder andere korstmos dennenbos kussentjesmos dennenbos kraaihei dennenbos en gaffeltandnios eikenbos zijn in dat opzicht bijzonder kwetsbare bostypen Vermesting en verzunng hebben invloed op de vitaliteit en productiviteit van bomen en op bodemkundige eigenschappen die beide op hun beurt weer effecten hebben op de karaktenstieke levensgemeenschappen van deze bossen, vooral gekenmerkt door bijzondere paddestoelen korstmossen en rnossen In het kader van het Overlevingsplan Bos en Natuur is onderzoek gedaan naar maatregelen die in deze bossen kunnen worden uitgevoerd om de negatie ve effecten van eutrofiering en verzuring op de bijzondere natuurwaarden tegen te gaan Daartoe zijn in de periode 1994 1999 effecten van plaggen en dunnen alleen dunnen en niets doen op een aantal ecosysteemkenmerken onder zocht Verondersteld werd dat deze maatregelen zouden leiden tot een terugzet ten van de successie naar het (korst )mosnjke stadium en een herstel van de ectomycorrhiza paddestoelen In de dennenbossen bleek de combinatie van plaggen en dunnen succesvol voor de bodemvegetatie en paddestoelenflora Deze ingreep leidde tot een teruqzet ting van de vegetatiesuccessie Op de ectomycorrhizapaddestOelen had deze ingreep tot gevolg dat zowel aantallen (Rode Lijst) soorten als vruchtlichamen waren toegenomen De maatregel dunnen alleen had niet of nauwelijks effect Vermindenng van de strooiselval op zich is derhalve onvoldoende voor herstel van de natuurwaarden De belangrijkste maatregel betreft de verlaging van de strooisel en humusvoorraad door plaggen Wel lijkt er sprake van een aanvullend positief effect door dunnen doordat daardoor de opbouw van een nieuwe strooi sel en humuslaag wordt vertraagd De maatregelen in de dennenbossen hebben geleid tot de gewenste ontwikkelingen Plaggen en dunnen is voor de dennen bossen een praktijknjpe maatregel Fris echter ook sprake van een duidelijke ten dens in de richting van de vegetatiesamenstelling zoals die bestond voor de ingrepen Om permanente verbetering te krijgen van de conditie is echter peno diek ingrijpen nodig In de eikenopstanden is sprake van ofwel een snelle terugkeer naar de uitgangs situatie ofwel een niet gewenste ontwikkeling Hier hebben de behandelingen slechts zeer beperkt geresulteerd in soorten uit eerdere successiestadia De behandelingen waren derhalve niet succesvol Hierbij kan een rol spelen dat (veel) te weinig organisch materiaal is verwijderd waardoor de nutrientendynamiek hoog is gebleven Het achterwege blijven van natuurherstel roept hier de vraag op of meer drastische ingrepen die lijken op die in de dennenbossen moeten worden uitgevoerd en onderzorht of dat het gaffeltandmos-eikenbos voor Nederland als verloren beschouwd moet worden
Belevingswaarde van het landschap van Winterswijk bij een multifunctioneel gras- en bouwlandgebruik
Veltman, D. ; Lyklema, W.F. ; Boonen, A.G. ; Kooijman, W. ; Mosterman, E. ; Pollaert, M. ; Korevaar, H. ; Geerts, R.H.E.M. - \ 2003
Wageningen : Plant Research International (Rapport / Plant Research International 68) - 52
landschap - landschapsecologie - perceptie - taxatie - plattelandsplanning - karteringen - landschapsbescherming - nederland - cultuurlandschap - gelderland - achterhoek - landscape - landscape ecology - perception - valuation - rural planning - surveys - landscape conservation - netherlands - cultural landscape - gelderland - achterhoek
3-Methyl 5-[(S)-2-methylbutyl] 4-[2-(difluoromethoxy)phenyl]-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate
Kooijman, H. ; Spek, A.L. ; Sobolev, A. ; Jongejan, H. ; Franssen, M.C.R. - \ 2002
Acta Crystallographica Section E 58 (2002). - ISSN 1600-5368 - p. 532 - 534.
Effect of acyl chain length and branching on the enantioselectivity of Candida rugosa lipase in the kinetic resolution of 4-(2-difluoromethoxyphenyl)-substituted 1,4-dihydropyridine 3,5-diesters
Sobolev, A. ; Franssen, M.C.R. ; Vigante, B. ; Cekavicus, B. ; Zhalubovskis, R. ; Kooijman, H. ; Spek, A.L. ; Duburs, G. ; Groot, Æ. de - \ 2002
Journal of Organic Chemistry 67 (2002). - ISSN 0022-3263 - p. 401 - 410.
|A dynamic whole-plant model of integrated metabolism of nitrogen and carbon; 1 comparative ecological implications of ammonium-nitrate interactions
Bijlsma, R.J. ; Lambers, H. ; Kooijman, S.A.L.M. - \ 2000
Plant and Soil 220 (2000)1/2. - ISSN 0032-079X - p. 49 - 69.
Growth responses to ozone in plant species from wetlands
Franzaring, J.H. ; Tonneijck, A.E.G. ; Kooijman, A.W.N. ; Dueck, Th.A. - \ 2000
Environmental and Experimental Botany 44 (2000)1. - ISSN 0098-8472 - p. 39 - 48.
Ten wet grassland species were fumigated with four concentrations of ozone (charcoal-filtered air, non-filtered air and non-filtered air plus 25 or 50 nl 1-1 ozone) in open-top chambers during one growing season to investigate the long-term effect of this air pollutant on various growth variables. Only Eupatorium cannabinum showed ozone-related foliar injury, while five species reacted with significantly ozone, enhanced senescence. Premature senescence was paralleled by a significant ozone-induced reduction of green leaf area in Achillea ptarmica, E. cannabinum and Plantago lanceolata. At the intermediate harvest performed after 28 days shoot weights were significantly decreased by ozone in A. ptarmica and increased in Molinia caerulea. At the final harvest performed at the end of the growing season two other species, Cirsium dissectum and E. cannabinum had a significantly reduced shoot weight due to ozone. Root biomass was determined only at the intermediate harvest. The root:shoot ratio (RSR) was significantly reduced in C. dissectum, while it increased in M. caerulea. Seven of the species developed flowers during the experiment. While no significant ozone effects on flowering date and flower numbers were detected, flower weights were significantly reduced in E. cannabinum and P. lanceolata. (C) 2000 Elsevier Science B.V.
|Responses of wet grassland species to ozone and possible ecological implications
Franzaring, J.H. ; Dueck, Th.A. ; Tonneijck, A.E.G. ; Kooijman, A.W.N. - \ 1999
Verhandlungen der Gesellschaft für Ökologie 29 (1999). - p. 53 - 58.
Lipase-mediated resolution of octahydro-3,3,8a-trimethyl-1-naphthalenol, a key intermediate in the total synthesis of lactaranes and marasmanes
Franssen, M.C.R. ; Jongejan, H. ; Kooijman, H. ; Spek, A.L. ; Bell, R.P.L. ; Wijnberg, J.B.P.A. ; Groot, C.P.G.M. de - \ 1999
Tetrahedron: Asymmetry 10 (1999). - ISSN 0957-4166 - p. 2729 - 2738.
Efficient synthesis and molecular structure of 2-hydroxyisophthaldehyde
Zondervan, C. ; Beuken, E.K. van den; Kooijman, H. ; Spek, A.L. ; Feringa, B.L. - \ 1997
Tetrahedron Letters 53 (1997). - ISSN 0040-4039 - p. 3111 - 3114.
|Growth response of wet grassland species to ozone
Dueck, Th.A. ; Kooijman, A.W.N. ; Tonneijck, A.E.G. - \ 1997
In: Abstracts of 5th US-Dutch International symposium on Air pollution in the 21st Century. Priority issues and policy trends, April 13-17,1997. Noordwijk, The Netherlands, Poster Abstract - p. 111 - 111.
Low molecular weight Cooperia oncophora antigens. Potentials to discriminate between susceptible and resistant calves after infection.
Diemen, P.M. van; Ploeger, H.W. ; Nieuwland, M.G.B. ; Rietveld, F.W. ; Eijsker, M. ; Kooijman, F.N.J. ; Kloosterman, A. ; Parmentier, H.K. - \ 1997
International Journal for Parasitology 27 (1997)5. - ISSN 0020-7519 - p. 587 - 593.
The recognition of low molecular weight proteins by sera obtained during a single oral (primary) infection with 100 000 3rd-stage Cooperia oncophora larvae was studied in calves. Three groups of 6 or 7 calves were selected based on different egg excretion patterns. SDS-gel electrophoresis of adult Cooperia antigen under reducing conditions, followed by Western blotting, revealed that resistance of individual calves to C. oncophora might be related with antibody responses (42 days post infection) against at least 2 protein fragments (14-16 kDa and 27 kDa). The 14-16-kDa protein complex was bound, to some extent, by individual sera from all calves. The intensity of staining was negatively correlated with egg excretion on Day 42 p.i. Calves with high egg counts on Day 21 p.i. either did not or only weakly recognized the 27-kDa band. It has to be established whether the 14-16 kDa (or recombinant 14.2 kDa) provides a tool for immunodiagnostics and whether the 27-kDa fragment can help further unravel immune-mediated resistance to Cooperia.
|Monitoring photosynthesis in evergreen mediterranean forests in order to assess the scientific and operational potential of the LEAF instrument
Berkhout, J.J.A. ; Jans, W.W.P. ; Jongejans, J. ; Kooijman, A.M. ; Raaphorst, S. ; Steingröver, E.G. - \ 1996
Delft : BCRS - ISBN 9789054111931 - 35
fotosynthese - bosbouw - remote sensing - luchtkarteringen - waterrelaties - wortels - bodem - toepassingen - middellandse-zeegebied - photosynthesis - forestry - remote sensing - aerial surveys - water relations - roots - soil - applications - mediterranean region
Resolution of a tetrahydrofuran ester by Candida rugosa lipase (CRL) and an examination of CRL's stereochemical preference in organic media.
Franssen, M.C.R. ; Jongejan, H. ; Kooijman, H. ; Spek, A.L. ; Camacho Mondril, N.L.F.L. ; Boavida dos Santos, P.M.A.C. ; Groot, Æ. de - \ 1996
Tetrahedron: Asymmetry 7 (1996). - ISSN 0957-4166 - p. 497 - 510.
|Detoxification of NHy: physiological support for effect threshold concentrations
Dueck, Th.A. ; Elderson, J. ; Kooijman, A.W.N. ; Eerden, L.J. van der - \ 1995
Unknown Publisher - 64 p.
|Effects of age and growth conditions
Steingröver, E.G. ; Tonneijck, A.E.G. ; Jans, W.W.P. ; Kooijman, A.W.N. - \ 1995
In: Physiology of forest-grown douglas-fir trees; effects of air pollution and drought / Steingröver, E.G., Jans, W.W.P., - p. 63 - 68.
Food mediated life history strategies in Daphnia magna : their relevance to ecotoxicological evaluations
Enserink, E.L. - \ 1995
Agricultural University. Promotor(en): J.H. Koeman; N. van der Hoeven. - S.l. : Enserink - ISBN 9789054854814 - 128
toxicologie - chemicaliën - cladocera - daphnia - zware metalen - modellen - onderzoek - daphnia magna - toxicology - chemicals - cladocera - daphnia - heavy metals - models - research - daphnia magna
The waterflea Daphnia magna is a widely used test organism in ecotoxicological studies. Acute and chronic laboratory tests yield basic information for the development of water quality standards, assessment of potential hazards of (new) chemicals, waste water licences and sanitation measures for contaminated sediments. Environmental risk assessment also includes extrapolation from laboratory to field, for which theoretical models are applied. Reliable results can only be obtained if:
The distance between a single-species test under laboratory conditions and the response of an aquatic ecosystem is enormous, in terms of complexity. A first step has been made by Kooijman, who developed a model to predict effects of toxicants on Daphnia populations from effects on individuals (Kooijman, 1986; Kooijman et al., 1989). From comparisons between experimental and simulated population dynamics research questions regarding critical model assumptions were derived.
The present study focuses on food availability, which plays a central role in the life history of D.magna. Its development and reproduction are dependent on food level, as well as its sensitivity to toxic stress. The importance of food for the culture of test animals was investigated, as a contribution to standardisation of toxicity tests. Besides, assumed relationships between food level and Daphnia growth and reproduction are validated, in order to support development of extrapolation models. The experimental approach has been chosen to address the research questions related to both toxicity testing and extrapolation models. New techniques were developed for that purpose. Cadmium, chromium and lead, which are designated as priority pollutants by the International Rhine Committee (1987), have been applied as model substances. The investigations have been carried out at the Instute for Inland Water Management an Waste Water Treatment in Lelystad.
New experimental methods
Competition mechanisms within a Daphnia population were investigated with a newly developed culture system (chapter 6 ). it consisted of two interconnected culture vessels, each holding a cohort. An air-driven flow of medium plus algae circulated between these vessels, hence allowing the cohorts to share the same food conditions. The system proved to be a useful tool for competition studies. It enables detailed studies of the exploitation of a common food source by competitors that are similar in morphology, or should be kept apart for other reasons. Different, externally driven food dynamics can be simulated. With a few adaptations the system can easily be extended to hold three or more competing groups.
It could be demonstrated in our studies that reproduction of females, which were exposed to an abrupt increase or decrease of food ration between the third and the fourth brood, was fully adapted to the new situation in three instars, or c. eight days at 20°C (standard laboratory temperature). Brood sizes ranged from 7 to 76 and neonate carapace lengths from 1.1 to 0.92 mm. The smallest young (0.80 mm) were observed in the first brood. The latter is a well-known phenomenon that is accounted for in toxicity test guidelines (e.g. OECD, 1984) by discouraging the use of the first brood. The main reason for this advice is reduced survival in controls, which may invalidate the test (e.g. Cowgill et al., 1986). The present study shows that large neonates contained more lipid reserves than small ones. Therefore we may expect a positive correlation between survival at starvation and body size. This was confirmed in the starvation experiments described in chapter 5 and Enserink (1989), but not in similar experiments in chapter 4 . In connection with unfed 48 h toxicity tests it is worth noting that median survival times never fen below 4 d, even for the smallest (0.77 mm) neonates.
An even more important reason to pay attention to neonate size is that small neonates can be more sensitive to toxicants than large young in acute (48 h) tests ( chapter 3 ). When exposed to cadmium there was a threefold difference between the LC 50 's for small and large animals. However, no such effect was found in toxicity tests with chromium(VI), i.e. LC 50 's were similar in all tests, which probably relates to different modes of action of these two metals.
In chronic (21 d) toxicity tests the initial size of test animals appeared to be less important ( chapter 4 ). Whereas the trends observed in acute tests were consistent in several trials (e.g. Enserink, 1989), this was not the case in chronic tests. The results suggest that environmental conditions during the test mask subtle differences in neonate size and lipid reserves. The variation in effect concentrations caused by non-simultaneous replication was in the same order of magnitude, i.e. a factor of 2, as the effects of initial body size. Probably, food supply during these tests was inadequately controlled.
The most conspicuous conclusion of the present studies is that maternal food ration is of paramount importance to neonate fitness and hence to the results of acute toxicity tests, at least for some chemicals (Enserink, 1989; Enserink et al ., 1990). Similar results were obtained independently by Baird et al . (1989b). More recently, a number of other investigators have confirmed these findings.
The reproductive strategy in D.magna was also observed by Cox et al . (1992), Naylor et al . (1992) and Viganò (1993). According to Naylor et al . (1992) the inverse relationship between maternal food level and neonate size also holds for dry weight, although this parameter appeared to be more variable than body length. Even under normal culture conditions, when food level is not purposely varied, brood to brood oscillations of neonate weight and length were inversely related to oscillations of mean clutch size (Viganò,1993; Lazorchak & Waller, 1993). Such variation can be caused by unstable quality or quantity of food supply, increased grazing capacity owing to body growth and periodic presence of neonates.
The results of the current studies suggest that the influence of maternal food conditions on the results of acute (48 h) toxicity tests depends on test substance. Cadmium toxicity was modified by neonate size, but the toxicity of chromium remained unaffected. The largest influence was reported for 3,4-dichloroaniline, i.e. a factor of 6 (Baird et al ., 1991). A significant positive correlation between neonate size and LC 50 was found for sodium bromide and 3,4-dichloroaniline (Naylor et al ., 1992), and copper (Lazorchak & Waller, 1993). Viganò (1993) found no effect of neonate size on LC 50 's for ethylbenzene and n -butylbenzene, but the variation of test results was very limited, as was the size range of the test animals. For cadmium however, the effect of maternal ration was confirmed (Baird et al ., 1991), but neonate length showed no correlation with LC 50 in the experiments of Naylor et al . (1992), which is inconsistent with the results of the present studies. Several differences between our study and that of Naylor et al. (1992) might account for these results, e.g. the presence of food during the test, the use of another clone and a different test medium. It is of interest to note that both studies were carried out according to standard, but different, test protocols. Whereas maternal food ration, which was purposely varied, accounted for a within-laboratory variation of a factor 3 in the present study and the experiments of Baird et al. (1991), who worked at the same laboratory as Naylor et al. (1993), a 20-fold difference occurred between the laboratories. From the viewpoint of standardization, sources of variation within and between laboratories are equally important.
The significance of maternal food conditions for toxicity tests has been clearly demonstrated above. It is therefore recommended to include pre-test conditions in standardization programmes and test guidelines. Several other factors are known to be relevant, for instance feeding conditions during the test (Winner et al., 1977; Chandini, 1988a, b; Soares, 1989; Lazorchak & Waller, 1993; Sims et al., 1993; Klüttgen & Ratte, 1994), genotype (Soares, 1989; Baird et al., 1991), medium (Winner, 1985) and even statistical evaluation of test results (Hoekstra, 1993). However, very little is known about their relative contributions and interactions. Ring-tests are excellent instruments to investigate such combined effects. At present, an international ring-test is conducted to improve the OECD guidelines (1984) for chronic toxicity tests, with respect to genotype, medium and feeding during the test. This investigation is coordinated by the University of Sheffield (UK), Department of Animal & Plant Sciences. In order to obtain a sufficient overview of sources of variation within and between laboratories and to identify the most important factors, further investigation is needed. Current guidelines do not garantee standardized test results in the strict sense of the word, which decreases the reliability of safe levels for water management and of bioassays conducted for regulatory purposes. Therefore, a collective decision should be made on:
In the model of Kooijman (1986) for growth and development of individual Daphnia a balance between mathematical simplicity and biological realism was pursued. Modelled individuals were aggregated into simulated single-species populations (Kooijman et al., 1989; Van der Hoeven, 1991). In this way, physiological effects of toxic chemicals can be translated into population dynamics, which was regarded as a step towards modelling the response of ecosystems to toxic stress. Ecosystems contain many interacting populations. In order to avoid a complex tangle of detailed sub-models a collection of assumptions was produced, partly based on conceptions of physical mechanisms, partly on the premise that everything is extremely simple unless it proves to be more complex and partly on empirical data. The idea was to strip details from the sub-models in the process towards the ecosystem model. The Daphnia model was regarded as a test case for a more general model, which should be applicable to many species (Kooijman et al ., 1987). Nevertheless, a certain amount of detail is nescessary for meaningful extrapolations to higher levels of organisation.
A comprehensive list of Kooijman's (1986) model assumptions at the level of the individual is given by Van der Hoeven (1991). In the present thesis a number of these assumptions was evaluated experimentally:
In chapters 3 and 4 a reproductive strategy for D. magna in reponse to food availability is described. Body size and lipid content of neonates appeared to be inversely related to maternal food ration. Cox et A (1992) observed no further decrease of neonate size when food was no longer restrictive, i.e. above the incipient limiting level. These findings do not agree with two model assumptions: size at birth is independent of food level and size-specific energy storage of a neonate is identical to the size-specific storage of its mother. The reproductive strategy mentioned above has important consequences for survival and development of neonates under low food conditions. Survival time at starvation can increase from 4 to 9 days with increasing neonate size (chapter 5 ). In addition, large and fat young can develop into their third instar without food (chapter 4 ). This may decrease time to first reproduction, as will be shown below.
In the model, deposition of the first clutch, i.e. the primiparous instar, is initiated as the female attains a certain body size, which is independent of food level. In chapter 5 however, body sizes of primiparae differed significantly among food rations, with minimum sizes at intermediate rations. A threshold body length for maturation was found two instars earlier, i.e. just before the preadolescent instar, in concordance with Ebert (1992). However, this threshold was not completely independent of food. At low food rations trade-offs occurred between growth and reproduction. One group of animals delayed their first brood in favour of body growth. The young of these delayed broods were significantly larger than young that were born earlier at the same maternal food ration, probably owing to increased instar duration. It was concluded that a minimum energy requirement for reproduction was met at this food ration.
A remarkable phenomenon was observed at low food rations. Allocation of energy reserves, i.e. yolk, to the ovaries appeared reversible. Accumulation during the first half of an instar and redistribution towards the end of the instar suggested that energy needs for the production of a new carapace have priority over egg production. As yet mathematical models of Daphnia do not
From the distribution of biomass during the production of the first brood it was concluded that the proportion of energy allocated to reproduction increases with food availability. Similar results were obtained by McCauley et al. (1990), who improved the simulations of their Daphnia model by incorporating a food-dependent fraction to reproduction (Gurney et al., 1990). In the model of Kooijman, however, the fraction of assimilated energy allocated to reproduction is assumed constant, except for starvation conditions.
Combined effects of food ration and exposure to lead on maturation were also investigated in chapter 5 . A significant interaction between food and lead concentration was observed, which means that toxic effects were dependent on food level. Body growth was reduced at both food levels, leading to smaller primiparae with smaller progeny at abundant food, whereas delayed maturation and egg mortality were observed at the low food ration. Except for egg mortality, the effects of lead on maturation resemble increased food stress. Similar observations have been made in experiments with copper (Winner et al., 1977) and cadmium (Chandini, 1989; Klüttgen & Ratte, 1994). Extrapolation from chronic toxicity tests, which are normally carried out with large food supply, to low food environments can therefore generate wrong conclusions.
Density oscillations in laboratory populations with constant food supply are a common phenomenon. However, it is not clear whether such behaviour is mainly caused by intrinsic properties of the populations themselves or by experimental irregularities. On the basis of an analysis of published population behaviour, Van der Hoeven (1989) suggested that the latter option is very probable. Therefore, the simulations of the Daphnia model, which show regular, persistent oscillations, have been questioned (Kooijman et al., 1989). The major driving force of these oscillations is synchronisation of life cycles during the decline phase of a population. This prediction mainly follows from the assumption that food intake is proportional to surface (-length 2) and maintenance costs are proportional to weight (-length 3). As a consequence, the rate of body growth declines as the animal approaches an ultimate size, which in turn is depressed at low food levels. Individuals which are smaller than the ultimate size continue to grow, whereas body growth is suspended by those which are larger than this size. This mechanism leads to convergence of body lengths. The assumed growth model is referred to as Von Bertalanffy's type I model (1969). Reproduction is closely synchronised owing to another assumption, i.e. first reproduction occurs at a fixed body size (cf. chapter 5 ).
Convergence and synchronisation among two juvenile cohorts was evaluated in an experimental set- up that simulated food dynamics and competition during a density peak and succeeding decline phase of a laboratory population (chapter 6 ). The cohorts, which came from consecutive broods of a common mother cohort, were separated while they shared the same food source. Two feeding regimes were used, i.e. constant food input and daily pulses, to examine effects of resource variability. Under the experimental conditions convergence was very slow or absent and no synchronisation of reproduction occurred. The larger animals performed best at constant low food levels, whereas the smaller cohort was abetter competitor at fluctuating food. Modelled convergence rates, using the Von Bertalanffy model, were unrealistically high. Therefore, the suitability of this model under the present conditions was discussed in comparison with other growth models. Parallel growth curves suggested a linear growth model for juvenile D.magna, although it was recognized that the shape of the growth curve is extremely dependent on the specific conditions of the study.
From the mechanisms described above it is concluded that close synchronisation of fife cycles in laboratory populations and hence severe oscillations are not expected. Parallel growth, increased individual variation at low food level (cf. Cox et al., 1992) and trade-offs with respect to first reproduction have a stabilizing effect. It has been shown that lipid reserves of mother and progeny are inversely related, which decreases the population growth rate and enhances the survival probability of neonates under resource limitation. In general, phenotypic plasticity, especially adaptation to low food, is underestimated in the present model assumptions. Simple models may perform satisfactory at the level of the individual, but they can lead to erroneous population dynamics. Incorporation of some more biology will undoubtly improve the model simulations and thereby the extrapolation of toxic effects from the individual to the population level. However, the balance between mathematical elegance and the full complexity of Daphnia is precarious. A stepwise incorporation of the most relevant life history strategies in combination with sensitivity analysis of the model could improve our understanding of population dynamics.
The results of chapter 5 and adverse effects on growth and reproduction, which are observed for many toxicants (cf. chapter 4 and Enserink et al., 1991), suggest that toxic substances impair Daphnia's capacity to efficiently exploit its food source. This could lead to increased densities of (edible) algae. However, effects on ecosystem level depend on many factors, e.g. relative susceptibility of competing zooplankton, predators and food organisms. For instance, Marshall & Mellinger (1980) observed both decreased and increased phytoplankton production in cadmium spiked enclosures of plankton communities. In the first case primary production was directly affected by the test substance and in the second case reduced zooplankton abundance compensated for toxic effects on the algae. In a review on pesticide stress in freshwater ecosystems Brock & Budde (1994) concluded that primary effects can be predicted from laboratory tests, if exposure of field populations can be estimated. However, secundary effects are unpredictable in most cases. Recently, Scholten et al. (1994) stated that eutrophication problems are enhanced by impaired zooplankton grazing, owing to the presence of toxic substances in surface water. Although their conclusions raised great controversy in The Netherlands, the above statement could serve as a valuable hypothesis in future investigations. At present, the influence of toxicants on aquatic ecosystems is largely unknown. Research on the combined effects of nutrients and micropollutants is certainly worth pursuing. Besides, it could stimulate further cooperation between ecologists and ecotoxicologists.
Dynamic energy budgets affect kinetics of xenobiotics in the marine mussel Mytilus edulis.
Haren, R.J.F. van; Schepers, H.E. ; Kooijman, S.A.L.M. - \ 1994
Chemosphere 29 (1994). - ISSN 0045-6535 - p. 163 - 189.
Environmental assessment of food packaging: impact and improvement.
Kooijman, J.M. - \ 1994
Packaging Technology and Science 7 (1994). - ISSN 0894-3214 - p. 111 - 121.
|Flavin dynamics in reduced flavodoxins: a time-resolved polarized fluorescence study.
Leenders, R. ; Kooijman, M. ; Hoek, A. van; Veeger, C. ; Visser, A.J.W.G. - \ 1993
European Journal of Biochemistry 211 (1993). - ISSN 0014-2956 - p. 37 - 45.
Environmental assessment of packaging: sense and sensibility.
Kooijman, J.M. - \ 1993
Environmental Management 17 (1993). - ISSN 0364-152X - p. 575 - 586.
|Consument wil vers én lang houdbaar.
Kooijman, J.M. - \ 1993
Chemisch Magazine 13 (1993). - ISSN 0167-2746 - p. 579 - 583.
|Minder milieubewust verpakken: verpakking is niet het enige dat je weggooit.
Kooijman, J.M. - \ 1992
PT. Procestechniek 47 (1992)9. - ISSN 0032-4094 - p. 50 - 54.
|Milieubeoordeling, een riskante zaak.
Kooijman, J.M. - \ 1992
Verpakken 12 (1992)2. - p. 28 - 30.
|Milieubeoordeling verpakkingen, lastig en riskant.
Kooijman, J.M. - \ 1992
Tijdschrift Inkoop & Logistiek 8 (1992)1/2. - p. 46 - 52.
|Packaging of foods: many demands and conflicting requirements.
Kooijman, J.M. - \ 1992
In: Proc. Eur. Symp. Food packaging materials. Technologigal Univ., Delft - p. 21 - 29.
|Ketenbeoordeling van verpakkingen 3. Uitwerking en resultaten.
Kooijman, J.M. ; Herk, K. van; Seters, A.P.R. van; Smink, G.C.J. - \ 1991
Voedingsmiddelentechnologie 24 (1991)26. - ISSN 0042-7934 - p. 37 - 40.
basisproducten - voedselindustrie - voedseltechnologie - verpakking - verkoopbevordering - milieuhygiëne - commodities - food industry - food technology - packaging - sales promotion - environmental hygiene
|Ketenbeoordeling van verpakken 2. Systeem voor beoordeling milieu-aspecten.
Kooijman, J.M. ; Reuvers-Rijnders, M. ; Seters, A.P.R. van; Smink, G.C.J. - \ 1991
Voedingsmiddelentechnologie 24 (1991)25. - ISSN 0042-7934 - p. 37 - 40.
uitrusting - voedselindustrie - voedseltechnologie - verpakking - verpakkingsmaterialen - verpakken - milieuhygiëne - machines - equipment - food industry - food technology - packaging - packaging materials - packing - environmental hygiene - machines
|Ketenbeoordeling van verpakken 1. Beoordeling van milieu-aspecten.
Kooijman, J.M. - \ 1991
Voedingsmiddelentechnologie 24 (1991)23. - ISSN 0042-7934 - p. 35 - 38.
uitrusting - voedselindustrie - voedselinspectie - voedingsmiddelenwetgeving - voedseltechnologie - wetgeving - verpakking - verpakkingsmaterialen - verpakken - milieuhygiëne - machines - equipment - food industry - food inspection - food legislation - food technology - legislation - packaging - packaging materials - packing - environmental hygiene - machines
Met dit en volgende artikelen over genoemd onderwerp wordt beoogd om bedrijven enig inzicht te geven in de mogelijkheden en beperkingen van milieubeoordelingssystemen. Op grond hiervan kan een begin worden gemaakt met een eigen milieuaanpak
Kooijman, J.M. - \ 1991
In: Handboek integrale milieuzorg - p. 101 - 112.
|Packaging, to be or not to be?
Kooijman, J.M. - \ 1991
Tijdschrift voor Marketing 25 (1991)2. - ISSN 0165-1439 - p. 6 - 14.
commodities - environment - environmental management - environmental protection - equipment - packaging - packaging materials - packing - quality - sales promotion - machines - basisproducten - milieu - milieubeheer - milieubescherming - uitrusting - verpakking - verpakkingsmaterialen - verpakken - kwaliteit - verkoopbevordering - machines
Een korte schets wordt gegeven van de technologie van het verpakken van levensmiddelen en enkele veranderingen en ontwikkelingen worden toegelicht
|Verduurzamen en beschermen van voedingsmiddelen: Een overzicht en de toepassing van clean-room-technieken.
Kooijman, J.M. - \ 1991
In: Proc. VCTN Congr. Contamination control, deel 2. Uitg. Noordervliet, Utrecht - p. 106 - 110.
|Ontwikkeling van abnormaal gedrag bij vleeskalveren in groepshuisvesting : effecten van ruwvoerverstrekking = Development of abnormal behaviour in group-housed veal calves : effects of roughage supply
Kooijman, J. ; Wierenga, H.K. ; Wiepkema, P.R. - \ 1990
Zeist : IVO "Schoonoord" (Rapport / IVO "Schoonoord" B-356) - 48
huisvesting, dieren - dierenwelzijn - kalveren - voedingsrantsoenen - vleesproductie - ruwvoer (roughage) - ? - animal behaviour - animal housing - animal welfare - calves - feed rations - meat production - roughage
Verpakken: niet te veel, niet te weinigh, juist van passe...
Kooijman, J.M. - \ 1990
Wageningen : Landbouwuniversiteit Wageningen - 31
voedselindustrie - voedseltechnologie - uitrusting - verpakking - verpakkingsmaterialen - verpakken - voedingsmiddelen - voedselproducten - landbouwproducten - colleges (hoorcolleges) - distributie - machines - food industry - food technology - equipment - packaging - packaging materials - packing - foods - food products - agricultural products - lectures - distribution - machines
Correlation between chlorophyll fluorescence and photoacoustic signal transients in spinach leaves.
Snel, J.F.H. ; Kooijman, M. ; Vredenberg, W.J. - \ 1990
Photosynthesis Research 25 (1990). - ISSN 0166-8595 - p. 259 - 268.
|Trace detection in agriculture and biology.
Bicanic, D.D. ; Harren, F. ; Reuss, J. ; Woltering, E. ; Snel, J. ; Voesenek, L. ; Zuidberg, B. ; Jalink, H. ; Bijnen, F. ; Blom, C. ; Sauren, H. ; Kooijman, M. ; Hove, L.W.A. van; Tonk, W.J.M. - \ 1989
In: Topics in current physics. Photoacoustic, photothermal and photochemical processes in gases / Hess, P., Heidelberg : Springer Verlag - ISBN 9783540513926 - p. 213 - 215.
|Conflict dustbathing behaviour on wood-shavings?
Liere, D.W. van; Kooijman, J. ; Wiepkema, P.R. - \ 1989
In: Proc. 3rd Eur. Symp. Poultry welfare, J.M. Faure, A.D. Mills (eds.). Tours, France - p. 265 - 268.
|Measurement of photosynthetic energy conversion using chlorophyll fluorescence and photoacoustic spectroscopy.
Snel, J.F.H. ; Kooijman, M. - \ 1988
In: Abstracts Joint Meeting Dutch and Swedish Societies Biophysics, Lunteren, The Netherlands - p. 1 - 1.
|Simulation analysis of the effects of SO2 on crops.
Kropff, M.J. ; Leemans, A. ; Smeets, W. ; Meijer, E. ; Zalm, A. van der; Kooijman, A. - \ 1988
|Landbouwbedrijfssystemen en methodieken van onderzoek.
Kooijman, M.L.M. ; Bruijn, G.H. de - \ 1986
Unknown Publisher - 12 p.
|Klimaat en teelt.
Kooijman, M.L.M. ; Rikken, G.A. ; Bruijn, G.H. de - \ 1986
Unknown Publisher - 20 p.
Kooijman, M.L.M. ; Driessen, P.M. ; Bruijn, G.H. de - \ 1986
Unknown Publisher - 21 p.
|Arbeid en teelt.
Kooijman, M.L.M. ; Thijssen, H.J.C. ; Bruijn, G.H. de - \ 1986
Unknown Publisher - 15 p.