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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    The thermoacidophilic methanotroph Methylacidiphilum fumariolicum SolV oxidizes subatmospheric H2 with a high-affinity, membrane-associated [NiFe] hydrogenase
    Schmitz, Rob A. ; Pol, Arjan ; Mohammadi, Sepehr S. ; Hogendoorn, Carmen ; Gelder, Antonie H. van; Jetten, Mike S.M. ; Daumann, Lena J. ; Camp, Huub J.M. Op den - \ 2020
    ISME Journal 14 (2020). - ISSN 1751-7362 - p. 1223 - 1232.

    The trace amounts (0.53 ppmv) of atmospheric hydrogen gas (H2) can be utilized by microorganisms to persist during dormancy. This process is catalyzed by certain Actinobacteria, Acidobacteria, and Chloroflexi, and is estimated to convert 75 × 1012 g H2 annually, which is half of the total atmospheric H2. This rapid atmospheric H2 turnover is hypothesized to be catalyzed by high-affinity [NiFe] hydrogenases. However, apparent high-affinity H2 oxidation has only been shown in whole cells, rather than for the purified enzyme. Here, we show that the membrane-associated hydrogenase from the thermoacidophilic methanotroph Methylacidiphilum fumariolicum SolV possesses a high apparent affinity (Km(app) = 140 nM) for H2 and that methanotrophs can oxidize subatmospheric H2. Our findings add to the evidence that the group 1h [NiFe] hydrogenase is accountable for atmospheric H2 oxidation and that it therefore could be a strong controlling factor in the global H2 cycle. We show that the isolated enzyme possesses a lower affinity (Km = 300 nM) for H2 than the membrane-associated enzyme. Hence, the membrane association seems essential for a high affinity for H2. The enzyme is extremely thermostable and remains folded up to 95 °C. Strain SolV is the only known organism in which the group 1h [NiFe] hydrogenase is responsible for rapid growth on H2 as sole energy source as well as oxidation of subatmospheric H2. The ability to conserve energy from H2 could increase fitness of verrucomicrobial methanotrophs in geothermal ecosystems with varying CH4 fluxes. We propose that H2 oxidation can enhance growth of methanotrophs in aerated methane-driven ecosystems. Group 1h [NiFe] hydrogenases could therefore contribute to mitigation of global warming, since CH4 is an important and extremely potent greenhouse gas.

    Impact of the invasive alien topmouth gudgeon (Pseudorasbora parva) and its associated parasite Sphaerothecum destruens on native fish species
    Spikmans, Frank ; Lemmers, Pim ; Camp, Huub J.M. op den; Haren, Emiel van; Kappen, Florian ; Blaakmeer, Anko ; Velde, Gerard van der; Langevelde, Frank van; Leuven, Rob S.E.W. ; Alen, Theo A. van - \ 2020
    Biological Invasions 22 (2020)2. - ISSN 1387-3547 - p. 587 - 601.
    Biodiversity threat - eDNA - Gasterosteus aculeatus - Leucaspius delineatus - Pathogen - Pungitius pungitius

    The Asian cyprinid Pseudorasbora parva is considered to be a major threat to native fish communities and listed as an invasive alien species of European Union concern. Our study aims to gain evidence-based knowledge on the impact of both P. parva and its parasite Sphaerothecum destruens on native fish populations by analysing fish assemblages and body condition of individuals of native fish species in floodplain water bodies that were invaded and uninvaded by P. parva. We explored the use of environmental DNA (eDNA) techniques to detect S. destruens. Prevalence of S. destruens in native fish species was assessed. Fish samplings showed significantly negative correlations between the abundance of P. parva and the native Leucaspius delineatus, and Pungitius pungitius and three biodiversity indices of the fish assemblages (Simpson’s diversity index, Shannon–Wiener index and evenness). Contrastingly, the abundances of the native Gasterosteus aculeatus and P. parva were positively related. In nearly all isolated water bodies with P. parva, this species is outnumbering native fish species. No effect of P. parva presence was found on body condition of native fish species. Sphaerothecum destruens was demonstrated to occur in both P. parva and G. aculeatus. Gasterosteus aculeatus is suggested to be an asymptomatic carrier that can aid the further spread of S. destruens. Analysis of eDNA proved to be a promising method for early detection of S. destruens, here showing that S. destruens presence coincided with P. parva presence. The ongoing invasion of both P. parva and S. destruens is predicted to pose a significant risk to native fish communities.

    State paternalism and institutional degradation at Treesleeper Eco-camp: Community-based tourism and the loss of sovereignty among Bushmen in Namibia
    Koot, Stasja ; Ingram, Verina Jane ; Bijsterbosch, Mariska - \ 2020
    Development Southern Africa 37 (2020)3. - ISSN 0376-835X - p. 432 - 445.
    Bushmen - Community-based tourism - institutional design principles - Namibia - state paternalism

    The Namibian government promotes community-based tourism (CBT) as market-based development. At Treesleeper Eco-camp, a CBT-project among marginalised Hai//om and !Xun Bushmen (San), we investigate how Bushmen's historically developed paternalist relations shape contemporary local institutional processes. Institutional design principles, seen as prerequisites for stable and robust institutions (norms, rules and regulations), and thus successful CBT, are used to analyse local changes of the project in relation to a government grant. Ironically, after the grant, Treesleeper generated less income and the consequent ‘upgrade’ intensified conflicts. This study shows that community control, ownership and participation are key factors for successful CBT-projects, but currently the state has obstructed these, just as various other ‘superior’ actors have also done (throughout history) in relation to ‘inferior’ Bushmen. We argue that paternalist ideologies perpetuate today in the Bushmen's relation with the state, leading to weaker institutions locally through dispossession of their sovereignty.

    Food capture, transport and swallowing in white-spotted bamboo sharks (Chiloscyllium plagiosum)
    Meer, N.M.M.E. van; Weller, H.I. ; Manafzadeh, A.R. ; Kaczmarek, E.B. ; Scott, B. ; Gussekloo, S.W.S. ; Wilga, C.D. ; Brainerd, E.L. ; Camp, A.L. - \ 2019
    In: SCIB 2019 Annual Meeting Abstracts. - Tampa : Society for Experimental Biology - p. 414 - 414.
    Macrophage polarization in fish transcriptional profiles and metabolic changes
    Wentzel, A.S. ; Petit, J. ; Boer, V.C.J. de; Forlenza, M. ; Wiegertjes, G. - \ 2019
    Fish and Shellfish Immunology 91 (2019). - ISSN 1050-4648 - p. 432 - 432.
    Macrophages of higher vertebrates can display a range of functional phenotypes, while the chief M1 and M2 activation states appear to operate under the guidance of primordially-conserved principles. We have been studying the evolutionary conservation of these M1 and M2 macrophage activation states in teleost carp, mainly by measuring functional responses such as nitric oxide production (M1) and arginase activity (M2). However, the picture of M1 and M2 activation states in teleosts is still far from complete. To complement our understanding of teleost macrophage polarization we first studied activation-state specific gene expression profiles through an unbiased whole transcriptome approach in addition to functional assays. Secondly, we studied the conservation of bioenergetic and metabolic pathways paramount to activation-state specific functions.

    Here we report differential transcriptional profiles for M1 (LPS stimulated) and M2 (exogenous cAMP stimulated) carp macrophages and discuss the conservation of these profiles, which include multiple conserved markers. In addition, we show an enhanced M1 profile when IFN-γ is combined with LPS.

    Although essential to direct and support macrophage activation-state specific functions, conservation of bioenergetic and metabolic pathways have not been studied in detail in polarized carp macrophages. Generally, mammalian M1 macrophages show relatively high glycolysis rates while M2 macrophages are geared towards oxidative phosphorylation to generate energy. We studied whether the enhancement of these specific energy metabolism pathways is conserved. We optimized for carp macrophages the determination of cellular oxygen consumption rate (OCR) as a measure for oxidative phosphorylation, and the determination of extracellular acidification rate (ECAR) as a measure for glycolysis, using the Seahorse real-time Mito Stress Test. We have gained insight in the energy metabolism pathways utilized by carp macrophages driven to M1 or M2 activation states by using specific parameters measured with this test. Both our whole transcriptome approach and assays to measure bioenergetic and metabolic pathways provide valuable additions to studies addressing the evolutionary conservation of M1 and M2 macrophage activation states.
    Shovelomics root traits assessed on the EURoot maize panel are highly heritable across environments but show low genotype-by-nitrogen interaction
    Marié, Chantal A. Le; York, Larry M. ; Strigens, Alexandre ; Malosetti, Marcos ; Camp, Karl Heinz ; Giuliani, Silvia ; Lynch, Jonathan P. ; Hund, Andreas - \ 2019
    Euphytica 215 (2019)10. - ISSN 0014-2336
    Abiotic stress - Genotype environment interaction - Heritability - Nitrogen - Root system architecture - Shovelomics

    The need for sustainable intensification of agriculture in the coming decades requires a reduction in nitrogen (N) fertilization. One opportunity to reduce N application rates without major losses in yield is breeding for nutrient efficient crops. A key parameter that influences nutrient uptake efficiency is the root system architecture (RSA). To explore the impact of N availability on RSA and to investigate the impact of the growth environment, a diverse set of 36 inbred dent maize lines crossed to the inbred flint line UH007 as a tester was evaluated for N-response over 2 years on three different sites. RSA was investigated by excavating and imaging of the root crowns followed by image analysis with REST software. Despite strong site and year effects, trait heritability was generally high. Root traits showing the greatest heritability (> 0.7) were the width of the root stock, indicative of the horizontal expansion, and the fill factor, a measure of the density of the root system. Heritabilities were in a similar range under high or low N application. Under N deficiency the root stock size decreased, the horizontal expansion decreased and the root stock became less dense. However, there was little differential response of the genotypes to low N availability. Thus, the assessed root traits were more constitutively expressed rather than showing genotype-specific plasticity to low N. In contrast, strong differences were observed for ‘stay green’ and silage yield, indicating that these highly heritable traits are good indicators for responsiveness to low N.

    Cultivation and functional characterization of 79 planctomycetes uncovers their unique biology
    Wiegand, Sandra ; Jogler, Mareike ; Boedeker, Christian ; Pinto, Daniela ; Vollmers, John ; Rivas-Marín, Elena ; Kohn, Timo ; Peeters, Stijn H. ; Heuer, Anja ; Rast, Patrick ; Oberbeckmann, Sonja ; Bunk, Boyke ; Jeske, Olga ; Meyerdierks, Anke ; Storesund, Julia E. ; Kallscheuer, Nicolai ; Lücker, Sebastian ; Lage, Olga M. ; Pohl, Thomas ; Merkel, Broder J. ; Hornburger, Peter ; Müller, Ralph Walter ; Brümmer, Franz ; Labrenz, Matthias ; Spormann, Alfred M. ; Camp, Huub J.M. Op den; Overmann, Jörg ; Amann, Rudolf ; Jetten, Mike S.M. ; Mascher, Thorsten ; Medema, Marnix H. ; Devos, Damien P. ; Kaster, Anne Kristin ; Øvreås, Lise ; Rohde, Manfred ; Galperin, Michael Y. ; Jogler, Christian - \ 2019
    Nature Microbiology 5 (2019). - ISSN 2058-5276 - p. 126 - 140.

    When it comes to the discovery and analysis of yet uncharted bacterial traits, pure cultures are essential as only these allow detailed morphological and physiological characterization as well as genetic manipulation. However, microbiologists are struggling to isolate and maintain the majority of bacterial strains, as mimicking their native environmental niches adequately can be a challenging task. Here, we report the diversity-driven cultivation, characterization and genome sequencing of 79 bacterial strains from all major taxonomic clades of the conspicuous bacterial phylum Planctomycetes. The samples were derived from different aquatic environments but close relatives could be isolated from geographically distinct regions and structurally diverse habitats, implying that ‘everything is everywhere’. With the discovery of lateral budding in ‘Kolteria novifilia’ and the capability of the members of the Saltatorellus clade to divide by binary fission as well as budding, we identified previously unknown modes of bacterial cell division. Alongside unobserved aspects of cell signalling and small-molecule production, our findings demonstrate that exploration beyond the well-established model organisms has the potential to increase our knowledge of bacterial diversity. We illustrate how ‘microbial dark matter’ can be accessed by cultivation techniques, expanding the organismic background for small-molecule research and drug-target detection.

    Intra-oropharyngeal food transport and swallowing in white-spotted bamboo sharks
    Meer, Noraly M.M.E. van; Weller, Hannah I. ; Manafzadeh, Armita R. ; Kaczmarek, Elska B. ; Scott, Bradley ; Gussekloo, Sander W.S. ; Wilga, Cheryl D. ; Brainerd, Elizabeth L. ; Camp, Ariel L. - \ 2019
    Journal of Experimental Biology 2019 (2019)222. - ISSN 0022-0949 - 9 p.

    Despite the importance of intraoral food transport and swallowing, relatively few studies have examined the biomechanics of these behaviors in non-tetrapods, which lack a muscular tongue. Studies show that elasmobranch and teleost fishes generate water currents as a ‘hydrodynamic tongue’ that presumably transports food towards and into the esophagus. However, it remains largely unknown how specific musculoskeletal motions during transport correspond to food motion. Previous studies of white-spotted bamboo sharks (Chiloscyllium plagiosum) hypothesized that motions of the hyoid, branchial arches and pectoral girdle, generate caudal motion of the food through the long oropharynx of modern sharks. To test these hypotheses, we measured food and cartilage motion with XROMM during intra-oropharyngeal transport and swallowing (N=3 individuals, 2–3 trials per individual). After entering the mouth, food does not move smoothly toward the esophagus, but rather moves in distinct steps with relatively little retrograde motion. Caudal food motion coincides with hyoid elevation and a closed mouth, supporting earlier studies showing that hyoid motion contributes to intra-oropharyngeal food transport by creating caudally directed water currents. Little correspondence between pectoral girdle and food motion was found, indicating minimal contribution of pectoral girdle motion. Transport speed was fast as food entered the mouth, slower and step-wise through the pharyngeal region and then fast again as it entered the esophagus. The food's static periods in the step-wise motion and its high velocity during swallowing could not be explained by hyoid or girdle motion, suggesting these sharks may also use the branchial arches for intra-oropharyngeal transport and swallowing
    Hydrological Context of Water Scarcity and Storage on the Mountain Ridges in Dogu’a Tembien
    Walraevens, Kristine ; Camp, Marc Van; Vandecasteele, Ine ; Clymans, W. ; Moeyersons, J. ; Frankl, A. ; Guyassa, Etefa ; Zenebe, A. ; Poesen, J. ; Descheemaeker, K.K.E. ; Nyssen, J. - \ 2019
    In: Geo-trekking in Ethiopia’s Tropical Mountains / Nyssen, J., Miro, A., Frankl, A., Springer Nature Switzerland (GeoGuide ) - ISBN 9783030049546 - p. 197 - 213.
    A highly seasonal and erratic rainfall pattern (Chap. 3) provokes general water scarcity in Dogu’a Tembien for eight months a year. This chapter shortly describes the hydrogeological context and hydrodynamics of actual surface and groundwater flow of the mountain catchments around Hagere Selam. Further, some positive effects of water harvesting techniques on the water availability are shown.
    Manuscripts how to build a cross-disciplinary institute: the curious case of the south american institute for resilience and sustainability studies
    Scheffer, Marten ; Mazzeo, Nestor - \ 2019
    Ecology and Society 24 (2019)2. - ISSN 1708-3087
    Art and science - Art-science collaboration - Institute - Resilience - SARAS - South America - Sustainability

    There is no recipe for setting up a new institute, especially if it is meant to be different from anything that currently exists. Here, we give a look behind the scenes at how we dreamt up the transdisciplinary South American Institute for Resilience and Sustainability Science (SARAS), located in Uruguay, and how, with help from a network of renowned freethinkers and dedicated doers, we made it happen. Trying to shape the institute over the first decade, we learned 10 important lessons that may be helpful for others in similar situations. (1) Securing a stable budget is essential, but a permanent challenge. (2) Structural international funding for a place-based institute is unlikely. (3) Having the institute outside the formal structure of a university gives liberty, but it is important to nurture good relationships. (4) An informal setting with ample scheduled time for walks, camp fires, and other leisure interactions helps participants build the trust and take the time needed to connect across disciplines and worldviews but can be seen as decadent by outsiders. (5) It is important to build resilience to the occasional reshuffling of cards inherent with government change. (6) It remains difficult for remote international board members to fathom the local dynamics and challenges inherent to running the institute on the ground. (7) Keeping the big idea alive while solving the continuous stream of everyday issues requires a combination of personalities with complementary skills in the dreamer-doer continuum. (8) There is a trade-off in selecting board members because the famous persons needed for credibility and for their extensive networks often have little time to contribute actively. (9) Truly linking science and arts requires long-term interaction between artists and scientists that are personally interested in this enterprise to allow for the necessary building of trust and mutual understanding. (10) A local sense of ownership is essential for long-term resilience.

    Transcriptional profiling of PPARα-/- and CREB3L3-/- livers reveals disparate regulation of hepatoproliferative and metabolic functions of PPARα
    Ruppert, P.M.M. ; Park, Jong-Gil ; Xu, Xu ; Hur, Kyu Yeon ; Kersten, A.H. ; Lee, Ann-Hwee - \ 2019
    GSE121096 - Mus musculus - PRJNA495632
    Peroxisome Proliferator-Activated receptor α (PPARα) and cAMP-Responsive Element Binding Protein 3-Like 3 (CREB3L3) are transcription factors involved in the regulation of lipid metabolism in the liver. The aim of the present study was to characterize the interrelationship between PPARα and CREB3L3 in regulating hepatic gene expression. Male wildtype, PPARα-/-, CREB3L3-/- and combined PPARα/CREB3L3-/- mice were subjected to a 16-hour fast or 4 days of ketogenic diet. Whole genome expression analysis was performed on liver samples. Under conditions of overnight fasting, the effects of PPARα ablation and CREB3L3 ablation on plasma triglyceride, plasma β-hydroxybutyrate, and hepatic gene expression were largely disparate, and showed only limited interdependence. Gene and pathway analysis underscored the importance of CREB3L3 in regulating (apo)lipoprotein metabolism, and of PPARα as master regulator of intracellular lipid metabolism. A small number of genes, including Fgf21 and Mfsd2a, were under dual control of PPARα and CREB3L3. By contrast, a strong interaction between PPARα and CREB3L3 ablation was observed during ketogenic diet feeding. Specifically, the pronounced effects of CREB3L3 ablation on liver damage and hepatic gene expression during ketogenic diet were almost completely abolished by the simultaneous ablation of PPARα. Loss of CREB3L3 influenced PPARα signalling in two major ways. Firstly, it reduced expression of PPARα and its target genes involved in fatty acid oxidation and ketogenesis. In stark contrast, the hepatoproliferative function of PPARα was markedly activated by loss of CREB3L3. These data indicate that CREB3L3 ablation uncouples the hepatoproliferative and lipid metabolic effects of PPARα. Overall, except for the shared regulation of a very limited number of genes, the roles of PPARα and CREB3L3 in hepatic lipid metabolism are clearly distinct and are highly dependent on dietary status.
    Transcriptional profiling of PPARα−/− and CREB3L3−/− livers reveals disparate regulation of hepatoproliferative and metabolic functions of PPARα
    Ruppert, Philip M.M. ; Park, Jong-Gil ; Xu, Xu ; Hur, Kyu Yeon ; Lee, Ann-Hwee ; Kersten, Sander - \ 2019
    BMC Genomics 20 (2019). - ISSN 1471-2164
    Background: Peroxisome Proliferator-Activated receptor α (PPARα) and cAMP-Responsive Element Binding Protein 3-Like 3 (CREB3L3) are transcription factors involved in the regulation of lipid metabolism in the liver. The aim of the present study was to characterize the interrelationship between PPARα and CREB3L3 in regulating hepatic gene expression. Male wild-type, PPARα−/−, CREB3L3−/− and combined PPARα/CREB3L3−/− mice were subjected to a 16-h fast or 4 days of ketogenic diet. Whole genome expression analysis was performed on liver samples. Results: Under conditions of overnight fasting, the effects of PPARα ablation and CREB3L3 ablation on plasma triglyceride, plasma β-hydroxybutyrate, and hepatic gene expression were largely disparate, and showed only limited interdependence. Gene and pathway analysis underscored the importance of CREB3L3 in regulating (apo)lipoprotein metabolism, and of PPARα as master regulator of intracellular lipid metabolism. A small number of genes, including Fgf21 and Mfsd2a, were under dual control of PPARα and CREB3L3. By contrast, a strong interaction between PPARα and CREB3L3 ablation was observed during ketogenic diet feeding. Specifically, the pronounced effects of CREB3L3 ablation on liver damage and hepatic gene expression during ketogenic diet were almost completely abolished by the simultaneous ablation of PPARα. Loss of CREB3L3 influenced PPARα signalling in two major ways. Firstly, it reduced expression of PPARα and its target genes involved in fatty acid oxidation and ketogenesis. In stark contrast, the hepatoproliferative function of PPARα was markedly activated by loss of CREB3L3. Conclusions: These data indicate that CREB3L3 ablation uncouples the hepatoproliferative and lipid metabolic effects of PPARα. Overall, except for the shared regulation of a very limited number of genes, the roles of PPARα and CREB3L3 in hepatic lipid metabolism are clearly distinct and are highly dependent on dietary status.
    Searching for Podaxis on the trails of early explorers in southern Africa
    Buys, M. ; Conlon, B. ; Fine Licht, Henrik H. De; Aanen, D.K. ; Poulsen, M. ; Beer, Z.W. de - \ 2018
    South African Journal of Botany 115 (2018). - ISSN 0254-6299 - p. 317 - 317.
    Podaxis pistillaris is the name often given to the torpedo-shaped mushrooms forming on termite mounds across southern Africa during the rainy season. Linnaeus described the species in 1871 based on a specimen from India. In 1881, he described a second species as Lycoperdon carcinomale from a South African specimen he received from Thunberg. In 1812, Burchell made a painting of the fungus during his exploration of southern Africa. In 1933, all 33 Podaxis species described by that time from Africa, Asia, Australia and the USA, were lumped as synonyms of P. pistillaris. Another 12 species were subsequently described, but most authors treated all these fungi as P. pistillaris. In a quest to resolve the taxonomy of the fungus, we studied Southern African specimens from various herbaria, and some specimens from the USA, Mexico, India, and Africa. We also visited the sites where Thunberg collected his specimen (Western Cape) and where Burchell made his painting (Northern Cape), but could not find fresh specimens. We distributed flyers to local communities in these areas and requested that they contact us should Podaxis be observed. Within six weeks we received specimens from a farm close to Burchell’s camp site, and more from the Northern and Eastern Cape. Ribosomal DNA sequences were successfully obtained from all the fresh and almost all herbarium specimens, including some older than 100 years. Phylogenetic analyses showed that the southern African specimens separate in at least five distinct species, some of which might represent novel taxa
    Kakuma refugee camp : Humanitarian urbanism in Kenya’s accidental city
    Jansen, B.J. - \ 2018
    Zed Books - ISBN 9781786991898 - 248 p.
    Groundwater salinity mapping of the Belgian coastal zone to improve local freshwater storage availability
    Vandevelde, Dieter ; Baaren, Esther Van; Delsman, Joost ; Karaoulis, Marios ; Oude Essink, Gualbert ; Louw, Perry de; Vermaas, Tommer ; Pauw, Pieter ; Kleine, Marco De; Thofte, Sara ; Teilmann, Rasmus ; Walraevens, Kristine ; Camp, Marc Van; Dominique, Huits ; Dabekaussen, Willem ; Gunnink, Jan ; Vandenbohede, Alexander - \ 2018
    In: 25th Salt Water Intrusion Meeting (SWIM 2018). - EDP Sciences (E3S Web of Conferences ) - 6 p.

    In the European TOPSOIL project, countries around the North Sea are searching for solutions for climate related threats. They explore the possibilities of using the topsoil layer to solve current and future water challenges. The main objective is to improve the climate resilience of the water management of the topsoil and shallow aquifers in the North Sea region. TOPSOIL is supported by the Interreg VB North Sea Region program in line with priority 3 of the program: 'Sustainable North Sea Region, protecting against climate change and preserving the environment'. The Belgian part of this project, called FRESHEM for GO-FRESH Vlaanderen ('FREsh Salt groundwater distribution by Helicopter ElectroMagnetic survey for Geohydrological Opportunities FRESH water supply'), focuses on mapping the salinity distribution of groundwater using airborne electromagnetics and aims to look into a number of measures that could increase the availability of freshwater for agriculture in the polder area. Two pilot projects will evaluate the possibilities for freshwater storage and aims to specify what measures can be taken to achieve this. Together with the other water users and water managers, The Flanders Environment Agency wants to prepare a plan for the realization of one or more pilot projects that can improve the availability of freshwater.

    Tree differences in primary and secondary growth drive convergent scaling in leaf area to sapwood area across Europe
    Petit, Giai ; Arx, Georg von; Kiorapostolou, Natasa ; Lechthaler, Silvia ; Prendin, Angela Luisa ; Anfodillo, Tommaso ; Caldeira, Maria C. ; Cochard, Hervé ; Copini, Paul ; Crivellaro, Alan ; Delzon, Sylvain ; Gebauer, Roman ; Gričar, Jožica ; Grönholm, Leila ; Hölttä, Teemu ; Jyske, Tuula ; Lavrič, Martina ; Lintunen, Anna ; Lobo-do-Vale, Raquel ; Peltoniemi, Mikko ; Peters, Richard L. ; Robert, Elisabeth M.R. ; Roig Juan, Sílvia ; Senfeldr, Martin ; Steppe, Kathy ; Urban, Josef ; Camp, Janne Van; Sterck, Frank - \ 2018
    New Phytologist 218 (2018)4. - ISSN 0028-646X - p. 1383 - 1392.
    Allocation - Climate change - Functional balance - Leaf area - Plant architecture - Sapwood - Structural balance - Xylem
    Trees scale leaf (AL) and xylem (AX) areas to couple leaf transpiration and carbon gain with xylem water transport. Some species are known to acclimate in AL: AX balance in response to climate conditions, but whether trees of different species acclimate in AL: AX in similar ways over their entire (continental) distributions is unknown. We analyzed the species and climate effects on the scaling of AL vs AX in branches of conifers (Pinus sylvestris, Picea abies) and broadleaved (Betula pendula, Populus tremula) sampled across a continental wide transect in Europe. Along the branch axis, AL and AX change in equal proportion (isometric scaling: b ˜ 1) as for trees. Branches of similar length converged in the scaling of AL vs AX with an exponent of b = 0.58 across European climates irrespective of species. Branches of slow-growing trees from Northern and Southern regions preferentially allocated into new leaf rather than xylem area, with older xylem rings contributing to maintaining total xylem conductivity. In conclusion, trees in contrasting climates adjust their functional balance between water transport and leaf transpiration by maintaining biomass allocation to leaves, and adjusting their growth rate and xylem production to maintain xylem conductance.
    Regulation of three virulence strategies of Mycobacterium tuberculosis : A success story
    Zondervan, Niels A. ; Dam, Jesse C.J. Van; Schaap, Peter J. ; Martins dos Santos, Vitor A.P. ; Suarez-Diez, Maria - \ 2018
    International Journal of Molecular Sciences 19 (2018)2. - ISSN 1661-6596
    CAMP - Divalent metal - Dormancy - Escape - Esx - Immune modulation - Iron - Manganese - Mycobacteria - Phagosome rupture - Pore - Virulence - Zinc
    Tuberculosis remains one of the deadliest diseases. Emergence of drug-resistant and multidrug-resistant M. tuberculosis strains makes treating tuberculosis increasingly challenging. In order to develop novel intervention strategies, detailed understanding of the molecular mechanisms behind the success of this pathogen is required. Here, we review recent literature to provide a systems level overview of the molecular and cellular components involved in divalent metal homeostasis and their role in regulating the three main virulence strategies of M. tuberculosis: immune modulation, dormancy and phagosomal rupture. We provide a visual and modular overview of these components and their regulation. Our analysis identified a single regulatory cascade for these three virulence strategies that respond to limited availability of divalent metals in the phagosome.
    Poverty and health among CDC plantation labourers in Cameroon: Perceptions, challenges and coping strategies
    Makoge, Valerie ; Vaandrager, Lenneke ; Maat, Harro ; Koelen, Maria - \ 2017
    PLoS Neglected Tropical Diseases 11 (2017)11. - ISSN 1935-2727 - 16 p.
    Creating better access to good quality healthcare for the poor is a major challenge to development. In this study, we examined inter-linkages between poverty and disease, referred to as poverty-related diseases (PRDs), by investigating how Cameroon Development Corporation (CDC) camp dwellers respond to diseases that adversely affect their health and wellbeing. Living in plantation camps is associated with poverty, overcrowding, poor sanitation and the rapid spread of diseases. In a survey of 237 CDC camp dwellers in Cameroon, we used the health belief model to understand the drivers (perceived threats, benefits and cues for treatment seeking) of reported responses. Using logistic regression analysis, we looked for trends in people’s response to malaria. We calculated the odds ratio of factors shown to have an influence on people’s health, such as food, water, sanitation challenges and seeking formal healthcare for malaria. Malaria (40.3%), cholera (20.8%) and diarrhoea (17.7%) were the major PRDs perceived by camp dwellers. We found a strong link between what respondents perceived as PRDS and hygiene conditions. Poverty for our respondents was more about living in poor hygiene conditions than lack of money. Respondents perceived health challenges as stemming from their immediate living environment. Moreover, people employed self-medication and other informal health practices to seek healthcare. Interestingly, even though respondents reported using formal healthcare services as a general response to illness (84%), almost 90% stated that, in the case of malaria, they would use informal healthcare services. Our study recommends that efforts to curb the devastating effects of PRDs should have a strong focus on perceptions (i.e. include diseases that people living in conditions of poverty perceive as PRDs) and on hygiene practices, emphasising how they can be improved. By providing insights into the inter-linkages between poverty and disease, our study offers relevant guidance for potentially successful health promotion interventions.
    Understanding poverty-related diseases in Cameroon from a salutogenic perspective
    Makoge, Valerie - \ 2017
    Wageningen University. Promotor(en): M.A. Koelen, co-promotor(en): H. Maat; H.W. Vaandrager. - Wageningen : Wageningen University - ISBN 9789463434515 - 193
    armoede - kameroen - malaria - tyfus - acquired immune deficiency syndrome - hiv-infecties - cholera - tuberculose - diarree - gezondheidsgedrag - gezondheidsvoorzieningen - spanningen - poverty - cameroon - malaria - typhoid - acquired immune deficiency syndrome - hiv infections - cholera - tuberculosis - diarrhoea - health behaviour - health services - stresses

    Poverty-related diseases (PRDs) assume poverty as a determinant in catching disease and an obstacle for cure and recovery. In Cameroon, over 48 % of the population lives below the poverty line. This dissertation starts from the premise that the relation between poverty and disease is mediated by a person’s capacity to cope with the challenges posed by the natural and social environment. The central problem addressed is that in (inter)national health promotion, disease eradication is overemphasized whereas strengthening the capacity of people to cope with harsh conditions is disregarded. Research efforts show a similar division in emphasis, resulting in a limited understanding of the way people deal with health challenges in conditions of poverty. This dissertation is based on the salutogenic model of health that emphasizes the combined effects of (natural) disease conditions, mental conditions and social factors as determinants of health. This implies an emphasis on health as a positive strategy to deal with stressors and also an emphasis on the agency of people to respond to challenges that hamper their health and wellbeing. The study is carried out among two different groups of people in Cameroon. These are workers including dependants of workers of the Cameroon Development Corporation (CDC) and students from the universities of Buea and Yaoundé. The overall aim of this dissertation is to understand how conditions of poverty impact the health of people and how they manage these challenges. Specifically, the study aims to unravel the interlinkages between poverty and health by creating a deeper understanding of the social and material dynamics which enable people’s capacity to preserve health, anticipate health risks, and mitigate or recover from stressors such as PRDs. The main research question addressed is: What factors underlie the maintenance of good health and overcoming stressors in the face of PRDs in Cameroon?

    Different research methods were used to collect data. Interviews were carried out with respondents from both groups addressing PRDs, other stressors and coping strategies. General surveys were carried out to identify perceptions as well as health behaviour patterns across the two groups. Standardised surveys were carried out to measure individual factors such as sense of coherence, resilience, self-efficacy, subjective well-being and self-rated health. Results presented in different empirical chapters of the thesis each respond to a specific research question. In Chapters 2 and 3 are presented surveys with 272 students and 237 camp-dwellers respectively. Perceptions, attributed causes of, and responses towards PRDs are explored as well as motivations for given responses to health challenges. In chapter 4, a qualitative study with 21 camp-dwellers and 21 students is presented in which the dynamics of health-seeking behaviour is highlighted. In this chapter also, factors which are influential in seeking formal healthcare are indicated. Chapter 5 elaborates on what people experience as stressors and the mechanisms they put in place to cope with the stressors. In this chapter, not only is the diversity of stressors outlined for both groups, but also presented are the different identified coping mechanisms put in place by respondents. Chapter 6 which is the last empirical chapter presents coping with PRDs through an analysis of individual, demographic and environmental factors.

    Based on the studies carried out, this thesis concludes that the two groups investigated are very aware of what PRDs are and can differentiate them from common diseases. Major PRDs listed by the two groups of respondents were malaria, cholera and diarrhoea. This classification is different from what is considered major PRDs by (inter)national health bodies such as the World Health Organisation and the Ministry of Public Health in Cameroon. Also, organisations such as CDC and Universities, offer limited contributions towards better health for camp-dwellers and students respectively. This is experienced relative to the living conditions, quality of the healthcare system and poor work or study conditions. That notwithstanding, people play an active role in maintaining their health through diverse coping mechanisms. Coping was most strongly related to enabling individual factors such as sense of coherence and subjective health, perceptions of effective strategies to respond to diseases as well as social factors such as the meaningful activities in the social groups to which they belong. The results presented in this thesis are intended to contribute to sustainable and effective response strategies towards PRDs.

    Exopolis reloaded : fragmented landscapes and no man’s lands in a North-Eastern Italian border region
    Altin, Roberta ; Minca, Claudio - \ 2017
    Landscape Research 42 (2017)4. - ISSN 0142-6397 - p. 385 - 399.
    asylum seekers - camp - exopolis - Landscapes of power - no man’s land

    This paper examines a ‘landscape of power’ in the marginal northeastern corner of Italy, near the Italian-Slovenian border. The landscape is centred around the small town of Gradisca and its highly contested centres for asylum seekers and marked by the concomitant presence of a giant shopping mall, the largest Italian war memorial, and an aestheticised wine district. The result of participant observation, visual and textual analysis, and selected interviews, this study reflects on the transformation of a former cold war border area into a mix of carceral, hospitality, commercial, residential, rural spatialities that seem to be entirely disconnected with each other and linked instead to broader regional, national and international geographies. This fragmented landscape, dominated by massive ‘fortified’ enclosures and with gradually deterritorialised in-between spaces, described here as no man’s land, may be provocatively analysed as an Italian exopolis.

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