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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    Molecular assessment of muscle health and function : The effect of age, nutrition and physical activity on the human muscle transcriptome and metabolom
    Hangelbroek, Roland W.J. - \ 2017
    Wageningen University. Promotor(en): A.H. Kersten; C.P.G.M. de Groot, co-promotor(en): M.V. Boekschoten. - Wageningen : Wageningen University - ISBN 9789463437103 - 205
    muscles - age - nutrition - physical activity - transcriptomes - metabolomes - elderly - creatine - phosphocreatine - vitamin d - atrophy - spieren - leeftijd - voeding - lichamelijke activiteit - transcriptomen - metabolomen - ouderen - creatine - fosfocreatine - vitamine d - atrofie

    Prolonged lifespan and decreased fertility will lead to an increased proportion of older adults in the world population (population aging). An important strategy to deal with population aging has been to promote healthy aging; not only to prevent mounting health care costs, but also to maintain independence and quality of life of older populations for as long as possible. Close to the opposite of the healthy aging is frailty. A major component of (physical) frailty is sarcopenia: age-related loss of muscle mass. Decreased muscle size and strength has been associated with a wide variety of negative health outcomes, including increased risk of hospitalization, physical disability and even death. Therefore, maintaining muscle size and strength is very important for healthy aging. Nutrition and physical activity are possible strategies to maintain or even improve muscle function with age.

    The effect of nutrition, age, frailty and physical activity on the function of skeletal muscle is complex. A better understanding of the molecular mechanisms involved can provide new insights in potential strategies to maintain muscle function over the life course. This thesis aims to investigate these mechanisms and processes that underlie the effects of age, frailty and physical activity by leveraging the sensitivity and comprehensiveness of transcriptomics and metabolomics.

    Chapter 2 and 3 describe the effects of age, frailty and resistance-type exercise training on the skeletal muscle transcriptome and metabolome. Both the transcriptome and metabolome show significant differences between frail and healthy older adults. These differences are similar to the differneces between healthy young men and healthy older adults, suggesting that frailty presents itself as a more pronounced form of aging, somewhat independent of chronological age. These age and frailty related differences in the transcriptome are partially reversed by resistance-type exercise training, in accordance with the observed improvement in muscle strength. Regression analysis revealed that the protocadherin gamma gene cluster may be important to skeletal muscle function. Protocadherin gamma is involved in axon guidance and may be upregulated due to the denervation-reinnervation cycles observed in skeletal muscle of older individuals. The metabolome suggested that resistance-type exercise training led to a decrease in branched-chain amino acid oxidation, as shown by a decrease in amino acid derived carnitines. Lastly, the blood metabolome showed little agreement with the metabolome in skeletal muscle, indicating that blood is a poor read-out of muscle metabolism.

    We assessed the effect of knee immobilization with creatine supplementation or placebo on the skeletal muscle transcriptome and metabolome in chapter 4. Knee immobilization caused muscle mass loss and strength loss in all participants, with no differences between creatine and placebo groups. Knee immobilization appeared to induce the HDAC4-myogenin axis, which is primarily associated with denervation and motor neuron diseases. The metabolome showed changes consistent with the decreased expression of energy metabolism genes. While acyl-carnitine levels tended to decrease with knee immobilization, one branched-chain amino acid-derived acyl carnitine was increased after knee immobilization, suggesting increased amino acid oxidation.

    Vitamin D deficiency is common among older adults and has been linked to muscle weakness. Vitamin D supplementation has been proposed as a strategy to improve muscle function among older populations. In chapter 5, supplementation with vitamin D (calcifediol, 25(OH)D) is investigated as nutritional strategy to improve muscle function among frail older adults. However, we observed no effect of vitamin D on the muscle transcriptome. These findings indicate the effects of vitamin D supplementation on skeletal muscle may be either absent, weak, or limited to a small subset of muscle cells.

    Transcriptomic changes due to different forms of muscle disuse are compared in chapter 6 (primarily knee immobilization and bed rest). The goal was to determine the similarities and differences among various causes of muscle atrophy in humans (primarily muscle disuse). Both knee immobilization and bed rest led to significant changes in the muscle transcriptome. However, the overlap in significantly changed genes was relatively small. Knee immobilization was characterized by ubiquitin-mediated proteolysis and induction of the HDAC4/Myogenin axis, whereas bed rest revealed increased expression of genes of the immune system and increased expression of lysosomal genes. Knee immobilization showed the highest similarity with age and frailty-related transcriptomic changes. This finding suggests that knee immobilization may be the most suitable form of disuse atrophy to assess the effectiveness of strategies to prevent age-related muscle loss in humans.

    The transcriptome and metabolome are incredibly useful tools in describing the wide array of biological systems within skeletal muscle. These systems can be modulated using physical activity (or lack thereof) as well as nutrition. This thesis describes some of these processes and highlights several unexplored genes and metabolites that may be important for maintaining or even optimizing muscle function. In the future, it may be possible to optimize both exercise and nutrition for each individual using these techniques; or even better, cheaper and less invasive alternatives.

    Separation ages for primates in new Dutch legislation = Scheidingsleeftijden van apen in nieuwe Nederlandse wetgeving
    Bracke, M.B.M. ; Hopster, H. - \ 2013
    Lelystad : Wageningen UR Livestock Research (Report / Wageningen UR Livestock Research 728) - 102
    primaten - spenen - leeftijd - diergedrag - dierenwelzijn - wetgeving - beleid - Nederland - primates - weaning - age - animal behaviour - animal welfare - legislation - policy - Netherlands
    An expert consultation was conducted on separation ages for several primate species mentioned in Dutch legislation (chimpanzees, rhesus, stump-tailed and long-tailed macaques, marmosets, douroucoulis and squirrel monkeys). In total 25 senior experts from 7 different countries participated. ‘Median’ (middle value) separation ages as suggested by the experts were 6 years for chimpanzees; 12 months for macaques used in research and 4 years for macaques used for breeding or kept in zoos or shelters; 12-16 months for marmosets; 18-24 months for douroucoulis; and 10-18 months for squirrel monkeys. The main arguments related to natural conditions (e.g. at what ages the animals can survive without milk or group support). The paper provides a structured, transparent approach for decision support, leading to the general recommendation to the Dutch government to upgrade existing separation ages in accordance with ages previously specified for separation (‘weaning’) of young primates into individual housing.
    Welfare of African catfish : effects of stocking density
    Nieuwegiessen, P.G. van de - \ 2009
    Wageningen University. Promotor(en): Johan Verreth, co-promotor(en): Johan Schrama. - [S.l.] : S.n. - ISBN 9789085049869 - 137
    clarias gariepinus - dierenwelzijn - bezettingsdichtheid - stressreactie - dierfysiologie - diergedrag - leeftijd - visteelt - aquacultuur - clarias gariepinus - animal welfare - stocking density - stress response - animal physiology - animal behaviour - age - fish culture - aquaculture
    The general aim of this thesis was to determine the impact of stocking density on welfare indicators in African catfish, Clarias gariepinus, cultured in a recirculating aquaculture system. The following factors were studied: 1) the effects of stocking density on physical, physiological, and behavioural responses of African catfish, 2) how age mediates the effects of stocking density on physical, physiological, and behavioural responses of African catfish, 3) the potential effects of chemical alarm cues on the welfare of farmed African catfish, and 4) the fitness consequences of different coping strategies in intensive husbandry systems
    Oudere koeien voor een duurzame houderij
    Gosselink, J.M.J. ; Bos, A.P. ; Bokma, S. ; Groot Koerkamp, P.W.G. - \ 2008
    V-focus 5 (2008)4. - ISSN 1574-1575 - p. 30 - 31.
    melkveehouderij - melkkoeien - leeftijd - melkopbrengst - bedrijfsresultaten in de landbouw - agrarische bedrijfsvoering - agrarische bedrijfsplanning - dairy farming - dairy cows - age - milk yield - farm results - farm management - farm planning
    Een oudere veestapel blijkt economisch gunstig te zijn. Wat moet er gebeuren om de leeftijd van de melkkoe omhoog te krijgen?
    Groei belangrijk voor tweedeworps zeug
    Hoving, L.L. ; Peet-Schwering, C.M.C. van der; Kemp, B. ; Soede, N.M. - \ 2008
    V-focus 5 (2008)april (2). - ISSN 1574-1575 - p. 44 - 45.
    varkenshouderij - zeugen - leeftijd - groei - worpgrootte - worpresultaten - zeugenvoeding - agrarische bedrijfsvoering - voedersystemen - pig farming - sows - age - growth - litter size - litter performance - sow feeding - farm management - feeding systems
    De reproductieresultaten van tweedeworpszeugen blijven vaak achter bij die van de eerste- en oudereworps zeugen. Groei van de jonge zeug blijkt hierbij een belangrijke rol te spelen. Wellicht dat een verhoogd voerniveau of een veranderende voersamenstelling verbetering kan brengen
    In de ban van de Betuwse dijken: deel 6 Opheusden; een bodemkundig, archeologisch en historisch onderzoek naar de opbouw en ouderdom van de Rijndijk te Opheusden
    Mulder, J.R. ; Franzen, P.F.J. - \ 2006
    Wageningen : Alterra (Alterra-rapport 900) - 59
    dijken - archeologie - bodemkarteringen - nederland - leeftijd - bodemprofielen - nederzetting - geschiedenis - kaarten - rijn - betuwe - dykes - age - settlement - history - archaeology - soil profiles - soil surveys - netherlands - maps - river rhine - betuwe
    In het kader van de dijkverzwaring heeft Alterra in opdracht van het Waterschap Rivierenland de bandijk van Opheusden in 2003 op drie plaatsen archeologisch en bodemkundig onderzocht
    Gezond werken tot je 67ste : overzichtsrapport maatregelen in Nederland
    Maas, E. van der; Vaandrager, L. - \ 2005
    Woerden : NIGZ (NIGZ- Werk & gezondheid 2) - 32
    ouderen - arbeid (werk) - participatie - leeftijd - gezondheid op het werk - elderly - labour - participation - age - occupational health
    In dit rapport worden de volgende onderwerpen behandeld: de wetgeving waarop gezond en veilig werken, maar ook het bevorderen van arbeidsparticipatie van ouderen, is gebaseerd; landelijke projecten en programma’s, die onder andere gericht zijn op kennisverspreiding en het beïnvloeden van vooroordelen over oudere werknemers; belangrijke spelers in het veld, op het gebied van kenniscentra, onderzoeksinstellingen en commerciële bureaus; praktijkvoorbeelden van organisaties die leeftijdsbeleid inzetten om op een verantwoorde manier met oudere werknemers binnen de organisatie om te gaan
    Genetic improvement for production and health in broilers
    Zerehdaran, S. - \ 2005
    Wageningen University. Promotor(en): Johan van Arendonk, co-promotor(en): Liesbeth van der Waaij. - [S.l.] : S.n. - ISBN 9789085042648 - 125
    vleeskuikens - genetische verbetering - genetische parameters - lichaamsvet - karkassamenstelling - leeftijd - huisvesting, dieren - ascites - vleeskuikenresultaten - diergezondheid - broilers - genetic improvement - genetic parameters - body fat - carcass composition - age - animal housing - ascites - broiler performance - animal health
    The objective of present thesis was to optimize the genetic improvement of production and health traits in broilers. The genetic correlations among abdominal, subcutaneous, and intramuscular fat showed that there is a high genetic correlation between abdominal and subcutaneous fat (0.54), whereas the genetic correlation between abdominal and intramuscular fat is almost zero (0.02). Therefore selection for reduced abdominal fat does not change the intramuscular fat content and consequently meat quality. The genetic correlations were estimated on broilers of different ages (48, 63, and 70 d). The results indicated that increase in growth at 48 d was accompanied by increase in valuable parts (breast meat and back half); at 70 d it was accompanied by an increase in abdominal fat percentage. In addition, the genetic correlation of BW at 48 d between individual cage and group housing demonstrated a genotype by environment interaction for performance of birds in different housing systems. The present research showed that including indirect carcass measurements in the broiler breeding schemes resulted in improved genetic gain for breast meat percentage and reduced rate of inbreeding, which is desirable for long-term selection. The improved genetic gain resulted from increased accuracy of selection due to the own performance of selection candidates for carcass traits. The reliability of the indirect measurements influences the usefulness of these methods. The correlation between BW and ascites related traits in the cold conditions were estimated using mixture model analysis. The results indicated that the overall correlations between BW and ascites traits are dependent on the relative frequency of ascitic and non-ascitic birds in the population. Finally, estimated genetic parameters for production and health traits were used in a simulation to illustrate the consequences of including health related traits together with production traits in a sustainable breeding program. The results showed that a reduction of 6% of response in production traits was sufficient to offset the negative response in health traits.
    Taste perception with age
    Mojet, J. - \ 2004
    Wageningen University. Promotor(en): J.H.A. Kroeze; Fons Voragen. - Wageningen : s.n. - ISBN 9789085040583 - 215
    smaakgevoeligheid - smaakdrempel - leeftijd - leeftijdsverschillen - reuk - taste sensitivity - taste threshold - age - age differences - smell
    Keywords: age, thresholds, supra-threshold intensities, pleasantness, optimally preferred concentration, olfactory deprivation,signal-to-noise ratio

    This thesis describes experiments studying age-related diferences in taste perception. Thresholds, supra-threshold intensities and pleasantness for ten different tastants, representing the five taste qualities sweet, sour, salty, bitter and umami were measured in the same group of elderly and young subjects. The tastants were dissolved in water and in product. Age has a deteriorating effect on taste sensitivity, which is already noticeable in the young-old group of elderly. First, this effect is generic in nature, i.e. more than 90% of the total variance attributable to age is due to age alone and less than 6% to age-related differences in the perception of the different taste qualities. Secondly, the differentiation between the different taste qualities is less distinct for elderly than for young people. A change in the signal-to-noise ratio at neural or perceptual level might be put forward to explain these phenomena. The outcome might support the hypothesis that the primary taste cortex is the locus of most accurate coding. Neither thresholds nor supra-threshold sensitivity were good predictors of the most preferred concentration of the tastants in product. Although the perceived intensities were lower for the elderly than for the young, the most preferred concentration of the tastants in product were similar for both age groups. It is suggested that the information about perception and affection might be processed in different regions of the brain. The most intriguing finding in this thesis is that smell seems to play a crucial role in taste perception. When the olfactory input is blocked, about 70% of the age differences in taste perception disappeared. Since taste and smell are so intimately related and accompanied by other sensations, such as mouthfeel, temperature and spiciness, it might not be a bad idea to investigate taste perception with a multimodal/multimethod approach, including all oral sensations in the investigation.

    In de ban van de Betuwse dijken; deel 5 Malburgen
    Mulder, J.R. ; Keunen, L.J. ; Zwart, A.J.M. - \ 2004
    Wageningen : Alterra (Alterra-rapport 405) - 162
    dijken - leeftijd - archeologie - geschiedenis - nederzetting - plattelandskern - bodemkarteringen - kaarten - gelderland - betuwe - dykes - age - archaeology - history - settlement - rural settlement - soil surveys - maps - gelderland - betuwe
    In de ban van de Betuwse dijken; deel 4 Angeren; een bodemkundig, historisch en archeologisch onderzoek naar de opbouw en ouderdom van de Rijndijk te Angeren (Over-Betuwe)
    Mulder, J.R. ; Franzen, P.F.J. ; Keunen, L.J. ; Zwart, A.J.M. - \ 2003
    Wageningen : Alterra (Alterra-rapport 404) - 111
    dijken - leeftijd - archeologie - geschiedenis - bodemprofielen - bodemkarteringen - kaarten - betuwe - gelderland - dykes - age - archaeology - history - soil profiles - soil surveys - maps - betuwe - gelderland
    In het kader van de dijkverzwaring heeft Alterra in opdracht van het Polderdistrict Betuwe bij de Nederlands-hervormde kerk te Angeren op twee plaatsen de opbouw en de ouderdom van een oud dijkvak onderzocht. Tot 1803 was het dijkvak circa 3,50 m hoog. In dat jaar werd de dijk waarschijnlijk met circa 90 cm verhoogd tot 4,40 m. In 1881/1883 vond een kleine dijkcorrectie plaats. Bij de Molenstraat werd de dijk niet meer dan 10 m naar buiten verplaatst. Daar moest de herberg van Jacobus Lange voor wijken. De funderingsresten van de herberg vonden we terug onder het dijklichaam. Het pand is eind zeventiende of begin achttiende eeuw gebouwd op een huisterp. De oudste vermelding van de herberg stamt uit 1790. Toen was Herman Hasenakker herbergier. Daarna runde Jacobus Lange de herberg tot zijn dood. Zijn stiefzoon Hendrik erfde de herberg. Na zijn dood in 1851 huurde Hendrik Sanders het pand. Circa 50 m oostwaarts tegenover de Hervormde kerk werd de dijk een paar meter naar binnen gelegd en verdween het noordelijke deel van de zeventiende-eeuwse muur om het kerkhof onder het talud van de dijk. Bij de opgraving kwam een restant van de muur tevoorschijn. De dijk is daar gedeeltelijk over de voet van een terp gelegd. De terp is waarschijnlijk een zeventiende-eeuwse uitbreiding van de oude terp, waarop de negende-eeuwse kerk is gebouwd. Het dijklichaam is voornamelijk opgebouwd uit kalkrijke zavel en klei. De Angerense dijk is tussen Angeren en Huissen bij de Waaij vermoedelijk in de zestiende eeuw twee maal doorgebroken. In 1769 brak de dijk daar nogmaals door.
    Leeftijdsbepaling van kokkels uit de Oosterschelde 1998 en 2000
    Kesteloo-Hendrikse, J.J. ; Riet, M. van - \ 2003
    IJmuiden : RIVO (RIVO rapport nr. C006/03) - 12
    kokkels - bivalvia - leeftijdsbepaling - leeftijd - oosterschelde - clams - bivalvia - age determination - age - eastern scheldt
    Ter onderbouwing van het beleid voor de kokkelvisserij in schelpdier-arme jaren wordt sinds 1990 in opdracht van het ministerie van Landbouw, Natuurbeheer en Visserij (LNV) door het RIVO-CSO jaarlijks het kokkelbestand (Cerastoderma edule) in de Oosterschelde, de Westerschelde en de Waddenzee geïnventariseerd. De kokkelbestandsopnames worden in het voorjaar uitgevoerd. In een aantal jaren is ook een bestandsopname in het najaar uitgevoerd. Daarnaast is in 1991 door het RIVO-CSO, onafhankelijk van de surveys, een onderzoek opgezet naar de groei en sterfte van kokkelbestanden in de Oosterschelde en in de Westerschelde. Dit onderzoek is opgezet om meer inzicht te krijgen in de factoren die van invloed kunnen zijn op de ontwikkeling van kokkelbestanden.
    Oude koe niet hetzelfde als duurzame koe
    Ouweltjes, W. - \ 2002
    Praktijkkompas. Rundvee 16 (2002)6. - ISSN 1570-8586 - p. 20 - 21.
    melkveehouderij - melkvee - melkkoeien - duurzaamheid (sustainability) - gebruiksduur - productieve levensduur - vervanging - veestapelstructuur - leeftijd - leeftijdsstructuur - dairy farming - dairy cattle - dairy cows - sustainability - longevity - productive life - replacement - herd structure - age - age structure
    De gedachte is dat minder duurzaamheid tot meer vervanging leidt.
    Natte bijproducten, vitamine E-verstrekking en slachtleeftijd bij rosekalveren
    Plomp, M. ; Heeres-van der Tol, J.J. ; Eikelenboom, G. - \ 2002
    Lelystad : Praktijkonderzoek Veehouderij (PraktijkRapport. Rundvee, paarden, schapen, geiten / Praktijkonderzoek Veehouderij 5) - 28
    vleeskalveren - kalveren - voedingsrantsoenen - bijproducten - brijvoedering - vitaminetoevoegingen - voedersupplementen - slacht - leeftijd - vleeskwaliteit - diervoeding - veal calves - calves - feed rations - byproducts - wet feeding - vitamin supplements - feed supplements - slaughter - age - meat quality - animal nutrition
    In dit rapport, waarin twee proeven zijn beschreven, wordt met name ingegaan op de houderijaspecten slachtleeftijd, het verstrekken van vitamine E en het aandeel natte bijproducten in het rantsoen.
    In de ban van de Betuwse dijken; deel 3 Doornenburg (Roswaard); een bodemkundig, historisch en archeologisch onderzoek naar de opbouw en ouderdom van de Rijndijk te Doornenburg (Over-Betuwe)
    Mulder, J.R. - \ 2002
    Wageningen : Alterra (Alterra-rapport 403) - 61
    dijken - leeftijd - archeologie - geschiedenis - bodemprofielen - nederland - bodemkarteringen - kaarten - historische geografie - gelderland - betuwe - bedijking - bodemkunde - cultuurhistorie - geologie - Rijn - dykes - age - archaeology - history - soil profiles - netherlands - soil surveys - maps - historical geography - gelderland - betuwe
    In het kader van de dijkverzwaring is in opdracht van het Polderdistrict Betuwe langs de Roswaard te Doornenburg op twee plekken de opbouw en de ouderdom van een oud dijkvak onderzocht. Het onderzochte dijkvak is om een middeleeuwse meanderlus van de Rijn gelegd. We hebben vrijwel zeker te maken met het oorspronkelijke dijklichaam, dat in de loop der eeuwen talloze malen aan herstel- en onderhoudswerkzaamheden onderhevig is geweest. Tot 1805 was het dijkvak circa 3,50 m hoog. In dat jaar werd de dijk met circa 90 cm verhoogd tot 4, 40 m. Bij de Kerkstraat was slechts het zuidelijke deel van de dijk verhoogd. Als een soort kade op de dijk. Waarschijnlijk had dit te maken met een afrit naar de Roswaard. Omstreeks 1880 werd de dijk nogmaals met 75 tot 90 cm klei opgehoogd en bereikte het dijklichaam een hoogte van circa 5, 20 m. Het dijklichaam is voornamelijk opgebouwd uit kalkrijke zavel en klei. De helling van binnentalud bedroeg circa 2 : 1. In 1799 brak het dijkvak op twee plaatsen door zonder de vorming van kolken. Met de aanleg van het Pannerdens Kanaal (1701-1707) kwam de leidijk tot stand en werd de bandijk om de Roswaard een slaperdijk, de Luiendijk genaamd.
    In de ban van de Betuwse dijken; deel 2 Oosterhout; een bodemkundig, historisch en archeologisch onderzoek naar de opbouw en ouderdom van de Waaldijk te Oosterhout (Over-Betuwe)
    Mulder, J.R. ; Spaan, F. ; Wolf, J.G.C. de - \ 2002
    Wageningen : Alterra (Alterra-rapport 311) - 85
    dijken - geschiedenis - geografie - bodemeigenschappen - leeftijd - archeologie - bodemkarteringen - kaarten - waal - gelderland - historische geografie - betuwe - bedijking - bodemkunde - cultuurhistorie - geologie - dykes - age - archaeology - history - geography - soil properties - soil surveys - maps - river waal - gelderland - historical geography - betuwe
    In het kader van de dijkverzwaring is in opdracht van het Polderdistrict Betuwe bij Oosterhout (Gld.) de opbouw en de ouderdom van een oud dijkvak onderzocht. Op drie plaatsen was het buitentalud van de dijk afgegraven. Het onderzochte dijkvak moet voor 1500 zijn aangelegd. De samenstelling van het onderste pakket wijkt enigszins af van de laag erboven. Dit zou kunnen wijzen op een noodkade (van voor 1500). Op 1 m beneden de kruin van de huidige dijk bevindt zich een oud wegdek, dat voor de dijkverzwaring van 1881/1883 is aangelegd. In die periode is de helling van het buitentalud van 1:3 naar 1:4 gebracht en bekleed met een laag baksteen. Onder de buitenteen van de dijk komt een laag kolenslib voor, die sinds circa 1870 door de Waal is afgezet. De overige Oosterhoutse dijkvakken zijn steeds weer teruggelegd als gevolg van talloze dijkdoorbraken. De oudst bekende is die van 1564, de jongste van 1820. De doorbraken vonden voornamelijk plaats daar waar de stroomrug van het Rietgraafsysteem de bandijkkruist. In het midden van de 16e eeuw lag Oosterhout als een gestrekt dijkdorp aan een schaardijk. Het voorland was door de aanleg van kribben aan de overzijde van de Waal aan erosie onderhevig. De schaardijk is in de 17e eeuw herhaaldelijk doorgebroken.In de 18e eeuw is door kribbenaanleg veel land aangewonnen. Na de doorbraak van 1820 werd de bandijk sterk naar binnengelegd. Het nieuwe dorp Oosterhout ontwikkelde zich loodrecht op de dijk.
    Humus een bron van rijkdom
    Kemmers, R.H. ; Mekkink, P. - \ 2001
    Nederlands Bosbouwtijdschrift 73 (2001)5. - ISSN 0028-2057 - p. 17 - 22.
    bossen - beschermde bossen - natuurreservaten - natuurbescherming - opstandsontwikkeling - plantensuccessie - stadia in de successie - zandgronden - leeftijd - humus - organisch bodemmateriaal - bosstrooisel - humeuze horizonten - humushorizonten - koolstof - stikstof - fosfor - mineralisatie - voedingsstoffenbeschikbaarheid - voedingsstoffen - voedingsstoffengehalte - bodemchemie - bodemvruchtbaarheid - bodem - bosbouw - bosreservaat - nutriënten - voedselrijkdom - forests - reserved forests - nature reserves - nature conservation - stand development - plant succession - seral stages - sandy soils - age - humus - soil organic matter - forest litter - humic horizons - humus horizons - carbon - nitrogen - phosphorus - mineralization - nutrient availability - nutrients - nutrient content - soil chemistry - soil fertility
    In bosreservaten op arme en rijke pleistocene zandgronden is de samenstelling van het humusprofiel onderzocht voor verschillende ontwikkelingsstadia (leeftijden) van het bos. Het zwaartepunt lag op het bepalen van de voorraden koolstof, fosfor (fosfaat) en stikstof en de stikstofmineralisatie. Ook is een inschatting gemaakt van de aandelen koolstof en stikstof in de verschillende compartimenten van het bosecosysteem (biomassa, strooisellaag, humeuze bovengrond)
    Effects of ageing and cultivation of grassland on soil nitrogen
    Velthof, G.L. ; Oenema, O. - \ 2001
    Wageningen : Alterra (Alterra-rapport 399) - 55
    graslanden - stikstof - uitspoelen - mineralisatie - denitrificatie - verliezen uit de bodem - ploegen als grondbewerking - teelt - leeftijd - nederland - bodemchemie - grasland - grondbewerking - landbouw - milieu - nutriënten - weidebouw - grasslands - nitrogen - leaching - mineralization - denitrification - losses from soil - ploughing - cultivation - age - netherlands
    Nitrogen losses from agriculture in the Netherlands have to be strongly decreased because of national and international policy (e.g. Nitrate Directive). The cultivation of grassland when grassland is renewed or converted into arable land may enhance net nitrogen mineralization and, thereby, nitrogen losses via leaching and denitrification. These nitrogen losses can be decreased by adjustment of management, but a good insight into the soil processes during ageing and after cultivation of grassland is required. A literature study was carried out to quantify the effects of ageing and cultivation of grassland on nitrogen losses from the soil. The study shows that the risk on losses increases when grassland age increases, the period between cultivation and reseeding increases and the nitrogen uptake capacity of the next crop decreases. In the Netherlands, only a few studies have been carried out and, especially, a quantification of the effects of cultivation on nitrogen losses under Dutch conditions is lacking. It is recommended to set up integral field studies in which both the agricultural and environmental effects of grassland cultivation are quantified. The results must be used to develop measures and tools to achieve environmentally and agriculturally sound systems of permanent and temporal grasslands.
    Internationale gevolgen van geïntegreerd bosbeheer in Nederland; verwaarloost Nederland de rol van bos als natuurlijke hulpbron?
    Nabuurs, G.J. ; Schelhaas, M.J. ; Goede, D. de - \ 2001
    Nederlands Bosbouwtijdschrift 73 (2001)5. - ISSN 0028-2057 - p. 29 - 32.
    bosbeheer - bosbouw - bossen - bosbestanden - opstandsstructuur - leeftijd - leeftijdsstructuur - leeftijdssamenstelling - boomleeftijd - houthandel - import - export - internationale handel - vraag - aanbod - opstandskenmerken - opstandsontwikkeling - europa - natuurlijke hulpbronnen - hulpbronnenbeheer - economie van natuurlijke hulpbronnen - bosopstanden - geïntegreerd bosbeheer - houtproductie - natuurlijke hulpbron - Nederland - forest administration - forestry - forests - forest resources - stand structure - age - age structure - age composition - age of trees - timber trade - imports - exports - international trade - demand - supply - stand characteristics - stand development - europe - natural resources - resource management - natural resource economics - forest stands - integrated forest management
    De lange-termijneffecten van een meer natuurlijk bosbeheer in Europa wat betreft de leeftijdsklassenverdeling van het Europese bos en de verwachte veranderingen in de import- en exportstromen van naald- en loofhout binnen Europa (Scandinavië, Oost-Europa, Centraal-Europa, Middellandse-Zeegebied). Ondanks de noodkreten van de verwerkende industrie zal er op korte en middellange termijn geen houttekort ontstaan, maar vanaf 2050 zal de voorziene stijging van de houtconsumptie niet meer gedekt worden door het Europese bos
    In de ban van de Betuwse dijken; deel 1 Loenen; een bodemkundig, historisch en archeologisch onderzoek naar de opbouw en ouderdom van de Waaldijk te Loenen (Over-Betuwe)
    Mulder, J.R. ; Gazenbeek, A.E. ; Linden, E. van der - \ 2001
    Wageningen : Alterra (Alterra-rapport 183) - 45
    dijken - leeftijd - geschiedenis - bodemeigenschappen - bodemprofielen - nederland - archeologie - bodemkarteringen - kaarten - waal - betuwe - dykes - age - archaeology - history - soil properties - soil profiles - netherlands - soil surveys - maps - river waal - betuwe
    In het kader van de dijkverzwaring is in opdracht van het Polderdistrict Betuwe bij Loenen de ouderdom en de opbouw van een oud dijkvak onderzocht, voordat het werd afgegraven en vervangen door een nieuw dijkvak. Het onderzochte dijkvak is aangelegd over een voormalige huisplaats, die vanaf de vijftiende of zestiende eeuw tot de negentiende eeuw bewoond is geweest. Het dijkvak dateert uit 1809. De kern bestaat uit een ringkade, die kort na de dijkdoorbraak van 1809 is aangelegd en die in de zomer daarop verhoogd is tot bandijk. In 1830 en omstreeks 1870 hebben nog twee verhogingen plaatsgevonden. De ringkade bestaat overwegend uit overslagzand, het dijklichaam uit compacte zavel en klei.
    Leeftijd bedrijven en energiebesparende opties in de glastuinbouw
    Bakker, R. ; Velden, N.J.A. van der; Verhaegh, A.P. - \ 1999
    Den Haag : Landbouw-Economisch Instituut - ISBN 9789052424743 - 45
    kassen - energiebehoud - tuinbouwbedrijven - leeftijd - glastuinbouw - greenhouses - energy conservation - market gardens - age - greenhouse horticulture
    Swimming and muscle structure in fish
    Spierts, I.L.Y. - \ 1999
    Agricultural University. Promotor(en): J.W.M. Osse; H.A. Akster; J.L. van Leeuwen. - S.l. : Spierts - ISBN 9789090127026 - 221
    vis - zwemmen - beweging - kinematica - spieren - spiervezels - lichaamsafmetingen - groei - leeftijd - ontogenie - spierfysiologie - morfologie - fish - swimming - movement - kinematics - muscles - muscle fibres - body measurements - growth - age - ontogeny - muscle physiology - morphology

    In this series of studies the relations between swimming behaviour of fish in general and extreme swimming responses in particular (called fast starts or escape responses) and the structure and ontogeny of the muscle system was investigated. Special attention was paid to relate functional differences between anterior and posterior parts of the axial myotomal muscles of fish to differences in their structural design. In the past considerable knowledge has been accumulated concerning the muscular system. There are however still many unsolved questions. What for example is the influence of swimming in different fish species on the ontogeny of their muscles. How is the development of the muscle system reflecting functional demands (e.g. strength of fibre, elastic properties etc.) and what is the relationship between muscle development on a molecular scale and a macro scale? These and other questions will partly be addressed in this study.

    Initially the larval muscle system and its function was investigated in general as fish larvae swim in a different hydrodynamic environment, compared to adult fish, characterised by the importance of viscous forces which can not be neglected (Osse, 1990). In contrast to adults, the different muscles during the early stages of life of many fish species (e.g. Rutilus rutilus , Alburnus alburnus , Leuciscus cephalus , Clupea harengus, Clarias gariepinus ) have an aerobic metabolism (El-Fiky et al., 1987). In yolk-sac larvae of Clarias gariepinus for example, at a time when gill development is still insufficient and muscle rely for oxygen supply on diffusion through the body surface, both the superficial red muscle layer as well as the inner 'larval white' muscle mass are aerobic. The superficial red layer initially only consisted of a monolayer. At the moment the gills started to develop the superficial red layer acquired additional fibres along the horizontal septum, resulting in a double layer of red fibres at this location. The differences in metabolism between the red aerobic fibres and the white anaerobic fibres develop during the free-swimming larval stage of e.g. roach ( Rutilus rutilus ) and rainbow trout ( Salmo gairdneri ) and the adult pattern of muscle fibre type distribution emerges (Hinterleitner et al., 1987). As this development probably occurs in relation to gill development, it is thought that the red layer of yolk-sac larvae has a negligible role in swimming but an important role in respiratory (El-Fiky et al., 1987). Once the adult pattern of muscle fibre type distribution has developed the actual differences between the various muscles can be studied in great detail.

    The effects of transmission of forces on the structure and function of different muscle fibre types and at different locations along the body axis were studied during swimming of adult carp ( Cyprinus carpio L.). The connection between muscle fibres and collagen fibres, myotendinous junctions (MTJs), was investigated electron-microscopically. Especially during extreme swimming movements such as escape fast-starts large forces are imposed on the muscular system and mainly on the MTJs. During these life-saving swimming movements large sarcomere strains (relative to sarcomere slack length) occurred. Muscle fibres in the tail region (together with the connective tissue) play an important role in the transmission of force produced by more anterior fibres. Posterior fibres have a longer phase of eccentric activity (active while being stretched) than the anterior fibres and will therefore develop greater forces (van Leeuwen et al., 1990; van Leeuwen, 1995). It was therefore expected that greater forces in these posterior fibres would be accompanied by stronger MTJs (a greater membrane amplification). Posterior (80% of the fork length, FL ) muscle fibres of carp indeed had much larger myotendinous surface areas than anterior fibres (40% FL ) and consequently can transmit larger forces and 'bear' larger loads during swimming. Red muscle fibres of carp had a larger membrane amplification at the MTJs than white fibres. Red fibres are active at lower tail beat frequencies (longer cycle times) than white fibres and for longer periods of time, resulting in a longer duration of the load on the junction of red fibres. Tidball and Daniel (1986) proposed that the degree of membrane amplification at MTJs not only depends on the magnitude but also on the duration of load on the junction. Curtis (1961) and Rand (1964) showed that the mechanical behaviour of cell membranes is dependent on loading time. Cells can survive a certain shear load (caused by applying either a large load for a short time or a small load for a longer time) by reducing the stress on the membrane through an amplification of the membrane area. It was therefore suggested that the larger membrane amplification at the MTJs of carp red muscle fibres may be related to the longer duration of the load on the junction in this fibre type.

    Not only the MTJs were subjected to large forces during fast-starts (accompanied by large strain fluctuations). High demands will also be imposed on the muscle system itself and the series elastic elements within the sarcomere unit, such as the titin filaments (Wang et al., 1991). This may be reflected in the type and structure of the elastic elements as different isoforms of titin seem to exist (Wang et al., 1991; Granzier and Wang, 1993a,b). To help elucidate the relation between the possible occurrence of different titin isoforms and the functional properties of different fibre types, the presence of different titin isoforms in red and white anterior and posterior fibres of the axial muscles of adult carp was investigated. Titin is a striated-muscle-specific giant muscle protein that spans the distance from the Z- and M-lines of the sarcomere (Wang, 1985; Maruyama, 1986, 1994; Trinick, 1991). The elastic segment of titin in the I-band is thought to function as a molecular spring that is responsible for maintaining the central positions of the thick filaments in contracting sarcomeres and develops passive tension upon sarcomere stretch (Horowits et al., 1986; Fürst et al. 1988; Wang et al., 1991, 1993; Granzier et al., 1996).

    Gel-electrophoresis of single fibres of carp revealed that the molecular mass of titin was larger in red than in white fibres. For both red and white fibres the molecular mass of titin was larger in posterior than in anterior muscle fibres. Thus depending on the fibre type and its location along the body axis different titin isoforms were expressed.

    Furthermore the contribution of titin to passive tension and stiffness of red anterior and red posterior fibres was determined in micro-mechanical experiments. It appeared that more passive tension and stiffness was needed to stretch fibres with smaller titin isoforms (red anterior fibres) to a certain sarcomere length than in fibres with larger titin isoforms (red posterior fibres). Continuous swimming is the most frequently used swimming mode in adult carp and is driven by the activity of red muscle. During this type of swimming sarcomere strain is larger in red muscle fibres, which have larger titin isoforms, than in the three-dimensionally folded white muscle tissue, due to differences in distance between the sarcomere and the body axis and differences in fibre arrangement between both types. As during cyclic swimming local curvature increases from anterior to posterior the sarcomere strain is consequently larger in posterior fibres, which have larger titin isoforms. The finding that exactly those fibres that are exposed to the largest sarcomere strains during continuous swimming also possessed the largest titin isoforms led to the suggestion that titin isoform and sarcomere strain are correlated in order to minimise energy loss during cyclic loading of muscle fibres.

    However, it was still unknown how large the maximum sarcomere strains actually were during the most extreme swimming responses of adult carp. Therefore a study on the kinematics and muscle dynamics of escape fast-starts of carp was conducted. Adult carp perform escape C- or S-starts, based on the typical body curvature of the fish during these movements. During the Mauthner initiated C-starts (Eaton et al., 1977; Kimmel et al., 1980) adult carp made a large angle of turn directed away from the stimulus (approximately 150°) with a high acceleration at 0.3 FL of up to 54 m s -2. The maximum sarcomere strains (both anteriorly and posterior) were approximately 27% for red fibres and approximately 16.5% for white fibres. During escape S-starts however maximum strain in anterior fibres was more than twice that of posterior fibres with an angle of turn of approximately 70°. This large anterior peak curvature enabled the fish to control the direction of escape better but with lower accelerations at 0.3 FL (approximately 40 m s -2), although little is known about the neuronal mechanisms controlling S-starts. The largest strains occurred in red anterior fibres during S-starts (39%). It was found that during continuous and intermittent swimming the largest strains (red posterior fibres, approximately 5%) were found in fibres with the largest titin isoforms. This enabled these fibres to attain large strain amplitudes with relatively low passive tensions.

    It was surprising to find that in all fast-starts both red and white muscle were simultaneously active at a given longitudinal location, whereas only red muscle were active during continuous swimming. Red fibres could contribute to muscle fibre shortening at the beginning of their mechanical response for a very short period of time (before the full response was reached). This implies that red fibres hence could contribute to force generation during these extremely fast swimming modes, although little. Red and white muscle at a given longitudinal location were not necessarily active synchronously and could be uncoupled during escape S-starts. In this way mechanically sub-optimal patterns of force generation can be avoided. In both C- and S-starts both anterior and posterior muscle were active whilst lengthening at a certain moment, thus initially absorbing power which results in significant force- and performance enhancement.

    Fish larval swimming on the other hand is very different from adult swimming. Small carp larvae of approximately 6.5-8 mm total length are subjected to relatively low Reynolds-regimes of approximately 200≤Re≤500 and therefore require special features to overcome effects of friction. As superficial red fibres of Cyprinid larvae are mainly used as a respiratory organ (see above), larval swimming behaviour is mainly powered by the inner 'larval white' fibres (El-Fiky et al., 1987). But how exactly are these inner 'larval white' fibres able to generate enough power to overcome these friction effects and reach velocities of over 20 bodylength s -1? As small carp larvae and adults show large differences in their swimming behaviour the sarcomere strain ranges during fast swimming of larvae were investigated, together with their size of titin. During fast swimming of carp larvae all muscle fibres showed maximum sarcomere strains of approximately 20%, whereas their titin appeared to be shorter than any titin isoform found in adult muscle. Apparently the molecular structure of titin changed in the course of ontogeny. This shorter titin isoform (requiring larger stress for the same strain) is thought to help restricting form changes of the swimming larvae and to increase the elastic contribution to the tail beat. Such molecules possibly also increase the resonant frequency of the beating tail and thereby provide the required high frequency for swimming in a relatively low Reynolds-regime.

    The present study corroborates the idea that strong relations exist between the structural design of the muscular system, from micro- to macro-level, and its functions, also in diverse levels, in a fish's specific habitat. Starting at a structural level, differences in muscle function during swimming of fish can be used in an effort to explain and possibly predict morphological differences between the various muscle types and even within the same muscle type.

    Invloed van assimilatiebelichting en plantleeftijd op de inductie van bloemtakken bij pot-phalaenopsis
    Uitermark, C.G.T. ; Mourik, N.M. van; Schuettler, H. - \ 1998
    Aalsmeer : Proefstation voor Bloemisterij en Glasgroente, Vestiging Aalsmeer (Rapport / Proefstation voor Bloemisterij en Glasgroente 144) - 30
    phalaenopsis - kunstlicht - verlichting - bloei - forceren van planten - leeftijd - phalaenopsis - artificial light - lighting - flowering - forcing - age
    Jongeren in Friesland
    Goede, M.P.M. de; Jansma, L.G. ; Ophem, J.A.C. van; Verhaar, C.H.A. - \ 1994
    Ljouwert : Fryske Akademy - 171
    sociale structuur - generaties - leeftijd - leeftijdsgroepen - menselijke relaties - sociale interactie - sociale systemen - adolescenten - kinderen - zuigelingen - nederland - sociale relaties - friesland - social structure - generations - age - age groups - human relations - social interaction - social systems - adolescents - children - infants - netherlands - social relations - friesland
    De invloed van de afpen - en verplantfrequentie op de kwaliteit van groveden en Corsicaanse den
    Jager, K. - \ 1977
    Wageningen : De Dorschkamp (Rapport / Rijksinstituut voor onderzoek in de bos- en landschapsbouw 'De Dorschkamp' no. 117) - 61
    bosbouw - bomen - plantmateriaal - leeftijd - pinus sylvestris - pinus nigra - forestry - trees - planting stock - age - pinus sylvestris - pinus nigra
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