Staff Publications

Staff Publications

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

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

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

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

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

    We have a manual that explains all the features 

    Records 1 - 20 / 227

    • help
    • print

      Print search results

    • export

      Export search results

    Check title to add to marked list
    Early-Warning Signals for Marine Anoxic Events
    Hennekam, Rick ; Bolt, Bregje van der; Nes, Egbert H. van; Lange, Gert J. de; Scheffer, Marten ; Reichart, Gert Jan - \ 2020
    Geophysical Research Letters 47 (2020)20. - ISSN 0094-8276
    anoxia - early-warning signals - Mediterranean Sea - sapropels - sedimentary trace metals - tipping points

    Predicting which marine systems are close to abrupt transitions into oxygen-deficient conditions (“anoxia”) is notoriously hard but important—as rising temperatures and coastal eutrophication drive many marine systems toward such tipping points. Rapid oxic-to-anoxic transitions occurred regularly within the eastern Mediterranean Sea on (multi)centennial time scales, and hence, its sedimentary archive allows exploring statistical methods that can indicate approaching tipping points. The here presented high-resolution reconstructions of past oxygen dynamics in the Mediterranean Sea reveal that early-warning signals in these deoxygenation time series occurred long before fast transitions to anoxia. These statistical indicators (i.e., rise in autocorrelation and variance) are hallmarks of so-called critical slowing down, signaling a steady loss of resilience of the oxygenated state as the system approaches a tipping point. Hence, even without precise knowledge of the mechanisms involved, early-warning signals for widespread anoxia in marine systems are recognizable using an appropriate statistical approach.

    Het Landelijk Waterkwaliteitsmodel : Uitbreiding van het Nationaal Water Model met waterkwaliteit ten behoeve van berekeningen voor nutriënten
    Bolt, F.J.E. van der; Kroon, T. ; Groenendijk, P. ; Renaud, L.V. ; Roovaart, J. van den; Janssen, C.M.C.M. ; Loos, S. ; Cleij, P. ; Linden, A. van den; Marsman, A. - \ 2020
    Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 3005) - 220
    De stuurgroep Nationaal Water Model heeft de opdracht gegeven een landelijk waterkwaliteitsmodel nutriënten te ontwikkelen. Dit Landelijk WaterKwaliteitsModel (LWKM) is gebaseerd op de recentste data, gebruikt de resultaten van het Landelijk hydrologisch Model en bouwt waar mogelijk voort op of maakt gebruik van onderdelen van eerdere modelinstrumenten als STONE en het Landelijk KRW-Verkenner Model (LKM). Dit rapport beschrijft de opzet, de realisatie, de gebruikte invoergegevens, de initialisatie, de kalibratie, de toetsing en resultaten van de eerste versie van het LWKM
    Times are changing : Implications of climate change for the occurrence and predictability of tipping points
    Bolt, Bregje van der - \ 2020
    Wageningen University. Promotor(en): M. Scheffer, co-promotor(en): E.H. van Nes. - Wageningen : Wageningen University - ISBN 9789463951807 - 146

    Complex systems in ecology and the climate can have tipping points. The term ‘tipping point’ is loosely defined as a threshold point in the conditions after which runaway change brings the system to a new stable state. Such a transition can have long-term dire consequences, and therefore it is of critical importance to understand why and when these transitions occur. Under the ongoing climate change, these critical transitions are projected to increase. However, little is understood about how relative timescales of the rate of environmental change and variability affect the occurrence and detectability of these critical transitions in nature and society. The aim of this thesis is to provide some insights in how differences in these timescales may affect critical transitions.

    This thesis starts with the analysis of bistability of marine anoxic events in the Mediterranean Sea. Reconstructed time series have been used to detect changes in resilience indicators prior to several abrupt shifts in the past climate. This is, however, only possible under a limited set of conditions. For the past marine anoxic events in the Mediterranean Sea, these conditions are met. Recent technological advances made it possible to construct high-resolution and (almost) evenly spaced time series of past widespread anoxic events in the Mediterranean Sea. In Chapter 2, we analysed whether past transitions in the Mediterranean Sea could have been predicted using the resilience indicators autocorrelation and variance. We show that the repeated shifts into marine anoxia in the Mediterranean Sea had the character of critical transitions, because there was a gradual increase in the temporal autocorrelation and variance in the deep cores (>1600 meter depth) before the onset of most events. Our results imply that future widespread anoxia in marine systems might be recognizable using an appropriate statistical approach and high-resolution records.

    These shifts to an anoxic state occurred relatively fast, but not all shifts to an alternative stable state unfold rapidly. Slowly responding systems show a gradual shift to the alternative state, once the tipping point has been passed. As the rate of the current environmental change is unprecedented, more system respond relatively slow to changes in the environment. The current resilience indicators are based on the theoretical finding that the system slows down close to the tipping point. But in these relatively slow systems, the recovery rates are always slow. Therefore, it is the question whether these resilience indicators flag that a relatively slow system is approaching a tipping point. In Chapter 3, we show that it is more difficult to quantify the resilience of a system that responds relatively slow. These results indicate that as the rates of environmental change keep increasing, it become more and more difficult to detect whether systems are approaching a tipping point. 

    Another risk under current rates of environmental change is that the rate of change in the conditions triggers a shift to an alternative stable state, whereas a change of the same magnitude but at slower rates would not. Only few studies describe this so-called ‘rate-tipping’ in ecological systems, but understanding rate-tipping is needed to understand and predict ecosystem response to the ongoing rapid environmental change. Therefore, we show in Chapter 4 that there can be rate-induced tipping for a range of initial conditions in a model of cyanobacteria with realistic parameter settings. A pulse in the environmental conditions, for example as a result of an extreme event, can cause a temporary collapse, depending on both the rate and the duration of the pulse. In addition, we showed that the type of environmental variability can influence the probability of inducing rate-tipping. These results imply that we need to incorporate critical rates of change in our ecosystems assessment and management.

    In addition to affecting the probability of inducing rate-tipping, environmental variability itself can bring a system past a tipping point. The variability is different in different parts of the climate, but because of climate change, the climatic variability is changing systematically in different parts of the world. Therefore, we analysed in Chapter 5 what the effect of changes in the memory of the climatic variability is on the chance of undergoing a critical transition. We show that chances of invoking such critical transitions are strongly affected by the climate memory as measured for instance by temporal autocorrelation in climatic variables. We illustrate the implications of this prediction with evidence from forests, corals reefs, poverty traps, violent conflict and ice-sheet instability. In all of these examples, the duration of anomalous dry or warm events increases the chance of invoking a critical transition. Our results imply that understanding the effects of altered climate variability requires research on climate memory.

    In the Afterthoughts I conclude that fast rates of environmental change and changes in environmental variability can affect the detectability and predictability of critical transitions. While the exact impacts of climate change are likely system-specific, interacting timescales make it difficult to untangle system dynamics from external forcing. The relations I describe throughout this thesis, however, are relative. This means that it is impossible to make general rules about whether resilience indicators can be observed, or if the conditions can be restored. Therefore, we should not give up on a priori detecting and reversing critical transitions driven by climate change.

    The opportunities of blockchain technology for crop insurance in Kenya
    Bolt, Jaclyn ; Berende, Michiel ; Sampao, Patrick - \ 2019
    Wageningen : Wageningen Environmental Research - 4 p.
    CCAFS
    Toll-Like Receptor-dependent immunomodulatory activity of Pycnogenol
    Verlaet, Annelies A.J. ; Bolt, Nieke van der; Meijer, Ben ; Breynaert, Annelies ; Naessens, Tania ; Konstanti, Prokopis ; Smidt, Hauke ; Hermans, Nina ; Savelkoul, Huub ; Teodorowicz, Gosia - \ 2019
    Wageningen University
    PRJEB29793 - ERP112142 - metagenome
    Background: Pycnogenol® (PYC), a patented herbal extract of French maritime pine bark, consists of a complex mixture of bioflavonoids. The main constituents of PYC are procyanidins; biopolymers consisting of units of catechin (CAT) and epicatechin. PYC is shown to exert immunomodulatory properties, nevertheless its underlying mechanisms are not yet fully elucidated. Methods: In this study, the effect of PYC and its constituent CAT on membrane Toll like receptor (TLR) activity was examined using stably transfected Human Embryonic Kidney cells. The Human monocytic leukaemia cell line THP-1 was used to examine the effect of PYC and CAT on pro-inflammatory cytokine release.Findings: We showed that non-metabolised PYC acts as agonist of TLR1/2, TLR2/6 and a partial agonist of TLR5, which resulted in the induction of pro-inflammatory cytokine secretion from THP-1 macrophages as well as activation of Nf-κB transcription factor. This effect was altered due to gastrointestinal metabolism, which revealed immuno-suppressive potential against TLR 1/2 and TLR 2/6 of the retentate fraction compared to the control sample. Moreover, the dialysed fraction did not show potential to induce pro-inflammatory cytokine secretion by THP-1 macrophages but the capacity to induce anti-inflammatory IL-10. Moreover, we showed that PYC on its own does not activate TLR4 but the formation of complexes with lipopolysaccharides (LPS) is required to stimulate the TLR4 receptor. We found that PYC and PYC-LPS complexes to the same extend dose-dependently increase pro-inflammatory cytokine levels (IL-8, IL-1β and TNF) and upregulate phosphorylation of the transcription factor NF-ĸB. No effects for CAT were observed on TLR activation and pro-inflammatory cytokine production levels. Conclusions: Our study stresses the importance of metabolism for biological activity of PYC compounds. Moreover our results suggest that bot non-metabolised as well as metabolised PYC acts via TLR 1/2 and TLR 2/6 next to TLR4.
    Landelijk WaterKwaliteitsModel-nutriënten (LWKM)
    Bolt, F.J.E. van der - \ 2019
    Participatieve monitoring in Lumbricus : Een brug tussen innovatie en implementatie
    Breman, B.C. ; Kuindersma, W. ; Meijerink, Sander ; Ellen, Gerald Jan ; Wassink, W. ; Brugmans, Bart ; Bolt, F.J.E. van der - \ 2019
    Water Governance (2019)1. - ISSN 2211-0224 - p. 46 - 49.
    Nederland staat voor een aantal grote uitdagingen op het gebied van het waterbeheer, dat heeft de zomer van 2018 nog maar eens extra duidelijk gemaakt. Omdat het klimaat verandert krijgen we vaker te maken met extreme neerslag en langdurige perioden van droogte. Dit heeft direct consequenties voor onder andere de waterkwaliteit en de waterkwantiteit. Op de hoger gelegen zandgronden in Nederland zijn deze consequenties zo mogelijk nog groter omdat hier de mogelijkheden om water tijdelijk te bergen of van elders aan te voeren vaak veel beperkter zijn.
    Financial resilience of Kenyan smallholders affected by climate change, and the potential for blockchain technology
    Bolt, J.S. - \ 2019
    Wageningen : CCAFS - 26 p.
    This study is part of the project ‘Incentives and innovative finance for scaling Climate Smart Agriculture (CSA) up and out’ which as part of the flagship ‘Climate-Smart Technologies and Practices’. Through case study research, the project aims to develop context-specific knowledge on the factors and conditions which constitute an effective technical and financial package to scale up and scale out CSA practices and businesses. The impact of these packages on the adoption of CSA and the resilience of farmers and Small to Medium Enterprises to climate change will be assessed by means of three case studies.
    The first case aimed at upscaling CSA with small scale food producers who were organised in village savings and loans in Tanzania. The second case study focused on climate smart villages using climate-smart financial diaries for scaling in Kenya. This third study focuses on the financial resilience of smallholder farmers in Kenya who are affected by climate change. We will use blockchain technology as a lens to discuss the potential impact provided through this innovative technology. In the next year we envisage to run a small pilot with blockchain technology in Kenya. Kenya is particularly interesting considering blockchain, as mobile payment systems are well and widely adopted. This enhances possibilities for linking blockchain technology.
    Climate risk assessment services for agri-food sector
    Groot, A. ; Bruin, K. de; Bolt, J. ; Verwey, P. ; Daniels, E. ; Hutjes, R. - \ 2019
    Wageningen : Wageningen Environmental Research (Wageningen Environmental Research report ) - 51
    Climate change and climate variability pose high risks to the agri-food business as it threatens ecosystems and impacts the natural capital on which companies depend. Agri-food companies have already suffered weather–related impacts in recent years, and most have seen an intensification of such impacts. Meanwhile, farming- and other communities on which the agri-food businesses depend for their supplies of agricultural commodities, raw materials and work force are also highly affected. Recognizing the problem, identifying climate related risks in the supply chain and responding with adaptation measures can help agri-food businesses to minimize their risks and strengthen resilience. Responding to the effects of climate change will also provide opportunities for innovative climate resilient products and services and open up new markets. For example, insurance agencies are already developing innovative climate-insurance products for communities at increased risk of weather-related natural disasters. New water-use efficient irrigation technologies are being developed and deployed to address increased water stress. This report describes a set of services WEnR can deliver to assist stakeholders in an agri-food chain to assess climatic risks and potential adaptation strategies to mitigate these risks. These services include development of regionalised / bias corrected climate change projections, climate change impact assessments, assessment of climate /weather related risks, assessment of potential business cases mitigating climatic risks. The services i.e. climate risk assessment described in this report are current being delivered in the Climate Smart Agriculture - East Africa project, but do have wider application opportunities as being described in the last chapter. Some of the climate risk activities are being carried out by WEnR, others by project partners.---Dit rapport beschrijft een aanpak en services die geleverd kunnen worden door medewerkers van Wageningen Environmental Research om partijen binnen agrifood ketens te helpen inzicht te krijgen in risico’s die hun business loopt als gevolg van klimaatverandering en hoe men deze risico’s zou kunnen verminderen en/of vermijden. De diensten die WEnR kan leveren omvatten: de ontwikkeling en visualisatie van klimaatprojecties voor specifieke regio’s, het bepalen van effecten van klimaatverandering op water beschikbaarheid en gewasproductie en het analyseren van risico’s voor ketenpartijen en hun business als gevolg van klimaatverandering. Ook kan WEnR helpen bij het identificeren en analyseren van businessideeën die klimaatrisico’s kunnen verminderen, maar die ook nieuwe kansen kunnen bieden. De ‘climate risk assessment’ aanpak die in dit rapport wordt beschreven wordt op dit moment toegepast in het Climate Smart Africa – East Africa project waarin WEnR participeert. In dit project worden sommige zogenaamde ‘climate risk assesssment activiteiten’ uitgevoerd door WEnR, anderen door projectpartners.
    Toll-Like Receptor-Dependent Immunomodulatory Activity of Pycnogenol®
    Verlaet, Annelies ; Bolt, Nieke van der; Meijer, Ben ; Breynaert, Annelies ; Naessens, Tania ; Konstanti, Prokopis ; Smidt, Hauke ; Hermans, Nina ; Savelkoul, Huub F.J. ; Teodorowicz, Malgorzata - \ 2019
    Nutrients 11 (2019)2. - ISSN 2072-6643
    catechin - gastrointestinal metabolism - immunomodulation - metabolites - partial agonist - Pycnogenol® - Toll-like receptors

    BACKGROUND: Pycnogenol® (PYC), an extract of French maritime pine bark, is widely used as a dietary supplement. PYC has been shown to exert anti-inflammatory actions via inhibiting the Toll-like receptor 4 (TLR4) pathway. However, the role of the other receptors from the TLR family in the immunomodulatory activity of PYC has not been described so far. AIM: The aim of this study was to investigate whether PYC might exert its immunomodulatory properties through cell membrane TLRs (TLR1/2, TLR5, and TLR2/6) other than TLR4. Moreover, the effect of gastrointestinal metabolism on the immunomodulatory effects of PYC was investigated. FINDINGS: We showed that intact non-metabolized PYC dose-dependently acts as an agonist of TLR1/2 and TLR2/6 and as a partial agonist of TLR5. PYC on its own does not agonize or antagonize TLR4. However, after the formation of complexes with lipopolysaccharides (LPS), it is a potent activator of TLR4 signaling. Gastrointestinal metabolism of PYC revealed the immunosuppressive potential of the retentate fraction against TLR1/2 and TLR2/6 when compared to the control fraction containing microbiota and enzymes only. The dialyzed fraction containing PYC metabolites revealed the capacity to induce anti-inflammatory IL-10 secretion. Finally, microbially metabolized PYC affected the colonic microbiota composition during in vitro gastrointestinal digestion. CONCLUSIONS: This study showed that gastrointestinal metabolism of PYC reveals its biological activity as a potential inhibitor of TLRs signaling. The results suggest that metabolized PYC acts as a partial agonist of TLR1/2 and TLR2/6 in the presence of the microbiota-derived TLR agonists (retentate fraction) and that it possesses anti-inflammatory potential reflected by the induction of IL-10 from THP-1 macrophages (dialysate fraction).

    Business models of SMEs as a mechanism for scaling Climate Smart Technologies: The case of Punjab, India
    Groot, A.M.E. ; Bolt, J.S. ; Jat, H.S. ; Jat, M.L. ; Kumar, M. ; Blok, Vincent ; Agarwal, T. - \ 2019
    Journal of Cleaner Production 210 (2019). - ISSN 0959-6526 - p. 1109 - 1119.
    Climate smart agriculture - smes - Business models
    Many Climate Smart Agricultural (CSA) technologies fail to achieve their full potential impact due to low levels of adoption by smallholder farmers and difficulties in scaling CSA. This paper presents how small and medium-sized enterprises (SMEs) can act as change agents for the uptake of CSA technologies where their business models may be seen as adoption and scaling mechanisms. Drawing upon our fieldwork in Punjab (India) during which over 100 respondents have been interviewed, critical issues and enabling factors for the business model of two types of SMEs, i.e. farmer cooperatives and individual service providers of climate smart technologies have been identified. Enabling factors supporting adoption are driven by scientific and practical evidence of CSA technologies, good partnership between SMEs and research institutes, good customer relationships and effective channels through farmers’ field trials. Critical issues consist of distortive government subsidies on energy and the lack of market intelligence affecting the profitability of the business model. Scaling is enhanced through market intelligence and a favouring regulatory landscape. However, difficult socio-economic circumstances and distortive government subsidies limit the role of SMEs business model as mechanism for scaling
    Climate smart agriculture as an investable business model for financial institutions? : workshop within the SDG Conference 'Towards Zero Hunger: Partnerships for Impact', 30-31 August 2018, Wageningen, The Netherlands
    Wattel, C.J. ; Asseldonk, M.A.P.M. van; Bolt, J.S. ; Ooms, Sonja ; Mensink, Mariel ; Ceccarelli, T. ; Louw, Corné de; Splinter, G.M. - \ 2018
    Wageningen University & Research (Workshop report Climate-Smart Agriculture as an investable business model ) - 33 p.
    Review of the methodologies used to derive groundwater characteristics for a specific area in The Netherlands
    Ritzema, H.P. ; Heuvelink, G.B.M. ; Heinen, M. ; Bogaart, P.W. ; Bolt, F.J.E. van der; Hack-ten Broeke, M.J.D. ; Hoogland, T. ; Knotters, M. ; Massop, H.T.L. ; Vroon, H.R.J. ; Bosch, H. van den - \ 2018
    Geoderma Regional 14 (2018). - ISSN 2352-0094
    Hydropedology - In-situ measurements - Phreatic groundwater table - Spatial interpolation - Temporal aggregation

    In this paper, we analyze the methods that are used in The Netherlands to upscale in-situ groundwater measurements in time and in space, and how the selected combinations of upscaling methods affect the resulting groundwater characteristic. In The Netherlands, a three-step approach is used to obtain groundwater characteristics for a specific area: (1) in-situ monitoring of the water table depth; (2) temporal upscaling; and (3) spatial interpolation and aggregation. The three-step approach is, however, not standardized, but a combination of the following methods is used: (i) four methods to measure/monitor the phreatic water table; (ii) four methods for temporal aggregation; and (iii) four methods for spatial interpolation and/or aggregation. Over the past sixty years, several combinations of these methods have been used. Our review shows that the use of these different combinations in the approach to measure and interpret water table depths has resulted in significant systematic differences in the corresponding groundwater characteristics and that there are many sources of potential error. Error in the in-situ measurement of the water table depth can be as high as 1 m. Errors in the temporal aggregation are in the range of 10 to 20 cm and for the spatial interpolation between 20 and 50 cm. We show that there has been no systematic assessment of how these errors influence the resulting groundwater characterization. Thus, we cannot answer the question of whether drought stress in The Netherlands is under- or overestimated. Based on these findings we give recommendations for a systematic approach to groundwater characterizations studies that can minimize the impact of errors.

    Demand and experiences with financial products and services in climate smart villages
    Groot, A. ; Steenis, O. van; Jans, W. ; Bolt, J.S. ; Recha, J. ; Kimeli, P. ; Radeny, M. ; Muhimbo, O. ; Osmond, E. ; Kitondo, D. ; Martinez Baron, D. ; Santacruz, V. ; Khatri-Chhetri, A. ; Jat, M. ; Aggrarwal, P. ; Chanana, N. ; Pant, A. ; Phuong Thanh, P. ; Dinh Tien, N. ; Korner, J. ; Sebastiaan, L. ; Ouedraogo, M. ; Zougmore, R. ; Nyour, B. ; Ibrahim, H. ; Maalong-Gae, P. ; Bawa, T. ; Diop, M. ; Long, T. ; Asseldonk, M. van; Wattel, C.J. - \ 2018
    Wageningen : Wageningen Environmental Research - 97
    Climate reddening increases the chance of critical transitions
    Bolt, Bregje van der; Nes, Egbert H. van; Bathiany, Sebastian ; Vollebregt, Marlies E. ; Scheffer, Marten - \ 2018
    Nature Climate Change 8 (2018)6. - ISSN 1758-678X - p. 478 - 484.
    Climate change research often focuses on trends in the mean and variance. However, analyses of palaeoclimatic and contemporary dynamics reveal that climate memory - as measured for instance by temporal autocorrelation - may also change substantially over time. Here, we show that elevated temporal autocorrelation in climatic variables should be expected to increase the chance of critical transitions in climate-sensitive systems with tipping points. We demonstrate that this prediction is consistent with evidence from forests, coral reefs, poverty traps, violent conflict and ice sheet instability. In each example, the duration of anomalous dry or warm events elevates chances of invoking a critical transition. Understanding the effects of climate variability thus requires research not only on variance, but also on climate memory.
    Modulating the gut microbiota by dietary guar gum protects against diet-induced obesity but promotes non-alcoholic steatohepatitis in mice
    Janssen, Aafke ; Houben, Tom ; Katiraei, Saeed ; Boutens, Lily ; Bolt, Nieke van der; Wang, Zeneng ; Brown, Jonathan M. ; Hazen, Stanley L. ; Shiri-Sverdlov, Ronit ; Willems van Dijk, Ko ; Vervoort, Jacques ; Stienstra, Rinke ; Hooiveld, Guido ; Kersten, Sander - \ 2017
    Wageningen University
    Mus musculus - GSE76087 - Mus musculus - GSE76087 - PRJNA306172
    Non-alcoholic fatty liver disease (NAFLD) is rapidly becoming the most common liver disease worldwide, yet the pathogenesis of NAFLD is only partially understood. Here, we investigated the role of the gut bacteria in NAFLD by stimulating the gut bacteria via feeding mice the fermentable dietary fiber guar gum and suppressing the gut bacteria via chronic oral administration of antibiotics. Guar gum feeding profoundly altered the gut microbiota composition, in parallel with reduced diet-induced obesity and improved glucose tolerance. Strikingly, despite reducing adipose tissue mass and inflammation, guar gum enhanced hepatic inflammation and fibrosis, concurrent with markedly elevated plasma and hepatic bile acid levels. Consistent with a role of elevated bile acids in the liver phenotype, treatment of mice with taurocholic acid stimulated hepatic inflammation and fibrosis. In contrast to guar gum, chronic oral administration of antibiotics effectively suppressed the gut bacteria, decreased portal secondary bile acid levels, and attenuated hepatic inflammation and fibrosis. Neither guar gum or antibiotics influenced plasma lipopolysaccharide levels. In conclusion, our data indicate a causal link between changes in gut microbiota and hepatic inflammation and fibrosis in a mouse model of NAFLD, possibly via alterations in bile acids.
    Modulation of the gut microbiota impacts nonalcoholic fatty liver disease: a potential role for bile acids
    Janssen, Aafke W.F. ; Houben, Tom ; Katiraei, Saeed ; Dijk, Wieneke ; Boutens, Lily ; Bolt, Nieke van der; Wang, Zeneng ; Brown, J.M. ; Hazen, Stanley L. ; Mandard, Stéphane ; Shiri-Sverdlov, Ronit ; Kuipers, Folkert ; Willems van Dijk, Ko ; Vervoort, Jacques ; Stienstra, Rinke ; Hooiveld, Guido J.E.J. ; Kersten, Sander - \ 2017
    Journal of Lipid Research 58 (2017)7. - ISSN 0022-2275 - p. 1399 - 1416.
    Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide, yet the pathogenesis of NAFLD is only partially understood. Here, we investigated the role of the gut bacteria in NAFLD by stimulating the gut bacteria via feeding mice the fermentable dietary fiber, guar gum (GG), and suppressing the gut bacteria via chronic oral administration of antibiotics. GG feeding profoundly altered the gut microbiota composition, in parallel with reduced diet-induced obesity and improved glucose tolerance. Strikingly, despite reducing adipose tissue mass and inflammation, GG enhanced hepatic inflammation and fibrosis, concurrent with markedly elevated plasma and hepatic bile acid levels. Consistent with a role of elevated bile acids in the liver phenotype, treatment of mice with taurocholic acid stimulated hepatic inflammation and fibrosis. In contrast to GG, chronic oral administration of antibiotics effectively suppressed the gut bacteria, decreased portal secondary bile acid levels, and attenuated hepatic inflammation and fibrosis. Neither GG nor antibiotics influenced plasma lipopolysaccharide levels. In conclusion, our data indicate a causal link between changes in gut microbiota and hepatic inflammation and fibrosis in a mouse model of NAFLD, possibly via alterations in bile acids.
    Bodemverdichting maakt veel los
    Bolt, F.J.E. van der; Hendriks, R.F.A. ; Sietzema, Auke ; Gerner, L. ; Akker, J.J.H. van den; Groenendijk, P. - \ 2016
    De gevolgen van bodemverdichting verkend
    Bodemverdichting in Vlaanderen : Gevolgen van bodemverdichting op het watertransport door een bodem
    Bolt, Frank van der; Cornelis, Wim ; Pue, Jan de; Hendriks, Rob ; Akker, Jan van den; Massop, Harry ; Joris, Ingeborg ; Dams, Jef ; Vos, Johan - \ 2016
    Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2725) - 143
    De gevolgen van bodemverdichting op het watertransport door een bodem zijn verkend. Een bodemfysische database is gecreëerd door naast historische metingen nieuwe metingen te verzamelen op verdichte percelen. Dat is gebeurd door op 26 percelen op 2 plekken op 3 diepten ongestoorde monsters te nemen en de bodemfysische eigenschappen te bepalen. Op 6 percelen zijn continue hydrologische metingen verricht van bodemvocht op 3 diepten en grondwaterstanden. De laatste metingen zijn gebruikt om te toetsen of het model SWAP met de gemeten bodemfysische eigenschappen in staat is het watertransport in het perceel te beschrijven. Met SWAP zijn voor 5 Vlaamse stroomgebiedjes de effecten van bodemverdichting verkend voor klimaatscenario’s door de verdichte en niet-verdichte toestand te vergelijken. De met de pedotransferfuncties en nieuwe data berekende effecten van verdere verdichting op de waterhuishouding blijken globaal gezien beperkt te zijn. Dit neemt niet weg dat de lokale effecten mogelijk aanzienlijk kunnen zijn, gelet op de grote variatie in bodemverdichting die binnen de percelen werd opgemeten. De verschillen tussen de verdichte en niet-verdichte situatie in stroomgebieden zijn beperkt. Klimaatscenario’s leiden op verdichte bodems tot meer oppervlakkige afstroming en meer droogtegevoeligheid
    What Do You Mean, 'Tipping Point'?
    Nes, E.H. van; Shojaei Arani, M. ; Staal, A. ; Bolt, B. van der; Flores, Bernardo M. ; Bathiany, S. ; Scheffer, M. - \ 2016
    Trends in Ecology and Evolution 31 (2016)12. - ISSN 0169-5347 - p. 902 - 904.
    Over the past 10 years the use of the term ‘tipping point’ in the scientific literature has exploded. It was originally used loosely as a metaphor for the phenomenon that, beyond a certain threshold, runaway change propels a system to a new state. Although several specific mathematical definitions have since been proposed, we argue that these are too narrow and that it is better to retain the original definition.
    Check title to add to marked list
    << previous | next >>

    Show 20 50 100 records per page

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