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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Engineering Geobacillus thermodenitrificans to introduce cellulolytic activity; expression of native and heterologous cellulase genes
Daas, Martinus J.A. ; Nijsse, Bart ; Weijer, Antonius H.P. van de; Groenendaal, Bart W.A.J. ; Janssen, Fons ; Oost, John van der; Kranenburg, Richard van - \ 2018
BMC Biotechnology 18 (2018)1. - ISSN 1472-6750
CBP - Cellulase - Geobacillus - Metagenome - β-Xylosidase

Background: Consolidated bioprocessing (CBP) is a cost-effective approach for the conversion of lignocellulosic biomass to biofuels and biochemicals. The enzymatic conversion of cellulose to glucose requires the synergistic action of three types of enzymes: exoglucanases, endoglucanases and β-glucosidases. The thermophilic, hemicellulolytic Geobacillus thermodenitrificans T12 was shown to harbor desired features for CBP, although it lacks the desired endo and exoglucanases required for the conversion of cellulose. Here, we report the expression of both endoglucanase and exoglucanase encoding genes by G. thermodenitrificans T12, in an initial attempt to express cellulolytic enzymes that complement the enzymatic machinery of this strain. Results: A metagenome screen was performed on 73 G. thermodenitrificans strains using HMM profiles of all known CAZy families that contain endo and/or exoglucanases. Two putative endoglucanases, GE39 and GE40, belonging to glucoside hydrolase family 5 (GH5) were isolated and expressed in both E. coli and G. thermodenitrificans T12. Structure modeling of GE39 revealed a folding similar to a GH5 exo-1,3-β-glucanase from S. cerevisiae. However, we determined GE39 to be a β-xylosidase having pronounced activity towards p-nitrophenyl-β-d-xylopyranoside. Structure modelling of GE40 revealed its protein architecture to be similar to a GH5 endoglucanase from B. halodurans, and its endoglucanase activity was confirmed by enzymatic activity against 2-hydroxyethylcellulose, carboxymethylcellulose and barley β-glucan. Additionally, we introduced expression constructs into T12 containing Geobacillus sp. 70PC53 endoglucanase gene celA and both endoglucanase genes (M1 and M2) from Geobacillus sp. WSUCF1. Finally, we introduced expression constructs into T12 containing the C. thermocellum exoglucanases celK and celS genes and the endoglucanase celC gene. Conclusions: We identified a novel G. thermodenitrificans β-xylosidase (GE39) and a novel endoglucanase (GE40) using a metagenome screen based on multiple HMM profiles. We successfully expressed both genes in E. coli and functionally expressed the GE40 endoglucanase in G. thermodenitrificans T12. Additionally, the heterologous production of active CelK, a C. thermocellum derived exoglucanase, and CelA, a Geobacillus derived endoglucanase, was demonstrated with strain T12. The native hemicellulolytic activity and the heterologous cellulolytic activity described in this research provide a good basis for the further development of G. thermodenitrificans T12 as a host for consolidated bioprocessing.

Klimaatverandering en kwelders: verdrinken of verjongen?
Vader, Lotte ; Kuiters, A.T. - \ 2018
In: Buigen of barsten / Schaminée, Joop, Janssen, John, Zeist : KNNV uitgeverij (Vegetatiekundige monografieën 7) - ISBN 9789050116602 - p. 96 - 123.
Revisiting the enzymatic kinetics of pepsin using isothermal titration calorimetry
Luo, Q. ; Chen, Dongxin ; Boom, R.M. ; Janssen, A.E.M. - \ 2018
Food Chemistry 268 (2018). - ISSN 0308-8146 - p. 94 - 100.
Pepsin is the first protease that food proteins encounter in the digestive tract. However, most of the previous studies on the enzymatic kinetics of pepsin were based on the hydrolysis of small synthetic peptides, due to the limitations in methodology and the complexity of protein substrate. To better understand the role of pepsin in protein digestion, we used isothermal titration calorimetry to study the enzymatic kinetics of pepsin with bovine serum albumin as the substrate. We found that pepsin has a higher catalytic rate at lower pH, while its affinity to substrate is lower. At the same pH, pepsin has lower activity and affinity at higher ionic strengths. We found contrasting kinetic parameters for pepsin-catalyzed hydrolysis of bovine serum albumin and of small synthetic peptides. Time-dependent kinetics also showed that pepsin has lower efficiency towards intermediate peptides during hydrolysis.
In vitro gastric digestion of protein-based structured food : An engineering approach
Luo, Qi - \ 2018
University. Promotor(en): Remko Boom, co-promotor(en): Anja Janssen. - Wageningen : Wageningen University - ISBN 9789463437707 - 174
Regulation of angiopoietin-like 4 and lipoprotein lipase in human adipose tissue
Dijk, Wieneke ; Schutte, Sophie ; Aarts, Edo O. ; Janssen, Ignace M.C. ; Afman, Lydia ; Kersten, Sander - \ 2018
Journal of Clinical Lipidology 12 (2018)3. - ISSN 1933-2874 - p. 773 - 783.
ANGPTL4 - Human adipose tissue - Lipid metabolism - LPL - Triglycerides
Background: Elevated plasma triglycerides are increasingly viewed as a causal risk factor for coronary artery disease. One protein that raises plasma triglyceride levels and that has emerged as a modulator of coronary artery disease risk is angiopoietin-like 4 (ANGPTL4). ANGPTL4 raises plasma triglyceride levels by inhibiting lipoprotein lipase (LPL), the enzyme that catalyzes the hydrolysis of circulating triglycerides on the capillary endothelium. Objective: The objective of the present study was to assess the association between ANGPTL4 and LPL in human adipose tissue, and to examine the influence of nutritional status on ANGPTL4 expression. Methods: We determined ANGPTL4 and LPL mRNA and protein levels in different adipose tissue depots in a large number of severely obese patients who underwent bariatric surgery. Furthermore, in 72 abdominally obese subjects, we measured ANGPTL4 and LPL mRNA levels in subcutaneous adipose tissue in the fasted and postprandial state. Results: ANGPTL4 mRNA levels were highest in subcutaneous adipose tissue, whereas LPL mRNA levels were highest in mesenteric adipose tissue. ANGPTL4 and LPL mRNA levels were strongly positively correlated in the omental and subcutaneous adipose tissue depots. In contrast, ANGPTL4 and LPL protein levels were negatively correlated in subcutaneous adipose tissue, suggesting a suppressive effect of ANGPTL4 on LPL protein abundance in subcutaneous adipose tissue. ANGPTL4 mRNA levels were 38% higher in the fasted compared to the postprandial state. Conclusion: Our data provide valuable insights into the relationship between ANGPTL4 and LPL in human adipose tissue, as well as the physiological function and regulation of ANGPTL4 in humans.
Lipid metabolism in Nannochloropsis gaditana during nitrogen starvation
Janssen, Jorijn H. - \ 2018
University. Promotor(en): Rene Wijffels, co-promotor(en): Maria Barbosa. - Wageningen : Wageningen University - ISBN 9789463437691 - 164
Classification of European and Mediterranean coastal dune vegetation
Marcenò, Corrado ; Guarino, Riccardo ; Loidi, Javier ; Herrera, Mercedes ; Isermann, Maike ; Knollová, Ilona ; Tichý, Lubomír ; Tzonev, Rossen T. ; Acosta, Alicia Teresa Rosario ; Fitzpatrick, Úna ; Iakushenko, Dmytro ; Janssen, John A.M. ; Jiménez-Alfaro, Borja ; Kacki, Zygmunt ; Keizer-Sedláková, Iva ; Kolomiychuk, Vitaliy ; Rodwell, John S. ; Schaminée, Joop H.J. ; Šilc, Urban ; Chytrý, Milan - \ 2018
Applied Vegetation Science (2018). - ISSN 1402-2001 - 27 p.
Ammophiletea - Biogeography - Expert system - Honckenyo-Elymetea - Koelerio-Corynephoretea canescentis - Phytosociology - Sand dune - Vegetation classification

Aims: Although many phytosociological studies have provided detailed local and regional descriptions of coastal dune vegetation, a unified classification of this vegetation in Europe and the Mediterranean Basin has been missing. Our aim is to produce a formalized classification of this vegetation and to identify the main factors driving its plant species composition at a continental scale. Location: Atlantic and Baltic coasts of Europe, Mediterranean Basin and the Black Sea region. Methods: We compiled a database of 30,759 plots of coastal vegetation, which were resampled to reduce unbalanced sampling effort, obtaining a data set of 11,769 plots. We classified these plots with TWINSPAN, interpreted the resulting clusters and used them for developing formal definitions of phytosociological alliances of coastal dune vegetation, which were included in an expert system for automatic vegetation classification. We related the alliances to climatic factors and described their biogeographic features and their position in the coastal vegetation zonation. We examined and visualized the floristic relationships among these alliances by means of DCA ordination. Results: We defined 18 alliances of coastal dune vegetation, including the newly described Centaureo cuneifoliae-Verbascion pinnatifidi from the Aegean region. The main factors underlying the differentiation of these alliances were biogeographic and macroclimatic contrasts between the Atlantic-Baltic, Mediterranean and Black Sea regions, along with ecological differences between shifting and stable dunes. The main difference in species composition was between the Atlantic-Baltic and Mediterranean-Black Sea regions. Within the former region, the main difference was driven by the different ecological conditions between shifting and stable dunes, whereas within the latter, the main difference was biogeographic between the Mediterranean and the Black Sea. Conclusions: The first formal classification of the European coastal dune vegetation was established, accompanied by an expert system containing the formal definitions of alliances, which can be applied to new data sets. The new classification system critically revised the previous concepts and integrated them into a consistent framework, which reflects the main gradients in species composition driven by biogeographic influences, macroclimate and the position of the sites in the coast-inland zonation of the dune systems. A revision of the class concept used in EuroVegChecklist is also proposed.

A liquid foam-bed photobioreactor for microalgae production
Jánoska, Ágnes - \ 2018
University. Promotor(en): Rene Wijffels, co-promotor(en): Marcel Janssen. - Wageningen : Wageningen University - ISBN 9789463432689 - 218
Effect of nitrogen addition on lipid productivity of nitrogen starved Nannochloropsis gaditana
Janssen, Jorijn H. ; Kastenhofer, Jens ; Hoop, Jacob A. de; Lamers, Packo P. ; Wijffels, René H. ; Barbosa, Maria J. - \ 2018
Algal Research 33 (2018). - ISSN 2211-9264 - p. 125 - 132.
Biomass composition - Nannochloropsis gaditana - Nitrogen addition during night - Nitrogen starvation - Triacylglycerol

Microalgae are a sustainable source of lipids. A commonly used strategy for lipid accumulation in microalgae is a two-step batch cultivation, with a growth phase followed by a nitrogen starvation phase. A problem with this process is the decrease in photosynthetic efficiency during the nitrogen starvation phase, which leads to low lipid productivities. In this research, a new process strategy was studied with the aim to improve lipid productivity of the microalgae Nannochloropsis gaditana. The nitrogen concentrations were chosen to assure consumption of most part of the nitrogen during the night. An improvement of the photosystem II maximum quantum yield and an increase in the dry weight and TAG concentration was achieved from day 7 of nitrogen starvation onwards when the culture was fed with nitrogen each night compared to a culture without nitrogen addition. Consequently, the time-average TAG yield on light was also higher after 7 days of nitrogen starvation. However, since the maximal time-averaged triacylglycerol (TAG) yield on light was reached after 3 days of nitrogen starvation, the improved photosynthetic activity did not lead to an increase of the maximal time-averaged TAG yield on light. The culture with nitrogen addition had a higher protein concentration (1.1 compared to 0.7 g L−1), showing that the added nitrogen was mainly used for protein production. A higher chlorophyll a content (2.0 compared to 0.8 μg mg−1) showed improved photosystem and that a small part of nitrogen was used for chlorophyll a. Small nightly nitrogen additions during batch cultivation of nitrogen starved N. gaditana did result in improvement in photosystem II maximal quantum yield, biomass concentration, TAG production and a higher time-averaged maximal TAG yield on light, after 7 days of nitrogen starvation.

Bouwen aan vertrouwen: woningbouwprogrammering aan de vooravond van de omgevingswet : eindrapport PROSPER-onderzoek
Wichard, Lars ; Janssen-Jansen, Leonie ; Spit, Tejo - \ 2018
Wageningen : Wageningen Universiteit, Land Use Planning - ISBN 9789463432696 - 79
Leucine Supplementation Does Not Attenuate Skeletal Muscle Loss during Leg Immobilization in Healthy, Young Men
Backx, E.M.P. ; Horstman, A.M.H. ; Marzuca-Nassr, G.N. ; Kranenburg, J. van; Smeets, J.S. ; Fuchs, C.J. ; Janssen, A.A.W. ; Groot, C.P.G.M. de; Snijders, T. ; Verdijk, L.B. ; Loon, L.J.C. van - \ 2018
Nutrients 10 (2018)5. - ISSN 2072-6643
Background: Short successive periods of physical inactivity occur throughout life and contribute considerably to the age-related loss of skeletal muscle mass. The maintenance of muscle mass during brief periods of disuse is required to prevent functional decline and maintain metabolic health. Objective: To assess whether daily leucine supplementation during a short period of disuse can attenuate subsequent muscle loss in vivo in humans. Methods: Thirty healthy (22 ± 1 y) young males were exposed to a 7-day unilateral knee immobilization intervention by means of a full leg cast with (LEU, n = 15) or without (CON, n = 15) daily leucine supplementation (2.5 g leucine, three times daily). Prior to and directly after immobilization, quadriceps muscle cross-sectional area (computed tomography (CT) scan) and leg strength (one-repetition maximum (1-RM)) were assessed. Furthermore, muscle biopsies were taken in both groups before and after immobilization to assess changes in type I and type II muscle fiber CSA. Results: Quadriceps muscle cross-sectional area (CSA) declined in the CON and LEU groups (p < 0.01), with no differences between the two groups (from 7712 ± 324 to 7287 ± 305 mm2 and from 7643 ± 317 to 7164 ± 328 mm2; p = 0.61, respectively). Leg muscle strength decreased from 56 ± 4 to 53 ± 4 kg in the CON group and from 63 ± 3 to 55 ± 2 kg in the LEU group (main effect of time p < 0.01), with no differences between the groups (p = 0.052). Type I and II muscle fiber size did not change significantly over time, in both groups (p > 0.05). Conclusions: Free leucine supplementation with each of the three main meals (7.5 g/d) does not attenuate the decline of muscle mass and strength during a 7-day limb immobilization intervention.
Brood ruiken is niet brood kiezen
Vingerhoeds, Monique - \ 2018
Provenance, Ideology and the Public Interest in Planning
Janssen-Jansen, Leonie ; Lloyd, Greg - \ 2018
In: The Routledge Handbook of Institutions and Planning in Action / Salet, Willem, Routledge - ISBN 9781138085732
Improved liquid foam-bed photobioreactor design for microalgae cultivation
Janoska, Agnes ; Barten, Robin ; Nooy, Sam de; Rijssel, Piotr van; Wijffels, René H. ; Janssen, Marcel - \ 2018
Algal Research 33 (2018). - ISSN 2211-9264 - p. 55 - 70.
Cultivation - Foam - Foam-bed photobioreactor - Microalgae - Surfactant
The liquid foam-bed photobioreactor is a recently developed photobioreactor concept that allows for cost reduction in microalgae cultivation. Long term operation was not yet achieved, due to degradation of the surfactant. In this study, Pluronic F68 was applied for foam stabilization. In order to compensate for the low algae partitioning to Pluronic F68 stabilized foam, liquid recirculation was introduced into the reactor design. The microalgal suspension was continuously pumped from the bottom of the reactor to the top of the foam column where it was allowed to drain down again through the foam. This new design allowed increased mixing and, thereby, a homogenous algae distribution within the reactor. The volumetric mass transfer coefficient for CO2 in the foam-bed was 0.14 s−1, revealing that the gas transfer rate is an order of magnitude higher compared to bubble column reactors. This characteristic, together with a very high gas residence time, allows for a dramatic reduction in gas flow rate and a high carbon dioxide utilization efficiency. Long-term cultivation (>500 h) of Chlorella sp. was achieved in a stable foam-bed. The areal productivity of the foam-bed photobioreactor was 57 g m−2 d−1, which is slightly lower than maximally achieved in flat panels under similar conditions. This is possibly related to substantial light scattering taking place in the foam leading to a steeper light gradient and increased reflection. The reactor dilution rate and the liquid recirculation rate were not optimized during our experiments and there is room for further improvement. During continuous reactor operation, biomass densities of >20 g L−1 could be maintained. This biomass density is a factor of 10 higher compared to traditional, liquid phase photobioreactors, thereby, contributing to reduced energy requirements for microalgae harvesting.
Potential of insect proteins for food and feed : Effect of endogenous enzymes and iron-phenolic complexation
Janssen, Renske H. - \ 2018
University. Promotor(en): Vincenzo Fogliano, co-promotor(en): Jean-Paul Vincken; Catriona Lakemond. - Wageningen : Wageningen University - ISBN 9789463437684 - 145
Sterke bewerking voedselingrediënten is onnodig
Geerts, Marlies - \ 2018
Protein intake in hospitalized older people with and without increased risk of malnutrition
Vasse, Emmelyne ; Beelen, J. ; Roos, N.M. de; Janssen, N. ; Groot, C.P.G.M. de - \ 2018
European Journal of Clinical Nutrition 72 (2018)6. - ISSN 0954-3007 - p. 917 - 919.
A protein intake of ≥1.2 grams per kg body weight (g/kg) is recommended for ill older adults. In a cross-sectional study, we investigated if this recommendation was met by 62 hospitalized adults of 65 years and older in a Dutch hospital. We compared protein intake between two subgroups based on the risk of malnutrition and the prescribed diet: a low risk group (n = 31) receiving a standard hospital diet and a medium/high risk group (n = 31) receiving a protein-enriched diet. A 24h-recall was performed to calculate protein intake per patient. Protein intake was on average 1.2 g/kg in the medium/high risk group and 0.9 g/kg in the low-risk group. Seventeen patients reached a protein intake of ≥1.2 g/kg. Fifteen patients had a protein intake below 0.8 g/kg. It seems sensible to consider providing a protein-enriched diet to all older hospitalized adults, regardless of their risk of malnutrition.
A Dutch perspective on urban growth boundaries : From containing to stimulating growth
Janssen-Jansen, Leonie ; Tan, Wendy - \ 2018
In: Instruments of Land Policy Taylor and Francis - ISBN 9781138201514 - p. 137 - 141.
Within international planning educational circles, the Netherlands has long been held up as an exemplar of effective national and regional land use planning practices. Well-known examples are the water management policies (van der Cammen and de Klerk 2012). The clearly defined administrative hierarchies, the policy consistency, and the management of the land resource with governmental controls in planning have been praised in planning literature. The Dutch planning system is seen as a great example for other countries, just as Sullivan’s Portland example (Bontje 2003; Fainstein 2005). The urban growth boundary (UGB) of the Regional Framework Plan of Portland is likewise one of the most outstanding elements of the land use planning system in State of Oregon. This is an example of an instrument accompanied by many other complementary ordinances, regulations, and rules that together result in a desired planning outcome. The UGB is therefore often compared to national planning instruments in the Netherlands intent on enforcing a strict boundary between the urban and the rural. In the Netherlands, this divide has always been a keystone concept of the land use planning system, which is to keep as much open space ‘open’ as possible, while concurrently address the need for expansion and growth by ensuring enough land for residential development in a context of land scarcity in the upcoming decades. This is a similar situation to Portland where the growth necessary for the next 20 years needs to be balanced by the geographical constraints of the nature and agricultural areas. Although the regional UGB enjoys statutory status in Portland, regional coordination is considered an informal norm within the Netherlands. For example, certain provinces keep to an 80–20 rule, whereby the majority of new developments should take place within existing urban contours. The regional focus of Portland’s planning system is relevant for international planners as most land use issues tend to cross administrative borders in nature and involve more than a single government level. On the surface, the Dutch planning system might not have much to offer as compared to Portland as the legal force is maintained mostly at the local level in the form of municipal land use plans (Needham 2016). Although the 2008 revision of the planning law (WRO 2008) does enable regional and inter-municipal zoning plans 138that can be brought forward by multiple municipalities or proposed by the Dutch regional government – the province – this instrument has been hardly implemented. From the provincial perspective, ‘overthrowing’ municipalities is politically not popular; municipalities – and their governors – focus on the land in their municipality as they are accountable for planning within the municipality, not outside.
A mega-nourishment creates novel habitat for intertidal macroinvertebrates by enhancing habitat relief of the sandy beach
Egmond, E.M. van; Bodegom, P.M. van; Berg, M.P. ; Wijsman, J.W.M. ; Leewis, L. ; Janssen, G.M. ; Aerts, R. - \ 2018
Estuarine Coastal and Shelf Science 207 (2018). - ISSN 0272-7714 - p. 232 - 241.
Beach management - Benthos - Community composition - Soft-sediment beach - Zonation
Globally, sandy beaches are subject to coastal squeeze due to erosion. Soft-sediment strategies, such as sand nourishment, are increasingly applied to mitigate effects of erosion, but have long-term negative impacts on beach flora and fauna. As a more ecologically and sustainable alternative to regular beach nourishments, a mega-nourishment has been constructed along the Dutch coast by depositing 21.5 Mm3 of sand, from which sand is gradually redistributed along the coast by natural physical processes. The 'sand Motor’ mega-nourishment was constructed as a long-term management alternative for coastal protection and is the first large-scale experiment of its kind. We evaluated the development of intertidal macroinvertebrate communities in relation to this mega-nourishment, and compared it to species composition of beaches subject to regular beach or no nourishment. We found that a mega-nourishment resulted initially in a higher macroinvertebrate richness, but a lower macroinvertebrate abundance, compared to regular beach nourishment. As there was no effect of year after nourishment, this finding suggests that colonization and/or local extinction were not limiting macroinvertebrate richness at the mega-nourishment. In addition, a mega-nourishment does not converge to an intertidal macroinvertebrate community similar to those on unnourished beaches within a time scale of four years. Beach areas at the mega-nourishment sheltered from waves harbored a distinct macroinvertebrate community compared to typical wave-exposed sandy beach communities. Thus, a mega-nourishment temporally creates new habitat for intertidal macroinvertebrates by enhancing habitat relief of the sandy beach. We conclude that a mega-nourishment may be a promising coastal defense strategy for sandy shores in terms of the macroinvertebrate community of the intertidal beach.
Greater mindful eating practice is associated with better reversal learning
Janssen, Lieneke K. ; Duif, Iris ; Loon, Ilke Van; Vries, Jeanne H.M. De; Speckens, Anne E.M. ; Cools, Roshan ; Aarts, Esther - \ 2018
Scientific Reports 8 (2018)1. - ISSN 2045-2322

Mindfulness-based interventions are thought to reduce compulsive behavior such as overeating by promoting behavioral flexibility. Here the main aim was to provide support for mindfulness-mediated improvements in reversal learning, a direct measure of behavioral flexibility. We investigated whether an 8-week mindful eating intervention improved outcome-based reversal learning relative to an educational cooking (i.e., active control) intervention in a non-clinical population. Sixty-five healthy participants with a wide BMI range (19-35 kg/m2), who were motivated to change their eating habits, performed a deterministic reversal learning task that enabled the investigation of reward- and punishment-based reversal learning at baseline and following the intervention. No group differences in reversal learning were observed. However, time invested in the mindful eating, but not the educational cooking intervention correlated positively with changes in reversal learning, in a manner independent of outcome valence. These findings suggest that greater amount of mindfulness practice can lead to increased behavioral flexibility, which, in turn, might help overcome compulsive eating in clinical populations.

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