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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    Antimicrobial Resistance in Salmonella enterica Serovar Paratyphi B Variant Java in Poultry from Europe and Latin America
    Castellanos, L.R. ; Graaf-Van Bloois, Linda Van Der; Donado-Godoy, Pilar ; Veldman, K.T. ; Duarte, Francisco ; Acuna, María T. ; Jarquín, Claudia ; Weill, Francois Xavier ; Mevius, D.J. ; Wagenaar, J.A. ; Hordijk, Joost ; Zomer, Aldert L. - \ 2020
    Emerging Infectious Diseases 26 (2020)6. - ISSN 1080-6040 - p. 1164 - 1173.
    Salmonella enterica serovar Paratyphi B variant Java sequence type 28 is prevalent in poultry and poultry meat. We investigated the evolutionary relatedness between sequence type 28 strains from Europe and Latin America using time-resolved phylogeny and principal component analysis. We sequenced isolates from Colombia, Guatemala, Costa Rica, and the Netherlands and complemented them with publicly available genomes from Europe, Africa, and the Middle East. Phylogenetic time trees and effective population sizes (Ne) showed separate clustering of strains from Latin America and Europe. The separation is estimated to have occurred during the 1980s. Ne of strains increased sharply in Europe around 1995 and in Latin America around 2005. Principal component analysis on noncore genes showed a clear distinction between strains from Europe and Latin America, whereas the plasmid gene content was similar. Regardless of the evolutionary separation, similar features of resistance to β-lactams and quinolones/fluoroquinolones indicated parallel evolution of antimicrobial resistance in both regions
    Heritability estimates of the novel trait ‘suppressed in ovo virus infection’ in honey bees (Apis mellifera)
    Graaf, Dirk C. de; Laget, Dries ; Smet, Lina De; Claeys Boúúaert, David ; Brunain, Marleen ; Veerkamp, Roel F. ; Brascamp, Evert W. - \ 2020
    Scientific Reports 10 (2020)1. - ISSN 2045-2322

    Honey bees are under pressure due to abnormal high colony death rates, especially during the winter. The infestation by the Varroa destructor mite and the viruses that this ectoparasite transmits are generally considered as the bees’ most important biological threats. Almost all efforts to remedy this dual infection have so far focused on the control of the Varroa mite alone and not on the viruses it transmits. In the present study, the sanitary control of breeding queens was conducted on eggs taken from drone brood for 4 consecutive years (2015–2018). The screening was performed on the sideline of an ongoing breeding program, which allowed us to estimate the heritabilities of the virus status of the eggs. We used the term ‘suppressed in ovo virus infection’ (SOV) for this novel trait and found moderate heritabilities for the presence of several viruses simultaneously and for the presence of single viral species. Colonies that expressed the SOV trait seemed to be more resilient to virus infections as a whole with fewer and less severe Deformed wing virus infections in most developmental stages, especially in the male caste. The implementation of this novel trait into breeding programs is recommended.

    Author Correction: Global status and conservation potential of reef sharks
    MacNeil, M.A. ; Chapman, Demian D. ; Heupel, Michelle ; Simpfendorfer, Colin A. ; Heithaus, Michael ; Meekan, Mark ; Harvey, Euan ; Goetze, Jordan ; Kiszka, Jeremy ; Bond, Mark E. ; Currey-Randall, Leanne M. ; Speed, Conrad W. ; Sherman, C.S. ; Rees, Matthew J. ; Udyawer, Vinay ; Flowers, Kathryn I. ; Clementi, Gina ; Valentin-Albanese, Jasmine ; Gorham, Taylor ; Adam, M.S. ; Ali, Khadeeja ; Pina-Amargós, Fabián ; Angulo-Valdés, Jorge A. ; Asher, Jacob ; Barcia, Laura García ; Beaufort, Océane ; Benjamin, Cecilie ; Bernard, Anthony T.F. ; Berumen, Michael L. ; Bierwagen, Stacy ; Bonnema, Erika ; Bown, Rosalind M.K. ; Bradley, Darcy ; Brooks, Edd ; Brown, J.J. ; Buddo, Dayne ; Burke, Patrick ; Cáceres, Camila ; Cardeñosa, Diego ; Carrier, Jeffrey C. ; Caselle, Jennifer E. ; Charloo, Venkatesh ; Claverie, Thomas ; Clua, Eric ; Cochran, Jesse E.M. ; Cook, Neil ; Cramp, Jessica ; D’Alberto, Brooke ; Graaf, Martin de; Dornhege, Mareike ; Estep, Andy ; Fanovich, Lanya ; Farabaugh, Naomi F. ; Fernando, Daniel ; Flam, Anna L. ; Floros, Camilla ; Fourqurean, Virginia ; Garla, Ricardo ; Gastrich, Kirk ; George, Lachlan ; Graham, Rory ; Guttridge, Tristan ; Hardenstine, Royale S. ; Heck, Stephen ; Henderson, Aaron C. ; Hertler, Heidi ; Hueter, Robert ; Johnson, Mohini ; Jupiter, Stacy ; Kasana, Devanshi ; Kessel, Steven T. ; Kiilu, Benedict ; Kirata, Taratu ; Kuguru, Baraka ; Kyne, Fabian ; Langlois, Tim ; Lédée, Elodie J.I. ; Lindfield, Steve ; Luna-Acosta, Andrea ; Maggs, Jade ; Manjaji-Matsumoto, B.M. ; Marshall, Andrea ; Matich, Philip ; McCombs, Erin ; McLean, Dianne ; Meggs, Llewelyn ; Moore, Stephen ; Mukherji, Sushmita ; Murray, Ryan ; Kaimuddin, Muslimin ; Newman, Stephen J. ; Nogués, Josep ; Obota, Clay ; O’Shea, Owen ; Osuka, Kennedy ; Papastamatiou, Yannis P. ; Perera, Nishan ; Peterson, Bradley ; Ponzo, Alessandro ; Prasetyo, Andhika ; Sjamsul Quamar, L.M. ; Quinlan, Jessica ; Ruiz-Abierno, Alexei ; Sala, Enric ; Samoilys, Melita ; Schärer-Umpierre, Michelle ; Schlaff, Audrey ; Simpson, Nikola ; Smith, Adam N.H. ; Sparks, Lauren ; Tanna, Akshay ; Torres, Rubén ; Travers, Michael J. ; Zinnicq Bergmann, Maurits van; Vigliola, Laurent ; Ward, Juney ; Watts, Alexandra M. ; Wen, Colin ; Whitman, Elizabeth ; Wirsing, Aaron J. ; Wothke, Aljoscha ; Zarza-Gonzâlez, Esteban ; Cinner, Joshua E. - \ 2020
    Nature (2020). - ISSN 0028-0836

    An Amendment to this paper has been published and can be accessed via a link at the top of the paper.

    Biosulfidogenesis mediates natural attenuation in acidic mine pit lakes
    Graaf, Charlotte M. van der; Sánchez-España, Javier ; Yusta, Iñaki ; Ilin, Andrey ; Shetty, Sudarshan A. ; Bale, Nicole J. ; Villanueva, Laura ; Stams, Alfons J.M. ; Sánchez-Andrea, Irene - \ 2020
    Microorganisms 8 (2020)9. - ISSN 2076-2607 - 26 p.
    Acidophiles - Bioremediation - Biosulfidogenesis - Lipid biomarker - Sulfate reduction - Sulfide neoformation - Sulfur disproportionation - Sulfur reduction

    Acidic pit lakes are abandoned open pit mines filled with acid mine drainage (AMD)—highly acidic, metalliferous waters that pose a severe threat to the environment and are rarely properly remediated. Here, we investigated two meromictic, oligotrophic acidic mine pit lakes in the Iberian Pyrite Belt (IPB), Filón Centro (Tharsis) (FC) and La Zarza (LZ). We observed a natural attenuation of acidity and toxic metal concentrations towards the lake bottom, which was more pronounced in FC. The detection of Cu and Zn sulfides in the monimolimnion of FC suggests precipitation of dissolved metals as metal sulfides, pointing to biogenic sulfide formation. This was supported by microbial diversity analysis via 16S rRNA gene amplicon sequencing of samples from the water column, which showed the presence of sulfidogenic microbial taxa in FC and LZ. In the monimolimnion of FC, sequences affiliated with the putative sulfate-reducing genus Desulfomonile were dominant (58%), whereas in the more acidic and metal-enriched LZ, elemental sulfur-reducing Acidianus and Thermoplasma spp., and disproportionating Desulfocapsa spp. were more abundant. Furthermore, the detection of reads classified as methanogens and Desulfosporosinus spp., although at low relative abundance, represents one of the lowest pH values (2.9 in LZ) at which these taxa have been reported, to our knowledge. Analysis of potential biomarker lipids provided evidence that high levels of phosphocholine lipids with mixed acyl/ether glycerol core structures were associated with Desulfomonile, while ceramide lipids were characteristic of Microbacter in these environments. We propose that FC and LZ function as natural bioremediation reactors where metal sulfide precipitation is mediated by biosulfidogenesis starting from elemental sulfur reduction and disproportionation at an early stage (LZ), followed by sulfate reduction at a later stage (FC).

    Time will tell : Dynamic sensory characteristics, hedonic perceptions and food-evoked emotions from first to last bite
    Bommel, Roelien van - \ 2020
    Wageningen University. Promotor(en): Markus Stieger; Kees de Graaf, co-promotor(en): Gerry Jager. - Wageningen : Wageningen University - ISBN 9789463954617 - 198
    A stepwise approach investigating salivary responses upon multisensory food cues
    Morquecho-Campos, Paulina ; Bikker, Floris J. ; Nazmi, Kamran ; Graaf, Kees de; Laine, Marja L. ; Boesveldt, Sanne - \ 2020
    Physiology and Behavior 226 (2020). - ISSN 0031-9384
    Cephalic-phase salivary response - Chewing - Gustation - Olfaction - Sight

    Exposure to sensory food cues such as smell, vision, taste and/or texture may trigger anticipatory physiological responses such as salivation, participating on adequate metabolism of the signaled food. However, the individual contribution of each sensory modality as well as the impact of particular food products on salivation and salivary composition remains unclear. Therefore, by systematically varying sensory modalities and nutrient content of food stimuli, we investigated their effect on saliva secretion, α-amylase activity and other salivary characteristics (pH level, buffering capacity, MUC5B concentration, and total protein content). Over 3 sessions, 46 normal-weight healthy participants were exposed to 12 conditions, consisting of 4 levels of sensory stimulation (odor, odor + vision, odor + vision + taste, and odor + vision + taste + mastication) and 3 types of stimuli (bread, high-in-starch; cucumber, low-in-starch; and parafilm as non-food control) during which saliva was collected. Linear mixed models showed a significant increase in salivation with increasing levels of sensory stimulation. α-amylase secretion rate increased upon the highest level of stimulation, which involved mastication, compared to odor and odor + visual level of stimulation. Other salivary characteristics varied with the level of sensory stimulation, which might be related to the total volume of salivation. The type of stimuli did not influence the saliva composition (α-amylase concentration nor other salivary components). Our findings indicate that cumulative sensory information, rather than specific (food) product, play a vital role in anticipatory salivary responses.

    Global status and conservation potential of reef sharks
    MacNeil, Aaron ; Chapman, Demian D. ; Heupel, Michelle ; Simpfendorfer, Colin A. ; Heithaus, Michael ; Meekan, Mark ; Harvey, Euan ; Goetze, Jordan ; Kiszka, Jeremy ; Bond, Mark E. ; Currey-Randall, Leanne M. ; Speed, Conrad W. ; Sherman, Samantha ; Rees, Matthew J. ; Udyawer, Vinay ; Flowers, Kathryn I. ; Clementi, Gina ; Valentin-Albanese, Jasmine ; Gorham, Taylor ; Adam, Shiham ; Khadeeja, Ali ; Pina-Amargós, Fabián ; Angulo-Valdés, Jorge A. ; Asher, Jacob ; García Barcia, Laura ; Beaufort, Océane ; Benjamin, Cecilie ; Bernard, Anthony T.F. ; Berumen, Michael L. ; Bierwagen, Stacy ; Bonnema, Erika ; Bown, Rosalind M.K. ; Bradley, Darcey ; Brooks, Edd ; Brown, Jed ; Buddo, Dayne ; Burke, Patrick ; Cáceres, Camila ; Cardeñosa, Diego ; Carrier, Jeffrey C. ; Caselle, Jennifer E. ; Charloo, Venkatesh ; Claverie, Thomas ; Clua, Eric ; Cochran, Jesse E.M. ; Cook, Neil ; Cramp, Jessica ; D’Alberto, Brooke ; Graaf, Martin de; Dornhege, Mareike ; Estep, Andy ; Fanovich, Lanya ; Farabough, Naomi F. ; Fernando, Daniel ; Flam, Anna L. ; Floros, Camilla ; Fourqurean, Virginia ; Garla, Ricardo ; Gastrich, Kirk ; George, Lachlan ; Graham, Rory ; Guttridge, Tristan ; Hardenstine, Royale S. ; Heck, Stephen ; Henderson, Aaron C. ; Hertler, Heidi ; Hueter, Robert ; Johnson, Mohini ; Jupiter, Stacy ; Kasana, Devanshi ; Kessel, Steven T. ; Kiilu, Benedict ; Kirata, Taratu ; Kuguru, Baraka ; Kyne, Fabian ; Langlois, Tim ; Lédée, Elodie J.I. ; Lindfield, Steve ; Luna-Acosta, Andrea ; Maggs, Jade ; Manjaji-Matsumoto, Mabel ; Marshall, Andrea ; Matich, Philip ; McCombs, Erin ; McLean, Dianne ; Meggs, Llewelyn ; Moore, Stephen ; Mukherji, Sushmita ; Murray, Ryan ; Kaimuddin, Muslimin ; Newman, Stephen J. ; Nogués, Josep ; Obota, Clay ; O’Shea, Owen ; Osuka, Kennedy ; Papastamatiou, Yannis P. ; Perera, Nishan ; Peterson, Bradley ; Ponzo, Alessandro ; Prasetyo, Andhika ; Quamar, Sjamsul ; Quinlan, Jessica ; Ruiz-Abierno, Alexei ; Sala, Enric ; Samoilys, Melita ; Schärer-Umpierre, Michelle ; Schlaff, Audrey ; Simpson, Nikola ; Smith, Adam N.H. ; Sparks, Lauren ; Tanna, Akshay ; Torres, Rubén ; Travers, Michael J. ; Zinnicq Bergmann, Maurits van; Vigliola, Laurent ; Ward, Juney ; Watts, Alexandra M. ; Wen, Colin ; Whitman, Elizabeth ; Wirsing, Aaron J. ; Wothke, Aljoscha ; Zarza-Gonzâlez, Esteban ; Cinner, Joshua E. - \ 2020
    Nature 583 (2020). - ISSN 0028-0836 - p. 801 - 806.

    Decades of overexploitation have devastated shark populations, leaving considerable doubt as to their ecological status1,2. Yet much of what is known about sharks has been inferred from catch records in industrial fisheries, whereas far less information is available about sharks that live in coastal habitats3. Here we address this knowledge gap using data from more than 15,000 standardized baited remote underwater video stations that were deployed on 371 reefs in 58 nations to estimate the conservation status of reef sharks globally. Our results reveal the profound impact that fishing has had on reef shark populations: we observed no sharks on almost 20% of the surveyed reefs. Reef sharks were almost completely absent from reefs in several nations, and shark depletion was strongly related to socio-economic conditions such as the size and proximity of the nearest market, poor governance and the density of the human population. However, opportunities for the conservation of reef sharks remain: shark sanctuaries, closed areas, catch limits and an absence of gillnets and longlines were associated with a substantially higher relative abundance of reef sharks. These results reveal several policy pathways for the restoration and management of reef shark populations, from direct top-down management of fishing to indirect improvement of governance conditions. Reef shark populations will only have a high chance of recovery by engaging key socio-economic aspects of tropical fisheries.

    The effect of replacing sucrose with L-arabinose in drinks and cereal foods on blood glucose and plasma insulin responses in healthy adults
    Pol, Korrie ; Graaf, Kees de; Diepeveen-de Bruin, Marlies ; Balvers, Michiel ; Mars, Monica - \ 2020
    Journal of Functional Foods 73 (2020). - ISSN 1756-4646
    Food matrix - Functionality - Glycaemic response - Insulin response - L-arabinose - Sucrose

    Glycaemic control is important in metabolic diseases such as diabetes and impaired glucose tolerance. L-arabinose inhibits the hydrolysis of sucrose into glucose and fructose. So far little is known about its functionality in different food matrices. We assessed the effect of replacing sucrose with L-arabinose in drinks and in cereal foods on blood glucose and insulin in healthy adults. Glucose and insulin responses were reduced when sucrose was replaced by L-arabinose in drinks. Replacement of sucrose in cereal foods did not affect glucose responses, however it reduced the insulin peak. L-arabinose without sucrose in a drink did not affect glucose responses. Therefore, replacing sucrose with L-arabinose is potentially a good strategy to lower glycaemic and insulin responses. However, the effects depend on the food matrix and the nutritional composition of the food. More research is warranted on the functionality of L-arabinose in different food matrices and in other populations.

    Effects of distraction on taste-related neural processing : a cross-sectional fMRI study
    Duif, Iris ; Wegman, Joost ; Mars, Monica M. ; Graaf, Cees De; Smeets, Paul A.M. ; Aarts, Esther - \ 2020
    American Journal of Clinical Nutrition 111 (2020)5. - ISSN 0002-9165 - p. 950 - 961.
    attention - consumption - distraction - fMRI - insula - orbitofrontal cortex - taste

    Background: In the current obesogenic environment we often eat while electronic devices, such as smart phones, computers, or the television, distract us. Such "distracted eating"is associated with increased food intake and overweight. However, the underlying neurocognitive mechanisms of this phenomenon are unknown. Objective: Our aim was to elucidate these mechanisms by investigating whether distraction attenuates processing in the primary and secondary taste cortices, located in the insula and orbitofrontal cortex (OFC), respectively. Methods: Forty-one healthy, normal-weight participants received fixed amounts of higher-And lower-sweetness isocaloric chocolate milk while performing a high-or low-distracting detection task during fMRI in 2 test sessions. Subsequently, we measured ad libitum food intake. Results: As expected, a primary taste cortex region in the right insula responded more to the sweeter drink (P < 0.001, uncorrected). Distraction did not affect this insular sweetness response across the group, but did weaken sweetness-related connectivity of this region to a secondary taste region in the right OFC (P-family-wise error, cluster, small-volume corrected = 0.020). Moreover, individual differences in distraction-related attenuation of taste activation in the insula predicted increased subsequent ad libitum food intake after distraction (r = 0.36). Conclusions: These results reveal a mechanism explaining how distraction during consumption attenuates neural taste processing. Moreover, our study shows that such distraction-induced decreases in neural taste processing contribute to individual differences in the susceptibility for overeating. Thus, being mindful about the taste of food during consumption could perhaps be part of successful prevention and treatment of overweight and obesity, which should be further tested in these target groups. This study was preregistered at the Open Science Framework as

    Tackling drought on high sandy ground
    Graaf, Myrjam de - \ 2020
    Outcome prediction of head and neck squamous cell carcinoma by MRI radiomic signatures
    Mes, Steven W. ; Velden, Floris H.P. van; Peltenburg, Boris ; Peeters, Carel F.W. ; Beest, Dennis E. te; Wiel, Mark A. van de; Mekke, Joost ; Mulder, Doriene C. ; Martens, Roland M. ; Castelijns, Jonas A. ; Pameijer, Frank A. ; Bree, Remco de; Boellaard, Ronald ; Leemans, C.R. ; Brakenhoff, Ruud H. ; Graaf, Pim de - \ 2020
    European Radiology (2020). - ISSN 0938-7994
    Factor analysis - Head and neck neoplasms - Magnetic resonance imaging - Prognosis

    Objectives: Head and neck squamous cell carcinoma (HNSCC) shows a remarkable heterogeneity between tumors, which may be captured by a variety of quantitative features extracted from diagnostic images, termed radiomics. The aim of this study was to develop and validate MRI-based radiomic prognostic models in oral and oropharyngeal cancer. Materials and Methods: Native T1-weighted images of four independent, retrospective (2005–2013), patient cohorts (n = 102, n = 76, n = 89, and n = 56) were used to delineate primary tumors, and to extract 545 quantitative features from. Subsequently, redundancy filtering and factor analysis were performed to handle collinearity in the data. Next, radiomic prognostic models were trained and validated to predict overall survival (OS) and relapse-free survival (RFS). Radiomic features were compared to and combined with prognostic models based on standard clinical parameters. Performance was assessed by integrated area under the curve (iAUC). Results: In oral cancer, the radiomic model showed an iAUC of 0.69 (OS) and 0.70 (RFS) in the validation cohort, whereas the iAUC in the oropharyngeal cancer validation cohort was 0.71 (OS) and 0.74 (RFS). By integration of radiomic and clinical variables, the most accurate models were defined (iAUC oral cavity, 0.72 (OS) and 0.74 (RFS); iAUC oropharynx, 0.81 (OS) and 0.78 (RFS)), and these combined models outperformed prognostic models based on standard clinical variables only (p < 0.001). Conclusions: MRI radiomics is feasible in HNSCC despite the known variability in MRI vendors and acquisition protocols, and radiomic features added information to prognostic models based on clinical parameters. Key Points: • MRI radiomics can predict overall survival and relapse-free survival in oral and HPV-negative oropharyngeal cancer. • MRI radiomics provides additional prognostic information to known clinical variables, with the best performance of the combined models. • Variation in MRI vendors and acquisition protocols did not influence performance of radiomic prognostic models.

    How oro-sensory exposure and eating rate affect satiation and associated endocrine responses-a randomized trial
    Lasschuijt, Marlou ; Mars, Monica ; Graaf, Cees de; Smeets, Paul A.M. - \ 2020
    American Journal of Clinical Nutrition 111 (2020)6. - ISSN 0002-9165 - p. 1137 - 1149.
    cephalic phase - eating behavior - eating rate - ghrelin - human - insulin - oro-sensory exposure - pancreatic polypeptide - satiation

    BACKGROUND: Longer oral processing decreases food intake. This can be attributed to greater oro-sensory exposure (OSE) and a lower eating rate (ER). How these factors contribute to food intake, and the underlying physiological mechanisms, remain unclear. OBJECTIVES: We aimed to determine the independent and simultaneous effects of OSE and ER on satiation and associated endocrine responses. METHODS: Forty participants in study 1 [mean ± SD age: 24 ± 4 y; BMI (in kg/m2): 22 ± 2] and 20 in study 2 (mean ± SD age: 23 ± 3 y; BMI: 23 ± 2) participated in a 2 × 2 randomized trial. In both studies, participants ate chocolate custard with added caramel sauce (low OSE) or caramel fudge (high OSE) and with short (fast ER) or long breaks (slow ER) in between bites, until fullness. In study 2, endocrine responses were measured during the meal. RESULTS: In study 1, participants ate (mean ± SEM) 42 ± 15 g less in the slow- than in the fast-ER condition, only within the high-OSE condition (P = 0.04). In study 2, participants ate 66 ± 21 g less in the high- than in the low-OSE condition and there were no intake differences between slow and fast ER (P = 0.35). Eight minutes after starting to eat, insulin concentrations increased by 42%-65% in all treatments compared with the control. At the end of the meal, insulin concentrations were 81% higher in the high-OSE, slow-ER than in the low-OSE, fast-ER condition (P = 0.049). Pancreatic polypeptide (PP) increased by 62%, 5 min after meal onset in the low-OSE, fast-ER condition (P = 0.005). Ghrelin concentrations did not change. CONCLUSIONS: Greater OSE increases insulin responsiveness. In contrast, PP responses are stronger when OSE is reduced and ER is fast. Insulin and PP responses may mediate the independent effects of OSE and ER on food intake. These may be beneficial eating strategies, particularly for type 2 diabetic patients, to control food intake and maintain glucose homeostasis.This trial was registered at as NL6544.

    Resting energy expenditure in cystic fibrosis patients decreases after lung transplantation, which improves applicability of prediction equations for energy requirement
    Hollander-Kraaijeveld, F.M. ; Lanen, A.S. van; Roos, N.M. de; Graaf, E.A. van de; Heijerman, H.G.M. - \ 2020
    Journal of Cystic Fibrosis (2020). - ISSN 1569-1993
    REE and REE/kg FFM significantly decrease after lung transplantation in CF patients. Prediction equations for energy requirement are inaccurate until a year after LTx. Measuring REE by indirect calorimetry is advised in CF patients before and until one year after LTx. Pre-LTx, energy requirements are at least 20% higher than predicted with common energy requirement equations.
    Sensory Evaluation of E-Liquid Flavors by Smelling and Vaping Yields Similar Results
    Krüsemann, Erna J.Z. ; Wenng, Franziska M. ; Pennings, Jeroen L.A. ; Graaf, Kees de; Talhout, Reinskje ; Boesveldt, Sanne - \ 2020
    Nicotine & Tobacco Research 22 (2020)5. - ISSN 1462-2203 - p. 798 - 805.

    INTRODUCTION: Sensory research on e-liquid flavors can be performed by means of smelling and vaping. However, data comparing smelling versus vaping e-liquid flavors are lacking. This study aims to investigate if smelling could be an alternative to vaping experiments by determining the correlation for hedonic flavor assessment between orthonasal smelling and vaping of e-liquids, for smokers and nonsmokers. METHODS: Twenty-four young adult smokers (mean age 24.8 ± 9.3) and 24 nonsmokers (mean age 24.9 ± 7.7) smelled and vaped 25 e-liquids in various flavors. Participants rated liking, intensity, familiarity, and irritation on a 100-mm Visual Analog Scale. Pearson correlations within and between smelling and vaping were calculated. Differences between user groups were calculated using t tests. RESULTS: Correlation coefficients between smelling and vaping based on mean group ratings were 0.84 for liking, 0.82 for intensity, 0.84 for familiarity, and 0.73 for irritation. Means of the within-subjects correlation coefficients were, respectively, 0.51, 0.37, 0.47, and 0.25. Correlations between smelling and vaping varied across individuals (ranging from -0.27 to 0.87) and flavors (-0.33 to 0.81). Correlations and mean liking ratings did not differ between smokers and nonsmokers. CONCLUSIONS: The strong group-level correlations between orthonasal smelling and vaping e-liquid flavors justify the use of smelling instead of vaping in future research. For example, smelling could be used to investigate differences in e-liquid flavor liking between (potential) user groups such as nicotine-naïve adolescents. The more modest within-subject correlations and variation across individuals and flavors merit caution in using smelling instead of vaping in other types of experiments. IMPLICATIONS: This study supports the use of orthonasal smelling (instead of vaping) e-liquids to measure hedonic flavor perception in some studies where vaping would be inappropriate or not feasible. Examples of research situations where smelling e-liquids may be sufficient are (1) investigating nicotine-naïve individuals (ie, nonusers), (2) investigating individuals under legal age for e-cigarette use (ie, youth and adolescents), (3) investigating brain responses to exposure of e-liquid flavors using functional magnetic resonance imaging or electroencephalogram, and (4) comparing hedonic flavor assessment between adolescent nonusers and current smokers to provide support for future regulations on e-liquid flavors.

    Foraging minds in modern environments : High-calorie and savory-taste biases in human food spatial memory
    Vries, Rachelle de; Vet, Emely de; Graaf, Kees de; Boesveldt, Sanne - \ 2020
    Appetite 152 (2020). - ISSN 0195-6663
    Cognitive bias - Eating behavior - Food spatial memory - Olfaction - Optimal foraging theory - Vision

    Human memory may show sensitivity to content that carried fitness-relevance throughout evolutionary history. We investigated whether biases in human food spatial memory exist and influence the eating behavior of individuals within the modern food environment. In two lab studies with distinct samples of 88 participants, individuals had to re-locate foods on a map in a computer-based spatial memory task using visual (Study 1) or olfactory (Study 2) cues that signaled sweet and savory high- and low-calorie foods. Individuals consistently displayed an enhanced memory for locations of high-calorie and savory-tasting foods – regardless of hedonic evaluations, personal experiences with foods, or the time taken to encode food locations. However, we did not find any clear effects of the high-calorie or savory-taste bias in food spatial memory on eating behavior. Findings highlight that content matters deeply for the faculty of human food spatial memory and indicate an implicit cognitive system presumably attuned to ancestral priorities of optimal foraging.

    Smelling our appetite? The influence of food odors on congruent appetite, food preferences and intake
    Morquecho-Campos, Paulina ; Graaf, Kees de; Boesveldt, Sanne - \ 2020
    Food Quality and Preference 85 (2020). - ISSN 0950-3293
    Congruency - Eating behavior - Explicit exposure - Macronutrients - Olfaction - Sensory-specific appetite

    We are surrounded by sensory food cues, such as odors, that may trigger (un)conscious decisions and even lead to (over)eating, it is therefore crucial to better understand the effect of food odors on behavioral responses. Food odor exposure has been shown to enhance appetite for food products with similar properties: sensory-specific appetite. This suggests that based on previous encounters with foods, we have learned to detect the nutritional content of foods, through our sense of smell. We investigated the influence of aware exposure of macronutrient-related odors on various measures of eating behavior, in a cross-over intervention study. Thirty two normal-weight healthy and unrestrained Dutch females took part in five test sessions. On each test session, they were exposed to one of five conditions (active smelling of clearly noticeable odors representing food high in carbohydrates, protein, and fat, low in calories, and a no-odor condition for 3-min) and assessed on specific appetite, food preferences and intake. Odor exposure increased congruent appetite after protein-related odor exposure. Similarly, protein-related odor exposure influenced the liking for protein foods and the preference ranking for savory products. However, food intake was not affected by smelling congruent food odors. Together this indicates that exposure to (aware) food odors may mostly influence appetite, but does not impact subsequent food intake. Moreover, appetite seems to be triggered by taste qualities rather than macronutrient information of the food, as signaled by olfactory cues. Future studies should investigate the role of awareness in more detail, to fully understand how odors might be used to steer people towards healthier food choices.

    Healthy is (not) tasty? Implicit and explicit associations between food healthiness and tastiness in primary school-aged children and parents with a lower socioeconomic position
    Heijden, Amy van der; Molder, Hedwig te; Graaf, Cees de; Jager, Gerry - \ 2020
    Food Quality and Preference 84 (2020). - ISSN 0950-3293
    Explicit associations - Food healthiness - Food tastiness - Implicit associations - Lower socioeconomic position - Primary school-aged children

    Many people implicitly (automatically) believe that unhealthy foods are tastier than healthy foods, even when they explicitly (deliberately) report that they don't. It is unclear whether this ‘unhealthy = tasty intuition’ is already present in childhood. Children from families with a lower socioeconomic position (SEP) consume poorer diets than children from families with a higher SEP. Paradoxically, populations with a lower SEP are underrepresented in research and least reached by lifestyle interventions. This study explored implicit and explicit associations between healthiness, tastiness and liking of foods in primary school-aged children and parents with a lower SEP. These associations and an estimate of dietary intake were assessed with implicit association tests and paper-and-pencil questionnaires, developed and adapted specifically for this target group. Participants were recruited at Dutch food banks. Results of 37 parent-child dyads indicated that children and parents implicitly associated healthy foods and tastiness more strongly with each other than healthy foods and not tasty (D = −0.19, p =.03 and D = −0.46, p <.001, respectively). Explicitly, parents showed similar results, while children rated pictures of unhealthy foods as tastier than pictures of healthy foods. Following the discrepancy between our hypotheses, results, and more unhealthy eating habits that often prevail in families with a lower SEP, potential explanations are discussed. We address the possibility that an internalised social norm was exposed, rather than an intrinsic belief. We propose that this research calls for in-depth qualitative research on food-related preferences and norms in the everyday life of low SEP families.

    Ultra-Processing or Oral Processing? A Role for Energy Density and Eating Rate in Moderating Energy Intake from Processed Foods
    Forde, Ciarán G. ; Mars, Monica ; Graaf, Kees De - \ 2020
    Current Developments in Nutrition 4 (2020)3. - ISSN 2475-2991
    eating rate - energy density - energy intake rate - food texture - metabolic disease - obesity - ultra-processed foods - unprocessed foods

    Background: Recent observational data and a controlled in-patient crossover feeding trial show that consumption of "ultra-processed foods" (UPFs), as defined by the NOVA classification system, is associated with higher energy intake, adiposity, and at a population level, higher prevalence of obesity. A drawback of the NOVA classification is the lack of evidence supporting a causal mechanism for why UPFs lead to overconsumption of energy. In a recent study by Hall the energy intake rate in the UPF condition (48 kcal/min) was >50% higher than in the unprocessed condition (31 kcal/min). Extensive empirical evidence has shown the impact that higher energy density has on increasing ad libitum energy intake and body weight. A significant body of research has shown that consuming foods at higher eating rates is related to higher energy intake and a higher prevalence of obesity. Energy density can be combined with eating rate to create a measure of energy intake rate (kcal/min), providing an index of a food's potential to promote increased energy intake. Objective: The current paper compared the association between measured energy intake rate and level of processing as defined by the NOVA classification. Methods: Data were pooled from 5 published studies that measured energy intake rates across a total sample of 327 foods. Results: We show that going from unprocessed, to processed, to UPFs that the average energy intake rate increases from 35.5 ± 4.4, to 53.7 ± 4.3, to 69.4 ± 3.1 kcal/min (P < 0.05). However, within each processing category there is wide variability in the energy intake rate. Conclusions: We conclude that reported relations between UPF consumption and obesity should account for differences in energy intake rates when comparing unprocessed and ultra-processed diets. Future research requires well-controlled human feeding trials to establish the causal mechanisms for why certain UPFs can promote higher energy intake.

    A feeling of full-filment : Sensory and physiological processes involved in satiation
    Lasschuijt, Marlou - \ 2020
    Wageningen University. Promotor(en): K. de Graaf, co-promotor(en): P.A.M. Smeets; M. Mars. - Wageningen : Wageningen University - ISBN 9789463952484 - 251

    Satiation is a process that occurs during eating and involves inhibitory signals at a sensory, hormonal, digestive and cognitive level. The taste and texture of food influence this process. Harder foods with an intense taste are more satiating, i.e. we need to eat less of these foods to feel full, compared to softer foods with lower taste intensity. Oro-sensory exposure (OSE), the in-mouth taste perception of food, thus plays an important role in satiation and influences meal size. However, how oro-sensory signals affect satiation is not fully understood. Therefore, the main aim of this thesis was to better understand the role of sensory signals in the physiological processes underlying satiation. To study this we investigated the effect of OSE (duration and intensity) and eating rate on food intake, associated (cephalic) endocrine responses and brain reactivity. 

    We started by investigating the independent contributions of oral processing duration and taste intensity and their combined effect on satiation (chapter 2). This was done by manipulating texture and sweet taste intensity of model foods (2x2 study design, soft and hard vs. sweet and high sweet). Hard textured model foods decreased food intake through increased OSE duration, whereas sweetness intensity did not affect intake.

    To better understand the physiology underlying the effects of oro-sensory exposure on satiation we studied the effect of texture and sweetness intensity on endocrine cephalic phase responses (chapter 3). Cephalic phase responses are neurally mediated anticipatory and conditioned responses to food cues and are considered the first phase of digestion. Insulin, pancreatic polypeptide and ghrelin responses were measured while participants modified sham fed (chew and spit) the same model foods as used in chapter 2. We expected a cephalic peak increase in these hormones 5-15 min after food exposure. However, we did not find a typical cephalic phase peak response for any of the hormones. Insulin levels tended to be higher 5 min after starting to chew but this increase could not be not be attributed to the texture or taste manipulations. In addition, we found that pancreatic polypeptide was more responsive to sweetness. Ghrelin concentrations were higher when chewing the hard texture compared to the soft texture model foods.

    Based on the results from chapter 2 and 3 we hypothesized that part of the mechanism behind the oro-sensory exposure duration effect on satiation might be eating rate. When the duration of oro-sensory exposure is increased, eating rate is slowed down. Previous studies have shown that a reduced eating rate also leads to a decrease in food intake. Additionally, we hypothesized that part of the reason why we did not find typical cephalic responses in chapter 2 was because the model foods scored ‘neutral’ on liking, whereas palatability may be important to trigger a cephalic response. We therefore investigated the effect of OSE duration and eating rate on food intake (palatable chocolate custard) and associated endocrine responses (chapter 4). Two studies were set up. In both studies subjects ate until fullness of chocolate custard with and without fudge pieces (low or high oro-sensory exposure) at two different eating rates (slow or fast eating rate). In study 1 participants received a small portion and in study 2 a larger portion. Additionally, blood samples were collected during the meal in study 2. We found that a reduced eating rate (ER) (only in the high oro-sensory exposure condition) (study 1) and increased oro-sensory exposure (study 2) decreased food intake but that this was dependent on the portion size. Eight minutes after starting to eat, insulin concentrations increased for all treatments compared to control. At the end of the meal insulin concentrations were higher in the high OSE, slow ER compared to the low OSE, fast ER condition. Pancreatic polypeptide increased at 5 min after meal onset in the low OSE, fast ER condition. There were no changes in ghrelin concentration. Greater OSE thus increases insulin responsiveness. In contrast, PP responses are stronger when OSE is reduced and ER is fast. Prandial Insulin and PP responses may mediate the independent effects of OSE and ER on food intake.

    To determine whether typical cephalic phase responses were specific to certain food cues or  sub-populations we quantified outcomes of existing literature on cephalic insulin and pancreatic polypeptide responses in a systematic review (chapter 5). In addition, we aimed to quantify the hypotheses made by previous qualitative cephalic phase reviews that cephalic responses allow for larger meal sizes, induce satiation earlier on in the meal and improve postprandial glucose homeostasis. A cephalic phase insulin and pancreatic polypeptide increase was observed in about half of all included treatments. About one fifth of the treatments induced a significant increase from baseline. The size of the cephalic insulin increase relative to spontaneous fluctuations was small and there was substantial variation in magnitude and onset time of cephalic insulin and pancreatic polypeptide responses between food cues and individuals. Based on this we concluded that cephalic phase insulin responses are small compared to spontaneous fluctuations. Although cephalic pancreatic polypeptide responses are of a larger magnitude, both show substantial variation in magnitude and onset time. Based on the current evidence, we refute the hypotheses that CPRs improve satiation and glucose homeostasis in daily life

    Finally, to determine how OSE or taste signals are processed in the brain to affect satiation we performed an fMRI study in which we measured neural reactivity to chocolate milk in the brain(stem) over the course of satiation (chapter 6). Additionally we measured gastric volume such that we could identify regions that respond solely to taste, independent of gastric distention. We found that taste activation in the parabrachial nuclei (PBN) in the brain stem, and bilateral (anterior) insula, amygdala and putamen gradually decreased as satiation increased, in line with the decrease in affective value of the chocolate milk stimuli. When subjects were hungry and completely satiated this effect could completely be explained by gastric filling, whereas this was not the case when subjects felt half full.  Responses of these brain regions are thus modulated by gastric volume and sensory satiation seems especially important early in the meal when not completely satiated.

    To conclude, we confirmed that increased OSE can decrease food intake. Insulin, PP and ghrelin cephalic phase responses do not mediate the oro-sensory exposure effect on satiation. Instead, we hypothesize that the underlying mechanisms are 1) a direct effect of oro-sensory exposure on satiation through sensory satiation and 2) an indirect effect of increased oro-sensory exposure duration which also slows down ingestion rate. This allows more time for stomach distention signals, hormone secretion, and early uptake of nutrients which are processed by the brain and induce satiation.

    Geoquímica microbiana del lago ácido y salino de la corta de la mina Brunita (La Unión, SE España)
    Sánchez-España, Javier ; Yusta, Iñaki ; Ilin, Andrey ; Graaf, Charlotte van der; Sánchez-Andrea, Irene - \ 2020
    Mine Water and the Environment 39 (2020). - ISSN 1025-9112 - p. 535 - 555.
    Acidic mine pit lakes - Bacterial sulfate reduction - Metal pollution - Natural attenuation

    We present the first study of a unique acidic lake formed in the Brunita open pit (La Unión mines, Cartagena, SE Spain). This pit lake exhibits chemical characteristics typical of AMD, such as low pH (pH 2.2–5.0) and high iron content (500–6400 mg/L total Fe). It also has some of the highest sulfate concentrations reported to date in pit lakes (26,000–38,400 mg/L SO42-) and transition metals like Mn (up to 2000 mg/L), Zn (500 mg/L), or Cu (250 mg/L). In addition, we found abnormally high concentrations of salt-forming ions (e.g. 5500 mg/L Mg, 750–1300 mg/L Cl, and 300–630 mg/L Na). The resulting high salinity (58‰) at the bottom creates a meromictic lake despite the lake’s low relative depth (9%), with an anoxic, reducing monimolimnion isolated from the oxygenated mixolimnion. In the monimolimnion, we observed decreased metal concentrations (e.g. Cu, Zn, Cd, Cr, Pb, Th). We hypothesize that these metals are being removed by interaction with biogenic H2S and subsequent precipitation as metal sulfides. Scanning electron microscopy shows sub-micron, spherical particles of ZnS in close association with cocci and rod-like bacteria. Analysis of the microbial community composition through 16S rRNA gene amplicon sequencing revealed different genera of sulfate-reducing bacteria (SRB) in the monimolimnion, including Desulfobacca, Desulfomonile, Desulfurispora, and Desulfosporosinus. Their apparent ability to reduce sulfate and selectively precipitate potentially toxic metals, and their resistance to this lake’s extreme geochemical conditions, makes these bacteria of great interest for biotechnological applications (e.g. bioremediation and biomining).

    Relating oral physiology and anatomy of consumers varying in age, gender and ethnicity to food oral processing behavior
    Ketel, Eva C. ; Wijk, Rene A. de; Graaf, Cees de; Stieger, Markus - \ 2020
    Physiology and Behavior 215 (2020). - ISSN 0031-9384
    Age - Ethnicity - Gender - Oral anatomy - Oral physiology - Oral processing behavior

    The aim of this study was to link parameters describing oral physiology and anatomy of consumers varying in age, gender and ethnicity to food oral processing behavior. Three groups of healthy consumers were compared: Dutch, Caucasian adults (18–30 yrs, n =32), Chinese, Asian adults (18–30 yrs, n =32) and Dutch, Caucasian older adults (65–85 yrs, n =32). Mastication performance, salivary flow rate (stimulated and unstimulated) and dental status were quantified to characterize oral physiology. Volume of oral cavity, tongue dimensions, facial anthropometry, height and weight were quantified to characterize anatomy. Oral processing behavior of three solid foods (carrot, cheese and sausage) was quantified by video recordings and eating rate (g/s), average consumption time (s), chews per bite (-) and average bite size (g) were determined. Dutch, Caucasian older adults had smaller volume of oral cavity, lower number of teeth and larger head width compared to Dutch, Caucasian adults. Chinese, Asian adults showed significantly higher mastication performance and larger head width compared to Dutch, Caucasian consumers, while dental status did not significantly differ between groups. Males had significantly larger volumes of oral cavity and larger head height and width compared to females. Dutch, Caucasian adults had a shorter average consumption time (s), less chews per bite and consumed the three foods with higher eating rate (g/s) compared to Dutch, Caucasian older adults. Chinese, Asian adults had a significantly longer average consumption time (s), more chews per bite, smaller average bite size (g) and lower eating rate (g/s) compared to Dutch, Caucasian adults. Twenty-one significant relationships were found between oral physiological and anatomical parameters and oral processing behavior. Body weight resulted in the largest β-values, indicating to be the anatomical parameter of largest influence on oral processing behavior. We conclude that only few oral physiological and anatomical parameters related with food oral processing behavior. We suggest that other factors, including cultural factors contribute to variation in food oral processing behavior between different consumer groups more than saliva flow, volume of oral cavity, mastication performance and dental status.

    The nutritious drink: a specialized nutrient supplement for adults and adults living with HIV in Malawi
    Rodas-Moya, Santiago - \ 2020
    Wageningen University. Promotor(en): K. de Graaf, co-promotor(en): S. de Pee. - Wageningen : Wageningen University - ISBN 9789463952200 - 183


    Undernutrition is a major problem in the world, affecting vulnerable population groups such as people living with HIV (PLHIV). Ready-to-use-therapeutic-foods or corn-soy-blends [e.g., Super Cereal (SC)] are often used to treat undernutrition among PLHIV. However, their acceptability and compliant use are not optimal. 


    To develop a culturally appropriate food nutrient supplement with sensory properties tailored to the preference, primarily of PLHIV, and potentially of adults from the general population, leading to more optimal micronutrient intake.


    We conducted two qualitative studies based on Grounded Theory. In-depth interviews with a triangulation of participants and an iterative approach to data collection were used to investigate the factors influencing preferences for food and nutrient supplements among PLHIV. Based on the results of the qualitative research, we developed eight samples of a nutritious drink.

    Next, we studied the olfactory and gustatory (chemosensory) function of PLHIV to assess whether they suffer from chemosensory losses that could explain possible differences in preferences for the eight samples of the nutritious drink. We used the Sniffin’ Sticks and Taste Strips to assess the olfactory and gustatory function of 100 PLHIV and 100 healthy adults for comparison.

    Subsequently, 100 PLHIV and 98 healthy adults evaluated the nutritious drink samples. We used hedonic scales for assessing liking, and CATA (check-all-that-apply) questions to develop a sensory characterization of the nutritious drink samples. Penalty analysis was conducted to identify the drivers of liking and disliking of the samples for subsequent product optimization.

    Our last study assessed the acceptability and ad libitum intake of the nutritious drink, RUTF, and SC. Fifty-four PLHIV evaluated the products, monadically on three consecutive days. The three food nutrient supplements were served in isocaloric portions of 1000 kcal each. Participants were instructed to consume the products ad libitum. The participants were also asked to rate their liking and wanting for each product. Time of consumption (ad libitum), the number of bites used to consume the products were also measured, and the eating rate was calculated.


    The findings from the qualitative studies indicated that PLHIV preferred a thick beverage slightly sweet and sour as a nutrient supplement. Maheu, a maize-based drink of sweet and sour flavor and a thick, gritty consistency was utilized as a benchmark for the development of the nutritious drink samples for Malawi. The results from the study on olfactory and gustatory function, suggest that PLHIV suffer from olfactory loss. However, their gustatory function was normal.

    The findings from the study using CATA questions showed clear and significant differences in the acceptability of the samples, but no significant differences in preferences between PLHIV and healthy adults. The sensory characterization of the samples made by the two groups was also similar. A preference toward sweet, somewhat sour, thick samples with a soft texture and a milky flavor was identified.

    The results from the ad libitum intake study showed a significantly higher intake of the nutritious drink (356 g) compared to RUTF (107 g) and SC-porridge (312 g). The average intake of eight essential micronutrients as a percentage of target quantities was 58 % from the nutritious drink, 33 % from RUTF, and 20 % from SC. The average caloric intake from the nutritious drink, RUTF, and SC was 507, 581, and 339 kcal, respectively.


    The combination of qualitative research and advanced techniques from sensory science allowed us to identify a product of high acceptability and to identify directions for tailoring the sensory properties of the product to the preference of the potential consumers. A more substantial weight of food and larger quantities of micronutrients were ingested from the nutritious drink compared to RUTF and SC. The nutritious drink also had a much higher eating rate compared to the semisolid supplements. These findings suggest that nutrient-dense food supplements in liquid form may be more effective than semisolid products (e.g., RUTF and SC) in treating undernutrition among PLHIV and other adults. Future research should focus on testing the efficacy of the nutritious drink in the treatment of undernutrition in comparison to RUTF and SC.

    Food preferences and intake in a population of Dutch individuals with self-reported smell loss: An online survey
    Postma, E.M. ; Graaf, C. De; Boesveldt, S. - \ 2020
    Food Quality and Preference 79 (2020). - ISSN 0950-3293
    Anosmia - Dietary intake - Eating behavior - Hyposmia - Macronutrients - Smell loss

    Olfaction plays a major role in food intake regulation. Losing the sense of smell might therefore affect eating behavior. This study investigated food preferences and intake in individuals suffering from self-reported smell loss with an online survey. Members of the Dutch Anosmia Foundation (DAF) performed the Macronutrient and Taste Preference Ranking Task (n = 71) to measure preference for foods high in fat, carbohydrates or protein and low energy foods, and for sweet and savory tastes. To assess dietary intake, adherence to the Dutch Dietary Guidelines for consumption of vegetables, fruit, fiber, fish, saturated fat, trans fatty acids, salt and alcohol was measured (n = 105). Results of the DAF participants were compared to local cohort groups. Both the control and DAF participants showed the lowest preference for carbohydrate-rich foods and highest preference for low-energy foods. Participants suffering from congenital smell loss showed an aberrant pattern, with a higher preference for fat. The total adherence score to the Dutch Dietary Guidelines was similar for the control and DAF group, but adherence scores for fiber, trans fatty acids and alcohol were lower in DAF participants. Overall, no major significant differences in food preferences and intake were found for participants who lost their sense of smell during life. Participants suffering from congenital smell loss did show changes in food preferences, suggesting they are potentially more taste-oriented during eating. Together these results show the importance of tailored advice on dietary intake for this patient group.

    Exploring in vitro gastric digestion of whey protein by time-domain nuclear magnetic resonance and magnetic resonance imaging
    Deng, Ruoxuan ; Janssen, Anja E.M. ; Vergeldt, Frank J. ; As, Henk Van; Graaf, Cees de; Mars, Monica ; Smeets, Paul A.M. - \ 2020
    Food Hydrocolloids 99 (2020). - ISSN 0268-005X
    Gastric digestion - Gel - In vitro - MRI - Time-domain NMR - Whey protein

    Gastric digestion is crucial for protein breakdown. Although it has been widely studied with in vitro models, verification in vivo remains a big challenge. Magnetic resonance imaging (MRI) has the potential to bridge this gap. Our objective was to use the transverse relaxation time (T2) and rate (R2 = T2 −1) to monitor hydrolysis of protein-rich food during in vitro gastric digestion. Whey protein solution and heat-induced hydrogels were digested by means of simulated gastric fluid (SGF). Free amino groups (–NH2 groups) and protein concentration in the supernatant were measured. T2 and R2 of the digestion mixture were determined by time-domain nuclear magnetic resonance (TD-NMR) and MRI. Subsequently, relative amplitudes (TD-NMR) for different T2 values and T2 distribution (MRI) were determined. For the solution, protein concentration and T2 did not change during digestion. For the gels, water in supernatant and gel phase could be discriminated on the basis of their T2 values. During digestion, R2 of supernatant correlated positively with protein (–NH2 groups) concentration in SGF. Also, the decrease in relative amplitude of gel fraction correlated linearly with the increase of supernatant protein concentration. MRI T2-mapping showed similar associations between R2 of supernatant and protein (–NH2 groups) concentration. In conclusion, T2-measurements by TD-NMR and MRI can be used to monitor in vitro gastric digestion of whey protein gels; TD-NMR measurements contributed to interpreting the MRI data. Thus, MRI has high potential for monitoring in vivo gastric digestion and this should be further pursued.

    Non-fasting bioelectrical impedance analysis in cystic fibrosis: Implications for clinical practice and research
    Hollander-Kraaijeveld, F.M. ; Lindeman, Y. ; Roos, N.M. de; Burghard, M. ; Graaf, E.A. van de; Heijerman, H.G.M. - \ 2020
    Journal of Cystic Fibrosis 19 (2020)1. - ISSN 1569-1993 - p. 153 - 158.
    Anthropometry - Body composition - Cystic fibrosis - FEV1%pred - Non-fasting - Single frequency bioelectrical impedance analysis

    Background: Nutritional status affects pulmonary function in cystic fibrosis (CF) patients and can be monitored by using bioelectrical impedance analysis (BIA). BIA measurements are commonly performed in the fasting state, which is burdensome for patients. We investigated whether fasting is necessary for clinical practice and research. Methods: Fat free mass (FFM) and fat mass (FM) were determined in adult CF patients (n = 84) by whole body single frequency BIA (Bodystat 500) in a fasting and non-fasting state. Fasting and non-fasting BIA outcomes were compared with Bland-Altman plots. Pulmonary function was expressed as Forced Expiratory Volume at 1 s percentage predicted (FEV1%pred). Comparability of the associations between fasting and non-fasting body composition measurements with FEV1%pred was assessed by multiple linear regression. Results: Fasting FFM, its index (FFMI), and phase angle were significantly lower than non-fasting estimates (−0.23 kg, p = 0.006, −0.07 kg/m2, p = 0.002, −0.10°, p = 0.000, respectively). Fasting FM and its index (FMI) were significantly higher than non-fasting estimates (0.22 kg, p = 0.008) 0.32%, p = 0.005, and 0.07 kg/m2, (p = 0.005). Differences between fasting and non-fasting FFM and FM were <1 kg in 86% of the patients. FFMI percentile estimates remained similar in 83% of the patients when measured after nutritional intake. Fasting and non-fasting FFMI showed similar associations with FEV1%pred (β: 4.3%, 95% CL: 0.98, 7.70 and β: 4.6%, 95% CI: 1.22, 8.00, respectively). Conclusion: Differences between fasting and non-fasting FFM and FM were not clinically relevant, and associations with pulmonary function remained similar. Therefore, BIA measurements can be performed in a non-fasting state.

    Indoor-visteelt verhoogt rendement
    Boedijn, Alexander ; Graaf, Marcel van de - \ 2019
    Surveillance van Listeria monocytogenes in Nederland, 2018
    Friesema, I.H.M. ; Kuiling, Sjoerd ; Heck, M. ; Wullings, Bart ; Voort, Menno van der; Freudenburg-de Graaf, W. ; Ende, A. van den; Franz, E. - \ 2019
    Infectieziekten bulletin 30 (2019)6. - ISSN 0925-711X
    Sinds 2008 is listeriose meldingsplichtig. In 2018 zijn 78 patiënten met listeriose geregistreerd, waaronder 7 zwangere vrouwen (9%). Vier volwassenen zijn ten gevolge van de infectie overleden (6%). De meeste listeriosepatiënten hadden ernstig onderliggende aandoeningen en/of gebruikten immunosuppressiva en/of maagzuurremmers. Een aantal risicoproducten werden in 2018 vaker door patiënten geconsumeerd dan in voorgaande jaren. De meest opvallende stijgers zijn corned beef, gerookte zalm, garnalen en kibbeling/lekkerbek. Whole-genome-sequencing (WGS)-gegevens lieten een aantal clusteringen van patiëntisolaten zien en ook waren een aantal patiëntisolaten geclusterd met voedselisolaten. De meeste clusters bestaan uit patiënten uit verschillende jaren bij wie (vrijwel) identieke stammen zijn aangetoond. Er lijkt dus sprake te zijn van stammen die vanuit persisterende bronnen levensmiddelen besmetten. WGS maakt deze nieuwe inzichten mogelijk en biedt ook nieuwe mogelijkheden om de ziektelast van listeriose verder te verminderen vanwege het grotere vermogen om verbanden te leggen tussen de levensmiddelen en patiënten.

    Listeria monocytogenes is een bacterie die overal in het milieu voorkomt. De bacterie kan zelfs onder ongunstige omstandigheden zoals droogte en lage temperaturen, overleven en groeien. Infectie bij de mens gebeurt voornamelijk via voedsel dat besmet wordt vanuit de productieomgeving. Het aantal mensen dat listeriose oploopt is niet heel groot, maar de ziektelast is door de ernst van de ziekte hoog. (1, 2) In Nederland bestaat er sinds 2005 een laboratoriumsurveillance voor L. monocytogenes en een aangifteplicht sinds december 2008. Sinds 2017 wordt WGS toegepast als standaard typeringsmethode. Daarnaast worden door de Nederlandse Voedsel en Waren Autoriteit (NVWA) jaarlijks diverse risicovolle voedingsmiddelen op L. monocytogenes onderzocht. In deze rapportage presenteren we de gezamenlijke resultaten van 2018 en vergelijken die met elkaar en ten opzichte van voorgaande jaren.
    Healthy is (not) tasty? Implicit and explicit associations between food healthiness andtastiness in primary school-aged children and parents with a lower socioeconomic position
    Heijden, A. van der; Molder, H.F.M. te; Graaf, C. de; Jager, G. - \ 2019
    - 1 p.
    Growth, maturation, sex-ration, length and age of European eel (Anguilla anguilla) in the Netherlands
    Hammen, T. van der; Wolfshaar, K.E. van de; Graaf, M. de; Leeuw, Joep de - \ 2019
    In: Eels biology, monitoring, management, culture and exploitation / Coulson, Paul, Don, Andy, 5m Publishing - ISBN 9781789180695 - p. 111 - 118.
    Spatial distribution, relative abundance and size composition of reef-associated sharks on St Eustatius, Saba and the Saba Bank (Caribbean Netherlands)
    Stoffers, Twan ; Graaf, Martin de; Machiels, Marcel ; Nagelkerke, Leo - \ 2019
    Spatial distribution, relative abundance and size composition of reef-associated sharks on St Eustatius, Saba and the Saba Bank (Caribbean Netherlands)
    Stoffers, Twan ; Graaf, Martin de; Machiels, Marcel ; Nagelkerke, Leo - \ 2019
    elasmobranchs - conservation - habitat preference
    The aim of this study was to undertake a baseline-survey on the spatial distribution, relative abundance and size composition of reef-associated sharks in St Eustatius, Saba and the Saba Bank, windward islands of the Caribbean Netherlands. From 2012 to 2014 376 sites were surveyed with stereo Baited Remote Underwater Video (sBRUV) deployments. Videos were analysed for shark presence and individual sharks were measured using stereo-video, enabling accurate length measurements. A total of 153 sharks belonging to six species were recorded. Mean probability of observing at least one shark per recording is 0.29. In 4.3% of the video deployments two or more sharks were observed. Nurse shark was the most frequently observed species (n = 78) followed by Caribbean reef shark (n = 62), blacktip reef shark (n = 6), tiger shark (n = 5), great hammerhead shark (n = 1) and silky shark (n = 1). Significant spatial differences in geographic location were found for abundances of G. cirratum and C. perezi. Mean probability of observing these shark species on St Eustatius and the Saba Bank was found to be twice as high as compared to Saba. Habitat complexity and depth also had significant effects on total shark abundances. Mean probability of observing a reef-associated shark increased with habitat complexity and decreased with depth. The effect of management zone was not significant. Individuals of G. cirratum were significantly larger on the Saba Bank and in sites with low habitat complexity. Judging by total shark abundances, the shark populations of the Saba Bank, Saba and St Eustatius appear to be in reasonably healthy state compared to other areas in the Caribbean. The vast majority of observed sharks were juveniles, indicating that these shallow waters may be used as nursery areas.
    E-liquid flavor preferences and individual factors related to vaping : A survey among dutch never-users, smokers, dual users, and exclusive vapers
    Romijnders, Kim A.G.J. ; Krüsemann, Erna J.Z. ; Boesveldt, Sanne ; Graaf, Kees de; Vries, Hein de; Talhout, Reinskje - \ 2019
    International Journal of Environmental Research and Public Health 16 (2019)23. - ISSN 1661-7827
    Attitude - Deliberation - Electronic cigarettes - Flavors - Knowledge - Perceived susceptibility - Preference - Smoking - Vaping

    Appealing product characteristics, such as flavors, may stimulate e-cigarette use. While switching to e-cigarettes may reduce harm for smokers, concerns exist about e-cigarette use among neversmokers. The role of flavors in the decision to switch to or refrain from vaping is unclear. This study used a bottom–up approach to investigate the relation between flavor preferences and individual factors related to vaping between various user groups. A cross-sectional survey was conducted among never-users (n = 407), smokers (n = 138), dual users (n = 122), and exclusive vapers (n = 61) in the Netherlands. Demographics, attractiveness of product characteristics, flavor preferences, and individual factors related to vaping (knowledge, trust, perceived susceptibility, attitude, social influence, deliberation, and intention) were assessed. The availability of different flavors was the most attractive characteristic of ecigarettes. Dual users and exclusive vapers had most often used tobacco and menthol/mint flavors when they first started vaping. Compared to dual users, exclusive vapers currently used more fruit and sweet flavors. Never-users who were interested in trying an e-liquid flavor had more knowledge about and a more positive attitude towards e-cigarettes. Smokers who were interested in trying a flavor had a more positive attitude towards e-cigarettes and experienced the social influence towards not using e-cigarettes as less strong than those who did not want to try any flavor. Hence, individual factors related to vaping differed depending on whether never-users and smokers wanted to try an e-liquid flavor. This means that flavors may moderate differences found in individual factors related to vaping, or vice versa.

    Nearly 20 000 e-liquids and 250 unique flavour descriptions: An overview of the Dutch market based on information from manufacturers
    Havermans, Anne ; Krüsemann, Erna J.Z. ; Pennings, Jeroen ; Graaf, Kees De; Boesveldt, Sanne ; Talhout, Reinskje - \ 2019
    Tobacco Control (2019). - ISSN 0964-4563
    consumer appeal - e-cigarettes - e-liquid manufacturing - e-liquids - flavor descriptions - marketing - tobacco product directive

    Objectives: Flavours increase attractiveness of electronic cigarettes and stimulate use among vulnerable groups such as non-smoking adolescents. It is important for regulators to monitor the market to gain insight in, and regulate the range of e-liquid flavours that is available to consumers. E-liquid manufacturers are required to report key product information to authorities in the European Member States in which they plan to market their products. This information was used to provide an overview of e-liquid flavour descriptions marketed in the Netherlands in 2017. Methods: Two researchers classified 19 266 e-liquids into the 16 main categories of the e-liquid flavour wheel, based on information from four variables in the European Common Entry Gate system. Flavour descriptions were further specified in subcategories. Results: For 16 300 e-liquids (85%), sufficient information was available for classification. The categories containing the highest number of e-liquids were fruit (34%), tobacco (16%) and dessert (10%). For all e-liquids, excluding unflavoured ones, 245 subcategories were defined within the main categories. In addition to previously reported subcategories, various miscellaneous flavours such as sandwich, buttermilk and lavender were identified. Conclusions: In 2017, ∼20 000 e-liquids were reported to be marketed in the Netherlands, in 245 unique flavour descriptions. The variety of marketed flavour descriptions reflects flavour preference of e-cigarette users as described in literature. Our systematic classification of e-liquids by flavour description provides a tool for organising the huge variety in market supply, serves as an example for other countries to generate similar overviews and can support regulators in developing flavour regulations.

    Letter of protest on new food label
    Graaf, Kees de - \ 2019
    #3 Waarom je beter langzaam kunt eten dan een dieethype volgen
    Graaf, C. de - \ 2019
    An E-Liquid Flavor Wheel: A Shared Vocabulary Based on Systematically Reviewing E-Liquid Flavor Classifications in Literature
    Krüsemann, Erna J.Z. ; Boesveldt, Sanne ; Graaf, Kees de; Talhout, Reinskje - \ 2019
    Nicotine & Tobacco Research 21 (2019)10. - ISSN 1462-2203 - p. 1310 - 1319.

    INTRODUCTION: E-liquids are available in a high variety of flavors. A systematic classification of e-liquid flavors is necessary to increase comparability of research results. In the food, alcohol, and fragrance industry, flavors are classified using flavor wheels. We systematically reviewed literature on flavors related to electronic cigarette use, to investigate how e-liquid flavors have been classified in research, and propose an e-liquid flavor wheel to classify e-liquids based on marketing descriptions. METHODS: The search was conducted in May 2017 using PubMed and Embase databases. Keywords included terms associated with electronic cigarette, flavors, liking, learning, and wanting in articles. Results were independently screened and reviewed. Flavor categories used in the articles reviewed were extracted. RESULTS: Searches yielded 386 unique articles of which 28 were included. Forty-three main flavor categories were reported in these articles (eg, tobacco, menthol, mint, fruit, bakery/dessert, alcohol, nuts, spice, candy, coffee/tea, beverages, chocolate, sweet flavors, vanilla, and unflavored). Flavor classifications of e-liquids in literature showed similarities and differences across studies. Our proposed e-liquid flavor wheel contains 13 main categories and 90 subcategories, which summarize flavor categories from literature to find a shared vocabulary. For classification of e-liquids using our flavor wheel, marketing descriptions should be used. CONCLUSIONS: We have proposed a flavor wheel for classification of e-liquids. Further research is needed to test the flavor wheels' empirical value. Consistently classifying e-liquid flavors using our flavor wheel in research (eg, experimental, marketing, or qualitative studies) minimizes interpretation differences and increases comparability of results. IMPLICATIONS: We reviewed e-liquid flavors and flavor categories used in research. A large variation in the naming of flavor categories was found and e-liquid flavors were not consistently classified. We developed an e-liquid flavor wheel and provided a guideline for systematic classification of e-liquids based on marketing descriptions. Our flavor wheel summarizes e-liquid flavors and categories used in literature in order to create a shared vocabulary. Applying our flavor wheel in research on e-liquids will improve data interpretation, increase comparability across studies, and support policy makers in developing rules for regulation of e-liquid flavors.

    Secret for getting fussy kids to eat their greens? A variety of veg
    Graaf, C. de - \ 2019
    Baby's first bites: a randomized controlled trial to assess the effects of vegetable-exposure and sensitive feeding on vegetable acceptance, eating behavior and weight gain in infants and toddlers
    Veek, S.M.C. van der; Graaf, C. de; Vries, J.H.M. de; Jager, G. ; Vereijken, C.M.J.L. ; Weenen, H. ; Winden, N. van; Vliet, M.S. van; Schultink, J.M. ; Wild, V.W.T. de; Janssen, S. ; Mesman, J. - \ 2019
    BMC Pediatrics 19 (2019)1. - ISSN 1471-2431 - 1 p.
    Complementary feeding - Infant - Responsive feeding - Self-regulation of energy intake - Toddler - Vegetable exposure - Vegetables

    BACKGROUND: The start of complementary feeding in infancy plays an essential role in promoting healthy eating habits. Evidence shows that it is important what infants are offered during this first introduction of solid foods: e.g. starting exclusively with vegetables is more successful for vegetable acceptance than starting with fruits. How infants are introduced to solid foods also matters: if parents are sensitive and responsive to infant cues during feeding, this may promote self-regulation of energy intake and a healthy weight. However, the effectiveness of the what and the how of complementary feeding has never been experimentally tested in the same study. In the current project the what and how (and their combination) are tested in one study to determine their relative importance for fostering vegetable acceptance and self-regulation of energy intake in infants. METHODS: A four-arm randomized controlled trial (Baby's First Bites (BFB)) was designed for 240 first-time Dutch mothers and their infants, 60 per arm. In this trial, we compare the effectiveness of (a) a vegetable-exposure intervention focusing on the what in complementary feeding; (b) a sensitive feeding intervention focusing on the how in complementary feeding, (c) a combined intervention focusing on the what and how in complementary feeding; (d) an attention-control group. All mothers participate in five sessions spread over the first year of eating solid foods (child age 4-16 months). Primary outcomes are vegetable consumption, vegetable liking and self-regulation of energy intake. Secondary outcomes are child eating behaviors, child anthropometrics and maternal feeding behavior. Outcomes are assessed before, during and directly after the interventions (child age 18 months), and when children are 24 and 36 months old. DISCUSSION: The outcomes are expected to assess the impact of the interventions and provide new insights into the mechanisms underlying the development of vegetable acceptance, self-regulation and healthy eating patterns in infants and toddlers, as well as the prevention of overweight. The results may be used to improve current dietary advice given to parents of their young children on complementary feeding. TRIAL REGISTRATION: The trial was retrospectively registered during inclusion of participants at the Netherlands National Trial Register (identifier NTR6572 ) and at ( NCT03348176 ). Protocol issue date: 1 April 2018; version number 1.

    Biology, monitoring, and management of a tropical marine gastropod: the Queen conch (Lobatus gigas) in the Caribbean
    Boman, B.E. - \ 2019
    Wageningen University. Promotor(en): A.C. Smaal, co-promotor(en): L.A.J. Nagelkerke; M. de Graaf. - Wageningen : Wageningen University - ISBN 9789463439909 - 207

    The marine gastropod queen conch (Lobatus gigas), found throughout the Wider Caribbean Region, supports one of the most important fisheries in the region. However, several biological characteristics (e.g. density-dependent mating and survival, slow-moving, a preference for shallow depths, and aggregating behaviour during the reproductive season) make the species particularly vulnerable to overfishing. The heavy exploitation of queen conch throughout large parts of its natural range, as well as degradation of juvenile and adult habitats, also has in many areas led to a reduction in population densities to unsustainable levels to a point where mating success can be negatively affected. In addition, a new invasive seagrass species (H. stipulacea) has already caused significant alterations to the structure of native seagrass habitats which are in many parts of the Caribbean important to juvenile conch, providing both nutrition and protection from predators. However, the impacts of this invasive seagrass on life-history parameters such as growth and survival remain unknown.

    Although many Caribbean nations have implemented policies with regard to queen conch protection and exploitation, recovery of overfished populations has been slow. These measures, however, are still mostly not harmonized among nations and often based on outdated and limited biological information. Management of queen conch is also often complicated by difficulties in data acquisition, partly caused by the logistically demanding and relatively expensive surveying of conch. Conventional survey methods using scuba are also limited to ca. 25 m depth due to safety limitations, making them unsuitable for collecting data across the entire depth range of conch, which extends to 60 m.

    The main objectives of this study were to address knowledge gaps of the biology and ecology of the queen conch so that the distribution and dynamics of this species in relation to its environment are better understood. Such information will further improve our knowledge of marine gastropod biology in general, as well as our understanding of the effects of direct and indirect human-induced pressures on queen conch in the Caribbean. In addition, this study aimed to tackle some methodological shortcomings in the surveying and assessment of queen conch. Ultimately, these findings could be instrumental in the management and conservation of the species.

    Reproductive characteristics are important biological reference points for the management of species. To improve the knowledge of queen conch reproductive biology (i.e. size-at-maturity and reproductive season), evaluation and comparison of the relationship between shell lip thickness and maturity in queen conch throughout the Wider Caribbean Region, using histological analysis of queen conch gonads was carried out. Furthermore, the influence of seawater temperature on the length of the reproductive season was investigated (chapter 2). We demonstrate a clear positive relationship between the thickness of the shell lip and the onset of maturity in queen conch, and that maturity occurs following the development of the lip. Lip thickness at 50% maturity (LT50) of both females and males varied between different locations in the Caribbean, although it did not correspond with variation in water temperature. In most cases, females had a larger LT50 than males indicating sexual dimorphism. Locations with a relatively high variation in water temperature had a significantly shorter reproductive season. The implementation of adequate minimum size regulation based on lip thickness (ca. 15 mm) and a Caribbean wide seasonal closure (May–September) using the most recent biological information from this study, taking into consideration the local differences in LT50 and reproductive season, will assist in developing a long-term sustainable queen conch fishery in the Caribbean.

    To address the methodological shortcomings in the surveying of queen conch, a novel towed video method (TVM) was developed and compared with a conventional survey method (i.e. belt transect [BT] using scuba divers) in a series of calibration transects in two different habitats (i.e. high complexity (HC) and low complexity (LC)) (chapter 3). In both habitats, adult live queen conch had similar counts with both methods. Adult dead conch were not mistaken for live conch and the results validate the use of TVM as a reliable sampling tool to estimate densities of live adult conch in both HC and LC habitats throughout the species’ depth range.

    In chapter 4, the spatial distribution of adult queen conch and how it varies in response to a number of known abiotic and biotic variables between sites which vary in environmental conditions was examined. By combining TVM with conventional belt-transects, a more comprehensive survey of conch abundance was performed at three sites in the Eastern Caribbean (Anguilla, St Eustatius, Saba Bank). Adult conch appeared in patchy distributions, mostly caused by spatial dependency, which was likely related to aggregating behaviour during spawning events. Environmental variables, such as algae cover, distance to the open ocean, and depth showed important non-linear effects on conch abundance, although these differed among sites. The proportion of reef and sand cover had important negative effects on conch abundance at all sites. High densities (>100 /ha) of adult conch were found only at depths >17 m at all three sites. The lack of strong generic location over-crossing relationships between abiotic and biotic factors and adult conch abundance and distribution is likely partly due to this spatial dependency, as well as different location-specific factors that affect different stages of the conch’s life-history. Furthermore, the results indicate that intermediate and deep areas (ca. 17 – 45 m) contain most of the reproductive output of conch in the survey sites and are therefore highly important for reproductive capacity. Thus, surveying areas at depths beyond the practical limitation of divers (<25 m) are of great importance to obtain more reliable population estimates.

    To provide a first insight into the possible impact of an invasive seagrass species (H. stipulacea) on queen conch, the diet and growth of juvenile conch in both native, mixed, and invasive seagrass beds was examined using stable isotope analysis and an in situ growth enclosure experiment (chapter 5). Organic material in the sediment (i.e. benthic diatoms and particulate organic matter [POM]) was found to be the most important source of carbon and nitrogen for juvenile queen conch in all three habitats investigated, and there was a significantly higher probability of positive growth in the native seagrass compared to the invasive seagrass. Due to the importance of the organic material in the sediment as a source of nutrition for juvenile conch, limited access to the sediment in the invasive seagrass can potentially cause inadequate nutritional conditions to sustain high growth rates. Thus, it is likely that there is a negative effect on juvenile queen conch growth currently inhabiting invasive seagrass beds, compared to native seagrass beds, when other potential sources of nutrition are not available. Although much uncertainty still exists regarding the effects of H. stipulacea on the population dynamics on queen conch, if lower growth rates in invasive seagrass beds is a general pattern, it would have ramifications for both births and deaths of conch and the overall carrying capacity of conch populations in the Caribbean.

    A better understanding of the spatial genetic structure (SGS) and the factors driving contemporary patterns of gene flow and genetic diversity of queen conch are fundamental for developing conservation and management plans for marine fisheries. A detailed study of SGS and genetic diversity was therefore performed using population genetic and multivariate analyses (chapter 6). Our study found that queen conch does not form a single panmictic population in the greater Caribbean. Significant levels of genetic differentiation were identified between Caribbean countries, within Caribbean countries, and among sites. Gene flow over the spatial scale of the entire Caribbean basin is constrained by oceanic distance, which may impede the natural recovery of overfished queen conch populations. Our results suggest a careful blend of local and international management will be required to ensure long-term sustainability for the species.

    This study has provided new insights into queen conch biology and population dynamics as well as methodological shortcomings so that the distribution and dynamics of this species in relation to its environment are better understood. Ultimately, the findings from this study can contribute to improving the management and conservation of the species. However, the species will in the future face new challenges, due to expected changes in abiotic and biotic factors, such as temperature, ocean currents, and seagrass species composition. As body temperature and thus their physiological functions (e.g. growth) are directly dependent on environmental condition in this ectotherm species, it is particularly vulnerable to climate change (Dillon et al. 2010). Consequently, life-history parameters (e.g. size-at-maturity, reproductive season, growth rate, spatial genetic structure) of queen conch should not be considered rigid as these can be expected to change in the short and long-term, putting an unknown time limit to the relevance of the current biological knowledge of these parameters. However, there is still much uncertainty regarding what degree queen conch and other species can adapt to environmental changes induced by climate change and invasive species. Therefore, commitment to long-term research and updates in current biological knowledge, life-history parameters and population dynamics of queen conch throughout its range will be required to adjust subsequent management and conservation strategies to ensure the long-term sustainability of the species.

    Impact of food odors signaling specific taste qualities and macronutrient content on saliva secretion and composition
    Morquecho-Campos, Paulina ; Bikker, Floris J. ; Nazmi, Kamran ; Graaf, Kees de; Laine, Marja L. ; Boesveldt, S. - \ 2019
    Appetite 143 (2019). - ISSN 0195-6663
    Cephalic phase response - Olfaction - Salivary protein - Salivation - Smell

    Olfactory food cues can induce appetite for similar food products in humans. Odors may thus signal essential information about a foods’ composition such as taste or even macronutrient content and may stimulate specific physiological responses in anticipation of food intake. Several studies have shown that sensory food cues could stimulate saliva secretion. However, potential differences between food odors in their effect on saliva secretion, or the effects of olfactory stimulation on changes in saliva composition remain to be elucidated. To gain more insight, we conducted two studies to determine the influence of various odors, representing different taste qualities (study 1) and macronutrients (study 2), on salivary biomarkers. In study 1, 36 participants were randomly exposed to no-odor, non-food, and odors signaling sweet, savory, and sour taste. In study 2, 60 participants were randomly exposed to no-odor, non-food, and odors signaling carbohydrates, protein, fat, and low-calorie food. For each condition, whole-mouth saliva was collected and saliva secretion rate determined. Furthermore, we determined mouth-watering perception (subjective salivation), visco-elasticity (study 1 only), mucin concentration, α-amylase and lingual lipase activity (study 2 only). For both studies, linear mixed model analyses showed that saliva secretion rate significantly increased by food odor exposure compared to no-odor and non-food conditions. However, no changes in salivary composition were observed. These findings indicate that food odors play a crucial role in anticipatory saliva responses and can thereby affect subsequent eating behavior.

    Multiple vs Single Target Vegetable Exposure to Increase Young Children's Vegetable Intake
    Poelman, Astrid A.M. ; Delahunty, Conor M. ; Broch, Maeva ; Graaf, C. de - \ 2019
    Journal of Nutrition Education and Behavior 51 (2019)8. - ISSN 1499-4046 - p. 985 - 992.
    acceptance - repeated exposure - variety - vegetable intake - young children

    Objective: To evaluate the effectiveness of repeated exposure to multiple vs single target vegetables in increasing young children's vegetable intake. Methods: A pilot randomized controlled trial (children aged 4–6 years, n = 32) was conducted, which exposed children at home 15 times over 5 weeks to either 1 (single target) or 3 (multiple target) vegetables. A comparison group did not change eating habits. Vegetable intake was measured by (1) a dinner meal consumed at research facilities, (2) 3-day weighed food records, and (3) usual vegetable intake (parent report). Measures were collected at baseline and either immediately after intervention (1), at 3-month follow-up (3) or both (2). Results: There were no differences between groups at baseline in vegetable intake. Usual vegetable intake increased in the multiple target group from.6 to 1.2 servings/d and did not change in other groups (P =.02). Food record data were not significant but underpowered. Vegetable intake from dinner meals was not significantly different between groups. Conclusions and Implications: Exposure to multiple vegetables simultaneously may be more effective than a single vegetable to increase young children's intake. Larger scale research is recommended to confirm the effectiveness of offering variety in exposure and to enhance the understanding of the mechanisms involved.

    Small food texture modifications can be used to change oral processing behaviour and to control ad libitum food intake
    Mosca, Ana Carolina ; Pohlenz Torres, Armando ; Slob, Evalien ; Graaf, Kees de; McEwan, Jean A. ; Stieger, Markus - \ 2019
    Appetite 142 (2019). - ISSN 0195-6663
    Eating rate - Food intake - Food texture - Oral processing behaviour - Satiation

    Little is known whether small modifications of food texture are sufficient to influence satiation. This study used four iso-caloric yogurts differing in viscosity (low/high) and granola particle size (small/large) to investigate the influence of small texture modifications on oral processing behaviour, eating rate and ad libitum intake. Yogurt viscosity differed by a factor of 1.57x to 1.81x. Granola particle size was 6 mm and 12 mm (2-fold difference). Granola particle concentration based on weight was constant (15% w/w). Oral processing behaviour was quantified by video recording consumers eating yogurt ad libitum (n = 104). Ratings for appetite, liking and product familiarity were also quantified. A decrease in yogurt viscosity significantly decreased spoon size, number of chews per spoon and oral exposure time per spoon but did not significantly affect eating rate and ad libitum intake. A decrease in granola particle size from 12 mm to 6 mm at constant weight concentration significantly increased number of chews per spoon and decreased spoon size, eating rate and ad libitum intake without affecting liking. The differences in eating rate and ad libitum intake between yogurts containing small and large granola particles were 5 g/min (7%) and 17 g (5%), respectively. We suggest that the volume of granola particles added to the yogurt and not the size of particles per se was the driver of oral processing behaviour. We conclude that relatively small modifications in yogurt texture, especially granola particle size, are sufficient to change oral processing behaviour and ad libitum intake. These findings demonstrate that small texture modifications of foods, such as the size of granola particles added to yogurt, can be used to modulate eating rate and food intake within a meal.

    Colouring perception: Package colour cues affect neural responses to sweet dairy drinks in reward and inhibition related regions
    Tijssen, Irene O.J.M. ; Smeets, Paul A.M. ; Goedegebure, Robert P.G. ; Zandstra, Elizabeth H. ; Graaf, Cees de; Jager, Gerry - \ 2019
    Appetite 142 (2019). - ISSN 0195-6663
    BOLD fMRI - Health interest - Impulsivity - Package colour - Product perception

    Extrinsic product cues such as package colour may change product perception and perceived reward value during product evaluation. Healthier foods (i.e., ‘light’, sugar- or fat-reduced) often have different packages than regular products, e.g., they may be less vibrantly coloured. People vary in their degree of health-interest and self-control ability and may be affected differently by package colour. This study assesses the extent to which package colour and participant characteristics interact and influence product perception and brain responses. Thirty-four healthy females performed a functional MRI task in which they viewed four differently coloured packages (regular vs. healthier; differing in brightness and saturation levels) with or without simultaneously tasting a either a regular or a healthier calorie-reduced drink. Results indicate main effects of package and taste and a package*taste interaction effect. Compared to healthier packages viewing regular packages enhanced activation in region implicated in inhibitory control (inferior frontal gyrus) and a reward-related region (striatum), the latter even more so as participants’ health interest increased (r = 0.43, p = 0.01). Incongruent package-taste combinations decreased activation in the orbitofrontal cortex (OFC, a region implicated in reward representation) compared to congruent combinations. Tasting the healthier compared to regular product enhanced activation in the middle and superior frontal gyrus, which are implicated in inhibitory control, as well as the striatum and OFC, suggesting a cognitively driven preference for the healthier product. In conclusion, this paper provides evidence for the conditions under which package colour and taste properties modulate neural correlates related to reward and inhibition. Individual differences in health-interest and impulsivity influence package- and taste-related neural correlates and thus underscore the importance of taking participant characteristics into account in food research.

    Diet and growth of juvenile queen conch Lobatus gigas (Gastropoda: Strombidae) in native, mixed and invasive seagrass habitats
    Boman, Erik Maitz ; Bervoets, Tadzio ; Graaf, Martin De; Dewenter, Jana ; Maitz, Anna ; Meijer Zu Schlochtern, Melanie P. ; Stapel, Johan ; Smaal, Aad C. ; Nagelkerke, Leopold A.J. - \ 2019
    Marine Ecology Progress Series 621 (2019). - ISSN 0171-8630 - p. 143 - 154.
    Caribbean - Halophila stipulacea - Invasive species - Mollusca - Stable isotope

    Juvenile queen conch are primarily associated with native seagrass such as Thalassia testudinum in large parts of their range in the Caribbean and the southern Gulf of Mexico. Here, a number of non-native seagrass species have been introduced including Halophila stipulacea, which is natural to the Red Sea and the Indo-Pacific. In the Caribbean, H. stipulacea often creates dense continuous mats with little or no sediment exposed, compared to native seagrass, which grows much less dense. We examined the diet and growth of juvenile conch in both native, mixed, and invasive seagrass beds using stable isotope analysis and an in situ growth enclosure experiment. Organic material in the sediment (i.e. benthic diatoms and particulate organic matter) was found to be the most important source of carbon and nitrogen for juvenile queen conch in all 3 habitats investigated, and there was a significantly higher probability of positive growth in the native seagrass compared to the invasive seagrass. Due to the importance of the organic material in the sediment as a source of nutrition for juvenile conch, limited access to the sediment in the invasive seagrass can potentially cause inadequate nutritional conditions to sustain high growth rates. Thus, it is likely that there is a negative effect on juvenile queen conch growth currently inhabiting invasive seagrass beds, compared to native seagrass beds, when other potential sources of nutrition are not available.

    A Medicago truncatula SWEET transporter implicated in arbuscule maintenance during arbuscular mycorrhizal symbiosis
    An, Jianyong ; Zeng, Tian ; Ji, Chuanya ; Graaf, Sanne de; Zheng, Zijun ; Xiao, Ting Ting ; Deng, Xiuxin ; Xiao, Shunyuan ; Bisseling, Ton ; Limpens, Erik ; Pan, Zhiyong - \ 2019
    New Phytologist 224 (2019)1. - ISSN 0028-646X - p. 396 - 408.
    arbuscular mycorrhiza (AM) - glucose - Medicago truncatula - sugar export - SWEET - symbiosis

    Plants form a mutualistic symbiosis with arbuscular mycorrhizal (AM) fungi, which facilitates the acquisition of scarce minerals from the soil. In return, the host plants provide sugars and lipids to its fungal partner. However, the mechanism by which the AM fungi obtain sugars from the plant has remained elusive. In this study we investigated the role of potential SWEET family sugar exporters in AM symbiosis in Medicago truncatula. We show that M. truncatula SWEET1b transporter is strongly upregulated in arbuscule-containing cells compared to roots and localizes to the peri-arbuscular membrane, across which nutrient exchange takes place. Heterologous expression of MtSWEET1b in a yeast hexose transport mutant showed that it mainly transports glucose. Overexpression of MtSWEET1b in M. truncatula roots promoted the growth of intraradical mycelium during AM symbiosis. Surprisingly, two independent Mtsweet1b mutants, which are predicted to produce truncated protein variants impaired in glucose transport, exhibited no significant defects in AM symbiosis. However, arbuscule-specific overexpression of MtSWEET1bY57A/G58D, which are considered to act in a dominant-negative manner, resulted in enhanced collapse of arbuscules. Taken together, our results reveal a (redundant) role for MtSWEET1b in the transport of glucose across the peri-arbuscular membrane to maintain arbuscules for a healthy mutually beneficial symbiosis.

    Phylogenomic investigation of IncI1-I plasmids harboring blaCMY-2 and blaSHV-12 in salmonella enterica and Escherichia coli in multiple countries
    Castellanos, Luis Ricardo ; Graaf-Van Bloois, Linda van der; Donado-Godoy, Pilar ; Mevius, Dik J. ; Wagenaar, Jaap A. ; Hordijk, Joost ; Zomer, Aldert L. - \ 2019
    Antimicrobial Agents and Chemotherapy 63 (2019)7. - ISSN 0066-4804
    Blc - Broiler - Chicken - DeoR - IS1294 - IS26 - ISEcp1 - S. Heidelberg - Salmonella Paratyphi B var. Java - SugE - Tn1721

    The objective of this study was to elucidate the genetic and evolutionary relatedness of blaCMY-2- and blaSHV-12-carrying IncI1-I plasmids. Phylogenomic analysis based on core genome alignments and gene presence/absence was performed for different IncI1-I sequence types (STs). Most IncI1-I/ST12 and IncI1-I/ ST231 plasmids had near-identical core genomes. The data suggest that widely occurring blaCMY-2-carrying IncI1-I/ST12 plasmids originate from a common ancestor. In contrast, blaSHV-12 was inserted independently into different IncI1-I/ST231-related plasmids.

    Loss rates of honey bee colonies during winter 2017/18 in 36 countries participating in the COLOSS survey, including effects of forage sources
    Gray, Alison ; Brodschneider, Robert ; Adjlane, Noureddine ; Ballis, Alexis ; Brusbardis, Valters ; Charrière, Jean Daniel ; Chlebo, Robert ; F. Coffey, Mary ; Cornelissen, Bram ; Amaro da Costa, Cristina ; Csáki, Tamás ; Dahle, Bjørn ; Danihlík, Jiří ; Dražić, Marica Maja ; Evans, Garth ; Fedoriak, Mariia ; Forsythe, Ivan ; Graaf, Dirk de; Gregorc, Aleš ; Johannesen, Jes ; Kauko, Lassi ; Kristiansen, Preben ; Martikkala, Maritta ; Martín-Hernández, Raquel ; Medina-Flores, Carlos Aurelio ; Mutinelli, Franco ; Patalano, Solenn ; Petrov, Plamen ; Raudmets, Aivar ; Ryzhikov, Vladimir A. ; Simon-Delso, Noa ; Stevanovic, Jevrosima ; Topolska, Grazyna ; Uzunov, Aleksandar ; Vejsnaes, Flemming ; Williams, Anthony ; Zammit-Mangion, Marion ; Soroker, Victoria - \ 2019
    Journal of Apicultural Research 58 (2019)4. - ISSN 0021-8839 - p. 479 - 485.
    Apis mellifera - beekeeping - citizen science - colony winter losses - forage sources - monitoring - mortality - survey

    This short article presents loss rates of honey bee colonies over winter 2017/18 from 36 countries, including 33 in Europe, from data collected using the standardized COLOSS questionnaire. The 25,363 beekeepers supplying data passing consistency checks in total wintered 544,879 colonies, and reported 26,379 (4.8%, 95% CI 4.7–5.0%) colonies with unsolvable queen problems, 54,525 (10.0%, 95% CI 9.8–10.2%) dead colonies after winter and another 8,220 colonies (1.5%, 95% CI 1.4–1.6%) lost through natural disaster. This gave an overall loss rate of 16.4% (95% CI 16.1–16.6%) of honey bee colonies during winter 2017/18, but this varied greatly from 2.0 to 32.8% between countries. The included map shows relative risks of winter loss at regional level. The analysis using the total data-set confirmed findings from earlier surveys that smaller beekeeping operations with at most 50 colonies suffer significantly higher losses than larger operations (p <.001). Beekeepers migrating their colonies had significantly lower losses than those not migrating (p <.001), a different finding from previous research. Evaluation of six different forage sources as potential risk factors for colony loss indicated that intensive foraging on any of five of these plant sources (Orchards, Oilseed Rape, Maize, Heather and Autumn Forage Crops) was associated with significantly higher winter losses. This finding requires further study and explanation. A table is included giving detailed results of loss rates and the impact of the tested forage sources for each country and overall.

    Diversity, abundance, distribution and habitat use of reef-associated sharks in the Dutch Caribbean : Field studies using Baited Remote Underwater Video (BRUV) and acoustic telemetry ; as part of the DCNA ‘Save Our Sharks’ project (Nationale Postcode Loterij)
    Winter, H.V. ; Graaf, M. de - \ 2019
    IJmuiden : Wageningen Marine Research (Wageningen Marine Research report C105/18) - 31
    Honey bee predisposition of resistance to ubiquitous mite infestations
    Broeckx, Bart J.G. ; Smet, Lina De; Blacquière, Tjeerd ; Maebe, Kevin ; Khalenkow, Mikalaï ; Poucke, Mario Van; Dahle, Bjorn ; Neumann, Peter ; Bach Nguyen, Kim ; Smagghe, Guy ; Deforce, Dieter ; Nieuwerburgh, Filip Van; Peelman, Luc ; Graaf, Dirk C. de - \ 2019
    Scientific Reports 9 (2019)1. - ISSN 2045-2322 - 1 p.

    Host-parasite co-evolution history is lacking when parasites switch to novel hosts. This was the case for Western honey bees (Apis mellifera) when the ectoparasitic mite, Varroa destructor, switched hosts from Eastern honey bees (Apis cerana). This mite has since become the most severe biological threat to A. mellifera worldwide. However, some A. mellifera populations are known to survive infestations, largely by suppressing mite population growth. One known mechanism is suppressed mite reproduction (SMR), but the underlying genetics are poorly understood. Here, we take advantage of haploid drones, originating from one queen from the Netherlands that developed Varroa-resistance, whole exome sequencing and elastic-net regression to identify genetic variants associated with SMR in resistant honeybees. An eight variants model predicted 88% of the phenotypes correctly and identified six risk and two protective variants. Reproducing and non-reproducing mites could not be distinguished using DNA microsatellites, which is in agreement with the hypothesis that it is not the parasite but the host that adapted itself. Our results suggest that the brood pheromone-dependent mite oogenesis is disrupted in resistant hosts. The identified genetic markers have a considerable potential to contribute to a sustainable global apiculture.

    Toll-like receptor agonists as adjuvants for inactivated porcine reproductive and respiratory syndrome virus (PRRSV) vaccine
    Vreman, Sandra ; McCaffrey, Joanne ; Popma-de Graaf, Ditta J. ; Nauwynck, Hans ; Savelkoul, Huub F.J. ; Moore, Anne ; Rebel, Johanna M.J. ; Stockhofe-Zurwieden, Norbert - \ 2019
    Veterinary Immunology and Immunopathology 212 (2019). - ISSN 0165-2427 - p. 27 - 37.
    Adjuvant - PRRSV - Skin vaccination - Toll-like receptor agonist - Vaccine

    Toll-like receptor (TLR) agonists can effectively stimulate antigen-presenting cells (APCs) and are anticipated to be promising adjuvants in combination with inactivated vaccines. In this study, the adjuvant potential of three different TLR-agonists were compared with an oil-in-water (O/W) adjuvant in combination with inactivated porcine reproductive and respiratory syndrome virus (iPRRSV) applied by different administration routes: intramuscular (i.m.) or into the skin using dissolving microneedle (DMN) patches. Pigs received a prime vaccination followed by a booster vaccination four weeks later. TLR1/2 (Pam3Cys), TLR7/8 (R848) or TLR9 (CpG ODN) agonists were used as adjuvant in combination with iPRRSV strain 07V063. O/W adjuvant (Montanide™) was used as reference control adjuvant and one group received a placebo vaccination containing diluent only. All animals received a homologous challenge with PRRSV three weeks after the booster vaccination. Antibody and IFN-γ production, serum cytokines and viremia were measured at several time-points after vaccination and/or challenge, and lung pathology at necropsy. Our results indicate that a TLR 1/2, 7/8 or 9 agonist as adjuvant with iPRRSV does not induce a detectable PRRSV-specific immune response, independent of the administration route. However, the i.m. TLR9 agonist group showed reduction of viremia upon challenge compared to the non-vaccinated animals, supported by a non-antigen-specific IFN-γ level after booster vaccination and an anamnestic antibody response after challenge. Montanide™-adjuvanted iPRRSV induced antigen-specific immunity after booster combined with reduction of vireamia. Skin application of TLR7/8 agonist, but not the other agonists, induced a local skin reaction. Further research is needed to explore the potential of TLR agonists as adjuvants for inactivated porcine vaccines with a preference for TLR9 agonists.

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