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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Effective elements of Dutch care-physical activity initiatives for low socioeconomic status adults
Mulderij, L.S. ; Wolters, F. ; Wagemakers, M.A.E. ; Verkooijen, K.T. - \ 2019
European Journal of Public Health 29 (2019)Supplement_4. - ISSN 1101-1262 - p. 297 - 298.
In care-physical activity (care-PA) initiatives, primary care and sports collaborate to stimulate PA among adults at risk of lifestyle related diseases. Preliminary results of Dutch care-PA initiatives for low socioeconomic status (SES) adults indicate that these initiatives successfully lower participants’ body weight and improve quality of life. However, insight into elements that make these initiatives work is lacking. Therefore, this research aims to unravel the effective elements of care-PA initiatives for low SES adults.

Concept Mapping (CM) was used as tool to identify and cluster the effective elements. Nineteen Dutch health promotion experts individually listed as many elements as they felt were of importance to the effectiveness of care-PA initiatives. Next, each expert was asked to cluster the elements and to score them on importance. Then, CS Global MAX software was used for multidimensional scaling and a hierarchical cluster analysis to develop a cluster map. Finally, the cluster map was presented, discussed, and refined in a group meeting with 11 of the experts.

The experts came up with 113 unique effective elements of care-PA initiatives for low SES adults, clustered into 11 clusters: 1) approach of professionals, 2) barriers experienced during the programme, 3) local embedding, 4) customisation of the programme to target population, 5) social support, 6) methods within the programme, 7) competencies of professionals, 8) accessibility of the programme, 9) actions within the programme, 10) recruitment of participants, and 11) intersectoral collaboration.

A valuable overview of the effective elements of care-PA initiatives for low SES adults was created. The results can be used to improve existing care-PA initiatives and to develop new ones targeted at low SES adults at risk of lifestyle related diseases. This may eventually help to reduce health inequalities between low and high SES adults.

Key messages
Concept mapping has been a useful group-based tool to obtain information on the effective elements of care-PA initiatives, in which individual input from health promotion experts has been collected.
The overview of effective elements of care-PA initiatives for low SES adults as presented in this study is valuable for the development of care-PA initiatives specifically targeted at low SES adults.
Accounting for seasonal and composition‐related variability in acoustic material properties in estimating copepod and krill target strength
Sakinan, Serdar ; Lawson, Gareth L. ; Wiebe, Peter H. ; Chu, Dezhang ; Copley, Nancy J. - \ 2019
Limnology and Oceanography: Methods (2019). - ISSN 1541-5856 - 19 p.
Estimation of abundance or biomass, using acoustic techniques requires knowledge of the frequency dependent acoustic backscatter characteristics, or target strength, of organisms. Target strength of zooplankton is typically estimated from physics-based models that involve multiple parameters, notably including the acoustic material properties (i.e., the contrasts in density and sound speed between the animal and surrounding seawater). In this work, variability in the acoustic material properties of two zooplankton species in the Gulf of Maine, the copepod (Calanus finmarchicus) and krill (Meganyctiphanes norvegica), was investigated relative to changing season as well as, for the copepod, temperature and depth. Increases in the density and sound speed contrasts of these species from fall to spring were observed. Target strength predictions based on these measurements varied between fall and spring by 2-3 dB in krill. Measurements were also conducted on C. finmarchicus lipid extract at changing temperature and pressure. The density contrast of the extract varied negatively with temperature, while the sound speed contrast changed by more than 10 % over the temperature and pressure ranges that the organism expected to occupy. C. finmarchicus target strength predictions showed that the combined effect of temperature and pressure can be significant (more than 10 dB) due to the varying response of lipids. The large vertical migration ranges and lipid accumulation characteristics of these species (e.g., the diapause behaviour of Calanus copepods) suggest that it is necessary for seasonal and environmental variability in material properties to be taken into account to achieve reliable measurements.
Effect of nickel and cobalt on methanogenic enrichment cultures and role of biogenic sulphide in metal toxicity attenuation
Luz Ferreira Martins Paulo, Lara da; Ramiro Garcia, Javier ; Mourik, Simon van; Stams, Fons ; Machado de Sousa, Diana - \ 2019
Wageningen University
PRJEB20620 - ERP022789
Metals play an important role in microbial metabolism by acting as cofactors for many enzymes. Supplementation of biological processes with metals may result in improved performance, but high metal concentrations are often toxic to microorganisms. In this work, methanogenic enrichment cultures growing on H2/CO2 or acetate were supplemented with trace concentrations of nickel (Ni) and cobalt (Co), but no significant increase in methane production was observed in most of the tested conditions. However, high concentrations of these metals were detrimental to methanogenic activity of the cultures. The amount of methane produced from H2/CO2 was reduced in 50% in the presence of 8 mM of Ni or 30 mM of Co (after 6 days of incubation), compared to controls without metal supplementation. When acetate was used as substrate, methane production was also reduced: in 18% with 8 mM of Ni and in 53% with 30 mM of Co (after 6 days of incubation). Metal precipitation with sulphide was further tested as a possible method to alleviate metal toxicity. Anaerobic sludge was incubated with Co (30 mM) and Ni (8mM) in the presence of sulphate or sulphide. The addition of sulphide helped to mitigate the toxic effect of the metals. Methane production from H2/CO2 was negatively affected in the presence of sulphate, possibly due to strong competition of hydrogenotrophic methanogens by sulphate-reducing bacteria. However, in the enrichment cultures growing on acetate, biogenic sulphide had a positive effect and higher amounts of methane were produced in these incubations than in similar assays without sulphate addition. The degree of competition between methanogens and sulphate-reducing bacteria is a determinant factor for the success of using biogenic sulphide as detoxification method.
Four insect oils as food ingredient: Physical and chemical characterisation of insect oils obtained by an aqueous oil extraction
Tzompa-Sosa, D.A. ; Yi, L. ; Valenberg, H.J.F. van; Lakemond, C.M.M. - \ 2019
Journal of Insects as Food and Feed 5 (2019)4. - ISSN 2352-4588 - p. 279 - 292.
Acheta domesticus - Alphitobius diaperinus - Aroma - Blaptica dubia - Insect oils - Novel food - Tenebrio molitor

Insect fractionation and insect ingredient characterisation is of relevance in view of the increase in insect production and demand of insect ingredients worldwide. This study aims to contribute to the knowledge of insect oils that were extracted from insects commercially reared in Europe. Oil was extracted from yellow mealworm, lesser mealworm, house cricket and Dubia cockroach by an aqueous based oil extraction method. These insect oils were physicochemically characterised on the most important parameters for food applications, namely thermal behaviour (differential scanning calorimeter), colour (spectrophotometry) and aroma compounds (gas chromatography-mass spectrometry). The amount and the composition of the un-extracted lipid fraction was determined by means of fatty acid (FA) profiling (gas chromatography with flame ionisation detector). Although no distinctive pattern was seen in all four species, it becomes clear from its FA profile that the extracted fat is more similar to the residue and cream fractions than to the pellet and supernatant. The amount of lipids that was not extracted was species dependent ranging from 40 to up to 82% of the total lipid content. Further work is needed to reduce the oil loss in this extraction. The extracted insect oil presented a wide range of melting peaks, from -30.7 to 22.7 °C, which makes them liquid-like at room temperature. Its thermal profile shows separated peaks showing that fat fractionation is feasible. Oil colour was bright yellow-reddish. Most oils had compounds related to pleasant aromas, except for Dubia cockroach. In the latter oil several acid compounds related to unpleasant aromas were identified. This study shows that yellow meal worm oil, lesser mealworm oil and cricket oil have characteristics desirable for table oils and for oils use as food ingredients.

Aphid resistance in Capsicum maps to a locus containing LRR-RLK gene analogues
Sun, Mengjing ; Voorrips, Roeland E. ; van’t Westende, Wendy ; Kaauwen, Martijn van; Visser, Richard G.F. ; Vosman, Ben - \ 2019
Theoretical and Applied Genetics (2019). - ISSN 0040-5752

Key message: A QTL for aphid resistance on pepper chromosome 2 was identified and validated. This QTL affects aphid survival and reproduction, and was fine mapped to a locus containing LRR-RLK analogues. Abstract: Myzus persicae is one of the most threatening insect pests that adversely affects pepper (Capsicum) cultivation. Resistance to aphids was previously identified in Capsicum baccatum. This study aimed at elucidating the genetics of aphid resistance in C. baccatum. A QTL analysis was carried out for M. persicae resistance in an F2 population derived from an intraspecific cross between a highly resistant plant and a susceptible plant. Survival and reproduction were used as resistance parameters. Interval mapping detected two QTLs affecting aphid survival (Rmpas-1) and reproduction (Rmprp-1), respectively, both localized in the same area and sharing the same top marker on chromosome 2. Use of this marker as co-factor in multiple-QTL mapping analysis revealed a second, minor QTL (Rmprp-2) only affecting aphid reproduction, on chromosome 4. Fine mapping confirmed the effects of Rmpas-1 and Rmprp-1 and narrowed the major QTL Rmprp-1 down to a genomic region of 96 kb which is predicted to encode four analogues of resistance genes of the receptor-like kinase family containing a leucine-rich repeat domain (LRR-RLKs). This work provides not only initial information for breeding aphid-resistant pepper varieties, but also forms the basis for future molecular analysis of gene(s) involved in aphid resistance.

Amazing grazing: A public and private partnership to stimulate grazing practices in intensive dairy systems
Schils, René ; Philipsen, Bert ; Hoekstra, Nyncke ; Holshof, Gertjan ; Zom, Ronald ; Hoving, Idse ; Reenen, Kees van; Stienezen, Marcia ; Klootwijk, Cindy ; Werf, Joop van der; Sebek, Léon ; Eekeren, Nick van; Dixhoorn, Ingrid van; Pol-van Dasselaar, Agnes van den - \ 2019
Sustainability 11 (2019)20. - ISSN 2071-1050
Agricultural innovation system - Dairy sector - Grassland - Interdisciplinary research - Stakeholders

In many intensive dairy regions in northwest Europe, a decline in grazing is observed. In the Netherlands, the proportion of dairy cows with access to pasture is declining, as well as the time spent grazing per cow. The decline in grazing is seen as an unwanted trend by many stakeholders and is, thus, under debate amongst dairy farmers, the dairy chain, and society. Therefore, a public-private partnership was initiated to encourage grazing by providing farmers with usable means of improving their grazing systems. The partnership involved stakeholders from the dairy farming community, dairy and feed industry, agrotechnical industries, advisory services, and research. The objective of this partnership was to develop and stimulate technological innovations and management measures that increase fresh grass intake at pasture. The innovation network combined an integrated research approach with farmer working groups and broader stakeholder interactive meetings. The project started with a comprehensive grass intake framework, which was the foundation for exploration of innovations. The framework consisted of six interlinked components: soil, grass growth, grass supply, grass intake, feed supplementation, and cow behavior. In a continuous interactive cycle, strategic choices were made to focus on potentially effective innovations. The use of a public-private partnership to develop usable innovations that encourage grazing practices proven to be a good approach to develop a shared vision among stakeholders. It provided a basis to work together toward innovative practices and to disseminate the outcomes to the foreseen users. The approach succeeded in design concepts for two specific innovations, i.e., weekly grass growth predictions and daily fresh grass intake tracking. We demonstrated that meaningful grazing and fresh grass intake are possible in intensive dairy systems with high stocking rates and high levels of supplementary feeding.

Novel COX-2 products of n-3 polyunsaturated fatty acid-ethanolamine-conjugates identified in RAW264.7 macrophages
Bus, Ian de; Zuilhof, Han ; Witkamp, Renger ; Balvers, Michiel ; Albada, Bauke - \ 2019
Journal of Lipid Research 60 (2019)11. - ISSN 0022-2275 - p. 1829 - 1840.
cyclooxygenase - cyclooxygenase 2 - fatty acid amides - fatty acid oxidation - high-performance liquid chromatography - inflammation - mass spectrometry - prostaglandins

Cyclooxygenase 2 (COX-2) plays a key role in the regulation of inflammation by catalyzing the oxygenation of PUFAs to prostaglandins (PGs) and hydroperoxides. Next to this, COX-2 can metabolize neutral lipids, including endocannabinoid-like esters and amides. We developed an LC-HRMS-based human recombinant (h)COX-2 screening assay to examine its ability to also convert n-3 PUFA-derived N-acylethanolamines. Our assay yields known hCOX-2-derived products from established PUFAs and anandamide. Subsequently, we proved that eicosapentaenoylethanolamide (EPEA), the N-acylethanolamine derivative of EPA, is converted into PGE3-ethanolamide (PGE3-EA), and into 11-, 14-, and 18-hydroxyeicosapentaenoyl-EA (11-, 14-, and 18-HEPE-EA, respectively). Interestingly, we demonstrated that docosahexaenoylethanolamide (DHEA) is converted by hCOX-2 into the previously unknown metabolites, 13- and 16-hydroxy-DHEA (13- and 16-HDHEA, respectively). These products were also produced by lipopolysaccharide-stimulated RAW267.4 macrophages incubated with DHEA. No oxygenated DHEA metabolites were detected when the selective COX-2 inhibitor, celecoxib, was added to the cells, further underlining the role of COX-2 in the formation of the novel hydroxylated products. This work demonstrates for the first time that DHEA and EPEA are converted by COX-2 into previously unknown hydroxylated metabolites and invites future studies toward the biological effects of these metabolites.

Genome Improvement and Genetic Map Construction for Aethionema arabicum, the First Divergent Branch in the Brassicaceae Family.
Nguyen, T.P. ; Mülich, Cornelia ; Mohammadin, Setareh ; Bergh, E. van den; Platts, A.E. ; Haas, Fabian B. ; Rensing, Stefan A. ; Schranz, M.E. - \ 2019
Genes, Genomes and Genomics 9 (2019)11. - ISSN 1749-0383 - p. 3521 - 3530.
The genus Aethionema is a sister-group to the core-group of the Brassicaceae family that includes Arabidopsis thaliana and the Brassica crops. Thus, Aethionema is phylogenetically well-placed for the investigation and understanding of genome and trait evolution across the family. We aimed to improve the quality of the reference genome draft version of the annual species Aethionema arabicum. Second, we constructed the first Ae. arabicum genetic map. The improved reference genome and genetic map enabled the development of each other. We started with the initially published genome (version 2.5). PacBio and MinION sequencing together with genetic map v2.5 were incorporated to produce the new reference genome v3.0. The improved genome contains 203 MB of sequence, with approximately 94% of the assembly made up of called (non-gap) bases, assembled into 2,883 scaffolds (with only 6% of the genome made up of non-called bases (Ns)). The N50 (10.3 MB) represents an 80-fold increase over the initial genome release. We generated a Recombinant Inbred Line (RIL) population that was derived from two ecotypes: Cyprus and Turkey (the reference genotype. Using a Genotyping by Sequencing (GBS) approach, we generated a high-density genetic map with 749 (v2.5) and then 632 SNPs (v3.0) was generated. The genetic map and reference genome were integrated, thus greatly improving the scaffolding of the reference genome into 11 linkage groups. We show that long-read sequencing data and genetics are complementary, resulting in an improved genome assembly in Ae. arabicum. They will facilitate comparative genetic mapping work for the Brassicaceae family and are also valuable resources to investigate wide range of life history traits in Aethionema.
Melamine-Based Microporous Organic Framework Thin Films on an Alumina Membrane for High-Flux Organic Solvent Nanofiltration
Amirilargani, Mohammad ; Yokota, Giovana N. ; Vermeij, Gijs H. ; Merlet, Renaud B. ; Delen, Guusje ; Mandemaker, Laurens D.B. ; Weckhuysen, Bert M. ; Winnubst, Louis ; Nijmeijer, Arian ; Smet, Louis C.P.M. de; Sudhölter, Ernst J.R. - \ 2019
ChemSusChem (2019). - ISSN 1864-5631
membranes - microporous materials - organic solvent nanofiltration - polymers - porous organic frameworks

Microporous polymer frameworks have attracted considerable attention to make novel separation layers owing to their highly porous structure, high permeability, and excellent molecular separation. This study concerns the fabrication and properties of thin melamine-based microporous polymer networks with a layer thickness of around 400 nm, supported on an α-alumina support and their potential use in organic solvent nanofiltration. The modified membranes show excellent solvent purification performances, such as n-heptane permeability as high as 9.2 L m−2 h−1 bar −1 in combination with a very high rejection of approximately 99 % for organic dyes with molecular weight of ≥457 Da. These values are higher than for the majority of the state-of-the-art membranes. The membranes further exhibit outstanding long-term operation stability. This work significantly expands the possibilities of using ceramic membranes in organic solvent nanofiltration.

Structural Plasticity of Intrinsically Disordered LEA Proteins from Xerophyta schlechteri Provides Protection In Vitro and In Vivo
Silva Artur, Mariana A. ; Rienstra, Juriaan ; Dennis, Timothy J. ; Farrant, Jill M. ; Ligterink, Wilco ; Hilhorst, Henk - \ 2019
Frontiers in Plant Science 10 (2019). - ISSN 1664-462X
intrinsic disorder - late embryogenesis abundant proteins - plant desiccation tolerance - resurrection plants - Xerophyta

Late embryogenesis abundant (LEA) proteins are essential to the ability of resurrection plants and orthodox seeds to protect the subcellular milieu against irreversible damage associated with desiccation. In this work, we investigated the structure and function of six LEA proteins expressed during desiccation in the monocot resurrection species Xerophyta schlechteri (XsLEAs). In silico analyses suggested that XsLEAs are hydrophilic proteins with variable intrinsically disordered protein (IDP) properties. Circular dichroism (CD) analysis indicated that these proteins are mostly unstructured in water but acquire secondary structure in hydrophobic solution, suggesting that structural dynamics may play a role in their function in the subcellular environment. The protective property of XsLEAs was demonstrated by their ability to preserve the activity of the enzyme lactate dehydrogenase (LDH) against desiccation, heat and oxidative stress, as well as growth of Escherichia coli upon exposure to osmotic and salt stress. Subcellular localization analysis indicated that XsLEA recombinant proteins are differentially distributed in the cytoplasm, membranes and nucleus of Nicotiana benthamiana leaves. Interestingly, a LEA_1 family protein (XsLEA1-8), showing the highest disorder-to-order propensity and protective ability in vitro and in vivo, was also able to enhance salt and drought stress tolerance in Arabidopsis thaliana. Together, our results suggest that the structural plasticity of XsLEAs is essential for their protective activity to avoid damage of various subcellular components caused by water deficit stress. XsLEA1-8 constitutes a potential model protein for engineering structural stability in vitro and improvement of water-deficit stress tolerance in plants.

Insights into heterologous biosynthesis of Arteannuin B and artemisinin in physcomitrella patens
Ikram, Nur Kusaira Khairul ; Kashkooli, Arman Beyraghdar ; Peramuna, Anantha ; Krol, Alexander R. Van Der; Bouwmeester, Harro ; Simonsen, Henrik Toft - \ 2019
Molecules 24 (2019)21. - ISSN 1420-3049
Artemisinin - Biotechnology - Malaria - Physcomitrella patens - Sesquiterpenoids

Metabolic engineering is an integrated bioengineering approach, which has made considerable progress in producing terpenoids in plants and fermentable hosts. Here, the full biosynthetic pathway of artemisinin, originating from Artemisia annua, was integrated into the moss Physcomitrella patens. Different combinations of the five artemisinin biosynthesis genes were ectopically expressed in P. patens to study biosynthesis pathway activity, but also to ensure survival of successful transformants. Transformation of the first pathway gene, ADS, into P. patens resulted in the accumulation of the expected metabolite, amorpha-4,11-diene, and also accumulation of a second product, arteannuin B. This demonstrates the presence of endogenous promiscuous enzyme activity, possibly cytochrome P450s, in P. patens. Introduction of three pathway genes, ADSCYP71AV1- ADH1 or ADS-DBR2-ALDH1 both led to the accumulation of artemisinin, hinting at the presence of one or more endogenous enzymes in P. patens that can complement the partial pathways to full pathway activity. Transgenic P. patens lines containing the different gene combinations produce artemisinin in varying amounts. The pathway gene expression in the transgenic moss lines correlates well with the chemical profile of pathway products. Moreover, expression of the pathway genes resulted in lipid body formation in all transgenic moss lines, suggesting that these may have a function in sequestration of heterologous metabolites. This work thus provides novel insights into the metabolic response of P. patens and its complementation potential for A. annua artemisinin pathway genes. Identification of the related endogenous P. patens genes could contribute to a further successful metabolic engineering of artemisinin biosynthesis, as well as bioengineering of other high-value terpenoids in P. patens.

Plant host and drought shape the root associated fungal microbiota in rice
Andreo-Jimenez, Beatriz ; Vandenkoornhuyse, Philippe ; Lê Van, Amandine ; Heutinck, Arvid ; Duhamel, Marie ; Kadam, Niteen ; Jagadish, Krishna ; Ruyter-Spira, Carolien ; Bouwmeester, Harro - \ 2019
PeerJ 2019 (2019)9. - ISSN 2167-8359
Drought - Fungi - Host - Microbiota - Oryza sativa (rice) - Yield

Background and Aim. Water is an increasingly scarce resource while some crops, such as paddy rice, require large amounts of water to maintain grain production. A better understanding of rice drought adaptation and tolerance mechanisms could help to reduce this problem. There is evidence of a possible role of root-associated fungi in drought adaptation. Here, we analyzed the endospheric fungal microbiota composition in rice and its relation to plant genotype and drought. Methods. Fifteen rice genotypes (Oryza sativa ssp. indica) were grown in the field, under well-watered conditions or exposed to a drought period during flowering. The effect of genotype and treatment on the root fungal microbiota composition was analyzed by 18S ribosomal DNA high throughput sequencing. Grain yield was determined after plant maturation. Results. There was a host genotype effect on the fungal community composition. Drought altered the composition of the root-associated fungal community and increased fungal biodiversity. The majority of OTUs identified belonged to the Pezizomycotina subphylum and 37 of these significantly correlated with a higher plant yield under drought, one of them being assigned to Arthrinium phaeospermum. Conclusion. This study shows that both plant genotype and drought affect the rootassociated fungal community in rice and that some fungi correlate with improved drought tolerance. This work opens new opportunities for basic research on the understanding of how the host affects microbiota recruitment as well as the possible use of specific fungi to improve drought tolerance in rice.

Influence of foliar kaolin application and irrigation on photosynthetic activity of grape berries
Garrido, Andreia ; Serôdio, João ; Vos, Ric De ; Conde, Artur ; Cunha, Ana - \ 2019
Agronomy 9 (2019)11. - ISSN 2073-4395
Grape berry tissues - Irrigation - Kaolin - Light micro-climates - Mitigation strategies - Photosynthesis - Photosynthetic pigments - Pulse amplitude modulated (PAM) fluorometry - Vitis vinifera L

Climate changes may cause severe impacts both on grapevine and berry development. Foliar application of kaolin has been suggested as a mitigation strategy to cope with stress caused by excessive heat/radiation absorbed by leaves and grape berry clusters. However, its effect on the light micro-environment inside the canopy and clusters, as well as on the acclimation status and physiological responses of the grape berries, is unclear. The main objective of this work was to evaluate the effect of foliar kaolin application on the photosynthetic activity of the exocarp and seeds, which are the main photosynthetically active berry tissues. For this purpose, berries from high light (HL) and low light (LL) microclimates in the canopy, from kaolin-treated and non-treated, irrigated and non-irrigated plants, were collected at three developmental stages. Photochemical and non-photochemical efficiencies of both tissues were obtained by a pulse amplitude modulated chlorophyll fluorescence imaging analysis. The maximum quantum efficiency (Fv/Fm) data for green HL-grown berries suggest that kaolin application can protect the berry exocarp from light stress. At the mature stage, exocarps of LL grapes from irrigated plants treated with kaolin presented higher Fv/Fm and relative electron transport rates (rETR200) than those without kaolin. However, for the seeds, a negative interaction between kaolin and irrigation were observed especially in HL grapes. These results highlight the impact of foliar kaolin application on the photosynthetic performance of grape berries growing under different light microclimates and irrigation regimes, throughout the season. This provides insights for a more case-oriented application of this mitigation strategy on grapevines.

“The truth is not in the middle”: Journalistic norms of climate change bloggers
Eck, Christel W. van; Mulder, Bob C. ; Dewulf, Art - \ 2019
Global environmental change : human and policy dimensions 59 (2019). - ISSN 0959-3780
Bloggers - Climate change - Climate change communications - Journalistic norms - Online media
Optimization of algae production on urine
Tuantet, Kanjana ; Temmink, Hardy ; Zeeman, Grietje ; Wijffels, René H. ; Buisman, Cees J.N. ; Janssen, Marcel - \ 2019
Algal Research 44 (2019). - ISSN 2211-9264
Microalgae production - Nutrient removal - Photobioreactor control - Urine treatment

Urine is a potential source of nutrients to grow microalgal biomass to be re-used as fertilizer and soil conditioner. In this study the impact of photobioreactor dilution rate on microalgae productivity and photosynthetic efficiency was assessed and used to determine operating conditions to reach both full nitrogen removal from urine and high biomass productivity. In addition, the possibility to work under day/night cycling was tested. To this end, the microalga Chlorella sorokiniana was grown on artificial urine and real human urine in bench-scale panel photobioreactors with short optical paths. At a light intensity of 1530 μmol⋅ m−2⋅s-1 photobioreactor productivity and photosynthetic efficiency was demonstrated to be maximal at reactor dilution rates between 0.10 and 0.15 h-1. A biomass yield of 1 g dry matter per mol of PAR photons was achieved. Biomass concentration, and accordingly nutrient removal efficiency, decreased at increasing reactor dilution rate. The experimental results could be reproduced by model simulations. These simulations allowed to demonstrate that the system must be operated at a dilution rate of less than 0.01 h-1 in order to reach complete nitrogen removal. In that scenario more than half of the potential biomass productivity is lost due to severe self-shading within the algal culture. Experiments with real human urine illustrated the problem of incomplete nitrogen removal and ammonium inhibition of growth at too high dilution rates. It is therefore suggested to apply an optimized pre-dilution of pure urine prior to treatment in a photobioreactor. Experiments under day-night cycles demonstrated that microalgal cultures quickly acclimate to such variable light conditions. Additional model simulations illustrated that a phototrophic system is most effective when diluted urine is fed to the photobioreactor during day time only. In that situation the lowest nitrogen concentration in the effluent can be reached at a maximal areal removal rate and photosynthetic efficiency.

Boosting farmer income: further insights from great cases
Guijt, W.J. ; Pfahl, Heather ; Jenkins, Beth ; Gneiting, Uwe - \ 2019
Farmer Income Lab - 8 p.
Last year’s research into “What works to raise farmer income” left us wondering whether we could learn more from cases of greater, more structural change in farmer income. New research this year took that work a bit further. What we found, and our preliminary insights on what is working and why, have just come out in this Stanford Social Innovation Review (SSIR Online) article, “Boosting Farmer Incomes in Agricultural Supply Chains”.
To complement the SSIR article, this article for the Farmer Income Lab describes our approach in greater detail. We also point to the need for additional applied research to fully understand underlying contributory factors and processes that made these programs successful. Such work can help business to make clearer and more strategic choices about how to invest their resources to effectively deploy promising practices intended to raise farmer income in their supply chains.
De toegankelijkheid van Jufferswaardin Renkum : bezoekaantallen, burgerparticipatie en communicatie
Goossen, C.M. ; Dekker, Lianne - \ 2019
Wageningen : Wageningen University & Research, Wetenschapswinkel (Wetenschapswinkel Rapport 353) - ISBN 9789463950435 - 87
This report discusses the results of the stakeholder analysis and the amount of recreational visits that was counted in the Natura 2000 area of the Jufferswaard in the period 2018-2019. The Jufferswaard, a 31 ha floodplain in the municipality of Renkum, is an area where recreation can take place. There are 55,000 visits a year, mainly from residents of the neighbouring villages of Renkum and Heelsum. On average there are 150 visits per day, mainly between 12.00 and 14.00. Sundays are by far the busiest days. In the future, on a beautiful and dry Sunday in the second half of February, the Pilot Group will be able to count 1 hour between 15.00 and 16.00 of the outgoing visit at each entrance gate. Based on the key figures from this study, the annual visit can then be roughly estimated. This is an inexpensive way for the Pilot Group to monitor the annual visit. According to the Pilogroep (a group of active citizens), the accessibility of the walking paths could be improved. They also have wishes for the preservation of cultural history in the area. These wishes are not directly shared by the owner of the Jufferswaard: Staatsbosbeheer. Other stakeholders are also active: the municipality of Renkum, the province of Gelderland, the Vallei and Veluwe Water Board and the nearby Parenco paper factory. The stakeholder analysis looked at what wishes were involved and how much influence the various stakeholders have. The wishes for the area were explained on the basis of nature images consisting of different management. The inhabitants of the municipality of Renkum were also heard by means of a survey in which they were asked about their wishes, nature images and recreational motives. It appears that although the nature images of the most important stakeholders, the Pilot Group and Staatsbosbeheer, differ, a compromise can be reached on the wishes of the Jufferswaard. This requires an improvement in communication on both sides. For the Pilot Group it is important that they present an unambiguous vision to the other stakeholders, and forStaatsbosbheer it is important that they communicate more from the experience of nature, because this is closer to the image of nature of recreational users. In this way the tension we see in de Jufferswaard between a more hierarchical role for the manager, who has to comply with statutory agreements, and citizens’ initiatives that expect a more collaborative and responsive role or demand a more effective role for the managers and the government, can be resolved. A situation can then be created that leads to cooperation on the basis of communication, understanding and trust in which the Pilot Group is heard and in which Staatsbosbeheer can benefit from the involvement of the Pilot Group. This could ultimately lead to a kind of management covenant. It is very positive for the Pilot Group that it is deploying its waste disposal activities (and thus taking a great deal of the work out of the hands of Staatsbosbeheer as manager) to show that it is in the process of putting into practice one of the most important wishes of the inhabitants and of the stakeholders. Through a networking and cooperative management style, Staatsbosbeheer can fulfill the desired “experiencing nature together”. The results of this project can serve as an example for other Natura 2000 floodplains in the Netherlands with similar issues and tensions between management styles.
Machine learning to realize phosphate equilibrium at field level in dairy farming
Mollenhorst, H. ; Haan, M.H.A. De; Oenema, J. ; Hoving-Bolink, A.H. ; Veerkamp, R.F. ; Kamphuis, C. - \ 2019
In: Precision Livestock Farming 2019. - Teagasc (Precision Livestock Farming 2019 - Papers Presented at the 9th European Conference on Precision Livestock Farming, ECPLF 2019 ) - ISBN 9781841706542 - p. 41 - 44.
Boosting - Crop yield - Machine learning - Manure - Phosphorus - Regression tree

An important factor in circular agriculture is efficient application of animal manure. Therefore, input and output of nutrients, like phosphorus (P), need to be balanced. Currently, manure application is regulated with rather fixed P application norms as a generic translation of P yields of grassland and maize. Predicting P yields based on field specific, historical data could be an important step to better balance P input and output. This study's objective was to predict P yields based on field and weather data, using machine learning. The dataset contained 640 records of yearly crop yields per field between 1993-2016 with information on P input and output, irrigation, and soil status at field level as well as local weather data. Generalized boosted regression (GBR) was used to predict P yields for the last five years based on information from all previous years. Model performance was evaluated per year as well as together by plotting observed versus predicted values of all five years in one plot. This final plot was compared to a plot with the currently used generic application norms. Model performance per year showed that GBR could predict the trend from low to high rather well (correlations of ~0.8). Results of the five years together showed that GBR performance was better than the generic application norms (correlation 0.68 vs 0.59; RMSE 7.3 vs 8.2). In conclusion, GBR contributed to defining more flexible P application norms with the aim to realize a phosphate equilibrium.

Older adults’ active involvement in an undergraduate program in gerontology: Motives and meaning
Sliepenbeek, Marjan ; Smits, Carolien ; Spelt, Elisabeth J.H. ; Jukema, Jan S. - \ 2019
Gerontology and Geriatrics Education (2019). - ISSN 0270-1960
cocreation - Gerontological competences - older adults - undergraduate education - volunteers

Two Dutch undergraduate programs in applied gerontology have teamed up with older volunteers to educate students in collaborating with older adults in the field of age-friendly service development. The research question of this study was: What are the motives and meanings of the older volunteers concerning their participation in an undergraduate program? An explorative descriptive qualitative design was used to study the motives and meanings of the older volunteers through semi-structured interviews (n = 11) and a focus group interview (n = 4). Two themes and nine categories emerged: (1) Personal norms and values (categories: responsible life attitude, contribution, self-determination), (2) Personal gain (categories: intergenerational education, personal development, staying healthy, pleasure, feeling appreciated, feeling connected). Personal norms and values and personal gains are meaningful to older volunteers in applied gerontology education. Universities should respect these when designing measures for improving participation methods.

Earthworms Coordinate Soil Biota to Improve Multiple Ecosystem Functions
Liu, Ting ; Chen, Xiaoyun ; Gong, Xin ; Lubbers, Ingrid M. ; Jiang, Yangyang ; Feng, Wen ; Li, Xianping ; Whalen, Joann K. ; Bonkowski, Michael ; Griffiths, Bryan S. ; Hu, Feng ; Liu, Manqiang - \ 2019
Current Biology 29 (2019)20. - ISSN 0960-9822 - p. 3420 - 3429.
bacterial-dominated channel - earthworm - ecosystem engineer - ecosystem service - soil fauna - soil microbe - sustainable agriculture

Liu et al. study a 13-year-old field experiment to show that earthworms are beneficial to agroecosystems from a multifunctional perspective. This work incorporates the concerns of negative effects of earthworms in recently published syntheses and highlights the potential pathways in which earthworms contribute to sustainable agriculture.

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