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.

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Impact of hydraulic and storage properties on river leakage estimates : A numerical groundwater flow model case study from southern Benin
Kpegli, Kodjo Apelete Raoul ; Zee, Sjoerd E.A.T.M. van der; Alassane, Abdoukarim ; Bier, George ; Boukari, Moussa ; Leijnse, Anton ; Louw, Perry G.B. de; Mama, Daouda - \ 2018
Journal of Hydrology: Regional Studies 19 (2018). - ISSN 2214-5818 - p. 136 - 163.
Benin - Discharge loss - Flow modelling - Groundwater recharge - Ouémé - River leakage

Study area: The coastal sedimentary basin including the Zou and Ouémé rivers in Benin. Study focus: River discharge loss is known to occur on the Zou and Ouémé rivers in southern Benin since a couple of decades ago. The reason behind this discharge reduction remained so far unclear. In this study, we focus on creating a 3D-numerical model of the system and on evaluating the sensitivity of leakage between the rivers and aquifers to various parameters. New hydrological insights for the region: Results show that leakages along the Zou river and Ouémé stream are tiny (i.e., ∼3% of the discharge losses). This implies that the observed water loss from the Zou and Ouémé rivers is not likely caused by the leakage (infiltration) along these rivers into the subsurface. The streambed conductance is found to be among the factors that impact less the computed leakages in the study area. This study has ranked the different hydraulic and storage properties in their order of importance with respect to the computation of river leakages along the concerned rivers. The determined rank of importance of the hydraulic and storage properties can guide river leakage modelling exercises in similar regions elsewhere.

Development of a conceptual groundwater flow model using a combined hydrogeological, hydrochemical and isotopic approach : A case study from southern Benin
Kpegli, Kodjo Apelete Raoul ; Alassane, Abdoukarim ; Zee, Sjoerd E.A.T.M. van der; Boukari, Moussa ; Mama, Daouda - \ 2018
Journal of Hydrology: Regional Studies 18 (2018). - ISSN 2214-5818 - p. 50 - 67.
Hydrochemistry - Isotope - Ouémé - Piezometry - Turonian-Coniacian aquifer

Study region: The Turonian-Coniacian aquifer system in the North of the Coastal Sedimentary Basin, southern Benin, West Africa. Study focus: The Turonian-Coniacian aquifer is the major aquifer in southern Benin and is the main source of water supply for the population. The pressure on groundwater resources from the Turonian-Coniacian aquifer is increasing since few artesian wells tapping into this aquifer already show decrease in their yields. Preventing extinction of the artesian outflows requires as a first step a thorough understanding of the groundwater flow system: groundwater recharge areas, downstream areas, and flow directions. In this study, a combined hydrogeological, hydrochemical and isotopic approach was applied to understand the groundwater flow within this aquifer and to develop a coherent conceptual groundwater flow model. New hydrological insights for the region: The piezometric results indicated three main groundwater flow directions. Stable isotopes results confirmed the piezometry as the most depleted and enriched values in Oxygen-18 and deuterium were found respectively in downstream areas (southern region) and in the recharge areas (northern region) indicated by the piezometry. Similarly, higher tritium contents (up to 3.5 Tritium Unit) characterize recharge areas and low tritium contents (<0.12 Tritium Unit) were found in downstream areas. The combination of these results with the geologic and topographic data led to a coherent conceptual groundwater flow model shown in this paper.

Understanding farm trajectories to better target agricultural technologies
Mama Sanogo, Ousmane - \ 2013
Genetical metabolomics in apples (Malus x domestica Borkh)
Khan, S.A. - \ 2012
University. Promotor(en): Evert Jacobsen, co-promotor(en): Henk Schouten. - S.l. : s.n. - ISBN 9789461731371 - 184
appels - malus - plantenveredeling - moleculaire veredeling - metabolomica - moleculaire genetica - genetische modificatie - apples - plant breeding - molecular breeding - metabolomics - molecular genetics - genetic engineering

The aim of this thesis was finding genes that control the production of potentially health beneficial metabolites in apple fruits. The approach was genetic mapping of secondary metabolites such as phenolic compounds in an F1 progeny, leading to the detection of genetic loci that controlled these metabolites. At these genetic loci candidate genes were identified, using the whole genome sequence of apple, and it was investigated whether the expression of these candidate genes in the F1 progeny correlated with the metabolite levels.

The cultivated apple (Malus x domestica Borkh) is among the most diverse and ubiquitously cultivated fruit species. It belongs to the family of Rosaceae which includes many commercial fruit species such as pear, strawberry, cherry, peach, apricot, almond, black cherry, and crab apple. Apple has a haploid chromosome number of 17. It is a self-incompatible and highly heterozygous crop. The breeding is further hampered by the long juvenile period which makes breeding in this crop a very slow process.

The saying “An apple a day keeps the doctor away” has encouraged many researchers to search for the “magic” ingredients found in apple. Due to the beneficial role of apple phenolics, it is also called as a “new agrochemical crop”. Apple possesses many health beneficial properties for human beings as it is a rich source of phenolic compounds.It has been associated with reducing the risks of certain diseases such as cancers, particularly prostate, liver, colon, and lung cancers, cardiovascular diseases, coronary heart diseases, asthma, type-2 diabetes, thrombotic stroke, and ischemic heart disease.

The second chapter of this thesis describes the construction of genetic linkage maps of the parents of a segregating population derived from the cross between the cultivars ‘Prima’ and ‘Fiesta’. For this purpose the already available linkage maps, as described in this chapter, were made denser by inclusion of 240 Diversity Array Technology (DArT) markers. Thus the total number of markers for ‘Prima’ and ‘Fiesta’ integrated map reached to 820. DArT-markers are hybridization based dominant DNA-markers. DArT provides a high-throughput whole genome genotyping platform for the detection and scoring of hundreds of polymorphic loci without any need for prior sequence information. This is the first report on DArT in horticultural trees. Genetic mapping of DArT markers in two mapping populations and their integration with other marker types showed that DArT is a powerful high throughput method for obtaining accurate and reproducible marker data, at low cost per data point. This method appears to be suitable for aligning the genetic maps of different segregating populations. Sequencing of the marker clones showed that they are significantly enriched for low copy, gene rich regions.

Chapter 3 describes metabolic diversity of Malus. Wild germplasm was compared to advanced breeding selections and to the segregating F1 population from the cross between the cultivars ‘Prima’ and ‘Fiesta’. The metabolic profiles were analyzed by means of liquid chromatography-mass spectrometry (LC-MS). LC-MS is an analytical chemistry technique that combines the physical separation capabilities of liquid chromatography with the mass analysis capabilities of mass spectrometry. This resulted in the detection of 418 putative metabolites in the peel and 254 in the flesh. Fruits from 23 wild species, eight advanced selections and the segregating F1 population were analyzed. The data were subjected to Principle Components Analysis (PCA). Variance analysis of the first PC showed that genetic variation accounted for 96.6 % in peel and 97.4 % in flesh of the total metabolic variation. Technical variation accounted for 1.4 % and 0.8%, while environmental variation accounted for 2.0% and 1.8% in peel and flesh respectively. The genetic variation between wild genotypes was very large, compared to the advanced selections and the F1 progeny. Only 8 % of the genetic variation of the first principle component was captured by the advanced selections. This indicates strong genetic erosion during breeding. This genetic erosion was mainly caused by reduction of the levels of several flavonoids including catechin, epicatechin and procyanidins. PCA of the F1 progeny of the ‘Prima’ x ‘Fiesta’ cross showed a clear 3:1 Mendelian segregation of metabolites. These metabolites were 4.2 fold less in both peel and flesh in progeny that had inherited the recessive alleles of a gene at the top of Linkage Group16 (LG16) from the heterozygous parents.

We found a separate group of 11 metabolites in peel and 12 in flesh. These metabolites were putatively identified as glycosylated forms of b-glycols: R-octane-1, 3-diol and its unsaturated form R-5-(Z)-octene-1, 3-diol which have a potential role in controlling infection by microorganisms and influence the aroma of some ciders. The levels of these metabolites were up to 50 fold more abundant in some progeny compared to both parents. Genetic mapping showed that this strong increase was caused by one locus at the top of LG8, in progeny that had inherited only the recessive alleles of that locus from the heterozygous parents. This research illustrates not only the strong genetic erosion in apple breeding regarding metabolic diversity, and strong reduction of flavonoids in some progeny, but also shows that inbreeding can lead to a strong increase of metabolites that were present at much lower levels in both parents and advanced selections. This loss and gain of metabolites was especially observed in case of accumulation of recessive alleles during inbreeding.

The genetic factors controlling metabolite composition were studied in more detail in Chapter 4. We investigated the genetic factors of the quantitative variation of these potentially beneficial compounds (Chapter 3, 4), by combining the genetic maps (Chapter 2) with the LC-MS data for thesegregating F1 population from the cross ‘Prima’ x ‘Fiesta’. This resulted into metabolite quantitative trait loci (mQTLs). When using the software MetaNetwork, 669 significant mQTLs were detected: 488 in the peel and 181 mQTLs in the flesh. Four linkage groups (LGs) i.e. LG1, LG8, LG13 and LG16 were found to contain mQTL hotspots, mainly regulating metabolites that belong to the phenylpropanoid pathway. These include various metabolites i.e. sinapate hexoside, coumaroyl hexoside, phloridzin, quinic acids, phenolic esters, kaempferol glycosides, quercetin glycosides, cyanidin pnetoside, flavan-3-ols (catechin, epicatechin), and procyanidins. The genetics of annotated metabolites was studied in more detail using MapQTL®. It was found that quercetin conjugates had mQTLs on LG1 and LG13. The most important mQTL hotspot with the largest number of metabolites was, however, detected at the top of LG16: mQTLs for 32 peel-related and 17 flesh-related phenolic compounds. The metabolites that mapped in the mQTL hotspot on LG16 all belong to the phenylpropanoid pathway of secondary metabolites. These compounds showed a monogenic Mendelian inheritance in a 3:1 segregation ratio. Procyanidins dimer II was used as a representative of the numerous compounds that mapped at the LG16 mQTL hotspot. By means of graphical genotyping of this monogenic trait, a genetic window could be made in which the gene that caused the mQTL hotspot should reside. We located structural genes involved in the phenolic biosynthetic pathway, using the genetic map together with the published whole genome sequence of apple. The structural gene leucoanthocyanidin reductase (MdLAR1) was detected in the mQTL hotspot window on LG16, as were seven transcription factor genes. To our knowledge, this is the first time that a QTL analysis was performed on such a high number of metabolites in an outbreeding plant species.

The expression of the candidate genes found in the mQTL window on LG16 was studied and discussed in Chapter 5. qPCR was used for this purpose and it was found that the expression of only the structural gene MdLAR1 was strongly positively correlated with the metabolite procyanidin dimer II content. Neither the expression profiles of other structural genes of the phenylpropanoid pathway, the transcription factor genes at the mQTL hotspot, nor of transcription factor genes outside the mQTLs hotspot, showed any significant correlation with the procyanidin dimmer II content that mapped at the mQTL hotpot. This indicates that MdLAR1 was the gene, which caused this mQTL hotspot (Chapter 5). The progeny that had inherited one or two copies of the dominant alleles (Mm, MM) showed on the average a 4.4 and 11.8 fold higher expression level of MdLAR1 respectively, compared to the progeny that had inherited the recessive alleles only (mm). This led to a 4.0 fold increase of procyanidin dimer II level at the ripe stage.

Strikingly, at the mQTL hotspot at the top of LG16, there is also a locus that controls acidity of the ripe fruits. However, the dominant alleles for acidity appeared to be in repulsion to the dominant alleles for high metabolite levels (Chapter 6). This shows that acidity is controlled by another gene than the metabolite levels. The combination of the genetic position based on the whole apple genome sequence, annotation of potential genes, and expression profiling indicated that the malic acid transporter gene MdALMT2 was responsible for the clear differences in malic acid content and pH in mature apple fruits of the segregating F1 population. The genetic inheritance of at least one dominant allele (MaMa/Mama) of this gene sufficed for a three-fold increase of the malic acid concentration and a reduction of the pH from 4 to 3 in ripe apples, compared to the presence of only the lower expressed recessive allele (mama). This malic acid transporter gene is located at the top of LG16.Malic acid is the predominant organic acid associated with the pH in apple fruits. It is synthesized in the cytoplasm and transported into the cell vacuole. The concentration of malic acid in the cell vacuole determines the pH of the cell. pH is very important for the overall taste of many fruits, including apple, and has profound effects on the organoleptic quality of apples. The pH of mature apples was genetically mapped on LG16 in the segregating population from the cross ‘Prima’ x ‘Fiesta’. To our knowledge, this is the first time that the genetic segregation of the pH in apple is assigned to a specific gene. Further, this gene has not been reported yet in conjunction to pH of apples or other fruits. After cloning of the MdALMT2 gene, it can be used for, proof of principle, influencing the acidic of existing varieties either by silencing this gene in more acidic cultivars or by inserting this gene into the low acidic cultivars. Another step would be to develop an allele specific molecular marker for selection (Marker Assisted Selection) of the acidity of fruits already at seedling stage, five years before the trees carry fruits.

In another study, a dominantly mutated allele of the transcription factor gene MdMYB10,including its upstream promoter, coding region and terminator sequence, was introduced by transformation into apple, strawberry and potato plants. The dominantly inherited mutant allele of MdMYB10 from apple induces anthocyanin production throughout the plant, also at the early stage after transformation. The aim was to determine whether MdMYB10 could be used as a visible selectable marker for plant transformation as an alternative to chemically selectable markers, such as kanamycin resistance. After transformation, the color of calli, shoots and well-growing plants were evaluated. Red and green shoots were harvested from apple explants and examined for the presence of the MdMYB10 gene by PCR analysis. Red shoots of apple explants always contained the MdMYB10 gene but not all MdMYB10 containing shoots were red. Strawberry plants transformed with the MdMYB10 gene showed anthocyanin accumulation in leaves and roots. No visible accumulation of anthocyanin could be observed in potato plants grown in vitro, even the ones carrying the MdMYB10 gene. However, acid methanol extracts of potato shoots or roots carrying the MdMYB10 gene contained up to four times higher anthocyanin content than control plants. Therefore, anthocyanin production as a result of the dominant MdMYB1010 gene can be used as a selectable marker for apple, strawberry and potato transformation, replacing kanamycin resistance gene such as nptII. We reported this MdMYB10 as a cisgenic selectable marker gene for apple transformation (Chapter 7). The results from all experimental chapters have been discussed in a broader sense in the general discussion (Chapter 8). The future prospectives and potential challenges in the genetical metabolomics are also highlighted. The approaches we developed in the current thesis could be used not only for developing potentially a more healthy and improved apple but can also be applied for the genetical metabolomics studies in other important crops.

Als mama niet kookt, eet puber geen groente
Woltering, E.J. - \ 2009
Kennis Online 6 (2009)dec. - p. 9 - 9.
groenten - voedselconsumptie - eetpatronen - adolescenten - jeugd - buitenshuis eten - voeding en gezondheid - vegetables - food consumption - eating patterns - adolescents - youth - eating out - nutrition and health
De beste manier om pubers meer groente te laten eten is te proberen het aanbod buitenshuis te verbeteren. Buiten de gezinsmaaltijd is groente voor jongeren een rariteit
Natuurbeleving is Gezond! Onderzoekers vinden steeds meer bewijzen
Verboom, J. - \ 2009
Mens en Natuur 60 (2009)2. - p. 4 - 6.
kinderen - natuur - landschapsbeleving - natuur- en milieueducatie - children - nature - landscape experience - nature and environmental education
Dit themanummer bevat diverse bijdragen over "kind en natuur". Eentje van een onderzoeker (Jana Verboom); van een fysiotherapeut annex natuurliefhebber uit Amsterdam, kijkend door de ogen van zijn eigen kind; een verslag van een enquete onder IVN afdelingen "zelf laten doen is leren ontdekken"), natuurpapa's en mama's op school; en een interview met een natuurfotograaf
Leavers, planners and dwellers : the decision to leave the parental home
Baanders, A.N. - \ 1998
Agricultural University. Promotor(en): Anke Niehof, co-promotor(en): P.J.J. Pennartz. - S.l. : Baanders - ISBN 9789054859024 - 245
gezinnen - samenstelling - sociologie - huisvesting - ouders - kinderen - dochters - zonen - jongvolwassenen - basisbehoeften - motivatie - besluitvorming - verwijdering - families - composition - sociology - housing - parents - children - daughters - sons - young adults - basic needs - motivation - decision making - removal
<p>Leaving the parental home is one of the most common events in the life course of individuals. It is a normal and natural thing to happen to virtually everyone at some time. However, despite the generality of the event, the transition is not the same for all. Furthermore, the generality of the event says nothing about changes in the patterns in home-leaving behaviour over time. During the past several decades, interesting shifts in the timing and arrangements of the transition have occurred. The question, central to this study, runs: What are the factors that influence the transition from living at home to living independently?</p><p>In the literature, there are mainly two perspectives dominating theoretical thinking about the determinants affecting departure from the parental home: an economic and a cultural one. First, in many previous demographic and economic studies, the search for an explanation of the changes in leaving home focused on the impact of the situational context on the individual's behaviour, i.e. the financial situation and the situation on the housing market, which constitute the young adult's opportunity structure. A second research tradition that has addressed the event of leaving home typically emphasises the normative context and the role of social norms which are believed to regulate the timing and arrangement of important life course transitions. This study aimed to determine more precisely the relative impact of each of these two factors. Furthermore, this study tried to find out whether, beside economic, housing and normative factors, additional aspects play a role in the decision to leave home, thus providing a more complete picture of the variety of factors that should be taken into account. An explorative analysis of written material collected among 300 students provided the necessary data to discover young adults' additional considerations in the matter of leaving home. These considerations appeared to deal with more practical and social-emotional aspects, and were briefly denoted as the Hotel-Mama factor. Apart from that, the qualitative material was used to obtain quantifiable information about the kind of normative expectations that are related to leaving home.</p><p>It is well known that since the 1950s remarkable social and economic changes have taken place in Dutch society, which undoubtedly have also affected the circumstances and opportunities of young adults. As one of our hypotheses emphasises the role of the opportunity structure in the decision to leave home, we start this study with a description of the relevant social and cultural changes, and a sociological assessment of the profound impact of these transformations on the social and economic position of young adults in general and on their opportunities to leave the parental home in particular (see chapter 2). This gives a solid base to our hypothesis that changes in home-leaving behaviour are related to economic and housing market opportunities. The presumed effect of the normative context is addressed in chapter 2 as well. Also, the temporal changes in leaving home that took place in the period between 1950 and 1980 and during the 1980s are reflected upon. The discussion results in the further elaboration and formulation of the research questions.</p><p>To illustrate how fluctuations in the situational context may be reflected in patterns of leaving home, chapter 4 examines at the aggregate level the shifts in behavioral patterns that occurred in the Netherlands during the 1980s, and relates them to the changing circumstances of this period. Three successive national Housing Demand Surveys (WBOs), conducted at the end of 1981, 1985 and 1989, provided the necessary data. It was concluded that although fluctuations in the situational context were indeed reflected in behavioral patterns, it was also evident that not all young adults react to a specific set of opportunities in the same way. Limited opportunities do not necessarily lead to a postponement of the transition, but in many instances rather to an adjustment of behavioral choices instead.</p><p>Both the discussion in chapter 2 and the results of chapter 4 made it clear that, nothwithstanding the useful insights a macro-level approach generates, it may sometimes be difficult or hazardous to draw firm conclusions regarding the effect of specific factors when analysing them on the aggregate level. It was therefore argued that a micro-level should be adopted, in which the decision to leave the parental home and its determinants are studied at the individual level.</p><p>In chapter 3, the Theory of Reasoned Action and its modifications are discussed and the theoretical model underlying this study, which is a modified version of the Theory of Planned Behaviour is presented. In order to use this theoretical model, it was necessary to specify the relevant consequences and the normative expectations that are related to leaving home. The qualitative method employed to identify prevailing perceptions on this subject is discussed in chapter 5.</p><p>Chapter 6 describes the process of setting up a cross-sectional survey among 1012 young adults of 18-26 years old, and the measurement and construction of relevant variables. The results of the analyses of the survey data are reported in chapters 7 and 8. By comparing the personal situation and subjective considerations of leavers, planners and dwellers, we tried to find evidence that the defined variables affect the decision to leave home as hypothesised (chapter 7). Chapter 8 aims to detect the most important determinants in this decision, either in the first stage (the stage of intention-formation), or in the second stage (in which the intention is effectuated into actual behaviour). The analyses revealed that the normative expectations of the parents play a decisive role in the first stage. Financial considerations are most important in the second stage. Particularly the subjective assessment of one's income situation appeared to be a crucial element. The type of housing young adults aimed at further affected their probability of leaving, with cheap 2 and 3 room accommodation clearly reducing a person's opportunities of finding a place to live and of leaving the parental home, and a quest for a single room or four room housing facilitating the transition. There is no convincing evidence that Hotel-Mama considerations affect the decision to leave home or to stay home.</p><p>Chapter 9 concludes this study with a summary overview of the research design and an evaluation of the main findings, followed by a discussion of their implications for policy, theory and research.</p>
DDE en tejido adiposo y riesgo de cancer de mama en Europa: estudio EURAMIC.
Martin-Moreno, J.M. ; Veer, P. van 't; Lobbezoo, I. ; Gomez-Aracena, J. ; Kok, F.J. ; Guallar, E. - \ 1996
Gaceta Sanitaria 10 (1996). - p. 41 - 41.
The ivory tower on the chess-board of integrated rural development.
Daane, J.R.V. ; Mama Adamou-N'Diaye, - \ 1989
In: Proc. 2nd Guelph-Wageningen network meeting. Guelph, Canada (1989) 25 pp
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