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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    Microtechnological Tools to Achieve Sustainable Food Processes, Products, and Ingredients
    Schroën, Karin ; Ruiter, Jolet de; Berton-Carabin, Claire C. - \ 2020
    Food Engineering Reviews 12 (2020). - ISSN 1866-7910 - p. 101 - 120.
    Emulsification - Filtration - Functionality testing - Ingredient fractionation - Microfluidics - Microtechnology - Organs on chip - Protein transition - Sensors - Sustainable food design

    One of the major challenges we face as humankind is supplying a growing world population with sufficient and healthy foods. Although from a worldwide perspective sufficient food is produced, locally, the situation can be dire. Furthermore, the production needs to be increased in a sustainable manner for future generations, which also implies prevention of food waste, and making better use of the available resources. How to contribute to this as food technologists is an ultimate question, especially since the tools that can investigate processes at relevant time scales, and dimensions, are lacking. Here we propose the use of microtechnology and show examples of how this has led to new insights in the fields of ingredient isolation (filtration), and emulsion/foam formation, which will ultimately lead to better-defined products. Furthermore, microfluidic tools have been applied for testing ingredient functionality, and for this, various examples are discussed that will expectedly contribute to making better use of more sustainably sourced starting materials (e.g., novel protein sources). This review will wrap up with a section in which we discuss future developments. We expect that it will be possible to link food properties to the effects that foods create in vivo. We thus expand the scope of this review that is technical in nature, toward physiological functionality, and ultimately to rational food design that is targeted to improve human health.

    'Betonnen' bovenlaag vraagt veel dieselolie
    Balen, Derk van; Ruiter, Harry de - \ 2020
    Efficacy and Safety of Peppermint Oil in a Randomized, Double-Blind Trial of Patients With Irritable Bowel Syndrome
    Weerts, Zsa Zsa R.M. ; Masclee, Ad A.M. ; Witteman, Ben J.M. ; Clemens, Cees H.M. ; Winkens, Bjorn ; Brouwers, Jacobus R.B.J. ; Frijlink, Henderik W. ; Muris, Jean W.M. ; Wit, Niek J. De; Essers, Brigitte A.B. ; Tack, Jan ; Snijkers, Johanna T.W. ; Bours, Andrea M.H. ; Ruiter-van der Ploeg, Annieke S. de; Jonkers, Daisy M.A.E. ; Keszthelyi, Daniel - \ 2020
    Gastroenterology 158 (2020)1. - ISSN 0016-5085 - p. 123 - 136.
    Functional Gastrointestinal Disorder - PERSUADE Study - RCT - Treatment

    Background & Aims: Peppermint oil is frequently used to treat irritable bowel syndrome (IBS), despite a lack of evidence for efficacy from high-quality controlled trials. We studied the efficacy and safety of small-intestinal–release peppermint oil in patients with IBS and explored the effects of targeted ileocolonic-release peppermint oil. Methods: We performed a double-blind trial of 190 patients with IBS (according to Rome IV criteria) at 4 hospitals in The Netherlands from August 2016 through March 2018; 189 patients were included in the intent-to-treat analysis (mean age, 34.0 years; 77.8% female; 57.7% in primary care), and 178 completed the study. Patients were randomly assigned to groups given 182 mg small-intestinal–release peppermint oil, 182 mg ileocolonic-release peppermint oil, or placebo for 8 weeks. The primary endpoint was abdominal pain response, as defined by the US Food and Drug Administration: at least a 30% decrease in the weekly average of worst daily abdominal pain compared with baseline in at least 4 weeks. The co-primary endpoint was overall relief of IBS symptoms, as defined by the European Medicines Agency. Secondary endpoints included abdominal pain, discomfort, symptom severity, and adverse events. Results: Abdominal pain response did not differ significantly between the peppermint oil and placebo groups: 29 of 62 patients in the small-intestinal–release peppermint oil group had a response (46.8%, P =. 170 vs placebo), 26 of 63 patients in the ileocolonic-release peppermint oil group had a response (41.3%, P =. 385 vs placebo), and 22 of 64 patients in the placebo group had a response (34.4%). We did not find differences among the groups in overall relief (9.7%, P =. 317 and 1.6%, P =. 351 vs 4.7% for placebo). The small intestinal peppermint oil did, however, produce greater improvements than placebo in secondary outcomes of abdominal pain (P =. 016), discomfort (P =. 020), and IBS severity (P =. 020). Adverse events, although mild, were more common in both peppermint oil groups (P <. 005). Conclusions: In a randomized trial of patients with IBS, we found that neither small-intestinal–release nor ileocolonic-release peppermint oil (8 weeks) produced statistically significant reductions in abdominal pain response or overall symptom relief, when using US Food and Drug Administration/European Medicines Agency recommended endpoints. The small-intestinal–release peppermint oil did, however, significantly reduce abdominal pain, discomfort, and IBS severity. These findings do not support further development of ileocolonic-release peppermint oil for treatment of IBS., Number: NCT02716285.

    Insights obtained by microtechnological observations as a basis for sustainable food processes design
    Ruiter, Jolet de - \ 2019
    Researchers build a biomimetic 'soft cannon' to understand how fungal spores are dispersed
    Ruiter, Jolet de - \ 2019
    Fungal artillery of zombie flies: infectious spore dispersal using a soft water cannon
    Ruiter, Jolet de; Arnbjerg-Nielsen, Sif Fink ; Herren, Pascal ; Høier, Freja ; Fine Licht, Henrik H. De; Jensen, Kaare H. - \ 2019
    Journal of the Royal Society, Interface 16 (2019)159. - ISSN 1742-5689 - 10 p.
    biomimetic soft cannon - dispersal range - Entomophthora muscae - force-balance model - fungal spore ejection - high-speed videography

    Dead sporulating female fly cadavers infected by the house fly-pathogenic fungus Entomophthora muscae are attractive to healthy male flies, which by their physical inspection may mechanically trigger spore release and by their movement create whirlwind airflows that covers them in infectious conidia. The fungal artillery of E. muscae protrudes outward from the fly cadaver, and consists of a plethora of micrometric stalks that each uses a liquid-based turgor pressure build-up to eject a jet of protoplasm and the initially attached spore. The biophysical processes that regulate the release and range of spores, however, are unknown. To study the physics of ejection, we design a biomimetic 'soft cannon' that consists of a millimetric elastomeric barrel filled with fluid and plugged with a projectile. We precisely control the maximum pressure leading up to the ejection, and study the cannon efficiency as a function of its geometry and wall elasticity. In particular, we predict that ejection velocity decreases with spore size. The calculated flight trajectories under aerodynamic drag predict that the minimum spore size required to traverse a quiescent layer of a few millimetres around the fly cadaver is approximately 10 µm. This corroborates with the natural size of E. muscae conidia (approx. 27 µm) being large enough to traverse the boundary layer but small enough (less than 40 µm) to be lifted by air currents. Based on this understanding, we show how the fungal spores are able to reach a new host.

    Application of microfluidics in the production and analysis of food foams
    Deng, Boxin ; Ruiter, Jolet De; Schroën, Karin - \ 2019
    Foods — Open Access Food Science Journal 8 (2019)10. - ISSN 2304-8158
    Coalescence - Dynamic surface tension - Emulsions - Foams - Microfluidics - Monodispersity - Up-scaling

    Emulsifiers play a key role in the stabilization of foam bubbles. In food foams, biopolymers such as proteins are contributing to long-term stability through several effects such as increasing bulk viscosity and the formation of viscoelastic interfaces. Recent studies have identified promising new stabilizers for (food) foams and emulsions, for instance biological particles derived from water-soluble or water-insoluble proteins, (modified) starch as well as chitin. Microfluidic platforms could provide a valuable tool to study foam formation on the single-bubble level, yielding mechanistic insights into the formation and stabilization (as well as destabilization) of foams stabilized by these new stabilizers. Yet, the recent developments in microfluidic technology have mainly focused on emulsions rather than foams. Microfluidic devices have been up-scaled (to some extent) for large-scale emulsion production, and also designed as investigative tools to monitor interfaces at the (sub)millisecond time scale. In this review, we summarize the current state of the art in droplet microfluidics (and, where available, bubble microfluidics), and provide a perspective on the applications for (food) foams. Microfluidic investigations into foam formation and stability are expected to aid in optimization of stabilizer selection and production conditions for food foams, as well as provide a platform for (large-scale) production of monodisperse foams.

    Diet-independent correlations between bacteria and dysfunction of gut, adipose tissue, and liver : A comprehensive microbiota analysis in feces and mucosa of the ileum and colon in obese mice with NAFLD
    Gart, Eveline ; Lima, Everton Souto ; Schuren, Frank ; Ruiter, Christa G.F. de; Attema, Joline ; Verschuren, Lars ; Keijer, Jaap ; Salic, Kanita ; Morrison, Martine C. ; Kleemann, Robert - \ 2019
    International Journal of Molecular Sciences 20 (2019)1. - ISSN 1661-6596
    Adipose tissue inflammation - Gut permeability - Liver - Non-alcoholic fatty liver disease - Obesity - Short-chain fatty acids

    Development of non-alcoholic fatty liver disease (NAFLD) is linked to obesity, adipose tissue inflammation, and gut dysfunction, all of which depend on diet. So far, studies have mainly focused on diet-related fecal microbiota changes, but other compartments may be more informative on host health. We present a first systematic analysis of microbiota changes in the ileum and colon using multiple diets and investigating both fecal and mucosal samples. Ldlr−/−.Leiden mice received one of three different energy-dense (ED)-diets (n = 15/group) for 15 weeks. All of the ED diets induced obesity and metabolic risk factors, altered short-chain fatty acids (SCFA), and increased gut permeability and NAFLD to various extents. ED diets reduced the diversity of high-abundant bacteria and increased the diversity of low-abundant bacteria in all of the gut compartments. The ED groups showed highly variable, partially overlapping microbiota compositions that differed significantly from chow. Correlation analyses demonstrated that (1) specific groups of bacteria correlate with metabolic risk factors, organ dysfunction, and NAFLD endpoints, (2) colon mucosa had greater predictive value than other compartments, (3) correlating bacteria differed per compartment, and (4) some bacteria correlated with plasma SCFA levels. In conclusion, this comprehensive microbiota analysis demonstrates correlations between the microbiota and dysfunctions of gut, adipose tissue, and liver, independent of a specific disease-inducing diet.

    Diet-independent correlations between NAFLD development and gut microbiota in mucosal and luminal compartments of the ilium and colon in LDL-/-Leiden
    Gart, E. ; Lima, Everton Souto ; Ruiter, Christa G.F. de; Attema, Joline ; Verschuren, Lars ; Caspers, Martien ; Schuren, Frank ; Kleemann, Robert ; Morrison, Martine C. - \ 2018
    Energy Flux : The Link between Multitrophic Biodiversity and Ecosystem Functioning
    Barnes, Andrew D. ; Jochum, Malte ; Lefcheck, Jonathan S. ; Eisenhauer, Nico ; Scherber, Christoph ; O'Connor, Mary I. ; Ruiter, Peter de; Brose, Ulrich - \ 2018
    Trends in Ecology and Evolution 33 (2018)3. - ISSN 0169-5347 - p. 186 - 197.
    ecological stoichiometry - ecosystem multifunctionality - food web - interaction network - metabolic theory - trophic cascade

    Relating biodiversity to ecosystem functioning in natural communities has become a paramount challenge as links between trophic complexity and multiple ecosystem functions become increasingly apparent. Yet, there is still no generalised approach to address such complexity in biodiversity–ecosystem functioning (BEF) studies. Energy flux dynamics in ecological networks provide the theoretical underpinning of multitrophic BEF relationships. Accordingly, we propose the quantification of energy fluxes in food webs as a powerful, universal tool for understanding ecosystem functioning in multitrophic systems spanning different ecological scales. Although the concept of energy flux in food webs is not novel, its application to BEF research remains virtually untapped, providing a framework to foster new discoveries into the determinants of ecosystem functioning in complex systems.

    CCDC 1858109: Experimental Crystal Structure Determination
    Keisar, Hodaya ; Ruiter, Graham de; Velders, A.H. ; Milko, Petr ; Gulino, Antonino ; Evmenenko, Guennadi ; Shimon, Linda J.W. ; Diskin-Posner, Yael ; Lahav, Michal ; Boom, Milko E. van der - \ 2018
    Weizmann Institute of Science
    PIHQEF : fac-tris{4-methyl-4'-[2-(pyridin-4-yl)ethenyl]-2,2'-bipyridine}-osmium bis(hexafluorophosphate) benzene toluene unknown solvate
    CCDC 1858110: Experimental Crystal Structure Determination
    Keisar, Hodaya ; Ruiter, Graham de; Velders, A.H. ; Milko, Petr ; Gulino, Antonino ; Evmenenko, Guennadi ; Shimon, Linda J.W. ; Diskin-Posner, Yael ; Lahav, Michal ; Boom, Milko E. van der - \ 2018
    Weizmann Institute of Science
    PIHQIJ : mer-tris{4-methyl-4'-[2-(pyridin-4-yl)ethenyl]-2,2'-bipyridine}-osmium bis(hexafluorophosphate) unknown solvate
    CCDC 1858108: Experimental Crystal Structure Determination
    Keisar, Hodaya ; Ruiter, Graham de; Velders, A.H. ; Milko, Petr ; Gulino, Antonino ; Evmenenko, Guennadi ; Shimon, Linda J.W. ; Lahav, Michal ; Boom, Milko E. van der - \ 2018
    Weizmann Institute of Science
    PIHQAB : tris{4-methyl-4'-[2-(pyridin-4-yl)ethenyl]-2,2'-bipyridine}-ruthenium bis(hexafluorophosphate) unknown solvate
    Modulation of litter decomposition by the soil microbial food web under influence of land use change
    Heijboer, Amber ; Ruiter, Peter C. de; Bodelier, Paul L.E. ; Kowalchuk, George A. - \ 2018
    Frontiers in Microbiology 9 (2018)NOV. - ISSN 1664-302X
    Agricultural abandonment - Carbon cycle - Decomposition - PLFA-SIP - Soil food web - Soil microbial community

    Soil microbial communities modulate soil organic matter (SOM) dynamics by catalyzing litter decomposition. However, our understanding of how litter-derived carbon (C) flows through the microbial portion of the soil food web is far from comprehensive. This information is necessary to facilitate reliable predictions of soil C cycling and sequestration in response to a changing environment such as land use change in the form of agricultural abandonment. To examine the flow of litter-derived C through the soil microbial food web and it’s response to land use change, we carried out an incubation experiment with soils from six fields; three recently abandoned and three long term abandoned fields. In these soils, the fate of 13C-labeled plant litter was followed by analyzing phospholipid fatty acids (PLFA) over a period of 56 days. The litter-amended soils were sampled over time to measure 13CO2 and mineral N dynamics. Microbial 13C-incorporation patterns revealed a clear succession of microbial groups during litter decomposition. Fungi were first to incorporate 13C-label, followed by G− bacteria, G+ bacteria, actinomycetes and micro-fauna. The order in which various microbial groups responded to litter decomposition was similar across all the fields examined, with no clear distinction between recent and long-term abandoned soils. Although the microbial biomass was initially higher in long-term abandoned soils, the net amount of 13C-labeled litter that was incorporated by the soil microbial community was ultimately comparable between recent and long-term abandoned fields. In relative terms, this means there was a higher efficiency of litter-derived 13C-incorporation in recent abandoned soil microbial communities compared to long-term abandoned soils, most likely due to a net shift from SOM-derived C toward root-derived C input in the soil microbial food web following land-abandonment.

    Soil food web assembly and vegetation development in a glacial chronosequence in Iceland
    Leeuwen, J.P. van; Lair, G.J. ; Gísladóttir, G. ; Sandén, T. ; Bloem, J. ; Hemerik, L. ; Ruiter, P.C. de - \ 2018
    Pedobiologia 70 (2018). - ISSN 0031-4056 - p. 12 - 21.
    Ecosystem functioning - Glacial succession - Iceland - Soil food web structure - Vegetation development

    Worldwide human activities threaten soil quality in terms of the soil's ability to deliver ecosystem services. This ongoing process of land degradation asks for effective strategies of soil protection. In this context, it is important to understand processes that build up and regenerate soil. The present study investigated how the soil ecosystem, including soil organisms, vegetation and soil ecological processes, develops during the process of soil formation in a chronosequence in a glacier forefield in Iceland. We hypothesised that along successional age we see increases in nutrient content, vegetation cover, and plant species richness linked to increases in soil food webs biomass and complexity. In line with our expectations all measured pools of carbon and nitrogen, and vegetation cover increased with age in the glacial forefield, but plant species richness levelled off after 30 years. Soil organisms generally increased in biomass with successional age, although some of the groups of soil organisms peaked at an intermediate successional stage. In contrast to our expectations, some of the calculated food web complexity metrics such as the number of trophic groups and trophic chain length did not increase linearly, but showed an intermediate peak or even decreased with successional age. However, plant cover and pools of carbon and nitrogen still increased after 120 years. From these results we conclude that soil ecosystem development takes more than a century under Icelandic climatic conditions to fully develop in terms of vegetation succession, food web structure and biogeochemical cycling.

    Sorting of Molecular Building Blocks from Solution to Surface
    Keisar, Hodaya ; Ruiter, Graham de; Velders, Aldrik H. ; Milko, Petr ; Gulino, Antonino ; Evmenenko, Guennadi ; Shimon, Linda J.W. ; Diskin-Posner, Yael ; Lahav, Michal ; Boom, Milko E. van der - \ 2018
    Journal of the American Chemical Society 140 (2018)26. - ISSN 0002-7863 - p. 8162 - 8171.

    We demonstrate that molecular gradients on an organic monolayer is formed by preferential binding of ruthenium complexes from solutions also containing equimolar amounts of isostructural osmium complexes. The monolayer consists of a nanometer-thick assembly of 1,3,5-tris(4-pyridylethenyl)benzene (TPEB) covalently attached to a silicon or metal-oxide surface. The molecular gradient of ruthenium and osmium complexes is orthogonal to the surface plane. This gradient propagates throughout the molecular assembly with thicknesses over 30 nm. Using other monolayers consisting of closely related organic molecules or metal complexes results in the formation of molecular assemblies having an homogeneous and equimolar distribution of ruthenium and osmium complexes. Spectroscopic and computational studies revealed that the geometry of the complexes and the electronic properties of their ligands are nearly identical. These subtle differences cause the isostructural osmium and ruthenium complexes to pack differently on modified surfaces as also demonstrated in crystals grown from solution. The different packing behavior, combined with the organic monolayer significantly contributes to the observed differences in chemical composition on the surface.

    Disentangling microbial decomposition networks : linking detritus-based soil microbial food webs to ecosystem processes
    Heijboer, Amber - \ 2018
    Wageningen University. Promotor(en): P.C. Ruiter; G.A. Kowalchuk, co-promotor(en): J. Bloem; P.L.E. Bodelier. - Wageningen : Wageningen University - ISBN 9789463437509 - 198

    Soils are crucial for a large number of ecosystem services and occupy an important position in driving the Earth’s biogeochemical cycles. Soils are therefore essential for e.g. agricultural food production, carbon sequestration, water purification and nutrient cycling. These soil functions are to a large extent governed by the huge biodiversity of soil life, which can be depicted in the form of a soil food web: a model that describes the feeding relationships among groups of species that live in the soil. A number of soil ecosystem services, as governed by soil life, are currently under considerable threat due to e.g. soil degradation, atmospheric nitrogen deposition and land use change. A proper understanding of the mechanisms underlying soil ecosystem functioning, in relation to global change, is important to anticipate these threats and to help ensure optimal functioning of our soils.

    Soil food web models have proven to be highly useful in the study of the long-term consequences of environmental change on soil communities and associated ecosystem functioning. Perhaps the most important ecosystem process driven by the soil food web is the decomposition of detritus: plant residues and soil organic matter. Via the decomposition of detritus, soil organisms determine the critical balance between sequestration and mineralization of carbon (C) and nutrients, affecting soil CO2 emissions to the atmosphere and nutrient availability for plants. Soil microbes (bacteria, fungi and protozoa) play a very important role in the decomposition of detritus by being the first consuming trophic level and by making up more than 90% of the total belowground biomass. In this way, soil microbes are the main influencers of C and nitrogen (N) dynamics in soil. However, detailed information on the microbial processing of different types of organic substrates in soil food webs is still missing. Due to the important role of soil microbial communities in C and N cycling, this information is crucial to incorporate in soil food web models in order to study the long-term consequences of global change on ecosystem functioning. This is especially important if one wants to use this information for targeted management of soil life, which is seen as a promising management tool to target optimal soil functioning in anticipation of a changing world. The main research aim of this thesis was therefore to disentangle the soil microbial food web in relation to an important type of environmental change: land use change.

    In chapter 2, I start with discussing how state-of-the-art empirical techniques can be used to collect trophic information that is needed to construct different types of empirically-based food webs: connectedness webs, semi-quantitative webs, energy flow webs and functional webs. I explain what types of information is needed from molecular and biogeochemical studies to create such soil food web models. I thereby give a comprehensive overview of the available empirical techniques with respect to the type of information they can provide for soil food web models.

    In chapter 3, I study litter-derived C flows through the soil microbial food web in six different ex-arable soils. In a 56-day incubation experiment, I compared the fate of litter-derived C flows through the soil microbial communities of recent and long-term abandoned soils. Soils were amended with 13C-labelled plant litter and microbial C flows were studied by tracing the labelling of biomarkers in the form of Phospholipid Fatty Acids Stable Isotope Probing (PLFA-SIP). PLFA-SIP revealed that soil microbial communities are less efficient in decomposing litter-derived C in long-term compared to recently abandoned soils. The reduced efficiency of litter-derived C decomposition is most likely due to a net shift of organic matter-derived C to root-derived C input in relation to time since abandonment of agricultural practices. The study further revealed a clear succession of microbial decomposers, both in time and quantity that was similar across all examined fields: fungi > G- bacteria > G+ bacteria ≥ actinomycetes > micro-fauna. This information gives a first quantitative insight in how litter-derived C flows through the detritus-based soil microbial food web.

    In chapter 4, I continue assessing C flows through the soil microbial community in more detail, by tracing the fate of three contrasting types of organic substrates. The same set of ex-arable soils as examined in chapter 3 were incubated for 28 days after the addition of a mixture of glycine, cellulose and vanillin. In each of the treatments one or none of these compounds was 13C-labelled, to trace the fate of a specific organic compound. Application of both PLFA-SIP and RNA-SIP analyses allowed me to 1) quantify substrate-derived C flows through the soil microbial food web and 2) assess soil microbial resource partitioning beyond the concepts of the bacterial and fungal energy channels. The analyses revealed the emergence of a specific microbial community that deals with the decomposition of recalcitrant material in long-term abandoned soils. Furthermore, the existence of soil microbial decomposer succession was further confirmed by revealing both intra-kingdom microbial decomposer successional patterns and intra-kingdom microbial resource partitioning on the taxonomic level of fungal and bacterial classes. These results further enhance the view that the understanding of soil microbial decomposition goes beyond the concepts of bacterial and fungal energy channels.

    In chapter 5, I assess the effects of contrasting types of organic matter inputs on microbial biomass, activity and community structure, as well as related ecosystem processes like N mineralization, microbial N immobilization, plant growth and nutrient uptake. In a pot experiment, Brussels sprouts were grown on arable soils that were mixed with 15N-labelled mineral fertilizer and a contrasting type of organic amendments. The experiment revealed that a number of ecosystem processes were directly related to soil microbial activity, while microbial N immobilization was mostly dependent on the soil microbial community structure. These outcomes support the idea that soil microbial community structure is important to take into account when assessing the effects of the soil organic inputs on soil ecosystem functioning and can be used to design nutrient management strategies for more sustainable agriculture.

    In chapter 6, I study the drivers of both soil microbial community structure and function on two spatial scales (landscape and local scale). It is shown that these two soil microbial community characteristics are controlled by a distinct set of drivers at local versus landscape scale. I show that soil microbial community structure is driven on the landscape level by phosphorous related variables, whereas soil microbial functioning is driven locally through vegetation patterns. It is therefore important that management strategies consider the scale-dependent action of soil microbial community drivers and take both soil microbial community function and structure into account to target the desired biogeochemical functioning of soils.

    Overall, this thesis gives the first high-resolution and quantitative image of detritus-based microbial food webs as affected by land use change and advances our understanding of soil food webs. Studying soil microbial food webs in a chronosequence of ex-arable fields revealed that a good understanding of soil microbial C flows, beyond the level of bacterial and fungal energy channels, is crucial to understand the effect of land-abandonment on the functioning of soil food webs. A thorough understanding of intra-kingdom variation in soil microbial C processing is therefore of vital importance to enhance our understanding of soil microbial functioning in response to global change, which is the key to success for targeted management of soil life in a changing world.

    A Diurnal Rhythm in Brown Adipose Tissue Causes Rapid Clearance and Combustion of Plasma Lipids at Wakening
    Berg, Rosa van den; Kooijman, Sander ; Noordam, Raymond ; Ramkisoensing, Ashna ; Abreu-Vieira, Gustavo ; Tambyrajah, Lauren L. ; Dijk, Wieneke ; Ruppert, Philip ; Mol, Isabel M. ; Kramar, Barbara ; Caputo, Rosanna ; Puig, Laura Sardón ; Ruiter, Evelien M. de; Kroon, Jan ; Hoekstra, Menno ; Sluis, Ronald J. van der; Meijer, Onno C. ; Willems van Dijk, Ko ; Kerkhof, Linda W.M. van; Christodoulides, Constantinos ; Karpe, Fredrik ; Gerhart-Hines, Zachary ; Kersten, Sander ; Meijer, Johanna H. ; Coomans, Claudia P. ; Heemst, Diana van; Biermasz, Nienke R. ; Rensen, Patrick C.N. - \ 2018
    Cell Reports 22 (2018)13. - ISSN 2211-1247 - p. 3521 - 3533.
    angiopoietin-like 4 - APOE3-Leiden.CETP mice - brown adipose tissue - circadian rhythm - diurnal rhythm - fatty acids - lipoprotein lipase - postprandial lipid response - triglycerides
    Many favorable metabolic effects have been attributed to thermogenic activity of brown adipose tissue (BAT). Yet, time of day has rarely been considered in this field of research. Here, we show that a diurnal rhythm in BAT activity regulates plasma lipid metabolism. We observed a high-amplitude rhythm in fatty acid uptake by BAT that synchronized with the light/dark cycle. Highest uptake was found at the onset of the active period, which coincided with high lipoprotein lipase expression and low angiopoietin-like 4 expression by BAT. Diurnal rhythmicity in BAT activity determined the rate at which lipids were cleared from the circulation, thereby imposing the daily rhythm in plasma lipid concentrations. In mice as well as humans, postprandial lipid excursions were nearly absent at waking. We anticipate that diurnal BAT activity is an important factor to consider when studying the therapeutic potential of promoting BAT activity. van den Berg et al. show a strong circadian rhythm in fatty acid uptake by brown adipose tissue that peaks at wakening regardless of the light exposure period. Consequently, postprandial lipid handling by brown adipose tissue is highest at wakening, resulting in the lowest postprandial plasma lipid excursions.
    Impact of prediagnostic smoking and smoking cessation on colorectal cancer prognosis : A meta-analysis of individual patient data from cohorts within the CHANCES consortium
    Ordóñez-Mena, J.M. ; Walter, V. ; Schöttker, B. ; Jenab, M. ; O'Doherty, M.G. ; Kee, F. ; Bueno-de-Mesquita, B. ; Peeters, P.H.M. ; Stricker, B.H. ; Ruiter, R. ; Hofman, A. ; Söderberg, S. ; Jousilahti, P. ; Kuulasmaa, K. ; Freedman, N.D. ; Wilsgaard, T. ; Wolk, A. ; Nilsson, L.M. ; Tjønneland, A. ; Quirós, J.R. ; Duijnhoven, F.J.B. van; Siersema, P.D. ; Boffetta, P. ; Trichopoulou, A. ; Brenner, H. - \ 2018
    Annals of Oncology 29 (2018)2. - ISSN 0923-7534 - p. 472 - 483.
    Colorectal neoplasms - Meta-analysis - Smoking - Smoking cessation - Survival
    Background: Smoking has been associated with colorectal cancer (CRC) incidence and mortality in previous studies and might also be associated with prognosis after CRC diagnosis. However, current evidence on smoking in association with CRC prognosis is limited. Patients and methods: For this individual patient data meta-analysis, sociodemographic and smoking behavior information of 12 414 incident CRC patients (median age at diagnosis: 64.3 years), recruited within 14 prospective cohort studies among previously cancer-free adults, was collected at baseline and harmonized across studies. Vital status and causes of death were collected for a mean follow-up time of 5.1 years following cancer diagnosis. Associations of smoking behavior with overall and CRC-specific survival were evaluated using Cox regression and standard meta-analysis methodology. Results: A total of 5229 participants died, 3194 from CRC. Cox regression revealed significant associations between former [hazard ratio (HR)=1.12; 95 % confidence interval (CI)=1.04-1.20] and current smoking (HR=1.29; 95% CI=1.04-1.60) and poorer overall survival compared with never smoking. Compared with current smoking, smoking cessation was associated with improved overall (HR<10 years=0.78; 95% CI=0.69-0.88; HR≥10 years=0.78; 95% CI=0.63-0.97) and CRC-specific survival (HR≥10 years=0.76; 95% CI=0.67-0.85). Conclusion: In this large meta-analysis including primary data of incident CRC patients from 14 prospective cohort studies on the association between smoking and CRC prognosis, former and current smoking were associated with poorer CRC prognosis compared with never smoking. Smoking cessation was associated with improved survival when compared with current smokers. Future studies should further quantify the benefits of nonsmoking, both for cancer prevention and for improving survival among CRC patients, in particular also in terms of treatment response.
    Linking ecology and epidemiology: The case of infected resource
    Selakovic, Sanja ; Ruiter, Peter C. de; Heesterbeek, Hans - \ 2017
    In: Adaptive Food Webs / Moore, J.C., de Ruiter, P.C., McCann, K.S., Wolters, V., Cambridge University Press - ISBN 9781107182110 - p. 384 - 405.

    Introduction Interspecific interactions in ecological communities are the main mechanisms that determine structure, functioning, and stability of ecosystems (May, 1972, 1973; Neutel et al., 2002; Alessina and Tang, 2012; Mougi and Kondoh, 2012, 2014). These interactions can be qualitatively positive, negative, or neutral, and pairs of these interactions between two species may be of opposite sign (e.g., trophic, parasitic) or of equivalent sign (e.g., mutualistic, competitive). Most of the research on ecological interactions has focused on feeding relations (Odum, 1971; Pimm, 1982; Levin et al., 2009; McCann, 2011; Moore and de Ruiter, 2012), but in recent studies of ecological communities this was extended to parasitic (Huxham et al., 1995; Thompson et al., 2004; Lafferty et al., 2006; Kuris et al., 2008) and non-parasitic non-trophic relations (Thebault and Fountaine, 2010; Fontaine et al., 2011; Kéfi et al., 2012; Mougi and Kondoh, 2012; Sauve et al., 2014). In this chapter, we focus on parasitic relations and notably on the question of how trophic interactions and infectious agents mutually influence each other. Here we will refer to the combined classes of infectious species as parasites (see next section for details). The impact of parasites in an ecological community can be quantified through their direct influence on the food-web structure, as well as more indirectly through the way they influence physiological traits of host species and trophic relations of the host and non-host species (Kéfi et al., 2012; Selakovic et al., 2014). In this chapter we first briefly discuss the diversity of parasitic interactions, their relationships with host and non-host species, as well as their effects on a simple consumer–resource relationship consisting of one host and one non-host species. The largest part of the chapter is devoted to exploring a basic model, to show how intricately ecological and epidemiological effects are interwoven, even in the simplest possible ecosystem consisting of two species. Even though this model is basic in the sense that it is low dimensional and not meant to realistically represent any particular system, the analysis does hint at broader ecological insight, for example into possible differences between terrestrial and aquatic ecosystems based on parasitic interaction. The simple analysis highlights the need to study the link between ecology and infectious disease epidemiology in more realistic models.

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