Staff Publications

Staff Publications

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

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

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

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

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Waarom is eten uit de magnetron minder smakelijk?
Esveld, Erik - \ 2018
FEM Growth and Yield Data - Tropical Lowland Rainforest – Suriname Mapane
Graaf, N.R. de; Jonkers, W.B.J. ; Jansen, J.J. ; Bongers, F. ; Sterck, F.J. ; Stuiver, B.M. ; Wirjosentono, J. ; Mohren, G.M.J. - \ 2018
growth and yield - uneven-aged mixed species forest - tropical lowland rainforest - tree diameter - tree height - cleaning - CELOS Silvicultural System
In 23 experimental plots of 1.0 ha in Mapane Suriname 570 subplots of 0.04 ha were laid out and 7980 trees were monitored between 1981 and 1997 with different grades of intermediate tending (cleaning) as treatment.
OP002 Assessment of disease activity patterns during the first 10 years after diagnosis in a population-based Crohn’s disease cohort shows a quiescent disease course for a substantial proportion of the population
Wintjens, D. ; Bergey, F. ; Saccenti, E. ; Jeuring, S. ; Romberg-Camps, M. ; Oostenbrug, L. ; Masclee, A. ; Jonkers, D. ; Martins Dos Santos, V. ; Pierik, M. - \ 2018
Journal of Crohn's and Colitis 12 (2018)supplement 1. - ISSN 1873-9946 - p. S001 - S003.
Background Representative studies concerning the long-term prognosis and disease course in Crohn’s disease (CD) primarily describe steroid exposure, need for surgery or hospitalisations, and disease progression as characteristics of an unfavourable outcome. Real-life data on long-term disease activity are lacking. We aimed to define clusters with different disease activity patterns in the population-based IBDSL cohort. Methods All CD patients from the IBDSL cohort with at least 10 years follow-up (>18 years, diagnosed between 1991 and 2004) were included. Data on demographics, disease phenotype, medication use, hospitalisations, and surgery were available. In addition, all endoscopy and imaging reports were scrutinised. Since diagnosis, active disease was defined for each yearly quarter by (i) active disease on endoscopy or imaging, (ii) hospitalisation, (iii) surgery, or (iv) treatment adjustment for increased symptoms. Subsequently, formula-based clusters were generated based on four previously published questionnaire-based disease activity patterns,1 completed with two additional clusters (Figure 1). Prediction models were created using discriminant analysis with PLS regression based on characteristics at baseline and 6 months after diagnosis. Results In total, 432 patients were included. During 10 years follow-up after diagnosis, patients experienced 4.2 (SD 3.8) quarters of active disease on average. The distribution of patients over different clusters is shown in Figure 1. Notably, 128 patients (29.6%) were classified as quiescent and, of these, 89.8% never received immunomodulators or biologics. Ileocolonic disease location (OR 0.45; 95% CI 0.21–0.91) and smoking at diagnosis (OR 0.44; 95% CI 0.26–0.70) were negatively associated with a quiescent disease course, while surgery at diagnosis (OR 3.02; 95% CI 1.39–6.64) was positively associated. Our best prediction model for a quiescent course had an area under the ROC curve of 0.72 (p < 0.001) at baseline and 0.75 (p < 0.001) at 6 months after diagnosis.
Age-dependent changes in GI physiology and microbiota : Time to reconsider?
An, Ran ; Wilms, Ellen ; Masclee, Ad A.M. ; Smidt, Hauke ; Zoetendal, Erwin G. ; Jonkers, Daisy - \ 2018
Gut 67 (2018)12. - ISSN 0017-5749 - p. 2213 - 2222.
ageing - gastrointestinal physiology - intestinal bacteria

Our life expectancy is increasing, leading to a rise in the ageing population. Ageing is associated with a decline in physiological function and adaptive capacity. Altered GI physiology can affect the amount and types of nutrients digested and absorbed as well as impact the intestinal microbiota. The intestinal microbiota is considered a key player in our health, and a variety of studies have reported that microbiota composition is changing during ageing. Since ageing is associated with a decline in GI function and adaptive capacity, it is crucial to obtain insights into this decline and how this is related to the intestinal microbiota in the elderly. Hence, in this review we focus on age-related changes in GI physiology and function, changes of the intestinal microbiota with ageing and frailty, how these are associated and how intestinal microbiota-targeted interventions may counteract these changes.

Elucidating the mechanism behind the laccase-mediated modification of poly(ethersulfone)
Slagman, Sjoerd ; Jonkers, Wendy A. ; Zuilhof, Han ; Franssen, Maurice C.R. - \ 2018
RSC Advances : An international journal to further the chemical sciences 8 (2018)48. - ISSN 2046-2069 - p. 27101 - 27110.

Laccase-mediated oligomerisation of 4-hydroxybenzoic acid (4-HBA) derivatives and simultaneous in situ surface modification has proven to be a cost-effective, easily applicable and eco-friendly strategy for preventing biofouling of poly(ethersulfone) (PES) water filtration membranes. Modification of the membrane surface has previously been hypothesised to occur through covalent bonding of enzymatically generated phenolic radicals to the polymeric membrane. The current study shows, however, that in situ formation of soluble phenolic oligomers does not result in covalent membrane modification. We studied in situ laccase-mediated oligomerisation of custom-synthesised positively charged and commercially available negatively charged monomeric phenols, and demonstrated that their mode of binding to PES is not covalent. In addition, soluble, non-soluble and on-resin PES model compounds were synthesised and used in the laccase-mediated oligomerisation of 4-HBA. Covalent bond formation between these model compounds and (oligomeric) 4-HBA could not be observed either. Furthermore, extensive washing of PES membranes modified through laccase-mediated oligomerisation of 4-HBA resulted in substantial discolouration of the membrane surface, showing that the layer of oligomerised phenolics could easily be removed. Altogether, it was concluded that laccase-assisted modification of PES membranes resulted from strong physical adsorption of phenolic oligomers and polymers rather than from covalent bonding of those.

P316 New approaches for IBD management based on text mining of digitalised medical reports and latent class modelling
Bergey, F. ; Saccenti, E. ; Jonkers, D. ; Heuvel, T. Van Den; Jeuring, S. ; Pierik, M. ; Martins Dos Santos, V. - \ 2017
Journal of Crohn's and Colitis 11 (2017)suppl_1. - ISSN 1873-9946 - p. S237 - S238.
De meerwaarde van watersportactiviteiten voor mensen met een beperking
Nieuwenhuizen, Jeroen van den; Jonge, F.H. de; Berends, Eva ; Horst, Milou van der; jong, Nynke de; Jonkers, Ilonka ; Liem, Windy Mulia ; Nimwegen, Judith van; Agro, Prince Pascal ; Peters, Saskia ; Pol, Ellen van der; Schmitz, Paulina ; Sluimer, Nienke ; Wagenaar, Marlijn - \ 2017
Wageningen : Wageningen University & Research, Wetenschapswinkel (Wetenschapswinkel rapport 337) - ISBN 9789463432139 - 28
Habitual diet and diet quality in Irritable Bowel Syndrome: A case-control study
Tigchelaar, Ettje F. ; Mujagic, Zlatan ; Zhernakova, Alexandra ; Hesselink, M. ; Meijboom, S. ; Perenboom, C.W.M. ; Masclee, A.A.M. ; Wijmenga, Cisca ; Feskens, E.J.M. ; Jonkers, D. - \ 2017
Neurogastroenterology & Motility 29 (2017)12. - ISSN 1365-2982
Background Diet is considered to be a key factor in symptom generation in Irritable Bowel Syndrome (IBS) and patients tend to exclude food products from their diet in pursue of symptom relief, which may impair diet quality. Methods We evaluated habitual dietary intake in IBS patients with regard to nutrients and food products using an extensive food frequency questionnaire. One hundred ninety-four IBS patients were compared to 186 healthy controls using multiple logistic regression analysis. An overall diet quality score was calculated for each participant based on the criteria of the Dutch Healthy Diet (DHD) index. Key Results A lower DHD-score was found for IBS (mean [SD]: 52.9 [9.6]) vs controls (55.1 [9.2], P=.02). The diet of patients was lower in fibers (21 g vs 25 g per day, P=.002) and fructose (14 g vs 16 g, P=.033), while higher in total fat (37% vs 36% of total energy intake, P=.010) and added sugars (46 g vs 44 g, P=.029). Differences in daily intake of food products included lower consumption of apples (40 g vs 69 g, P<.001), pasta (28 vs 37 g, P=.029) and alcoholic beverages (130 g vs 193 g, P=.024) and higher consumption of processed meat (38 g vs 29 g, P<.001). Some of these findings correlated with gastrointestinal symptoms, showing differences between IBS subtypes. Conclusions and Inferences Differences in habitual diet were described, showing lower diet quality in IBS patients compared to controls, with increased consumption of fat and lower intake of fibers and fructose. Our data support the importance of personalized and professional nutritional guidance of IBS patients.
Local Ion Signatures (LIS) for the examination of comprehensive two-dimensional gas chromatography applied to fire debris analysis
Lopatka, Martin ; Sampat, Andjoe A. ; Jonkers, Steffan ; Adutwum, Lawrence A. ; Mol, Hans G.J. ; Weg, Guido van der; Harynuk, James J. ; Schoenmakers, Peter J. ; Asten, Arian van; Sjerps, Marjan J. ; Vivó-Truyols, Gabriel - \ 2017
Forensic Chemistry 3 (2017). - ISSN 2468-1709 - p. 1 - 13.
Chemometrics - Comprehensive two-dimensional gas chromatography (GC × GC–MS) - Fire Debris Analysis (FDA) - Likelihood ratio (LR) - Local Ion Signature (LIS)

Forensic examination of fire debris evidence is a notoriously difficult analytical task due to the complexity and variability of sample composition. The use of comprehensive two-dimensional gas chromatography with mass spectrometry detection (GC × GC–MS) allows the coupling of orthogonal retention mechanisms and therefore a high peak capacity. We demonstrate recent innovations in combining chemometric techniques for data reduction and feature selection, with evaluation of the evidence for forensic questions pertaining to the detection and subsequent classification of ignitable liquid residue (ILR) in fire debris samples. Chromatograms are divided into non-overlapping spatially delimited regions; for each of these regions a Local Ion Signature (LIS) is computed by summing the intensities, per nominal mass/charge over all points contained within each region. This yields a reduced feature space representing the original data as a set of consolidated ion traces. Subsequent feature selection is performed by evaluating the individual efficacy of each feature using a univariate score-based likelihood ratio (LR) approach for discriminating between pairs of same or different type samples. The retained features are used to model each ILR class using linear discriminant analysis (LDA). Results are demonstrated for 155 arson samples containing a diversity of substrate compounds and several known ignitable liquids. ILR detection is performed at 84% accuracy with fewer than 1% false positives followed by subsequent classification. Likelihood ratio distributions are presented referring to both detection and classification tasks.

A novel biomarker panel for irritable bowel syndrome and the application in the general population
Mujagic, Zlatan ; Tigchelaar, Ettje F. ; Zhernakova, Alexandra ; Ludwig, Thomas ; Ramiro-Garcia, Javier ; Baranska, Agnieszka ; Swertz, Morris A. ; Masclee, A.A.M. ; Wijmenga, Cisca ; Schooten, Frederik J. Van; Smolinska, Agnieszka ; Jonkers, Daisy M.A.E. - \ 2016
Scientific Reports 6 (2016). - ISSN 2045-2322

Biological markers that measure gut health and diagnose functional gastro-intestinal (GI) disorders, such as irritable bowel syndrome (IBS), are lacking. The objective was to identify and validate a biomarker panel associated with the pathophysiology of IBS that discriminates IBS from healthy controls (HC), and correlates with GI symptom severity. In a case-control design, various plasma and fecal markers were measured in a cohort of 196 clinical IBS patients and 160 HC without GI symptoms. A combination of biomarkers, which best discriminates between IBS and HC was identified and validated in an independent internal validation set and by permutation testing. The correlation between the biomarker panel and GI symptom severity was tested in IBS patients and in a general population cohort of 958 subjects. A set of 8 biomarker panel was identified to discriminate IBS from HC with high sensitivity (88.1%) and specificity (86.5%). The results for the IBS subtypes were comparable. Moreover, a moderate correlation was found between the biomarker panel and GI symptom scores in the IBS (r = 0.59, p <0.001) and the general population cohorts (r = 0.51, p = 0.003). A novel multi-domain biomarker panel has been identified and validated, which correlated moderately to GI symptom severity in IBS and general population subjects.

Richtlijnen ondervoeding worden niet nageleefd
Ziylan, Canan - \ 2016
Intestinal Microbiota And Diet in IBS: Causes, Consequences, or Epiphenomena?
Rajilic-Stojanovic, M. ; Jonkers, D.M. ; Salonen, A. ; Hanevik, K. ; Raes, J. ; Jalanka, J. ; Vos, W.M. de; Manichanh, C. ; Golic, N. ; Enck, P. ; Philippou, E. ; Iraqi, F.A. ; Clarke, G. ; Spiller, R.C. ; Penders, J. - \ 2015
American Journal of Gastroenterology 110 (2015)2. - ISSN 0002-9270 - p. 278 - 287.
Irritable bowel syndrome (IBS) is a heterogeneous functional disorder with a multifactorial etiology that involves the interplay of both host and environmental factors. Among environmental factors relevant for IBS etiology, the diet stands out given that the majority of IBS patients report their symptoms to be triggered by meals or specific foods. The diet provides substrates for microbial fermentation, and, as the composition of the intestinal microbiota is disturbed in IBS patients, the link between diet, microbiota composition, and microbial fermentation products might have an essential role in IBS etiology. In this review, we summarize current evidence regarding the impact of diet and the intestinal microbiota on IBS symptoms, as well as the reported interactions between diet and the microbiota composition. On the basis of the existing data, we suggest pathways (mechanisms) by which diet components, via the microbial fermentation, could trigger IBS symptoms. Finally, this review provides recommendations for future studies that would enable elucidation of the role of diet and microbiota and how these factors may be (inter)related in the pathophysiology of IBS
Serotonergic reinforcement of intestinal barrier function is impaired in irritable bowel syndrome
Keszthelyi, D. ; Troost, F.J. ; Jonkers, D.M. ; Eijk, H.M. van; Lindsey, P.J. ; Dekker, J. ; Buurman, W.A. ; Masclee, A.A.M. - \ 2014
Alimentary Pharmacology and Therapeutics 40 (2014)4. - ISSN 0269-2813 - p. 392 - 402.
reuptake transporter - visceral sensitivity - permeability - expression - tight - 5-hydroxytryptamine - predominant - 5-ht - sert - gut
Background Alterations in serotonergic (5-HT) metabolism and/or intestinal integrity have been associated with irritable bowel syndrome (IBS). Aims To assess the effects of the precursor of 5-HT, 5-hydroxytryptophan (5-HTP), on mucosal 5-HT availability and intestinal integrity, and to assess potential differences between healthy controls and IBS patients. Methods Fifteen IBS patients and 15 healthy volunteers participated in this randomised double-blind placebo-controlled study. Intestinal integrity was assessed by dual-sugar test and by determining the mucosal expression of tight junction proteins after ingestion of an oral bolus of 100 mg 5-HTP or placebo. Mucosal serotonergic metabolism was assessed in duodenal biopsy samples. Results 5-HTP administration significantly increased mucosal levels of 5-HIAA, the main metabolite of 5-HT, in both healthy controls (7.1 +/- 1.7 vs. 2.5 +/- 0.7 pmol/mg, 5-HTP vs. placebo, P = 0.02) and IBS patients (20.0 +/- 4.8 vs. 8.1 +/- 1.3 pmol/mg, 5-HTP vs. placebo, P = 0.02), with the latter group showing a significantly larger increase. Lactulose/L-rhamnose ratios were significantly lower after administration of 5-HTP (P <0.05) in healthy controls and were accompanied by redistribution of zonula occludens-1 (ZO-1), pointing to reinforcement of the barrier. In IBS, expression of the tight junction proteins was significantly lower compared to healthy controls, and 5-HTP resulted in a further decrease in occludin expression. Conclusions Oral 5-HTP induced alterations in mucosal 5-HT metabolism. In healthy controls, a reinforcement of the intestinal barrier was seen whereas such reaction was absent in IBS patients. This could indicate the presence of a serotonin-mediated mechanism aimed to reinforce intestinal barrier function, which seems to dysfunction in IBS patients.
Ethanol Impairs Intestinal Barrier Function in Humans through Mitogen Activated Protein Kinase Signaling: A Combined In Vivo and In Vitro Approach
Elamin, E. ; Masclee, A. ; Troost, F. ; Pieters, H.J. ; Keszthelyi, D. ; Aleksa, K. ; Dekker, J. ; Jonkers, D. - \ 2014
PLoS ONE 9 (2014)9. - ISSN 1932-6203
alcoholic liver-disease - caco-2 cell monolayer - paracellular permeability - actin cytoskeleton - aldehyde dehydrogenases - epithelial barrier - tight - disruption - consumption - metabolism
Background: Ethanol-induced gut barrier disruption is associated with several gastrointestinal and liver disorders. Aim: Since human data on effects of moderate ethanol consumption on intestinal barrier integrity and involved mechanisms are limited, the objectives of this study were to investigate effects of a single moderate ethanol dose on small and large intestinal permeability and to explore the role of mitogen activated protein kinase (MAPK) pathway as a primary signaling mechanism. Methods: Intestinal permeability was assessed in 12 healthy volunteers after intraduodenal administration of either placebo or 20 g ethanol in a randomised cross-over trial. Localization of the tight junction (TJ) and gene expression, phosphorylation of the MAPK isoforms p38, ERK and JNK as indicative of activation were analyzed in duodenal biopsies. The role of MAPK was further examined in vitro using Caco-2 monolayers. Results: Ethanol increased small and large intestinal permeability, paralleled by redistribution of ZO-1 and occludin, downregulation of ZO-1 and up-regulation of myosin light chain kinase (MLCK) mRNA expression, and increased MAPK isoforms phosphorylation. In Caco-2 monolayers, ethanol increased permeability, induced redistribution of the junctional proteins and F-actin, and MAPK and MLCK activation, as indicated by phosphorylation of MAPK isoforms and myosin light chain (MLC), respectively, which could be reversed by pretreatment with either MAPK inhibitors or the anti-oxidant L-cysteine. Conclusions: Administration of moderate ethanol dosage can increase both small and colon permeability. Furthermore, the data indicate a pivotal role for MAPK and its crosstalk with MLCK in ethanol-induced intestinal barrier disruption.
Cytotoxicity and metabolic stress induced by acetaldehyde in human intestinal LS174T goblet-like cells
Elamin, E. ; Masclee, A. ; Troost, F. ; Dekker, J. ; Jonkers, D. - \ 2014
American Journal of Physiology. Gastrointestinal and Liver Physiology 307 (2014)3. - ISSN 0193-1857 - p. G286 - G294.
mediated endothelial permeability - inflammatory-bowel-disease - in-vitro - epithelial barrier - liver-disease - oral-mucosa - aldehyde dehydrogenases - plasma endotoxin - tight junctions - ethanol
There is compelling evidence indicating that ethanol and its oxidative metabolite acetaldehyde can disrupt intestinal barrier function. Apart from the tight junctions, mucins secreted by goblet cells provide an effective barrier. Ethanol has been shown to induce goblet cell injury associated with alterations in mucin glycosylation. However, effects of its most injurious metabolite acetaldehyde remain largely unknown. This study aimed to assess short-term effects of acetaldehyde (0, 25, 50, 75, 100 mu M) on functional characteristics of intestinal goblet-like cells (LS174T). Oxidative stress, mitochondrial function, ATP, and intramitochondrial calcium (Ca2+) were assessed by dichlorofluorescein, methyltetrazolium, and bioluminescence, MitoTracker green and rhod-2 double-labeling. Membrane integrity and apoptosis were evaluated by measuring lactate dehydrogenase (LDH), caspase 3/7, and cleavage of cytokeratin 18 (CK18). Expression of mucin 2 (MUC2) was determined by cell-based ELISA. Acetaldehyde significantly increased reactive oxygen species generation and decreased mitochondrial function compared with negative controls (P <0.05). In addition, acetaldehyde dose-dependently decreased ATP levels and induced intramitochondrial Ca2+ accumulation compared with negative controls (P <0.05). Furthermore, acetaldehyde induced LDH release and increased caspase3/7 activity and percentage of cells expressing cleaved CK18 and increased MUC2 protein expression compared with negative controls (P <0.0001). ATP depletion and LDH release could be largely prevented by the antioxidant N-acetylcysteine, suggesting a pivotal role for oxidative stress. Our data demonstrate that acetaldehyde has distinct oxidant-dependent metabolic and cytotoxic effects on LS174T cells that can lead to induction of cellular apoptosis. These effects may contribute to acetaldehyde-induced intestinal barrier dysfunction and subsequently to liver injury.
Activation of the Epithelial-to-Mesenchymal Transition Factor Snail Mediated Acetaldehyde-Induced Intestinal Epithelial Barrier Disruption
Elamin, E. ; Masclee, A. ; Troost, F. ; Dekker, J. ; Jonkers, D. - \ 2014
Alcoholism : Clinical and Experimental Research 38 (2014)2. - ISSN 0145-6008 - p. 344 - 353.
transcription factor snail - caco-2 cell monolayers - tight junctions - paracellular permeability - in-vitro - adherens junctions - ethanol oxidation - colonic flora - expression - cirrhosis
Background : Acetaldehyde (AcH) is mutagenic and can reach high concentrations in colonic lumen after ethanol consumption and is associated with intestinal barrier dysfunction and an increased risk of progressive cancers, including colorectal carcinoma. Snail, the transcription factor of epithelial-mesenchymal transition, is known to down-regulate expression of tight junction (TJ) and adherens junction (AJ) proteins, resulting in loss of epithelial integrity, cancer progression, and metastases. As AcH is mutagenic, the role of Snail in the AcH-induced disruption of intestinal epithelial TJs deserves further investigation. Our aim was to investigate the role of oxidative stress and Snail activation in AcH-induced barrier disruption in Caco-2 monolayers. Methods : The monolayers were exposed from the apical side to AcHL-cysteine. Reactive oxygen species (ROS) generation and Snail activation were assessed by ELISA and immunofluorescence. Paracellular permeability, localization, and expression of ZO-1, occludin, E-cadherin, and -catenin were examined using transepithelial electrical resistance (TEER), fluorescein isothiocyanate-labeled dextran 4 kDa (FITC-D4), immunofluorescence, and ELISA, respectively. Involvement of Snail was further addressed by inhibiting Snail using small interfering RNA (siRNA). Results : Exposure to 25M AcH increased ROS generation and ROS-dependently induced Snail phosphorylation. In addition, AcH increased paracellular permeability (decrease in TEER and increase in FITC-D4 permeation) in association with redistribution and decrease of TJ and AJ protein levels, which could be attenuated by L-cysteine. Knockdown of Snail by siRNA attenuated the AcH-induced redistribution and decrease in the TJ and AJ proteins, in association with improvement of the barrier function. Conclusions : Our data demonstrate that oxidative stress-mediated Snail phosphorylation is likely a novel mechanism contributing to the deleterious effects of AcH on the TJ and AJ, and intestinal barrier function.
Lupine and rapeseed protein concentrate in fish feed: a comparative assessment of the techno-functional properties using a shear cell device and an extruder
Draganovic, V. ; Boom, R.M. ; Jonkers, J. ; Goot, A.J. van der - \ 2014
Journal of Food Engineering 126 (2014). - ISSN 0260-8774 - p. 178 - 189.
trout oncorhynchus-mykiss - rainbow-trout - wheat gluten - glass-transition - kernel meal - starch - extrusion - products - moisture - quality
The techno-functional properties of soy, lupine and rapeseed protein concentrates (SPC, LPC and RPC, respectively) in fish feed were evaluated relative to fish meal (FM). The effects were studied using a shear cell device and an extruder with emphasis on the added moisture content. Six diets were formulated: an SPC-based diet with 300 g SPC kg-1, diets containing 100 and 200 g LPC kg-1 or 100 and 200 g RPC kg-1 and an FM-based diet with 450 g FM kg-1. Each diet was extruded with an added moisture content of 29%, 25% and 22% of the mash feed rate. It was found that the technological properties of LPC closely resemble FM, being high solubility, low water-holding capacity (WHC) and low paste viscosity. The LPC 100 and 200 g kg-1 diets could be extruded at 22% moisture, which gives an extrudate with reduced drying requirements. In addition, less specific mechanical energy was needed for extrusion. In contrast, both SPC and RPC have high WHC and paste viscosity. This explains the higher feed moisture required during extrusion. The properties of the feeds containing RPC could be well within the ranges acceptable for commercial fish feed use at even higher moisture content compared with SPC. The results of the extrusion trials confirmed the observations made from the shear cell device. Thus, the shear cell device can be used to study processing conditions that are close to extrusion conditions.
Letter: role of diet in the onset and relapse of inflammatory bowel disease from the patients' perspective - authors' reply
Spooren, C.E.G.M. ; Pierik, M. ; Zeegers, M.P.A. ; Feskens, E.J.M. ; Masclee, A.A.M. ; Jonkers, D.M.A.E. - \ 2014
Alimentary Pharmacology and Therapeutics 39 (2014)3. - ISSN 0269-2813 - p. 340 - 341.
Short-Chain Fatty Acids Activate AMP-Activated Protein Kinase and Ameliorate Ethanol-Induced Intestinal Barrier Dysfunction in Caco-2 Cell Monolayers
Eamin, E.E. ; Masclee, A.A. ; Dekker, J. ; Pieters, H.J. ; Jonkers, D.M. - \ 2013
The Journal of Nutrition 143 (2013)12. - ISSN 0022-3166 - p. 1872 - 1881.
alcoholic liver-disease - induced gut leakiness - paracellular permeability - signaling pathway - oxidative stress - epithelial-cells - colonic function - dietary fiber - leaky gut - butyrate
Short-chain fatty acids (SCFAs) have been shown to promote intestinal barrier function, but their protective effects against ethanol-induced intestinal injury and underlying mechanisms remain essentially unknown. The aim of the study was to analyze the influence of SCFAs on ethanol-induced barrier dysfunction and to examine the role of AMP-activated protein kinase (AMPK) as a possible mechanism using Caco-2 monolayers. The monolayers were treated apically with butyrate (2, 10, or 20 mmol/L), propionate (4, 20, or 40 mmol/L), or acetate (8, 40, or 80 mmol/L) for 1 h before ethanol (40 mmol/L) for 3 h. Barrier function was analyzed by measurement of transepithelial resistance and permeation of fluorescein isothiocyanate-labeled dextran. Distribution of the tight junction (TJ) proteins zona occludens-1, occludin, and filamentous-actin (F-actin) was examined by immunofluorescence. Metabolic stress was determined by measuring oxidative stress, mitochondrial function, and ATP using dichlorofluorescein diacetate, dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide, and bioluminescence assay, respectively. AMPK was knocked down by small interfering RNA (siRNA), and its activity was assessed by a cell-based ELISA. Exposure to ethanol significantly impaired barrier function compared with controls (P <0.0001), disrupted TJ and F-actin cytoskeleton integrity, and induced metabolic stress. However, pretreatment with 2 mmol/L butyrate, 4 mmol/L propionate, and 8 mmol/L acetate significantly alleviated the ethanol-induced barrier dysfunction, TJ and F-actin disruption, and metabolic stress compared with ethanol-exposed monolayers (P <0.0001). The promoting effects on barrier function were abolished by inhibiting AMPK using either compound C or siRNA. These observations indicate that SCFAs exhibit protective effects against ethanol-induced barrier disruption via AMPK activation, suggesting a potential for SCFAs as prophylactic and/or therapeutic factors against ethanol-induced gut leakiness.
Fatty Acid Ethyl Esters Induce Intestinal Epithelial Barrier Dysfunction via a Reactive Oxygen Species-Dependent Mechanism in a Three-Dimensional Cell Culture Model
Elamin, E. ; Masclee, A.A.M. ; Juuti-Uusitalo, K. ; IJzendoorn, S. van; Troost, F. ; Pieters, H.J. ; Dekker, J. ; Jonkers, D. - \ 2013
PLoS ONE 8 (2013)3. - ISSN 1932-6203
acetaldehyde-induced increase - pancreatic acinar-cells - tight junction proteins - kappa-b activation - paracellular permeability - nonoxidative metabolites - tyrosine phosphorylation - ethanol-metabolism - hydrogen-peroxide - heavy drinkers
Background & Aims: Evidence is accumulating that ethanol and its oxidative metabolite, acetaldehyde, can disrupt intestinal epithelial integrity, an important factor contributing to ethanol-induced liver injury. However, ethanol can also be metabolized non-oxidatively generating phosphatidylethanol and fatty acid ethyl esters (FAEEs). This study aims to investigate the effects of FAEEs on barrier function, and to explore the role of oxidative stress as possible mechanism. Methods: Epithelial permeability was assessed by paracellular flux of fluorescein isothiocyanate-conjugated dextran using live cell imaging. Cell integrity was evaluated by lactate dehydrogenase release. Localization and protein levels of ZO-1 and occludin were analyzed by immunofluorescence and cell-based ELISA, respectively. Intracellular oxidative stress and cellular ATP levels were measured by dichlorofluorescein and luciferase driven bioluminescence, respectively. Results: In vitro, ethyl oleate and ethyl palmitate dose dependently increased permeability associated with disruption and decreased ZO-1 and occludin protein levels, respectively, and increased intracellular oxidative stress without compromising cell viability. These effects could partially be attenuated by pretreatment with the antioxidant, resveratrol, pointing to the role of oxidative stress in the FAEEs-induced intestinal barrier dysfunction. Conclusions: These findings show that FAEEs can induce intestinal barrier dysfunction by disrupting the tight junctions, most likely via reactive oxygen species-dependent mechanism.
Alterations in mucosal neuropeptides in patients with irritable bowel syndrome and ulcerative colitis in remission: A role in pain symptom generation?
Keszthelyi, D. ; Troost, F.J. ; Jonkers, D.M. ; Helyes, Z. ; Hamer, H.M. ; Ludidi, S. ; Vanhoutvin, S. ; Venema, K. ; Dekker, J. ; Szolcsanyi, J. ; Masclee, A.A. - \ 2013
European Journal of Pain 17 (2013)9. - ISSN 1090-3801 - p. 1299 - 1306.
vanilloid receptor vr1 - gastrointestinal-tract - abdominal-pain - substance-p - axonal-transport - trpv1 receptor - messenger-rna - rectal mucosa - expression - disease
Background Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder characterized by chronic abdominal pain. The transient receptor potential vanilloid 1 (TRPV1) channel, which is involved in visceral pain signalling, has been shown to be up-regulated in IBS. Activation of TRPV1 leads to the release of neuropeptides, such as somatostatin and substance P (SP). We hypothesized that increased pain perception in IBS could be explained by increased transcription in TRPV1 and/or altered levels of neuropeptides. We therefore assessed the transcription of TRPV1 and the mucosal concentration of somatostatin and SP in IBS in comparison to healthy volunteers and patients with ulcerative colitis (UC) in remission as disease controls, and to ascertain their relationship to pain symptoms. Method Sigmoid colonic mucosal samples were collected from 12 patients with IBS, 34 patients with UC in remission and 9 healthy volunteers, in which groups TRPV1 mRNA levels were determined using quantitative polymerase chain reaction and neuropeptide concentrations by radioimmunoassay. Pain symptom intensity was determined by questionnaires. Results Transcription of TRPV1 as well as the concentration of neuropeptides were significantly higher in IBS, but only the former correlated with pain symptom severity. Conclusion Increased transcription of TRPV1 may provide a possible explanation for pain generation in IBS. While the neuropeptides SP and somatostatin were both found to be increased in IBS, these changes are not sufficient to explain pain generation. Pain generation in IBS is probably explained by a complex redundancy in the regulation of local nociceptive mechanisms, which remains a subject of intensive investigation.
Ethanol metabolism and its effects on the intestinal epithelial barrier
Elamin, E.E. ; Masclee, A.A. ; Dekker, J. ; Jonkers, D.M. - \ 2013
Nutrition Reviews 71 (2013)7. - ISSN 0029-6643 - p. 483 - 499.
acid ethyl-esters - caco-2 cell monolayer - alcoholic liver-disease - tight-junction barrier - induced gut leakiness - mediated acetaldehyde production - human gastrointestinal-tract - inflammatory-bowel-disease - pancreatic acinar-cells - chain kinase expression
Ethanol is widely consumed and is associated with an increasing global health burden. Several reviews have addressed the effects of ethanol and its oxidative metabolite, acetaldehyde, on the gastrointestinal (GI) tract, focusing on carcinogenic effects or alcoholic liver disease. However, both the oxidative and the nonoxidative metabolites of ethanol can affect the epithelial barrier of the small and large intestines, thereby contributing to GI and liver diseases. This review outlines the possible mechanisms of ethanol metabolism as well as the effects of ethanol and its metabolites on the intestinal barrier. Limited studies in humans and supporting in vitro data have indicated that ethanol as well as mainly acetaldehyde can increase small intestinal permeability. Limited evidence also points to increased colon permeability following exposure to ethanol or acetaldehyde. In vitro studies have provided several mechanisms for disruption of the epithelial barrier, including activation of different cell-signaling pathways, oxidative stress, and remodeling of the cytoskeleton. Modulation via intestinal microbiota, however, should also be considered. In conclusion, ethanol and its metabolites may act additively or even synergistically in vivo. Therefore, in vivo studies investigating the effects of ethanol and its byproducts on permeability of the small and large intestines are warranted.
Sustainability assessment of salmonid feed using energy, classical exergy and eco-exergy analysis
Draganovic, V. ; Jorgensen, S.E. ; Boom, R.M. ; Jonkers, J. ; Goot, A.J. van der - \ 2013
Ecological Indicators 34 (2013). - ISSN 1470-160X - p. 277 - 289.
krill euphausia-superba - life-cycle assessment - environmental impacts - production systems - farmed salmon - ethanol - organisms - products - chains - wheat
Reduction of the environmental impact of feed products is of paramount importance for salmon farming. This article explores the potential to compare three thermodynamically based ecological indicators. The environmental impact of partial replacement of fish meal (FM) and fish oil with alternative ingredients was investigated using energy, classical exergy and eco-exergy analysis. Seven hypothetical feeds were formulated: one with high levels of FM and fish oil, four feeds based on plant ingredients, one containing krill meal, and one based on algae-derived products. Analysis included cultivation of crops and algae, fishing for fish and krill, industrial processing of these ingredients and production of complete fish feed. Because most harvested products are refined in multiple product outputs that have good value to society, two scenarios were compared. In the base case scenario, no allocation of co-products was used and all the environmental costs were ascribed to one specific co-product. Co-product allocation by mass was used in the second scenario; this is considered to be the preferred scenario because it accurately reflects the individual contributions of the co-products to the environmental impact of the feed products. For this scenario, the total energy consumption for a fish-based diet was 14,500 MJ, which was similar to a krill diet (15,600 MJ), about 15–31% higher than plant-based diets, and 9% higher than an algae diet. Substituting FM and fish oil with alternative ingredients resulted in minor changes in total classical exergy degradation (2–16% difference). The calculations based on energy only consider the energy conservation based on the First Law of Thermodynamics, whereas those based on classical exergy also takes the Second Law of Thermodynamics into account; energy that can do work is distinguished from energy that is lost as heat to the environment. The calculations based on eco-exergy consider the total loss of work energy in the environment including the work energy associated with the information embodied in the genomes of organisms. The diet based on fishery-derived ingredients was the highest total work energy consumer compared with plant-based diets (24–30% greater), the diet containing krill meal (25% greater), and the algae diet (four times higher). Thus, reducing FM and fish oil levels in fish feed can contribute significantly to more sustainable aquaculture. In particular, algae-derived products in aquafeeds could drastically decrease environmental costs in the future.
Wheat gluten in extruded fish feed: Effects on morphology and on physical and functional properties
Draganovic, V. ; Goot, A.J. van der; Boom, R.M. ; Jonkers, J. - \ 2013
Aquaculture Nutrition 19 (2013)6. - ISSN 1353-5773 - p. 845 - 859.
structural characteristics - lysine supplementation - salmonid feeds - rainbow-trout - oil uptake - products - protein - meal - microstructure - digestibility
This article focuses on understanding the role of vital wheat gluten on the structural parameters of extruded fish feed and its correlation to the physical and functional properties. Gluten–soy protein concentrate blends with five gluten concentrations (0–200 g kg-1) were produced. An abrupt reduction in oil uptake was observed with the 200 g gluten kg-1 blend. Inclusion of gluten from 100 to 200 g kg-1 resulted in unacceptable product properties. Sinking of feed pellets with 0 and 50 g gluten kg-1 was 100%, whereas only 36% of pellets with 200 g gluten kg-1 sank. We suspect that this is due to a relationship between morphological structure and oil impregnation during coating of feeds. The addition of gluten at 200 g kg-1 gave a smoother and non-porous outer surface. Pellets without gluten had a larger number of cells that were smaller than 200 µm (P <0.05) compared with pellets with 100 and 200 g gluten kg-1. More spherical cell shapes (P <0.01) and a compact structure were favoured in the presence of gluten. The closed porosity increased (P <0.05), whereas interconnectivity between pores decreased (P <0.01), with increasing gluten content from 0 to 200 g kg-1. The effects of the addition of gluten are probably related to the film-forming properties of gluten.
Microbiota conservation and BMI signatures in adult monozygotic twins
Tims, S. ; Derom, C. ; Jonkers, D.M.A.E. ; Vlietinck, R. ; Saris, W.H. ; Kleerebezem, M. ; Vos, W.M. de; Zoetendal, E.G. - \ 2013
ISME Journal 7 (2013). - ISSN 1751-7362 - p. 707 - 717.
human gut - crohns-disease - phylogenetic microarray - intestinal microbiota - identical-twins - sp nov. - bacteria - obesity - host - ecology
The human gastrointestinal (GI) tract microbiota acts like a virtual organ and is suggested to be of great importance in human energy balance and weight control. This study included 40 monozygotic (MZ) twin pairs to investigate the influence of the human genotype on GI microbiota structure as well as microbial signatures for differences in body mass index (BMI). Phylogenetic microarraying based on 16S rRNA genes demonstrated that MZ twins have more similar microbiotas compared with unrelated subjects (P
Does acute tryptophan depletion affect peripheral serotonin metabolism in the intestine?
Keszthelyi, D. ; Troost, F.J. ; Jonkers, D.M. ; Donkelaar, E.L. van; Dekker, J. ; Buurman, W.A. ; Masclee, A.A. - \ 2012
American Journal of Clinical Nutrition 95 (2012)3. - ISSN 0002-9165 - p. 603 - 608.
5-hydroxyindoleacetic acid - gastrointestinal-tract - cerebrospinal-fluid - brain - permeability - depression - cortisol - reuptake - humans - lumbar
Background: Serotonin (5-hydroxytryptamine; 5-HT), a tryptophan metabolite, plays an important regulatory role in the human central nervous system and in the gastrointestinal tract. Acute tryptophan depletion (ATD) is currently the most widely established method to investigate 5-HT metabolism. Objective: The aim of this study was to assess the effect of an acute decrease in the systemic availability of tryptophan on intestinal 5-HT metabolism and permeability. Design: Thirty-three healthy volunteers (17 with ATD, 3 of whom dropped out; 16 placebo) participated in this randomized placebo-controlled study. Plasma and duodenal mucosal concentrations of 5-HT, 5-hydroxyindoleacetic acid (5-HIAA), and kynurenic acid (KA) were measured by HPLC-mass spectrometry. Intestinal barrier function was assessed with a multisugar plasma test, and analysis of tight junction transcription was performed in duodenal biopsy samples obtained by gastroduodenoscopy. Results: Mucosal 5-HT, 5-HIAA, and KA concentrations remained unaltered by ATD. In contrast, ATD significantly decreased plasma 5-HT (P <0.05) and 5-HIAA (P <0.0001) concentrations. After endoscopy, a significant increase in plasma 5-HT concentrations was observed in the placebo group (P = 0.029) compared with the ATD group. Moreover, a significant increase in plasma KA concentrations over time was found in the placebo group (P <0.05). No changes in intestinal barrier function were observed. Conclusions: An acute decrease in precursor availability does not affect mucosal concentrations of serotonergic metabolites, in contrast with systemic concentrations. ATD alters biochemical responses to acute stress from the endoscopic examination reflected by lower 5-HT concentrations. Changes in 5-HT concentrations were paralleled by alterations in KA concentrations, which suggest competition between the 2 metabolic pathways for the mutual precursor. This trial was registered at clinicaltrials.gov as NCT00731003. Am J Clin Nutr 2012;95:603-8.
Effector identification in the lettuce on Tight Junction Integrity: In Vitro Study in a Three Dimensional Intestinal Epithelial Cell Culture Model
Elamin, E. ; Jonkers, D. ; Juuti-Uusitalo, K. ; IJzendoorn, S. van; Troost, F. ; Duimel, H. ; Broers, J. ; Verheyen, F. ; Dekker, J. ; Masclee, A. - \ 2012
PLoS ONE 7 (2012)4. - ISSN 1932-6203
paracellular permeability - liver-disease - alcohol-consumption - induced increase - molecular-basis - leaky gut - barrier - tissue - monolayer - complex
Background: Intestinal barrier dysfunction and translocation of endotoxins are involved in the pathogenesis of alcoholic liver disease. Exposure to ethanol and its metabolite, acetaldehyde at relatively high concentrations have been shown to disrupt intestinal epithelial tight junctions in the conventional two dimensional cell culture models. The present study investigated quantitatively and qualitatively the effects of ethanol at concentrations detected in the blood after moderate ethanol consumption, of its metabolite acetaldehyde and of the combination of both compounds on intestinal barrier function in a three-dimensional cell culture model. Methods and Findings: Caco-2 cells were grown in a basement membrane matrix (Matrigel (TM)) to induce spheroid formation and were then exposed to the compounds at the basolateral side. Morphological differentiation of the spheroids was assessed by immunocytochemistry and transmission electron microscopy. The barrier function was assessed by the flux of FITC-labeled dextran from the basal side into the spheroids' luminal compartment using confocal microscopy. Caco-2 cells grown on Matrigel assembled into fully differentiated and polarized spheroids with a central lumen, closely resembling enterocytes in vivo and provide an excellent model to study epithelial barrier functionality. Exposure to ethanol (10-40 mM) or acetaldehyde (25-200 mu M) for 3 h, dose-dependently and additively increased the paracellular permeability and induced redistribution of ZO-1 and occludin without affecting cell viability or tight junction-encoding gene expression. Furthermore, ethanol and acetaldehyde induced lysine residue and microtubules hyperacetylation. Conclusions: These results indicate that ethanol at concentrations found in the blood after moderate drinking and acetaldehyde, alone and in combination, can increase the intestinal epithelial permeability. The data also point to the involvement of protein hyperacetylation in ethanol- and acetaldehyde-induced loss of tight junctions integrity.
Towards sustainable fish feed production using novel protein sources
Draganovic, V. ; Goot, A.J. van der; Boom, R.M. ; Jonkers, J. - \ 2012
Duurzaam Doenderzoek in de Zeeuwse delta: Ervaringen met het kwantificeren van ecosysteemdiensten
Smit, A. ; Verzandvoort, S.J.E. ; Jonkers, W. - \ 2012
Bodem (2012)4. - ISSN 0925-1650 - p. 30 - 33.
bodem - landschap - ecosysteemdiensten - bodemwater - wateropslag - duurzaamheid (sustainability) - zeeland - soil - landscape - ecosystem services - soil water - water storage - sustainability
Voor het project Doenderzoek is voor elf ecosysteemdiensten in Zeeland de potentïële levering van deze diensten in kaart gebracht. Tijdens de uitwerking bleken definities, benutting van diensten, databeschikbaarheid en schaal belangrijke factoren te zijn. In dit artikel laten we zien welke lessen we hebben geleerd.
Meer water met regelbare drainage?
Stuyt, L.C.P.M. ; Bolt, F.J.E. van der; Snellen, W.B. ; Groenendijk, P. ; Schipper, P.N.M. ; Harmsen, J. ; Bakel, P.J.T. van; Ruijtenberg, R. ; Jonkers, D.A. ; Peerboom, J.M.P.M. ; Buck, A.J. de; Huinink, M. ; Rijken, M. ; Straat, A.A. van der; Talsma, M.J.G. - \ 2012
Amersfoort : Stowa (Rapport / STOWA 2012-33) - ISBN 9789057735707 - 60
drainage - grondwaterstand - agrarische bedrijfsvoering - peilbeheer - groundwater level - farm management - water level management
Dit rapport geeft aan de hand van resultaten van vijf Nederlandse praktijkproeven inzicht in de mogelijkheden van regelbare of peilgestuurde drainage. Deze vorm van drainage - waarbij boeren de grondwaterstand op hun percelen flexibel kunnen regelen - houdt in tegenstelling tot conventionele drainage veel beter rekening met de uiteenlopende wensen en behoeften vanuit de landbouw, natuur, milieu en waterbeheer. Dit kan de realisatie van waterkwaliteits- en waterkwantiteitsdoelstellingen door waterschappen bevorderen en tegelijkertijd de bedrijfsvoering van agrariërs verbeteren.
Vuurwerk & vogels provincie Utrecht : afwegingskader voor vergunningverlening ten aanzien van vuurwerkevenementen in en nabij Utrechtse Vogelrichtlijngebieden inclusief twee casestudies
Ottburg, F.G.W.A. ; Molenaar, J.G. de; Jonkers, D.A. ; Henkens, R.J.H.G. - \ 2012
Wageningen : Alterra (Alterra-rapport 2347) - 40
publieksevenementen - festivals - licenties - nadelige gevolgen - vogels - wildbescherming - geluidshinder - natura 2000 - utrecht - spectator events - licences - adverse effects - birds - wildlife conservation - noise pollution
In Alterra rapport 1694 ‘Vuurwerk & Vogels; afwegingskader voor vergunningverlening ten aanzien van vuurwerkevenementen in en nabij Brabantse Vogelrichtlijngebieden’ wordt een afwegingskader voor vergunningverlening voorvuurwerkevenementen in en nabij Brabantse Vogelrichtlijngebieden gegeven. De belangrijkste uitkomsten van deze studie worden samengevat in de tabellen 7 en 8, namelijk ‘Vuurwerktypen en beslisregels met betrekking tot gebruik bij evenementen van Vogelrichtlijngebieden voor de broedvogels en niet-broedvogels van Brabantse Natura 2000-gebieden’. De provincie Utrecht heeft Alterra verzocht om de tabellen 7 en 8 uit rapport 1694 uit te breiden met tien broedvogels en één niet-broedvogel voor de Utrechtse Natura 2000-gebieden en Beschermde Natuurmonumenten in de provincie Utrecht. Naast de gevraagde uitbreiding van vogelsoorten is Alterra ook verzocht om twee casestudies te behandelen; een vuurwerkevenement in de uiterwaard bij Rhenen en een vuurwerkevenement in Maarssen nabij de Oostelijke Vechtplassen.
Duurzaam doenderzoek in de Zeeuwse delta : Ecosysteemdiensten in de praktijk : deelresultaat 4.1 : Verslag van de werkbijeenkomst "De waardering van ecosysteemdiensten (doenderdag 2), Deelresultaat 4.2: Kansen voor duurzaam gebruik van bodem, ondergrond en landschap op basis van voorbeelprojecten
Verzandvoort, S.J.E. ; Smit, A. ; Jonkers, W. ; Baaren, E.S. ; Braat, L.C. - \ 2012
Wageningen : Alterra, Wageningen-UR - 52
ecosysteemdiensten - projecten - bodembeheer - natuurbeheer - landschapsbeheer - inventarisaties - zeeland - ecosystem services - projects - soil management - nature management - landscape management - inventories
Reflectie op de rol van het project Duurzaam Doenderzoek in de Zeeuwse Delta in het werk aan duurzame ontwikkeling van de Provincie Zeeland. Duurzaamheid vormgeven via het concept van ecosysteemdiensten. Het bijzondere van dit project zit niet in de theoretische benadering vanuit bodem en natuur, maar in het feit dat we het gebeurt, en wel met mensen uit de praktijk. Daardoor adresseren we ecosysteemdiensten in de richting van de praktijk. Partijen binnenhalen om mee te denken geeft een interactie die niet mogelijk zou zijn alleen redenerend vanuit het eigen beleidsveld of sector.
Impacts on biomass, nutrients and water
Schmidt, P. ; Poels, R.L.H. ; Ketner, P. ; Jonkers, W.B.J. - \ 2011
In: Sustainable Management of Tropical Rainforests / Werger, M.J.A., Paramaribo : Tropenbos International (Tropenbos Series 25) - ISBN 9789051131017 - p. 100 - 135.
Impacts on forest structure and plant diversity
Schmidt, P. ; Jonkers, W.B.J. ; Ketner, P. ; Dijn, B.P.E. De - \ 2011
In: Sustainable Management of Tropical Rainforests / Werger, M.J.A., Paramaribo : Tropenbos International (Tropenbos Series 25) - ISBN 9789051131017 - p. 74 - 99.
Tree growth, recruitment and mortality after logging and refinement
Jonkers, W.B.J. - \ 2011
In: Sustainable Management of Tropical Rainforests / Werger, M.J.A., Paramaribo : Tropenbos International (Tropenbos Series 25) - ISBN 9789051131017 - p. 46 - 73.
The CELOS Management System: concept, treatments and costs
Jonkers, W.B.J. ; Hendrison, J. - \ 2011
In: Sustainable Management of Tropical Rainforests / Werger, M.J.A., Paramaribo : Tropenbos International (Tropenbos Series 25) - ISBN 9789051131017 - p. 29 - 45.
Prospects for the CELOS Management System (Part III: Conclusions and recommendations)
Jonkers, W.B.J. ; Graaf, N.R. de; Hendrison, J. ; Ketner, P. ; Mohren, G.M.J. ; Schmidt, P. ; Hout, P. van der; Kanten, R.F. ; Zagt, R.J. - \ 2011
In: Sustainable Management of Tropical Rainforests - The CELOS Management System / Werger, M.J.A., Paramaribo : Tropenbos International, Paramaribo, Suriname (Tropenbos Series 25) - ISBN 9789051131017 - p. 257 - 263.
The FRP1 F-box gene has different functions in sexuality, pathogenicity and metabolism in three fungal pathogens
Jonkers, W. ; Kan, J.A.L. van; Tijm, P. ; Lee, Y.W. ; Tudzynski, P. ; Rep, M. ; Michielse, C.B. - \ 2011
Molecular Plant Pathology 12 (2011)6. - ISSN 1464-6722 - p. 548 - 563.
vascular wilt fungus - fusarium-oxysporum - botrytis-cinerea - gibberella-zeae - map kinase - reduced pathogenicity - filamentous fungi - protein-kinase - g-alpha - virulence
Plant-pathogenic fungi employ a variety of infection strategies; as a result, fungi probably rely on different sets of proteins for successful infection. The F-box protein Frp1, only present in filamentous fungi belonging to the Sordariomycetes, Leotiomycetes and Dothideomycetes, is required for nonsugar carbon catabolism and pathogenicity in the root-infecting fungus Fusarium oxysporum. To assess the role of Frp1 in other plant-pathogenic fungi, FRP1 deletion mutants were generated in Fusarium graminearum and Botrytis cinerea, and their phenotypes were analysed. Deletion of FgFRP1 in F. graminearum led to impaired infection of barley roots, but not of aerial plant parts. Deletion of BcFRP1 in B. cinerea did not show any effect on pathogenicity. Sexual reproduction, however, was impaired in both F. graminearum and B. cinerea FRP1 deletion mutants. The mutants of all three fungi displayed different phenotypes when grown on an array of carbon sources. The F. oxysporum and B. cinerea deletion mutants showed opposite growth phenotypes on sugar and nonsugar carbon sources. Replacement of FoFRP1 in F. oxysporum with the B. cinerea BcFRP1 resulted in the restoration of pathogenicity, but also in a switch from impaired growth on nonsugar carbon sources to impaired growth on sugar carbon sources. This effect could be ascribed in part to the B. cinerea BcFRP1 promoter sequence. In conclusion, the function of the F-box protein Frp1, despite its high sequence conservation, is not conserved between different fungi, leading to differential requirements for pathogenicity and carbon source utilization.
Assessment of the effects of fish meal, wheat gluten, soy protein concentrate and feed moisture on extruder system parameters and the technical quality of fish feed
Draganovic, V. ; Goot, A.J. van der; Boom, R.M. ; Jonkers, J. - \ 2011
Animal Feed Science and Technology 165 (2011)3-4. - ISSN 0377-8401 - p. 238 - 250.
trout oncorhynchus-mykiss - extrusion conditions - physical-properties - rainbow-trout - aquaculture feeds - screw extrusion - replacement - products - cooking - starch
Evaluation of feed ingredient functionality plays a vital role in modern fish feed manufacturing practice. The aim of this study was to examine the extrusion behaviour of blends containing alternative protein sources from plant origin to fish meal (FM), such as wheat gluten (WG) and soy protein concentrate (SPC), and the consequences for the physical attributes of the resulting feed extrudates. A mixture design was applied, varying the levels of protein sources included in the formulation from 50 to 450 g kg-1. Each diet was produced with added feed moisture content of 20, 26 and 32 g/100 g (wet basis). The partial least squares regression models were fitted and their performance was evaluated on the basis of R2 and the root mean squared error of cross-validation over the complete data set. A higher inclusion level of FM in the diet decreased the values of the extruder system parameters, such as torque, pressure at the die and melt temperature. In contrast, inclusion of SPC significantly increased the values of these extruder-related parameters. The viscoelastic properties of WG gave higher radial expansion; FM showed the opposite effect. The results show that the feed moisture was the dominant factor for extrudate density and oil absorption capacity. Products with higher breaking strength were observed with increasing levels of WG and SPC. Combining the product requirements for both extrudate density and hardness showed that the largest optimal compositional range is available at low feed moisture content. However, maximum FM replacement is possible at high feed moisture content
Eemuiterwaarden Bruggematen en Wolkenberg : inventarisatie van het voorkomen van amfibieën en de ringslang in het kader van inrichtingsmaatregelen
Ottburg, F.G.W.A. ; Jonkers, D.A. - \ 2011
Wageningen : Alterra (Alterra-rapport 2159) - 36
uiterwaarden - reptielen - amphibia - habitatverbindingszones - habitats - natuurbeheer - inventarisaties - eemland - utrecht - river forelands - reptiles - habitat corridors - nature management - inventories
Natuurmonumenten heeft in het beheergebied Eemland het plan om inrichtingsmaatregelen uit te voeren in de uiterwaarden Bruggematen en Wolkenberg. Alterra en ecologisch adviesbureau Greendesk is gevraagd om specifiek een inventarisatie uit te voeren naar het voorkomen van amfibieën en ringslang in beide uiterwaarden. Hierin komen weinig soorten amfibieën voor en de aantallen daarvan zijn laag. Bijzonder is de aanwezigheid van rugstreeppadlarven in Wolkenberg. Tijdens het onderzoek zijn geen ringslangen vastgesteld. De dichtstbijzijnde bekende populaties komen voor in de omgeving van de Stichtse Brug en De Birkt. Aanbevolen wordt om het tussenliggende gebied in kaart te brengen. Waar bevindt zich geschikt habitat voor de ringslang? In een vervolg hierop kan worden overwogen waar en hoeveel stapstenen er nodig zijn om beide populaties te verbinden. Naast de formele opdracht zijn ook andere faunagroepen meegenomen tijdens de inventarisaties. Dit rapport sluit af met het hoofdstuk ‘Aanbevelingen voor beheer en inrichting’.
Electronic Supplementary Material of the paper: Dynamics and ecological consequences of avian influenza virus infection in greater white-fronted geese in their winter staging areas
Kleijn, D. ; Munster, V.J. ; Ebbinge, B.S. ; Jonkers, D.A. ; Muskens, G.J.D.M. ; Randen, Y. van; Fouchier, R.A.M. - \ 2010
Behoud de bittervoorn, spaar de zwanenmossel : innovatief ecologisch baggeren in de waaien van Eemland
Ottburg, F.G.W.A. ; Roodhart, J. ; Jonkers, D.A. - \ 2010
Vakblad Natuur Bos Landschap 7 (2010)8. - ISSN 1572-7610 - p. 4 - 7.
zoetwatervissen - vissen - amphibia - baggeren - monitoring - eemland - utrecht - freshwater fishes - fishes - dredging
Bittervoorns en zwanenmossels hebben een bijzondere symbiose. Wanneer door reguliere baggerwerkzaamheden de niet-beschermde zwanenmossel verdwijnt, kan dit daardoor desastreuze gevolgen hebben voor de voortplanting van de bittervoorn. Een innovatieve wijze van baggeren biedt uitweg. Verwezen wordt naar twee Alterra rapporten, verschenen over Vissen in Eemland
Architectuur tussen kennisvraag en -aanbod
Jonkers, B. ; Nijlunsing, W. ; Beers, G. ; Zaane, D. van - \ 2010
Groene Kennis Coöperatie
informatiesystemen - informatiemanagement - procesarchitectuur - kennismanagement - kennismodellering - kennisoverdracht - agrarisch onderwijs - information systems - information management - process architecture - knowledge management - knowledge modeling - knowledge transfer - agricultural education
Begin 2010 is een werkgroep aan de slag gegaan met het uitwerken van de business en informatiestructuur van Groen Kennisnet en het doen van een voorstel van de inrichting van GKN informatiemanagement. Dit document is het resultaat van dit proces.
Vissen en amfibieën in het beheergebied Eemland van Vereniging Natuurmonumenten : verspreiding van zoetwatervissen en amfibieën in de Noordpolder te Veen, Noordpolder te Veld, Zuidpolder te Veld, Maatpolder en Bikkerspolder
Ottburg, F.G.W.A. ; Jonkers, D.A. - \ 2010
Wageningen : Alterra (Alterra-rapport 2060) - 145
zoetwatervissen - vissen - amphibia - soorten - soortenrijkdom - polders - inventarisaties - nederland - natuurgebieden - eemland - utrecht - freshwater fishes - fishes - species - species richness - inventories - netherlands - natural areas
Zowel in 2007 als in 2008 is in een aantal eigendommen van Natuurmonumenten in Eemland, de waaien beoosten de Eem en een deel van de Noordpolder te Veen onderzoek gedaan naar het voorkomen van vissoorten. De verspreiding van deze soorten wordt in dit rapport beschreven. Ook worden de bijvangsten van amfibieën behandeld. In totaal zijn twintig verschillende vissoorten gevangen. Onder de gevangen vissoorten bevonden zich er vier van de landelijke Rode Lijst: bittervoorn, grote modderkruiper, kroeskarper en vetje
Dynamics and ecological consequences of avian influenza virus infection in greater white-fronted geese in their winter staging areas
Kleijn, D. ; Munster, V.J. ; Ebbinge, B.S. ; Jonkers, D.A. ; Müskens, G.J.D.M. ; Randen, Y. van; Fouchier, R.A.M. - \ 2010
Proceedings of the Royal Society. B: Biological Sciences 277 (2010)1690. - ISSN 0962-8452 - p. 2041 - 2048.
wild mallard ducks - affect body condition - a virus - migratory waterfowl - branta-canadensis - north-america - vice-versa - birds - h5n1 - paramyxoviruses
Recent outbreaks of highly pathogenic avian influenza (HPAI) in poultry have raised interest in the interplay between avian influenza (AI) viruses and their wild hosts. Studies linking virus ecology to host ecology are still scarce, particularly for non-duck species. Here, we link capture–resighting data of greater white-fronted geese Anser albifrons albifrons with the AI virus infection data collected during capture in The Netherlands in four consecutive winters. We ask what factors are related to AI virus prevalence and whether there are ecological consequences associated with AI virus infection in staging white-fronted geese. Mean seasonal (low pathogenic) AI virus prevalence ranged between 2.5 and 10.7 per cent, among the highest reported values for non-duck species, and occurred in distinct peaks with near-zero prevalence before and after. Throat samples had a 2.4 times higher detection frequency than cloacal samples. AI virus infection was significantly related to age and body mass in some but not other winters. AI virus infection was not related to resighting probability, nor to maximum distance travelled, which was at least 191 km during the short infectious lifespan of an AI virus. Our results suggest that transmission via the respiratory route could be an important transmission route of AI virus in this species. Near-zero prevalence upon arrival on their wintering grounds, in combination with the epidemic nature of AI virus infections in white-fronted geese, suggests that white-fronted geese are not likely to disperse Asian AI viruses from their Siberian breeding grounds to their European wintering areas.
Naar een beheerplan voor Eilandspolder-Oost als Natura2000-gebied : van top-down invoeren naar bouwen aan sociaal draagvlak?
Apeldoorn, R.C. van; Jonkers, D.A. ; Ottburg, F.G.W.A. ; Wamelink, G.W.W. - \ 2010
Wageningen : Wetenschapswinkel Wageningen UR (Alterra-rapport nr. 1988) - 65
fauna - natuurbescherming - flora - waterkwaliteit - habitats - baggeren - natura 2000 - weidevogels - visfauna - natuurgebieden - noord-holland - nature conservation - water quality - dredging - grassland birds - fish fauna - natural areas
Halverwege de 20e eeuw kwamen zwaardere landbouwmachines, nieuwe meststoffen en minder, maar grotere boeren in de Eilandspolder. En daarmee ontstond de behoefte aan ontsluiting, verkaveling, paden, dammen en bruggen. Maar de natuur en het open veenweidelandschap kwamen in het gedrang en claimden hun rechten. De Eilandspolder was al in 1979 tot Vogelrichtlijngebied uitgeroepen en in 1992 werd de Eilandspolder-Oost ook onder de Habitatrichtlijn gebracht. Het hele gebied werd Natura2000- gebied en de natuurwaarden en de agrarische belangen kwamen scherp tegenover elkaar te staan. Natuurliefhebbers en omwonenden waren inmiddels flink ongerust geworden over de ingrijpende plannen. Zij vonden elkaar in de Stichting Open Polders, maar ze mist de specialistische ecologische kennis die nodig is om een inbreng te kunnen leveren in de discussies rond dit nieuwe beheerplan voor het Natura2000-gebied. Wetenschapswinkel in Wageningen en de onderzoekers van Alterra bereid waren de ecologische eisen van de doelen te beschrijven, die bepalend zijn voor inrichting en beheer en die als basis en richtlijnen kunnen dienen voor het beheerplan. Hiermee kan ook worden nagegaan wat we gezien de instandhoudingsdoelen straks in het beheerplan terug moeten vinden. Gesprekken zijn gevoerd met terreinbeheerders die betrokken zijn bij het beheer van het gebied, waaronder het voorgenomen baggerplan
The effect of a multispecies probiotic on the composition of the faecal microbiota and bowel habits in chronic obstructive pulmonary disease patients treated with antibiotics
Koning, C.J. ; Jonkers, D. ; Smidt, H. ; Rombouts, F.M. ; Pennings, H.J. ; Wouters, E. ; Stobberingh, E. ; Stockbrügger, R.W. - \ 2010
The British journal of nutrition 103 (2010)10. - ISSN 0007-1145 - p. 1452 - 1460.
gradient gel-electrophoresis - 16s ribosomal-rna - gastrointestinal-tract microbiota - human intestinal microbiota - quantitative-analysis - temporal stability - healthy-volunteers - human feces - pcr-dgge - bacteria
Short-term antibiotic treatment profoundly affects the intestinal microbiota, which may lead to sustained changes in microbiota composition. Probiotics may restore such a disturbance. The objective of the present study was to investigate the effect of a multispecies probiotic on the faecal microbiota during and after antibiotic intake in patients with a history of frequent antibiotic use. In this randomised, placebo-controlled, double-blind study, thirty chronic obstructive pulmonary disease (COPD) patients treated with antibiotics for a respiratory tract infection received 5 g of a multispecies probiotic or placebo twice daily for 2 weeks. Faecal samples were collected at 0, 7, 14 and 63 d. Changes in the composition of the dominant faecal microbiota were determined by PCR-denaturing gradient gel electrophoresis (DGGE). Changes in bacterial subgroups were determined by quantitative PCR and culture. Bowel movements were scored daily according to the Bristol stool form scale. During and after antibiotic treatment, DGGE-based similarity indices (SI) were high ( >/= 84 %) and band richness was relatively low, both remaining stable over time. No difference in SI was observed between patients with and without diarrhoea-like bowel movements. The multispecies probiotic had a modest effect on the bacterial subgroups. Nevertheless, it affected neither the composition of the dominant faecal microbiota nor the occurrence of diarrhoea-like bowel movements. The dominant faecal microbiota was not affected by antibiotics in this COPD population, suggesting an existing imbalance of the microbiota, which may also have contributed to the lack of effect by probiotic intake
Analyses of human colonic mucus obtained by an in vivo sampling technique
Hamer, H.M. ; Jonkers, D.M.A.E. ; Loof, A. ; Vanhoutvin, S.A.L.W. ; Troost, F.J. ; Venema, K. ; Kodde, A. ; Koek, G.H. ; Schipper, R.G. ; Heerde, W.L. van; Brummer, R.J. - \ 2009
Digestive and Liver Disease 41 (2009)8. - ISSN 1590-8658 - p. 559 - 564.
inflammatory-bowel-disease - ulcerative-colitis - mucosal cytokine - trefoil peptide - sialic acids - filter-paper - mucins - rats - glycoproteins - resistance
Background The mucus layer is an important dynamic component of the epithelial barrier. It contains mucin glycoproteins and other compounds secreted by the intestinal epithelium, such as secretory IgA. However, a standardized in vivo sampling technique of mucus in humans is not yet available. Aim To assess the validity and feasibility of mucin and protein determinations in human colonic mucus collected under physiological conditions. Subjects and methods Triplicate colonic mucus samples were collected in 11 healthy volunteers using cytology brushes during sigmoidoscopy. As an indication of the quantity of collected mucus, total protein and mucin concentrations were determined by measuring oligosaccharide equivalents and monosaccharides. Also secretory IgA and sialic acid concentrations were determined and proteomic analysis was performed using surface enhanced laser desorption/ionization-time of flight-mass spectrometry. Results Mean values of secretory IgA and sialic acid corrected for the amount of mucus ranged from 0.16 to 1.81 g secretory IgA/mmol oligosaccharide equivalents and from 12.6 to 48.6 g sialic acid/mmol oligosaccharide equivalents. Proteomic analysis of mucus is feasible and cluster analysis showed subject specific profiles. Conclusion Using cytology brushes, human colonic mucus can be sampled and under physiological conditions. These samples could give information on the composition and quality of the mucus layer.
Cradle to Cradle in gebiedsontwikkeling : omgaan met duurzaam bodemgebruik in de praktijk
Jonkers, W. ; Roghair, C.J. ; Smit, A. ; Velden, J.A. van der - \ 2009
Bodem 19 (2009)6. - ISSN 0925-1650 - p. 35 - 38.
bodem - duurzaamheid (sustainability) - regionale planning - gebiedsontwikkeling - cradle to cradle - zeeland - soil - sustainability - regional planning - area development
Het denken in kringlopen, vermeerderen van waarden en duurzaam evolueren is de essentie van het concept van Cradle to Cradle (C2C). Om dit in gebiedsprojecten, inclusief het bodemsysteem, vorm te geven is nog niet zo eenvoudig. Toch krijgt het C2C-concept binnen gebiedsontwikkeling steeds meer belangstelling door duurzaam bodemgebruik een integrale plaats te geven in gebiedsprocessen. Vanuit de C2C invalshoek spelen dan vragen over de functie van bodem binnen het gebied, het toevoegen van waarde aan de bodem, het gebruiken van de kwaliteiten en het robuust functionerend houden van het bodemsysteem. Voor DLG, Alterra en de provincie Zeeland reden om een workshop te organiseren. De deelnemers kregen aan de hand van casusgebieden in Zeeland de volgende opdrachten: vorm met elkaar een beeld van de ondergrond van de gebieden. Analyseer de kansen die de ondergrondkwaliteiten hier bieden. Leg de wensen van de streek naast de kansenschets. En overleg vanuit je rollen als opdrachtgever en uitvoerder waar je tot een optimaal duurzaam gebruik van de bodem kunt komen binnen de scopie van de opdracht
Vissen in de waaien van Eemland : visstandbemonstering in het kader van de Flora- en faunawet voor het baggeren van de waaien in Eemland
Ottburg, F.G.W.A. ; Jonkers, D.A. - \ 2009
Wageningen : Alterra (Alterra-rapport 1787) - 94
baggeren - vissen - visbestand - monitoring - ecologie - eemland - dredging - fishes - fishery resources - ecology
In het kader van de Flora- en faunawet (Ff-wet) aanvraag voor het baggeren van de waaien van Eemland is een visstandbemonstering uitgevoerd naar de aanwezige vissoorten in de waaien. Er is in het bijzonder aandacht geweest voor de Ff-wet soorten die vermeld staan in de tabellen 2 en 3 van de Ff-wet, zoals kleine modderkruiper en bittervoorn. De waaien vormen een onderdeel van een groter hydrologisch geheel binnen Eemland. De laatste 14 jaar zijn de waaien niet meer gebaggerd. Hierdoor is een baggerachterstand ontstaan en/of zijn de waaien verland. Deze waaien zijn niet alleen van ecologisch belang, maar vervullen ook een cultuurhistorische rol. Vereniging Natuurmonumenten en Waterschap Vallei & Eem zetten zich in voor het behoud van de waaien.
Ecologische effecten van het militair gebruik van de Schietrange 'Vliehors' op de Vliehors en omgeving, te verwachten ecologische effecten op natuurwaarden
Apeldoorn, R.C. van; Smit, C.J. ; Molenaar, J.G. de; Jonkers, D.A. ; Henkens, R.J.H.G. - \ 2008
Wageningen : Alterra - 118 p.
Vuurwerk & vogels : afwegingskader voor vergunningverlening ten aanzien van vuurwerkevenementen in en nabij Brabantse vogelrichtlijngebieden
Ottburg, F.G.W.A. ; Molenaar, J.G. de; Jonkers, D.A. - \ 2008
Wageningen : Alterra (Alterra-rapport 1694)
vogels - wildbescherming - vergunningen - publieksevenementen - natuurbescherming - geluidshinder - nederland - noord-brabant - birds - wildlife conservation - permits - spectator events - nature conservation - noise pollution - netherlands
Het Vuurwerkbesluit van 16 januari 2004 geeft aan dat het tot ontbranding brengen van vuurwerk niet door particulieren mag worden gedaan (behalve oudejaarsdag). Bij het houden van een vuurwerkevenement in of in de omgeving van een Brabants Vogelrichtlijngebied waarbij een verstorend effect kan optreden, moet een vergunning in het kader van de Natuurbeschermingswet worden aangevraagd. Deze studie geeft aan: 1. welke afstanden gewenst zijn tot het vogelgebied; 2. voor de diverse categorieën vuurwerk de verwachte verstoringen voor de vogels
The effect of a multispecies probiotic on the intestinal microbiota and bowel movements in healthy volunteers taking the antibiotic amoxycillin
Koning, C.J.M. ; Jonkers, D.M.A.E. ; Stobberingh, E.E. ; Mulder, L. ; Rombouts, F.M. ; Stockbrügger, R.W. - \ 2008
American Journal of Gastroenterology 103 (2008)1. - ISSN 0002-9270 - p. 178 - 189.
chain fatty-acids - lactobacillus-gg - saccharomyces-boulardii - double-blind - bacterial metabolism - cefpodoxime proxetil - plantarum 299v - fecal enema - diarrhea - prevention
BACKGROUND: One of the side effects of antimicrobial therapy is a disturbance of the intestinal microbiota potentially resulting in antibiotic-associated diarrhea (AAD). In this placebo-controlled double-blind study, the effect of a multispecies probiotic on the composition and metabolic activity of the intestinal microbiota and bowel habits was studied in healthy volunteers taking amoxycillin. METHODS: Forty-one healthy volunteers were given 500 mg amoxycillin twice daily for 7 days and were randomized to either 5 g of a multispecies probiotic, Ecologic® AAD (109 cfu/g), or placebo, twice daily for 14 days. Feces and questionnaires were collected on day 0, 7, 14, and 63. Feces was analyzed as to the composition of the intestinal microbiota, and ß-glucosidase activity, endotoxin concentration, Clostridium difficile toxin A, short chain fatty acids (SCFAs), and pH were determined. Bowel movements were scored according to the Bristol stool form scale. RESULTS: Mean number of enterococci increased significantly from log 4.1 at day 0 to log 5.8 (day 7) and log 6.9 (day 14) cfu/g feces (P <0.05) during probiotic intake. Although no other significant differences were observed between both intervention groups, within each group significant changes were found over time in both microbial composition and metabolic activity. Moreover, bowel movements with a frequency ¿3 per day for at least 2 days and/or a consistency ¿5 for at least 2 days were reported less frequently in the probiotic compared to the placebo group (48%vs 79%, P <0.05). CONCLUSIONS: Apart from an increase in enterococci no significant differences in microbial composition and metabolic activity were observed in the probiotic compared with the placebo group. However, changes over time were present in both groups, which differed significantly between the probiotic and the placebo arm, suggesting that the amoxycillin effect was modulated by probiotic intake. Moreover, the intake of a multispecies probiotic significantly reduced diarrhea-like bowel movements in healthy volunteers receiving amoxycillin
Verdediging van Nederlands milieubeleid in Brussel wordt `n opgave
Jonkers, D. ; Aarts, H.F.M. - \ 2007
V-focus 2004 (2007). - ISSN 1574-1575 - p. 20 - 23.
milieubeleid - veehouderij - dierlijke meststoffen - agrarische bedrijfsvoering - gemeenschappelijk landbouwbeleid - nederland - beleidsevaluatie - mineralenboekhouding - environmental policy - livestock farming - animal manures - farm management - cap - netherlands - policy evaluation - nutrient accounting system
Douwe Jonkers, manager Landbouw, Mest en Mineralen bij het ministerie van VROM en namens VROM lid van het Europese Nitraatcomité voert samen met collega's onderhandelingen over het derogatiebeleid in Brussel. Volgens hem zijn maatregelen op bedrijfsniveau nodig om het Nederlandse milieubeleid te kunnen verdedigen
De huismus verdwijnt: is het tij te keren?
Apeldoorn, R.C. van; Klok, C. ; Hemerik, L. ; Jonkers, D.A. - \ 2007
De Levende Natuur 108 (2007)2. - ISSN 0024-1520 - p. 49 - 51.
fringillidae - populatiedynamica - stedelijke gebieden - population dynamics - urban areas
In 2006 organiseerde Vogelbescherming Nederland een dag over stadsvogels. Regelmatig dook de huismus (Passer domesticus) op als voorbeeld van de groep soorten die typisch is voor steden en dorpen en waar het niet goed mee gaat. Wat er schokkend aan is, dat niet goed bekend is, hoe groot de achteruitgang is en waardoor deze precies wordt veroorzaakt
Road lightning and grassland birds: local influence of road lightning on a black-tailed godwit population
Molenaar, H. de; Sanders, M.E. ; Jonkers, D.A. - \ 2006
In: Ecological consequences of artificial night lighting / Rich, C., Longcore, T., Washington DC, USA : Island Press - ISBN 1559631295 - p. 114 - 136.
The in vivo transgenic zebrafish reporter gene assay for bioanalysis of exposure and effects of estrogenic chemicals in the aquatic environment
Legler, J. ; Zee, M. van der; Ven, L.T.M. van der; Jonkers, C.C.H. ; Vethaak, A.D. ; Burg, B. van der; Murk, A.J. - \ 2006
In: Estrogens and xenoestrogens in the aquatic environment: An integrated approach for field monitoring and effect assessment / Vethaak, D., Schrap, M, de Voogt, P., Pensacola : SETAC-scientific book (SETAC Technical Publications Series ) - ISBN 9781880611852 - 512 p.
Farming Valley : de agrarische productie heruitgevonden
Broens, D.W. ; Es, H. van; Vos, G. ; Kooten, O. van; Wijnands, J.H.M. - \ 2006
In: De plooibaarheid van Nederland: groot, slim, breed, schoon / Jonkers, M., Amsterdam : Dialogues - ISBN 9085980097 - p. 12 - 29.
plattelandsontwikkeling - plattelandsplanning - nederland - innovaties - toekomst - creativiteit - rural development - rural planning - netherlands - innovations - future - creativity
Het toekomstig ruimtegebruik van het platteland. Het bevat de afzonderlijke bijdragen: Benutting van het platteland; Farming valley; Leisure valley; Senior valley; Water valley
Mogelijke effecten van verlichting uit Rustenburg op kwalificerende en andere vogelsoorten in de Bovenste Polder onder Wageningen
Molenaar, J.G. de; Jonkers, D.A. ; Ottburg, F.G.W.A. - \ 2005
Wageningen : Alterra (Alterra-rapport 1237)
woonwijken - kunstlicht - nadelige gevolgen - vogels - uiterwaarden - gelderland - fauna - residential areas - artificial light - adverse effects - birds - river forelands
Deze publicatie beschrijft de resultaten van een quick scan naar de mogelijke effecten van verlichting van de geplande bouw van de wijk Rustenburg in Wageningen op een aantal vogelsoorten in de Bovenste Polder. Aanvullend worden mitigerende maatregelen voorgesteld. Het betreft met name de kwalificerende soorten van de Vogelrichtlijn. Voorts wordt zijdelings aandacht geschonken aan reptielen en amfibieën
Het experiment Gaasterland; resultaten van het procesonderzoek en het ecologisch onderzoek
Kuindersma, W. ; Molenaar, J.G. de; Kolkman, G. ; Jonkers, D.A. ; Duinhoven, G. van - \ 2005
Wageningen : Alterra - 16
natuurbescherming - participatie - natuurbeheer - natuurontwikkeling - friesland - gaasterland - nature conservation - participation - nature management - nature development
In 1990 werd heel Nederland, en dus ook het Friese Gaasterland, geconfronteerd met het Natuurbeleidsplan. Dit plan was bedoeld om de bestaande natuurgebieden met elkaar te verbinden en nieuwe natuurgebieden te creëren. In 2018 zou er dan een zogenaamde Ecologische Hoofdstructuur (EHS) moeten liggen: een landsdekkend netwerk van aaneengesloten natuurgebieden. Belangrijkste uitzondering daarop is Gaasterland. Nadat de provincie haar plannen gereed had, volgde er een heuse opstand in Gaasterland. Na veel overleg kwam uiteindelijk het experiment Gaasterland tot stand. In dit experiment is geprobeerd om vergelijkbare natuur aan te leggen als in de plannen voor de EHS, maar met het grote verschil dat de inwoners zelf in grote lijnen mochten gaan bepalen waar er welke natuur zou komen liggen. Deze brochure is gebaseerd op twee rapporten: Vertrouwen en samenwerking in het experiment Gaasterland Een procesevaluatie over tien jaar natuurontwikkeling(en) (Alterra rapport 1229,W. Kuindersma en G. Kolkman) Meten en wegen in het Experiment Gaasterland Een ecologische evaluatie van vijf jaar agrarisch en particulier natuurbeheer (Alterra rapport 1230, J.G. de Molenaar, D.A. Jonkers en G. Kolkman)
Secundairy Data-Analysis Mapane-Plots 1981-1997
Jansen, J.J. ; Bongers, F.J.J.M. ; Graaf, N.R. de; Jonkers, W.B.J. ; Sterck, F.J. ; Stuiver, B.M. ; Wirjosentono, J. - \ 2005
Wageningen : WUR - 43 p.
Meten en wegen in het experiment Gaasterland; een ecologische evaluatie van agrarisch en particulier natuurbeheer
Molenaar, J.G. de; Jonkers, D.A. ; Kolkman, G. - \ 2005
Wageningen : Alterra (Alterra-rapport 1230) - 60
natuurbescherming - monitoring - evaluatie - landbouwgrond - ecologische hoofdstructuur - agrarisch natuurbeheer - weidevogels - gaasterland - friesland - nature conservation - evaluation - agricultural land - ecological network - agri-environment schemes - grassland birds
Deze studie is een verslag van een onderzoek naar het experiment Gaasterland. Het experiment Gaasterland is de specifieke manier waarop in Gaasterland het EHS beleid wordt vormgegeven. Via een eigen systeem, de natuurmeetlat, wordt geprobeerd om de oorspronkelijke EHS-doelen, op een andere manier te bereiken. In deze studie is beschreven hoe de natuurmeetlat werkt en hoe ver men is in het bereiken van de natuurpunten en met welke natuurkwaliteit dit samengaat. Het blijkt dat voor sommige categorieën er snel veel punten zijn binnengehaald en dat het voor andere categorieën duidelijk lastiger is om het beoogde resultaat te halen. Drie categorieën waarvoor natuurpunten kunnen worden behaald krijgen in deze studie extra aandacht omdat hier ook daadwerkelijk veldonderzoek naar de natuurkwaliteit is gedaan: weidevogelbeheer, botanisch beheer van percelen en botanisch beheer van perceelsranden
Procesinnovatie tuinbouwdelta : kaderhoofdstuk
Jonkers, H.L. ; Holthuijzen, A. ; Kooten, O. van - \ 2005
[S.l.] : Bureau voor Strategieontwikkeling en Systeeminnovatie (Position papers tuinbouwdelta ) - 25 p.
EHS-experiment Gaasterland; 2 effectiviteit agrarisch weidevogelbeheer
Molenaar, J.G. de; Jonkers, D.A. ; Vereijken, P.F.G. ; Kolkman, G. - \ 2005
Wageningen : Alterra (Alterra-rapport 1131) - 51
graslandbeheer - vogels - natuurbescherming - agrarisch natuurbeheer - weidevogels - agro-ecologie - gaasterland - friesland - grassland management - birds - nature conservation - agri-environment schemes - grassland birds - agroecology
In dit rapport worden de resultaten gepresenteerd van een onderzoek naar de effectiviteit van weidevogelbeheer. Het doel van het ecologische onderzoek is in andere, algemenere bewoordingen na te gaan of natuurbeheer door agrariërs (SAN) een goed alternatief is voor natuurbeheer door natuurbeschermingsorganisaties (SN). De concrete vraag van het hiervoor opgezette weidevogelonderzoek luidt: ¿Hoe verhouden de resultaten van weidevogelbeheersovereenkomsten die zijn afgesloten met boeren (`SAN-/boerenbeheer¿) zich tot die van enerzijds gangbaar intensief graslandbeheer en anderzijds tot die van weidevogelbeheer door natuurbeschermingsorganisaties (`SN/reservaatbeheer¿)? De resultaten hebben betrekking op de dichtheden van broedparen, de lotgevallen van de weidevogellegsels en zo mogelijk die van de kuikens.
Modulating effect of the A-278C promoter polymorphism in the cholesterol 7alpha-hydroxylase gene on serum lipid levels in normolipidaemic and hypertriglyceridaemic individuals
Hofman, M.K. ; Groenendijk, M. ; Verkuijlen, P.J.J.H. ; Jonkers, I.J.A.M. ; Mohrschladt, M.F. ; Smelt, A.H.M. ; Princen, H.M.G. - \ 2004
European Journal of Human Genetics 12 (2004)11. - ISSN 1018-4813 - p. 935 - 941.
apolipoprotein-e polymorphism - bile-acid kinetics - density-lipoprotein - 7-alpha-hydroxylase gene - cyp7 gene - disease - mice - hyperlipoproteinemia - quantitation - association
The rate-limiting enzyme in the conversion of cholesterol into bile acids is cholesterol 7alpha-hydroxylase (CYP7A1). An A to C substitution 278 bp upstream in the promoter of the CYP7A1 gene was found to be associated with variations in serum lipid levels in normolipidaemic populations. In the present study, we investigated the involvement of this polymorphism in four different lipid disorders: hypertriglyceridaemia (HTG), combined hyperlipidaemia (CH), familial dysbetalipoproteinaemia (FD) and familial hypercholesterolaemia (FH). In a normolipidaemic male population, homozygous for the apoE3 isoform, an association was found between the AA genotype and higher levels of serum triglycerides (AA: +34%, P=0.036). In HTG patients, the AA genotype was associated with significantly higher concentrations of total cholesterol (+23%, P=0.005). There was a tendency towards increased levels of serum triglycerides (+39%, P=0.06), VLDL-triglycerides (+48%, P=0.053) and VLDL-cholesterol (+35%, P=0.059). No significant associations were found between serum lipid levels and the CYP7A1 polymorphism in patients with CH, FD and FH. Our results show that the A-278C polymorphism in the CYP7A1 gene has an effect on triglyceride levels in normolipidaemic males and on cholesterol levels in patients with hypertriglyceridaemia.
Ecologische gevolgen sanering Target 14 SR Vliehors; beschrijving van de gevolgen in het kader van het natuurbeschermingsrecht
Koolstra, B.J.H. ; Jonkers, D.A. - \ 2004
Wageningen : Alterra (Alterra-rapport 960) - 54
recht - wetgeving - herstel - habitats - regulatie - natuurbescherming - eilanden - nederland - habitatrichtlijn - militaire activiteiten - friesland - nederlandse waddeneilanden - law - legislation - rehabilitation - regulation - nature conservation - islands - netherlands - habitats directive - military activities - dutch wadden islands
In verband met de voorgenomen sanering van een bommendoel op de Vliehors (Vlieland) zijn de ecologische gevolgen van deze sanering in beeld gebracht. Tevens zijn deze gevolgen beoordeeld in het kader van ondermeer de Natuurbeschermingswet, de Vogel- en Habitatrichtlijn en de Flora- en Faunawet.
De ruimte spreekt voor zich; waar liggen de natuurlijke kansen voor wonen, werken, landbouw, recreëren en natuur?
Eijsackers, H.J.P. ; Jonkers, J. - \ 2004
Utrecht : Lemma (Voorstudies en achtergronden / RMNO nr. V.03) - ISBN 9059312961 - 84
landgebruiksplanning - landbouw - natuurbescherming - openluchtrecreatie - land use planning - agriculture - nature conservation - outdoor recreation
Het doel van deze publicatie is de discussie over de ruimtelijke ordening van Nederand een natuurlijke basis te geven door kennis over de ondergrond die plek in de besluitvorming te geven die het verdient. In het kader van dit project zijn via een viertal kansenkaarten aangegeven hoe die kennis over de ondergrond van toepassing zou kunnen zijn voor gebruiksfuncties. Ter onderbouwing zijn er een twintigtal gesprekken met experts gevoerd en rapporten en artikelen doorgenomen. Deze publicatie bevat kansenkaarten voor: wonen en werken; natuur; landbouw; groene recreatie
Sustainable management of rainforest in Cameroon
Jonkers, W.B.J. ; Foaham, B. - \ 2004
Wageningen : Tropenbos International (Tropenbos-Cameroon Series 9) - ISBN 9051130716 - 93 p.
Verkenning van het effect van recreatie op broedvogels : literatuurstudie en koppeling modellen FORVISITS en LARCH
Henkens, R.J.H.G. ; Jochem, R. ; Jonkers, D.A. ; Molenaar, J.G. de; Pouwels, R. ; Reijnen, M.J.S.M. ; Visschedijk, P.A.M. ; Vries, S. de - \ 2003
Wageningen : Natuurplanbureau (Werkdocument / Planbureau-werk in uitvoering 2003/29) - 62
recreatie - milieueffect - broedvogels - nadelige gevolgen - modellen - nederland - recreation - environmental impact - breeding birds - adverse effects - models - netherlands
Inventarisatie ten behoeve van Natuurplanbureau
Broedvogels van het eiland De Dode Hond in 2002
Jonkers, D.A. - \ 2003
Hilversum : Vogelwerkgroep Het Gooi en Omstreken (Uitgave / Vogelwerkgroep Het Gooi en Omstreken 136) - 28
broedvogels - nestelen - inventarisaties - eilanden - noord-holland - randmeren - breeding birds - nesting - inventories - islands
Dode Hond is een kunstmatig eiland in het Eemmeer. In het nabijgelegen dorp Spakenburg staat het eiland bekend onder de naam 'Vogeleiland'. Dit heeft zijn oorsprong in het doel van het eiland als depot voor grond die vrijkwam bij de aanleg van de dijk van Flevoland. In die tijd vlogen veel vogels rond het eiland om in de pas gestorte grond naar voedsel te zoeken. Vele vogelsoorten en andere dieren kunnen hier ongestoord leven.
Screening of nutritional status in The Netherlands
Kruizenga, H.M. ; Wierdsma, N.J. ; Bokhorst, M.A.E. van; Schueren, D.E. van der; Hollander, H.J. ; Jonkers-Schuitema, C.F. ; Heijden, E. van der; Melis, G.C. ; Staveren, W.A. van - \ 2003
Clinical Nutrition 22 (2003)2. - ISSN 0261-5614 - p. 147 - 152.
malnutrition - complications - prevalence - disease
Background and Aims: In 2001, the Dutch Dietetic Association conducted a national screening on malnutrition. The goal of this screening was to determine the prevalence of disease-related malnutrition in The Netherlands in all fields of medical care and to investigate the involvement of the dietitian in the treatment of malnutrition. Methods: Eight thousand five hundred and twenty nine patients were screened of which data of 7606 patients could be analysed. Eighty one per cent (6150) of the patients were hospital patients. Eleven per cent (808) of the patients lived in a nursing home. Seven per cent (533) of the patients were home-care patients, who were measured at home or at the general practitioner's office. The origin of 115 patients (2%) was not registered. Age, height, weight, unintentional weight loss, kind of illness and intervention by a dietitian were registered. Malnutrition was defined as >10% unintentional weight loss during the past 6 months and risk of malnutrition was defined as 5-10% unintentional weight loss during the past 6 months. Results: Twelve per cent (884) of all patients appeared to be malnourished. Thirteen per cent (962) were at risk of malnutrition and 75% (5760) were well nourished. Fifty four per cent of the malnourished patients were referred to a dietitian. Oncological disease was more associated with malnutrition than non-oncological disease (in particular in the head and neck, lung and intestinal areas). Also, non-oncological gastro-intestinal and lung disease patients were often categorised as malnourished. Elderly patients (>75 years) were more at risk of malnutrition. BMI and unintentional weight loss did not correlate well. Conclusion: In this national survey conducted by dietitians, including a convenience sample of mainly institutionalised patients, approximately 25% of patients in all medical fields were categorised as moderately or severely malnourished. About half of these patients were seen by a dietitian. (C) 2003 Elsevier Science Ltd. All rights reserved.
Population dynamics of Garcinia lucida (Clusiaceae) in Cameroonian Atlantic forests.
Guedje, N.M. ; Lejoly, J. ; Nkongmeneck, B.A. ; Jonkers, W.B.J. - \ 2003
Forest Ecology and Management 177 (2003). - ISSN 0378-1127 - p. 231 - 241.
density-dependence - plant-populations - tropical trees - matrix models - growth rate - new-zealand - products - conservation - extraction - impact
Garcinia lucida Vesque (Clusiaceae) is a highly valued non-timber forest tree. The bark and the seeds are exploited and commercialised for medicinal purposes and palm wine processing in Cameroon, Gabon and Equatorial Guinea. The bark is often removed over almost the entire circumference of the stem, leading to high mortality. To identify the processes or the life stages that influence the population dynamics and to forecast the potential effects of harvesting, a demography study was carried and a matrix model was constructed to characterise the population dynamics of G. lucida in the South Cameroonian Atlantic humid forests. The study revealed that height and diameter growth values were very low and may constitute biological disadvantages for the dynamics of the species. The flowering and fruiting model, the absence of seed dormancy, and the high germination and seedling survival rates constituted advantages for the population dynamics, which is characterised by effective regeneration strategies. Rates of growth, survival and fecundity allowed calculations of transition probabilities of the matrix model. The value of the dominant eigenvalue (lambda) was 1.063, slightly higher than the value expected for stable populations. The sensitivities of lambda to changes showed that the population growth was most sensitive to changes in tree growth, particularly in the seedling stage. Elasticity analysis showed that growth and fecundity elements had much lower contributions to lambda, indicating that the harvesting of seeds may have a low impact on population growth. However, the population growth was highly sensitive to changes in survival probability, particularly among trees of 5-10 cm, diameter at breast height (dbh). The last stages, containing the large reproductive individuals over 10 cm dhb, which are interesting for the bark extraction, accounted for lowest elasticity, indicating that the extraction of bark may have at least a low impact on population growth. Thus, there maybe a good scope for sustainable extraction of G. lucida bark in these stages. The size-class 5-10 cm dbh proved by loop analysis to be the most important reproductive stage for population maintenance. However, individuals in this size-class are also exploited by forest gatherers, and increased exploitation pressure on trees in this size-class is likely to have a considerable impact on the population growth and to compromise the scope for sustainable exploitation of this resource. (C) 2002 Elsevier Science B.V All rights reserved.
Wegverlichting en natuur; IV effecten van wegverlichting op het ruimtelijk gedrag van zoogdieren
Molenaar, J.G. de; Henkens, R.J.H.G. ; Braak, C.J.F. ter; Duyne, C. van; Hoefsloot, G. ; Jonkers, D.A. - \ 2003
Delft [etc.] : Rijkswaterstaat DWW [etc.] (DWW-rapport nr. DWW-2003-012) - 72
belichting - wegen - zoogdieren - gedrag - nederland - kunstlicht - diergedrag - illumination - roads - mammals - behaviour - netherlands - artificial light - animal behaviour
Effecten van lichtvervuiling op fauna
Stadsnatuur en draagvlak
Timmermans, W. ; Jonkers, D.A. - \ 2002
In: Handboek ruimtelijke ordening en milieu; editie 2001-2002 / Roggema, R.E., Schreuders, A.J.M., Janssen, M.O., Hofstra, H., Vuijk, E.J., Jansen, C.W., Timmermans, W., Alphen aan den Rijn : Kluwer - ISBN 901407591X - p. 345 - 357.
Stromende wateren
Verdonschot, P.F.M. ; Nijboer, R.C. ; Higler, B. - \ 2002
In: Watertypegerichte normstelling voor nutriënten in oppervlaktewater / van Liere, E., Jonkers, D.A., Bilthoven : RIVM (RIVM rapport 703715005) - p. 57 - 67.
eutrofiëring - oppervlaktewater - waterkwaliteit - nederland - kwaliteitsnormen - nitraten - fosfaten - eutrophication - surface water - water quality - nitrates - phosphates - quality standards - netherlands
Kentallen zijn geëvalueerd, die aangeven bij welke waarde van het kental een verandering optreedt van de geëutrofieerde toestand van een watertype naar de heldere gewenste ecologische toestand. Bij het onderzoek is aangenomen dat nutrienten-reductie de enige sturende factor was. Voor fosfaten en nitraten is een norm vastgesteld voor: beken, sloten, meren, vennen; en tevens voor het IJsselmeer, Volkerak en de Rijn. Om benedenstroomse kwetsbare wateren te beschermen werden er tevens voor enige gevallen "afwentelingswaarden" berekend.
Sloten
Arts, G.H.P. ; Kolk, J.W.H. van der; Janse, J.H. ; Liere, L. van - \ 2002
In: Watertypegerichte normstelling voor nutriënten in oppervlaktewater / van Liere, E., Jonkers, D.A., Bilthoven : RIVM (RIVM rapport 703715005) - p. 47 - 56.
Vennen
Arts, G.H.P. ; Wortelboer, R. - \ 2002
In: Watertypegerichte normstelling voor nutriënten in oppervlaktewater / van Liere, E., Jonkers, D.A., Bilthoven : RIVM (RIVM rapport 703715005) - p. 39 - 47.
Fauna en terreinkenmerken van bos; een studie naar de relatie tussen terreinkenmerken en de geschiktheid van bos als habitat voor een aantal diersoorten
Jong, J.J. de; Apeldoorn, R.C. van; Bink, F.A. ; Jonkers, D.A. ; Mabelis, A.A. ; Molenaar, J.G. de; Sierdsema, H. ; Stumpel, A.H.P. ; Verboom, B. - \ 2002
Wageningen : Alterra (Alterra-rapport 565) - 66
fauna - wild - biodiversiteit - habitats - bossen - bosbedrijfsvoering - beoordeling - modellen - karakteristieken - bosecologie - nederland - wildlife - biodiversity - forests - forest management - assessment - models - characteristics - forest ecology - netherlands
In dit rapport wordt een methode beschreven waarmee de geschiktheid van het bos als habitat voor verschillende diersoorten kan worden bepaald op basis van de terreinkenmerken van het bos. De methode is gebaseerd op HSI-modellen. Er zijn 10 terreinkenmerken gebruikt om de habitatgeschiktheid te bepalen. Naast het onderdeel dat de habitatgeschiktheid van bos aangeeft, is er een onderdeel toegevoegd dat de bosbeheerder informatie geeft over de soorten die in het bos voor kunnen voorkomen op basis van de ligging en grootte van het bos. Voor zes diergroepen is de relatie tussen de terreinkenmerken en de habitatgeschiktheid weergegeven.
Reduced impact logging in Sarawak, Guyana and Cameroon: the reasons behind differences in approach
Jonkers, W.B.J. - \ 2002
In: Applying reduced impact logging to advance sustainable forest management / Enters, T., Durst, P.B., Applegate, G.B., Kho, P.C.S., Man, G., Bangkok : FAO - ISBN 9789747946239 - p. 199 - 207.
Effect of nutrient loading on surface waters in polder Bergambacht, the Netherlands
Liere, L. van; Janse, J. ; Jeuken, M. ; Puijenbroek, P. van; Schoumans, O.F. ; Hendriks, R.F.A. ; Roelsma, J. ; Jonkers, D. - \ 2002
In: Agricultural effects on ground and surface waters: research at the edge of science and society : proceedings of an international conference held at Wageningen, The Netherlands, in October 2000 / Steenvoorden, J., Claessen, F., - p. 213 - 218.
waterverontreiniging - nitraten - fosfaten - sloten - oppervlaktewater - modellen - krimpenerwaard - hydrologie - landbouw - milieu - nutriënten - waterbeheer - waterkwaliteit - Zuid-Holland - Bergambacht - ditches - surface water - water pollution - nitrates - phosphates - models
Unrevealing the complexity: an ITTO project has been investigating a strategy for sustainable forest management in Cameroon
Foahom, B. ; Jonkers, W.B.J. ; Schmidt, P. - \ 2001
Tropical forest update 11 (2001)4. - ISSN 1022-5439 - p. 7 - 9.
Broedvogels in 2000 op de Blaricummer- en Tafelbergheide
Jonkers, D.A. - \ 2001
Hilversum : Vogelwerkgroep Het Gooi en Omstreken - 30
broedvogels - nestelen - monitoring - inventarisaties - heidegebieden - habitats - noord-holland - het gooi - ornithologie - breeding birds - nesting - inventories - heathlands
Landscape survey, land evaluation and land use planning in south Cameroon
Gemerden, B.S. van; Hazeu, G.W. ; Hommel, P.W.F.M. ; Kekem, A.J. van; Ntonga, J.C. ; Waterloo, M.J. - \ 2001
In: Seminar proceedings "Sustainable management of African rain forest", held in Kribi, Cameroon, November 1999; Part II: symposium. Wageningen, Tropenbos, 2001 / Jonkers, W.B.J., Foahom, B., Schmidt, P., - p. 17 - 37.
bodem - landevaluatie - landinrichting - landschapsecologie - regenwoud - vegetatie - Afrika - Kameroen
De ecologische waarden van marinevliegkamp Valkenburg en omgeving; een evaluatie van bestaande gegevens en expert kennis
Oost, L. ; Molenaar, J.G. de; Jonkers, D.A. ; Henkens, R.J.H.G. - \ 2001
Wageningen : Alterra (Alterra-rapport 245) - 46
natuurwaarde - flora - fauna - inventarisaties - habitats - bodem - hydrologie - bufferzones - groene zones - landgebruiksplanning - groene hart - zuid-holland - ecologie - fysische geografie - natuurbehoud - vliegveld - vogels - Valkenburg - natural value - inventories - soil - hydrology - buffer zones - green belts - land use planning
In de Vijfde Nota Ruimtelijke Ordening staat de militaire luchthaven Valkenburg gepland voor ontwikkeling als stedelijk gebied. Binnen de betreffende gemeentes (Wassenaar, Katwijk, Valkenburg) zijn diverse natuurbeschermingsorganisaties voorstander voor het behoud van de luchthaven. Om vanuit de optiek van natuurwaarden een bijdrage aan de discussie en besluitvorming te leveren is Alterra gevraagd om de potentiële ecologische waarde van het marinevliegkamp te beschrijven
Boterdorpsche Plas nabij Rotterdam Airport?; aanvaringsrisico's tussen vogels en vliegtuigen in relatie tot aanleg en inrichting van de waterplas
Oost, L. ; Henkens, R.J.H.G. ; Jonkers, D.A. ; Molenaar, J.G. de - \ 2001
Wageningen : Alterra (Alterra-rapport 299) - 28
luchthavens - vogels - nadelige gevolgen - meren - habitats - rotterdam - ecologie - fauna - luchtvaart - ornithologie - ruimtelijke ordening - vliegveld - watervogels - Zuid-Holland - Bergschenhoek - airports - birds - adverse effects - lakes
Onderzoek naar de vogelaantrekkende werking van een mogelijke waterplas in een VINEX locatie te Bergschenhoek. Dit met het oog op de vliegveiligheid voor vliegtuigen die van en naar Rotterdam Airport vliegen. De opdracht van de gemeente Bergschenhoek was om na te gaan of de aanleg van de waterplas in de gedachte grootte en vorm een risico zou toevoegen op aanvaringen tussen vogels en vliegtuigen. Ook was de vraag of er buiten de gedachte grote waterplas andere varianten van een woonwijk met water mogelijk waren.
Natuur in de polder Schieveen; maken en delen
Bezemer, V. ; Jonkers, D.A. - \ 2001
Wageningen : Alterra (Alterra-rapport 263) - 48 p.
ecologie - natuurontwikkeling - ruimtelijke ordening - planologie - weidevogels - Zuid-Holland
Interacties tussen grote grazers en recreanten; een verkenning van risico's en oplossingen
Henkens, R.J.H.G. ; Berends, H.A. ; Jonkers, D.A. ; Molenaar, J.G. de - \ 2001
Wageningen : Alterra (Alterra-rapport 249) - 45
herbivoren - begrazing - natuurgebieden - gedrag - recreatie - risico - risicoschatting - grote grazers - nederland - openluchtrecreatie - nadelige gevolgen - herbivores - grazing - natural areas - behaviour - recreation - risk - risk assessment - large herbivores - netherlands - outdoor recreation - adverse effects
Zijn grote grazers gevaarlijk voor recreanten? Deze onderzoeksvraag werd gesteld naar aanleiding van een (gering) aantal serieuze incidenten. Voor het onderzoek werd de ter zake doende literatuur doorgespit en werd een adviescommissie bestaande uit wetenschappers, beheerders en beleidsmakers geraadpleegd. Het resultaat hiervan maakt duidelijk dat het risico momenteel niet onverantwoord groot is. De ontwikkelingen in het recreatie- en natuurbeleid zullen echter wel leiden tot een toename van het aantal interacties tussen grote grazers en recreanten en daarmee tot een toename van de kans op incidenten. Om de risico's ook in de toekomst acceptabel te houden is een intensievere voorlichting over het natuurlijke gedrag en de omgang met de dieren geen overbodige luxe. Dit geldt vooral voor recreanten maar ook voor menig beheerder. Daarnaast wordt gepleit voor de ingebruikneming van een incidentenregistratieformulier om zo mogelijk de ware toedracht van een incident te kunnen achterhalen en vastleggen. Ook toepassingsgericht onderzoek ten behoeve van de inrichting en het begrazingsbeheer van natuurterreinen behoort tot de oplossingsrichtingen.
Toename nijlganzen geen bedreiging voor ooievaars
Jonkers, D.A. - \ 2001
Vogelnieuws 14 (2001)1. - ISSN 1383-0643 - p. 15 - 15.
Integration of ecological knowledge in sustainable management of rain forests of south Cameroon, with special reference to Mychorrhiza associations
Onguene, N.A. ; Kuyper, T.W. ; Mbelli, H. ; Gemerden, B.S. van; Ntonga, J.C. - \ 2001
In: Sustainable management of African rain forests: proceedings of Kribi seminar, November 1999, part II / Jonkers, W.B.J., Foahom, B., Schmidt, P., Cameroon : The Tropenbos-Cameroon Programme - p. 50 - 58.
Landscape survey, land evaluation and land use planning in south Cameroon
Gemerden, B.S. van; Hazeu, G.W. ; Hommel, P.W.F.M. ; Kekem, A.J. van; Ntonga, J.C. ; Waterloo, M.J. - \ 2001
In: Sustainable management of African rain forests: proceedings of Kribi seminar, November 1999, part I: Workshop / Foahom, B., Jonkers, W.B.J., Nkwi, P.N., Cameroon : The Tropenbos-Cameroon Programme - p. 43 - 62.
The social and legal aspects of forest management
Nkwi, P.N. ; Benda-Beckmann, F. von; Berg, J. van den; Geschiere, P. ; Nkoumbele, F. ; Tiayon, F.F. - \ 2001
In: Seminar proceedings Sustainable management of African rain forests. Part II: Symposium : Sustainable management of African rain forests, Kribi, Cameroon, 1999 / W.B.J. Jonkers, B. Foahom, P. Schmidt (eds.). - Wageningen : The Tropenbos Foundation, 2001 - p. 132 - 149.
Logging Methods applied in Southern Cameroon and ways for their improvement
Leersum, G.J.R. van; Ngibaat, F. ; Laan, E.A. ; Jonkers, W.B.J. - \ 2001
In: Sustainable Management of African Rain Forest. Part I: Workshops : Sustainable Management of African Rain Forest. , 1999, Kribi - Kameroen / Foahom, B., Wageningen, Nederland : The Tropenbos Foundation - ISBN 9789051130478 - p. 203 - 209.
Sustainable Management of African Rain Forest Part I: Workshops
Foahom, B. ; Jonkers, W.B.J. ; Nkwi, P.N. ; Schmidt, P. ; Tchatat, M. - \ 2001
Wageningen : The Tropenbos Foundation - ISBN 9789051130478 - 274
regenbossen - bosbedrijfsvoering - duurzaamheid (sustainability) - landgebruiksplanning - plattelandsgemeenschappen - participatie - biodiversiteit - houtteelt - zwerflandbouw - houtkap - kameroen - rain forests - forest management - sustainability - land use planning - rural communities - participation - biodiversity - silviculture - shifting cultivation - logging - cameroon
An integrated approach towards participatory forest management : a proposal for the TCP site
Lescuyer, G. ; Fines, J.P. ; Reutelingsperger, E. - \ 2001
In: Sustainable management of African rain forest. Part II Symposium / W.B.J. Jonkers, B. Foahom & P. Schmidt. - Wageningen : Tropenbos Foundation, 2001. - ISBN 90-5113-051-1 - p. 5 - 16.
Liana diversity and the effects of climber cutting
Parren, M.P.E. ; Bongers, F.J.J.M. - \ 2001
In: In: Sustainable Management of African Rain Forest. Part II: Symposium / Jonkers, W.B.J., Foahom, B., Schmidt, P., Wageningen : The Tropenbos Foundation - ISBN 9789051130515 - p. 89 - 101.
Silvicultural monitoring in permanent sample plots in Ebom forest, Southern Cameroon
Bibani Mbarga, R. ; Jonkers, W.B.J. - \ 2001
In: In: Sustainable Management of African Rain Forest. Part II: Symposium / Jonkers, W.B.J., Foahom, B., Schmidt, P., Wageningen : The Tropenbos Foundation - ISBN 9789051130515 - p. 102 - 111.
Conclusions and Recommendations
Tchatat, M. ; Schmidt, P. ; Foahom, B. ; Jonkers, W.B.J. - \ 2001
In: Sustainable Management of African Rain Forest. Part II: Symposium / Jonkers, W.B.J., Foahom, B., Schmidt, P., Wageningen : The Tropenbos Foundation - ISBN 9789051130515 - p. 158 - 159.
Introduction to the Tropenbos-Cameroon Programme and its Master Management Plan
Jonkers, W.B.J. ; Fines, J.P. ; Tchatat, M. - \ 2001
In: Sustainable Management of African Rain Forest. Part II: Symposium / Jonkers, W.B.J., Foahom, B., Schmidt, P., Wageningen : The Tropenbos Foundation - ISBN 9789051130515 - p. 1 - 4.
Logging methods applied in South Cameroon and ways for their improvement
Leersum, G.J.R. van; Ngibaot, F. ; Laan, E.A. ; Jonkers, W.B.J. - \ 2001
In: Sustainable Management of African Rain Forest. Part II: Symposium / Jonkers, W.B.J., Foahom, B., Schmidt, P., Wageningen : The Tropenbos Foundation - ISBN 9789051130515 - p. 82 - 88.
Sustainable Management of African Rain Forest. Part II: Symposium
Jonkers, W.B.J. ; Foahom, B. ; Schmidt, P. - \ 2001
Wageningen : The Tropenbos Foundation - ISBN 9789051130515 - 159
regenbossen - bosbedrijfsvoering - duurzaamheid (sustainability) - landgebruiksplanning - plattelandsgemeenschappen - participatie - biodiversiteit - houtteelt - zwerflandbouw - houtkap - kameroen - rain forests - forest management - sustainability - land use planning - rural communities - participation - biodiversity - silviculture - shifting cultivation - logging - cameroon
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