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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Food reward from a behavioural and (neuro)physiological perspective
Bruijn, Suzanne E.M. - \ 2017
Wageningen University. Promotor(en): C. de Graaf; R.F. Witkamp, co-promotor(en): G. Jager. - Wageningen : Wageningen University - ISBN 9789463436748 - 154
food - physiological functions - feeding behaviour - food preferences - perception - hormones - responses - neurohormonal control - stomach bypass - gastric bypass - satiety - voedsel - fysiologische functies - voedingsgedrag - voedselvoorkeuren - perceptie - hormonen - reacties - neurohormonale controle - maag bypass - buik bypass - verzadigdheid

Food reward is an important driver of food intake and triggers consumption of foods for pleasure, so-called hedonic eating, even in the absence of any energy deficits. Hedonic eating can trigger overeating and may therefore lead to obesity. Given the rise in obesity rates and the health risks associated with being obese, hedonic eating and food reward are important phenomena to study. This thesis aimed to add on to the existing knowledge on food reward. The phenomenon was approached from a behavioural, sensory and (neuro)physiological perspective in healthy, lean and in obese gastric bypass populations.

For the behavioural perspective, the main outcome measure used in this thesis was food preferences. To be able to study food preferences for four macronutrient and two taste categories, a new food preference task was developed. In chapter 2, the development and validation of the Macronutrient and Taste Preference Ranking Task (MTPRT) were described. The MTPRT uses a ranking method to determine preferences for four macronutrient (high-carbohydrate, high-fat, high-protein, low-energy) and two taste (sweet and savoury) categories.

For the sensory and physiological perspective, focus was put on the endocannabinoid system (ECS): a neuromodulatory system that plays a role in food reward. To gain more insight into this role, the effect of ECS modulation with pharmacological challenges on sensory perception of sweet taste and on food preferences were studied, as well as endocannabinoid responses to food intake. In chapter 3 it was shown that inhaling Cannabis with low doses of Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) does not alter sweet taste intensity perception and liking in humans, nor does it affect food preferences. Vice versa, in chapter 4 it was found that liking of a food taste does not affect endocannabinoid responses to food intake, after controlling for expectations. When palatability of the food is unknown until the first bite, response of endocannabinoids, ghrelin and pancreatic polypeptide did not differ between a palatable and a neutral food across anticipatory, consummatory and post-ingestive phases of food intake. Endocannabinoid and ghrelin plasma concentrations decreased after food intake, which suggests an orexigenic function for endocannabinoids.

In chapters 5, 6 and 7, studies with patients who underwent Roux-en-Y gastric bypass surgery were described. These studies were intended to gain more insight into alterations in food reward in relation to (morbid) obesity and in response to surgical treatment by RYGB surgery.

First, in chapter 5 food preferences were assessed before, and at two months and one year after RYGB. It was shown that patients have decreased preference for high-carbohydrate and high-fat foods, and increased preference for low-energy foods after compared with before surgery. In addition, liking ratings for the high-carbohydrate and high-fat foods were decreased after RYGB surgery, whereas liking of low-energy products changed minimally. Potential mechanisms behind these alterations in food preferences include changes in neural processing of food cues and changes in appetite-related gut hormones.

In chapter 6, it was shown that alterations in food preferences after RYGB surgery are indeed related to changes in neural activation in response to food cues. With regards to the appetite-related hormones it was shown that plasma concentrations of the endocannabinoid anandamide were increased after compared with before surgery. Plasma concentrations of other endocannabinoids and ghrelin did not change. Moreover, changes in endocannabinoid or ghrelin concentrations did not correlate with changes in food preferences or neural response to food cues. Together, these results suggest that changes in neural processing of food cues contribute to changes in food preferences towards low-energy foods, and provide a first indication that the endocannabinoid system does not seem to play a role in this process.

To gain more insight into behavioural responses to food cues, a response-inhibition paradigm was used in chapter 7, in which response-inhibition to high-energy and low-energy food cues was assessed during brain imaging. The behavioural data did not show differences in performance when comparing before and two months after RYGB surgery. The brain imaging data showed that activation in reward-related brain areas was decreased in response to both high- and low-energy food pictures after RYGB surgery. Also, prefrontal brain areas were more activated in response to the high-energy pictures, which suggests improved response inhibition.

In conclusion, the findings in this thesis show that modulating the ECS with low doses of THC and CBD does not influence sweet taste perception and liking and food preferences, and vice versa, food taste liking in the absence of expectations does not affect endocannabinoid responses to food intake. With regards to RYGB surgery it was uncovered that changes in food preferences after RYGB surgery are related to altered brain reward processing, but no relation with changes in endocannabinoid tone was found. The success of RYGB surgery and the changes in food choice might in part be caused by an improved inhibitory response to high-energy foods.

How virtual shade sheds light on plant plasticity
Bongers, Franca J. - \ 2017
Wageningen University. Promotor(en): N.P.R. Anten, co-promotor(en): R. Pierik; J.B. Evers. - Wageningen : Wageningen University - ISBN 9789463432047 - 140
planten - fenotypen - fenotypische variatie - modellen - arabidopsis - natuurlijke selectie - schaduw - reacties - concurrentie tussen planten - licht - plants - phenotypes - phenotypic variation - models - arabidopsis - natural selection - shade - responses - plant competition - light

Phenotypic plasticity is the ability of a genotype to express multiple phenotypes in accordance with different environments. Although variation in plasticity has been observed, there is limited knowledge on how this variation results from natural selection. This thesis analyses how variation in the level of plasticity influences light competition between plants and how this variation could result from selection, driven by light competition, in various environments. As an exemplary case of phenotypic plasticity, this thesis focusses on phenotypic responses of the annual rosette plant Arabidopsis thaliana (Brassicaceae) in response to the proximity of neighbour plants, as signalled through the red : far—red (R:FR) ratio, which are responses associated with the shade avoidance syndrome (SAS).

Plant experiments were conducted to measure variation in these plastic responses and a functional-structural plant (FSP) model was created that simulates plant structures in 3D and includes these organ-level plastic responses while simulating explicitly a heterogeneous light environment. Simulating individual plants that explicitly compete for light, while their phenotype changes through plasticity, gave insights in the role of the level of phenotypic plasticity and site of signal perception on plant competitiveness. In addition, an analysis on how natural selection in different environments acts on the level of plasticity was performed by combining FSP simulations and evolutionary game theoretical (EGT) principles.

Right light colour gives plant a boost : research shows relationship light and plant immunity
Velden, P. van; Hofland-Zijlstra, J.D. - \ 2015
In Greenhouses : the international magazine for greenhouse growers 4 (2015)2. - ISSN 2215-0633 - p. 16 - 17.
glastuinbouw - snijbloemen - plantenontwikkeling - belichting - schimmelziekten - ziektebestrijding - reacties - verrood licht - landbouwkundig onderzoek - greenhouse horticulture - cut flowers - plant development - illumination - fungal diseases - disease control - responses - far red light - agricultural research
Light could be an important factor as to whether a plant is sensitive to fungal infestation or not. This is a whole new angle because until now only the relationship with the greenhouse climate was considered: perhaps it’s too dry, too wet, too warm or too cold. Even at a high RH a plant doesn’t need to suffer from disease, according to the researchers Jantineke Hofland-Zijlstra and Luc Stevens. They are carrying out fundamental research on plant immunity in relation to light.
Parasitism overrides herbivore identity allowing hyperparasitoids to locate their parasitoid host using herbivore-induced plant volatiles
Zhu, F. ; Broekgaarden, C. ; Weldegergis, B.T. ; Harvey, J.A. ; Vosman, B. ; Dicke, M. ; Poelman, E.H. - \ 2015
Molecular Ecology 24 (2015)1. - ISSN 0962-1083 - p. 2886 - 2899.
cabbage brassica-oleracea - time rt-pcr - nicotiana-attenuata - insect herbivores - gene-expression - trophic levels - defense - responses - specialist - generalist
Foraging success of predators profoundly depends on reliable and detectable cues indicating the presence of their often inconspicuous prey. Carnivorous insects rely on chemical cues to optimize foraging efficiency. Hyperparasitoids that lay their eggs in the larvae or pupae of parasitic wasps may find their parasitoid hosts developing in different herbivores. They can use herbivore-induced plant volatiles (HIPVs) to locate parasitized caterpillars. Because different herbivore species induce different HIPV emission from plants, hyperparasitoids may have to deal with large variation in volatile information that indicates host presence. In this study, we used an ecogenomics approach to first address whether parasitized caterpillars of two herbivore species (Pieris rapae and P. brassicae) induce similar transcriptional and metabolomic responses in wild Brassica oleracea plants and, second, whether hyperparasitoids Lysibia nana are able to discriminate between these induced plant responses to locate their parasitoid host in different herbivores under both laboratory and field conditions. Our study revealed that both herbivore identity and parasitism affect plant transcriptional and metabolic responses to herbivory. We also found that hyperparasitoids are able to respond to HIPVs released by wild B. oleracea under both laboratory and field conditions. In addition, we observed stronger attraction of hyperparasitoids to HIPVs when plants were infested with parasitized caterpillars. However, hyperparasitoids were equally attracted to plants infested by either herbivore species. Our results indicate that parasitism plays a major role in HIPV-mediated plant-hyperparasitoid interactions. Furthermore, these findings also indicate that plant trait-mediated indirect interaction networks play important roles in community-wide species interactions.
Evaluating Aquatic invertebrate vulnerability to insecticides based on intrinsic sensitivuty, biological traits, and toxic mode of action
Rico, A. ; Brink, P.J. van den - \ 2015
Environmental Toxicology and Chemistry 34 (2015)8. - ISSN 0730-7268 - p. 1907 - 1917.
ecological risk-assessment - fresh-water arthropods - species sensitivity - community structure - lambda-cyhalothrin - short-term - responses - microcosms - recovery - stream
In the present study, the authors evaluated the vulnerability of aquatic invertebrates to insecticides based on their intrinsic sensitivity and their population-level recovery potential. The relative sensitivity of invertebrates to 5 different classes of insecticides was calculated at the genus, family, and order levels using the acute toxicity data available in the US Environmental Protection Agency ECOTOX database. Biological trait information was linked to the calculated relative sensitivity to evaluate correlations between traits and sensitivity and to calculate a vulnerability index, which combines intrinsic sensitivity and traits describing the recovery potential of populations partially exposed to insecticides (e.g., voltinism, flying strength, occurrence in drift). The analysis shows that the relative sensitivity of arthropods depends on the insecticide mode of action. Traits such as degree of sclerotization, size, and respiration type showed good correlation to sensitivity and can be used to make predictions for invertebrate taxa without a priori sensitivity knowledge. The vulnerability analysis revealed that some of the Ephemeroptera, Plecoptera, and Trichoptera taxa were vulnerable to all insecticide classes and indicated that particular gastropod and bivalve species were potentially vulnerable. Microcrustaceans (e.g., daphnids, copepods) showed low potential vulnerability, particularly in lentic ecosystems. The methods described in the present study can be used for the selection of focal species to be included as part of ecological scenarios and higher tier risk assessments.
What reported food-evoked emotions may add: A model to predict consumer food choice
Gutjar, S. ; Dalenberg, J.R. ; Graaf, C. de; Wijk, R.A. de; Palascha, A. ; Renken, Remco J. ; Jager, G. - \ 2015
Food Quality and Preference 45 (2015). - ISSN 0950-3293 - p. 140 - 148.
consumption experience - responses - satisfaction - liking - taste - package - questionnaires - behavior - design - impact
Food-evoked emotions provide information that goes beyond the information from traditional hedonic ratings. The objectives of our study were: (i) to investigate how intrinsic (sensory) and extrinsic (packaging) cues affect consumers’ emotional responses to foods, and (ii) to explore whether emotional responses to these cues combined with liking, predict actual food choice. Participants (n = 103) rated emotional responses to seven products under a blind taste, a package and a package and taste condition using the EsSense Profile™. During the blind taste condition participants also scored liking of the products. Test products were breakfast drinks and desserts. Food choice was measured in two different breakfast sessions reflecting a different choice context. In one choice context, products were presented blind to taste, after which participants chose one out of the seven foods to consume for breakfast. In the other choice context, participants based their choice on the package of the seven foods without tasting them. Results showed that emotions evoked by food products could be organised in a two-dimensional space, representing a valence (pleasantness) and an activation/arousal dimension. Specific emotional profiles generated for products differed across the blind taste, package and the package and taste condition, meaning that intrinsic and extrinsic product properties elicit in part different emotions. Liking and valence together had the strongest predictive value for product choice based on the product’s taste. The combination of liking, valence and arousal had the strongest predictive value for package-based choice. In conclusion, food-evoked emotions add predictive value to solely liking ratings, and may guide consumers’ product choice behaviour.
Simulation of the phenological development of wheat and maize at the global scale
Bussel, L.G.J. van; Stehfest, E. ; Siebert, S. ; Müller, C. ; Ewert, F. - \ 2015
Global Ecology and Biogeography 24 (2015)9. - ISSN 1466-822X - p. 1018 - 1029.
climate-change - winter-wheat - annual crops - photoperiod sensitivity - geographical variation - temperature - responses - adaptation - cultivars - model
To derive location-specific parameters that reflect the geographic differences among cultivars in vernalization requirements, sensitivity to day length (photoperiod) and temperature, which can be used to simulate the phenological development of wheat and maize at the global scale. Location: Global. Methods: Based on crop calendar observations and literature describing the large-scale patterns of phenological characteristics of cultivars, we developed algorithms to compute location-specific parameters to represent this large-scale pattern. Vernalization requirements were related to the duration and coldness of winter, sensitivity to day length was assumed to be represented by the minimum and maximum day lengths occurring at a location, and sensitivity to temperature was related to temperature conditions during the vegetative development phase of the crop. Results: Application of the derived location-specific parameters resulted in high agreement between simulated and observed lengths of the cropping period. Agreement was especially high for wheat, with mean absolute errors of less than 3 weeks. In the main maize cropping regions, cropping periods were over- and underestimated by 0.5-1.5 months. We also found that interannual variability in simulated wheat harvest dates was more realistic when accounting for photoperiod effects. Main conclusions: The methodology presented here provides a good basis for modelling the phenological characteristics of cultivars at the global scale. We show that current global patterns of growing season length as described in cropping calendars can be largely reproduced by phenology models if location-specific parameters are derived from temperature and day length indicators. Growing seasons can be modelled more accurately for wheat than for maize, especially in warm regions. Our method for computing parameters for phenology models from temperature and day length offers opportunities to improve the simulation of crop productivity by crop simulation models developed for large spatial areas and for long-term climate impact projections that account for adaptation in the selection of varieties.
A generic microfluidic biosensor of G protein-coupled receptor activation - impedance measurements of reversible morphological changes of reverse transfected HEK293 cells on microelectrodes
Srivastava, S.K. ; Ramaneti, R. ; Roelse, M. ; Duy Tong, H. ; Vrouwe, E.X. ; Brinkman, A.G.M. ; Smet, L.C.P.M. de; Rijn, C.J.M. van; Jongsma, M.A. - \ 2015
RSC Advances : An international journal to further the chemical sciences 5 (2015). - ISSN 2046-2069 - p. 52563 - 52570.
drug discovery - assays - technology - mechanism - responses - targets - design
Impedance spectroscopy of cell lines on interdigitated electrodes (IDEs) is an established method of monitoring receptor-specific cell shape changes in response to certain analytes. Normally, assays are done in multiwells making it a bulky, static and single use procedure. Here, we present a biosensor allowing sequential application of biological test samples with an automated microfluidic system. It is capable of monitoring relative changes in impedance using castellated IDEs of 250–500 mm diameter, covered with stable or reverse transfected HEK293 cells. Reversible activation of the Neurokinin 1 (NK1) receptor in stable cell lines was observed in response to a series of 5 minute exposures from 1 pM–10 nM of the specific ligand Substance P (SP) using impedance measurements at 10 mV and 15 kHz. An optimal flow speed of 10 ml min 1 was chosen for the 10 ml flow cell. The EC50 of 10 pM was about 10 times lower than the EC50 based on measuring changes in the calcium ion concentration. The method was also shown to work with reverse transfected cells. Plasmid DNA encoding the NK1 gene was spotted onto the electrodes and pre-incubated with a transfection agent. The overlaid HEK293 cells were subsequently transfected by the underlying DNA. After challenge with SP, the cells induced an activation response similar to the stable cell line. The microfluidic micro-electrode reverse transfection system opens up possibilities to perform parallel measurements on IDE arrays with distinct receptors per IDE in a single flow channel .
Species-specific plant-soil feedback effects on above-ground plant-insect interactions
Kos, M. ; Tuijl, M.A.B. ; Roo, J. de; Mulder, P.P.J. ; Bezemer, T.M. - \ 2015
Journal of Ecology 103 (2015)4. - ISSN 0022-0477 - p. 904 - 914.
below-ground herbivory - pyrrolizidine alkaloids - senecio-jacobaea - multitrophic interactions - community composition - tyria-jacobaeae - responses - succession - pathogens - nutrients
1.Plant–soil feedback (PSF) effects on plant performance strongly depend on the plant species that conditioned the soil. Recent studies have shown that PSF can change above-ground plant–insect interactions via soil-mediated changes in plant quality, but whether these effects depend on species-specific soil conditioning is unknown. We examined how PSF effects of several plant species influence above-ground plant–aphid interactions. 2.We grew ragwort (Jacobaea vulgaris) in field soil conditioned specifically by 10 plant species, belonging to three functional groups (grasses, forbs and legumes), in a multispecies mixture of the conditioned soils and in control (unconditioned) field soil. We measured plant biomass, concentrations of primary (amino acids) and secondary (pyrrolizidine alkaloids) metabolites in phloem exudates, and performance of the generalist aphid Brachycaudus cardui and the specialist Aphis jacobaeae. 3.We observed that plant species, via species-specific effects on soil fungal communities, exerted unique plant–soil effects on J. vulgaris biomass, amino acid concentrations in phloem exudates and aphid performance. The direction and magnitude of the species-specific PSF effects on aphid performance differed between both aphid species. PSF effects on soil fungal communities, plant biomass and A. jacobaeae performance also differed between grasses, forbs and legumes, with soil conditioning by forbs resulting in lowest plant biomass and aphid performance. 4.Synthesis. Our study provides novel evidence that PSF effects on above-ground plant–insect interactions are highly species specific. Our results add a new dimension to the rapidly developing research fields of PSF and above-below-ground interactions, and highlights that these fields are tightly linked.
Organising a safe space for navigating social-ecological transformations to sustainability
Pereira, L. ; Karpouzoglou, T.D. ; Doshi, S. ; Frantzeskaki, N. - \ 2015
International Journal of Environmental Research and Public Health 12 (2015)6. - ISSN 1660-4601 - p. 6027 - 6044.
transitions - innovation - framework - systems - perspective - governance - complexity - knowledge - responses - pathways
The need for developing socially just living conditions for the world’s growing population whilst keeping human societies within a ‘safe operating space’ has become a modern imperative. This requires transformative changes in the dominant social norms, behaviours, governance and management regimes that guide human responses in areas such as urban ecology, public health, resource security (e.g., food, water, energy access), economic development and biodiversity conservation. However, such systemic transformations necessitate experimentation in public arenas of exchange and a deepening of processes that can widen multi-stakeholder learning. We argue that there is an emergent potential in bridging the sustainability transitions and resilience approaches to create new scientific capacity that can support large-scale social-ecological transformations (SETs) to sustainability globally, not just in the West. In this article, we elucidate a set of guiding principles for the design of a ‘safe space’ to encourage stronger interactions between these research areas and others that are relevant to the challenges faced. We envisage new opportunities for transdisciplinary collaboration that will develop an adaptive and evolving community of practice. In particular, we emphasise the great opportunity for engaging with the role of emerging economies in facilitating safe space experimentation.
Climate change impact and adaptation research requires integrated assessment and farming systems analysis: a case study in the Netherlands
Reidsma, P. ; Wolf, J. ; Kanellopoulos, A. ; Schaap, B.F. ; Mandryk, M. ; Verhagen, J. ; Ittersum, M.K. van - \ 2015
Environmental Research Letters 10 (2015)4. - ISSN 1748-9326
european-union - crop yields - agriculture - responses - models - wheat - variability - improvement - strategies - scenarios
Rather than on crop modelling only, climate change impact assessments in agriculture need to be based on integrated assessment and farming systems analysis, and account for adaptation at different levels. With a case study for Flevoland, the Netherlands, we illustrate that (1) crop models cannot account for all relevant climate change impacts and adaptation options, and (2) changes in technology, policy and prices have had and are likely to have larger impacts on farms than climate change. While crop modelling indicates positive impacts of climate change on yields of major crops in 2050, a semiquantitative and participatory method assessing impacts of extreme events shows that there are nevertheless several climate risks. A range of adaptation measures are, however, available to reduce possible negative effects at crop level. In addition, at farm level farmers can change cropping patterns, and adjust inputs and outputs. Also farm structural change will influence impacts and adaptation. While the 5th IPCC report is more negative regarding impacts of climate change on agriculture compared to the previous report, also for temperate regions, our results show that when putting climate change in context of other drivers, and when explicitly accounting for adaptation at crop and farm level, impacts may be less negative in some regions and opportunities are revealed. These results refer to a temperate region, but an integrated assessment may also change perspectives on climate change for other parts of the world.
To be in time: egg deposition enhances plant-mediated detection of young caterpillars by parasitoids
Pashalidou, F.G. ; Gols, R. ; Berkhout, B.W. ; Weldegergis, B.T. ; Loon, J.J.A. van; Dicke, M. ; Fatouros, N.E. - \ 2015
Oecologia 177 (2015)2. - ISSN 0029-8549 - p. 477 - 486.
different larval instars - pieris-brassicae - specialist herbivore - volatile emissions - cotesia-glomerata - host location - oviposition - responses - maize - generalist
Animals use information from their environment while foraging for food or prey. When parasitic wasps forage for hosts, they use plant volatiles induced by herbivore activities such as feeding and oviposition. Little information is available on how wasps exploit specific plant volatiles over time, and which compounds indicate changes in host quality. In experiments investigating the role of herbivore-induced plant volatiles in wasp foraging, induction of plant response is usually achieved by placing larvae on clean plants instead of allowing the natural sequence of events: to let eggs deposited by the herbivore develop into larvae. We compared the attraction of the parasitoid Cotesia glomerata to volatiles emitted by black mustard (Brassica nigra) plants induced by eggs and successive larval stages of the Large Cabbage White butterfly (Pieris brassicae) to the attraction of this parasitoid to black mustard plant volatiles induced only by larval feeding in a wind tunnel setup. We show that wasps are attracted to plants infested with eggs just before and shortly after larval hatching. However, wasp preference changed at later time points towards plants induced only by larval feeding. These temporal changes in parasitoid attraction matched with changes in the chemical compositions of the blends of plant volatiles. Previous studies have shown that host quality/suitability decreases with caterpillar age and that P. brassicae oviposition induces plant defences that negatively affect subsequently feeding caterpillars. We investigated parasitoid performance in hosts of different ages. Wasp performance was positively correlated with preference. Moreover, parasitism success decreased with time and host stage. In conclusion, the behaviour of Cotesia glomerata is fine-tuned to exploit volatiles induced by eggs and early host stages that benefit parasitoid fitness.
High natural antibody titers of indigenous chickens are related with increased hazard in confinement
Wondmeneh, E. ; Arendonk, J.A.M. van; Waaij, E.H. van der; Ducro, B.J. ; Parmentier, H.K. - \ 2015
Poultry Science 94 (2015)7. - ISSN 0032-5791 - p. 1493 - 1498.
laying hens - responses - survival - immunity - corticosterone - population - strains - stress - innate - plasma
Natural antibody (NAb) levels and survival rates were evaluated in 4 breeds of laying hens in Ethiopia: indigenous, improved indigenous, exotic layer, and crossbred. Titers of NAb isotypes IgG and IgM binding keyhole limpet hemocyanin (KLH) in serum were measured at 20, 26, 35, and 45 wk age. Repeated-measure ANOVA showed that IgG and IgM levels vary with time within each breed (P <0.05). Indigenous chickens had significantly (P <0.05) higher NAb levels at all ages. The Cox proportional hazard analysis showed increased hazard with increased levels of NAbs in the exotic layers (P <0.05). However, the reduced hazards with increased levels of NAbs were not significant in the improved indigenous and crossbred chickens. Indigenous chickens showed increased hazard with increasing levels of NAb (P > 0.05). We concluded that not only the NAb levels but also the effect of Nabs on survival vary between indigenous and improved breeds. The results indicate that NAb levels are associated with survival in elite (improved) breeds, but are associated with increased hazard in indigenous chickens.
Effect of maternal dry period length on colostrum immunoglobulin content and natural and specific antibody titers in calves
Mayasari, N. ; Vries Reilingh, G. de; Nieuwland, M.G.B. ; Remmelink, G.J. ; Parmentier, H.K. ; Kemp, B. ; Knegsel, A.T.M. van - \ 2015
Journal of Dairy Science 98 (2015)6. - ISSN 0022-0302 - p. 3969 - 3979.
dairy-cows - energy-balance - milk-production - bovine somatotropin - metabolic status - performance - responses - lactation - pathogen - antigen
The objective was to study the effect of dry period length in dairy cows on immunoglobulin content and natural antibodies (NAb) titers in colostrum, growth, and plasma natural and specific antibody titers in plasma of calves. Holstein-Friesian dairy cows (n = 167) were randomly assigned to 3 dry period lengths (0, 30, or 60 d). Colostrum production, concentration of colostrum IgG and IgM, and titers of NAb (isotypes IgG and IgM) binding keyhole limpet hemocyanin (KLH) and human serum albumin (HuSA) in colostrum were measured. Female calves were immunized with both KLH and HuSA at wk 6 and 10 of life. Titers of NAb and specific antibody (SpAb) for isotypes IgG, IgM, and total immunoglobulin (IgT) binding KLH or HuSA were determined in plasma of female calves. Primary and secondary antibody responses to KLH or HuSA from wk 6 and 10 were expressed as the increase in antibody titers to wk 10 and 11 of life after primary and secondary challenges, respectively. Pregnancy length for cows with a 0-d dry period was 3 d shorter compared with cows with a 30- or 60-d dry period. Birth weight of calves from cows with a 0-d dry period was lower compared with calves from cows with a 30-d dry period. Growth of calves until 12 wk of life was not affected by dry period length. Colostrum production and IgG and IgM concentration in colostrum were lower for cows with a 0-d dry period than a 60-d dry period. Natural IgG and IgM titers binding KLH or HuSA were lower in colostrum from cows with a 0-d dry period compared with cows with a 60-d dry period. Natural antibody titers (IgG, IgM, and IgT) binding KLH or HuSA in plasma were lower during the first 2 wk of life for calves from cows with a 0-d dry period compared with calves from cows with a 30- or 60-d dry period. After primary and secondary immunization of calves with KLH and HuSA, SpAb titers of calves were not affected by dry period length. After secondary immunization, the response of IgG and IgT binding KLH was higher in plasma of calves from cows with a 0-d dry period. The results of this study demonstrate that, although omission of the dry period of dairy cows leads to lower plasma NAb titers in calves during the first 2 wk of life, SpAb titers in calves were not affected and even the secondary antibody responses were enhanced compared with calves from cows with a 30- or 60-d dry period.
Macroinvertebrate survival during cessation of flow and streambed drying in a lowland stream
Verdonschot, R.C.M. ; Oosten-Siedlecka, A.M. van; Braak, C.J.F. ter; Verdonschot, P.F.M. - \ 2015
Freshwater Biology 60 (2015)2. - ISSN 0046-5070 - p. 282 - 296.
invertebrate communities - prairie stream - desert stream - drought - intermittent - assemblages - responses - rivers - recolonization - resilience
1.The number of perennial low-order lowland streams likely to experience intermittent flow is predicted to increase in north-western Europe. To understand the effects of such a change on macroinvertebrates, a field experiment was carried out in a currently perennial sandy lowland stream. 2.Using a before–after control–impact design, the flow regime was manipulated to yield two distinct treatments: stagnation (although with little water loss) and drying of the stream (although artificial remnant pools remained in the bed). There was also an unmanipulated control reach. The two treatments were applied simultaneously in separate, consecutive reaches, resulting in 29 days of stagnation and 25 days of streambed drying with surface water only present in the remnant pools. Changes in macroinvertebrate richness, abundance and community composition were recorded, and we assessed whether these changes could be explained by ecological preferences for flow of the various taxa. 3.Stagnation resulted in only minor changes in community composition. A small number of rheophilic taxa disappeared, while taxa preferring standing waters complemented those already present, increasing total biodiversity. In remnant pools in the otherwise dry reach, richness and abundance peaked after they became isolated, indicating a concentration of invertebrates. A subsequent steep decline in richness coincided with hypoxia and increasing conductivity. Culex pipiens/torrentium colonised the pools and was then dominant. Only a small subset of the assemblage successfully used the dry streambed as a refuge. 4.The effect of a shift from perennial to intermittent flow evidently depends on the degree of habitat change. Environmental conditions after cessation of flow are crucial in determining lowland stream macroinvertebrate persistence during water drawdown.
Experimental illumination of natural habitat - an experimental set-up to assess the direct and indirect ecological consequences of artificial light of different spectral composition
Spoelstra, K. ; Grunsven, R.H.A. van; Donners, M. ; Huijgens, T. ; Slaterus, R. ; Berendse, F. ; Visser, M.E. ; Veenendaal, E.M. - \ 2015
Philosophical Transactions of the Royal Society B. Biological sciences 370 (2015). - ISSN 0962-8436 - 8 p.
predation risk - beach mice - bats - night - ultraviolet - wavelength - pollution - responses - vision - time
Artificial night-time illumination of natural habitats has increased dramatically over the past few decades. Generally, studies that assess the impact of artificial light on various species in the wild make use of existing illumination and are therefore correlative. Moreover, studies mostly focus on short-term consequences at the individual level, rather than long-term consequences at the population and community level—thereby ignoring possible unknown cascading effects in ecosystems. The recent change to LED lighting has opened up the exciting possibility to use light with a custom spectral composition, thereby potentially reducing the negative impact of artificial light. We describe here a large-scale, ecosystem-wide study where we experimentally illuminate forest-edge habitat with different spectral composition, replicated eight times. Monitoring of species is being performed according to rigid protocols, in part using a citizen-science-based approach, and automated where possible. Simultaneously, we specifically look at alterations in behaviour, such as changes in activity, and daily and seasonal timing. In our set-up, we have so far observed that experimental lights facilitate foraging activity of pipistrelle bats, suppress activity of wood mice and have effects on birds at the community level, which vary with spectral composition. Thus far, we have not observed effects on moth populations, but these and many other effects may surface only after a longer period of time.
Analysing chemical-induced changes in macroinvertebrate communities in aquatic mesocosm experiments: a comparison of methods
Szöcs, E. ; Brink, P.J. van den; Lagadic, L. ; Caquet, T. ; Roucaute, M. ; Auber, A. ; Bayona, Y. ; Liess, M. ; Ebke, P. ; Ippolito, A. ; Braak, C.J.F. ter; Brock, T.C.M. ; Schäfer, R.B. - \ 2015
Ecotoxicology 24 (2015)4. - ISSN 0963-9292 - p. 760 - 769.
fresh-water microcosms - fungicide carbendazim - pond mesocosms - responses - insecticide - models - impact - chlorpyrifos - zooplankton - conclusions
Mesocosm experiments that study the ecological impact of chemicals are often analysed using the multivariate method ‘Principal Response Curves’ (PRCs). Recently, the extension of generalised linear models (GLMs) to multivariate data was introduced as a tool to analyse community data in ecology. Moreover, data aggregation techniques that can be analysed with univariate statistics have been proposed. The aim of this study was to compare their performance. We compiled macroinvertebrate abundance datasets of mesocosm experiments designed for studying the effect of various organic chemicals, mainly pesticides, and re-analysed them. GLMs for multivariate data and selected aggregated endpoints were compared to PRCs regarding their performance and potential to identify affected taxa. In addition, we analysed the inter-replicate variability encountered in the studies. Mesocosm experiments characterised by a higher taxa richness of the community and/or lower taxonomic resolution showed a greater inter-replicate variability, whereas variability decreased the more zero counts were encountered in the samples. GLMs for multivariate data performed equally well as PRCs regarding the community response. However, compared to first axis PRCs, GLMs provided a better indication of individual taxa responding to treatments, as separate models are fitted to each taxon. Data aggregation methods performed considerably poorer compared to PRCs. Multivariate community data, which are generated during mesocosm experiments, should be analysed using multivariate methods to reveal treatment-related community-level responses. GLMs for multivariate data are an alternative to the widely used PRCs
Natural (auto)antibodies in calves are affected by age and diet
Khobondo, J.O. ; Nieuwland, M.G.B. ; Webb, L.E. ; Bokkers, E.A.M. ; Parmentier, H.K. - \ 2015
Veterinary Quarterly 35 (2015)2. - ISSN 0165-2176 - p. 64 - 75.
reactive antibody repertoires - autoantibody repertoire - dairy-cows - serum igm - stability - responses - antigens - health - adults
Background: Natural autoantibodies (N(a)ab) were found in every species tested so far, and are likely important in maintaining homeostasis. Objectives: (1) To determine N(a)ab in Bos taurus calves, (2) evaluate effects of diet and age on N(a)ab binding repertoires in calves, and (3) delineate bovine liver cell lysate (BLL) antigens related with variation in rumen score and body weight. Animals and methods: Effects of age and diet on staining of BLL fragments by IgM and IgG antibodies in serum samples collected at 20 or at 26 weeks of age from bull calves either fed a restricted or ad libitum diet were analyzed using quantitative Western blotting. Correlations between fragments stained and grouping of calves were done by Principal Component Analysis (PCA). Redundancy analysis (RDA) was done to relate rumen score and body weight variation at slaughter at 27 weeks of age with stained BLL fragments. Results: In sera from all calves IgM and IgG antibodies binding BLL antigens were found. Corresponding fragments were stained, but quantitative differences in staining intensities were related to diet and age for both IgM and IgG. PCA revealed that age had a greater influence than diet on BLL fragment staining. RDA suggested that staining by IgM or IgG of specific BLL fragments was related with variation in rumen score and body weight. Conclusions and clinical importance: Analyses of N(a)ab in serum could be a potential tool to estimate the health status of cattle, and be used to evaluate effects of husbandry practices.
Disentangling above- and belowground neighbor effects on the growth, chemistry and arthropod community on a focal plant
Kos, M. ; Bukovinszky, T. ; Mulder, P.P.J. ; Bezemer, T.M. - \ 2015
Ecology 96 (2015)1. - ISSN 0012-9658 - p. 164 - 175.
soil feedback - associational susceptibility - vegetational diversity - competition - herbivores - root - resistance - responses - fertilization - density
Neighboring plants can influence arthropods on a focal plant and this can result in associational resistance or associational susceptibility. These effects can be mediated by above- and belowground interactions between the neighbor and focal plant, but determining the relative contribution of the above- and belowground effects remains an open challenge. We performed a common garden experiment with a design that enabled us to disentangle the above- and belowground effects of five different plant species on the growth and chemistry of the focal plant ragwort (Jacobaea vulgaris), and the arthropod community associated to this plant. Aboveground effects of different neighboring plant species were more important for the growth and quality of J. vulgaris and for the arthropod abundance on this plant than belowground effects of neighbors. This remained true when only indirect neighbor effects (via affecting the biomass or quality of the focal plant) were considered. The aboveground neighbor effects on arthropod abundance on the focal plant were strongly negative. However, the magnitude of the effect depended on the identity of the neighboring species, and herbivore abundance on the focal plant was higher when surrounded by conspecific than by heterospecific plants. We also observed interactions between above- and belowground neighbor effects, indicating that these effects may be non-additive. We conclude that above- and belowground associational effects are not equally strong, and that neighbor effects on plant-arthropod interactions occur predominantly aboveground.
Longer Oral Exposure with Modified Sham Feeding Does Not Slow Down Gastric Emptying of Low- and High-Energy-Dense Gastric Loads in Healthy Young Men
Wijlens, G.M. ; Erkner, A. ; Mars, M. ; Graaf, C. de - \ 2015
The Journal of Nutrition 145 (2015)2. - ISSN 0022-3166 - p. 365 - 371.
food-intake - appetite - stimulation - fat - responses - humans - satiation - ghrelin - liquids - volume
Background: A long oral exposure to food and a high-energy density of food are shown to increase satiety feelings. The effect of energy density is predominantly caused by an inhibition of gastric emptying. It is hypothesized that prolonging oral exposure may have an additional effect on this inhibition of gastric emptying. However, little human data are available to support this hypothesis. Objective: The objective was to assess the effect of oral exposure duration to food on gastric emptying rate of gastric loads (GLs) low and high in energy density and on satiety feelings. Methods: Twenty-six healthy men (22 ± 3 y, 23 ± 1 kg/m2) participated in a randomized crossover trial with 4 treatments and a control. Treatments consisted of either 1- or 8-min modified sham feeding (MSF) of cake, and a GL of either 100 or 700 kcal infused in the stomach via a nasogastric tube (500 mL, 62.5 mL/min). The control consisted of no MSF and a GL of 500 mL of water. Gastric emptying rate was assessed with a 13C breath test. Breath samples and satiety feelings were collected at fixed time points until 90 min after start of the treatment. Results: Gastric emptying rate and satiety feelings were not affected by duration of MSF (P = 0.27). However, the 700-kcal GL treatments slowed gastric emptying [41% lower area under the curve (AUC)] and increased satiety feelings (22–31% higher AUC) compared with the 100-kcal GL treatments (P <0.001). No interaction between MSF duration and energy density of GL was found (P = 0.44). Conclusions: Higher gastric energy density inhibited gastric emptying and increased satiety feelings in healthy young men. However, prolonging oral exposure to food did not have an additional effect. This study provides more insight in satiety regulation. This trial was registered at as NTR3601.
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