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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Convergent xylem widening among organs across diverse woody seedlings
Zhong, Mengying ; Castro-Díez, Pilar ; Puyravaud, Jean Philippe ; Sterck, Frank J. ; Cornelissen, Johannes H.C. - \ 2019
New Phytologist 222 (2019)4. - ISSN 0028-646X - p. 1873 - 1882.
leaf area - organs - plant size - stem height - tissue density - vessel diameter - xylem anatomy

Xylem conduit diameter (D max ) of woody angiosperm adults scales with plant size and widens from the stem apex downwards. We hypothesized that, notwithstanding relative growth rate (RGR), growth form or leaf habit, woody seedling conduit D max scales linearly with plant size across species; this scaling should be applicable to all vegetative organs, with consistent conduit widening from leaf via stem to main root and coupling with whole-leaf area and whole-stem xylem area. To test these hypotheses, organ-specific xylem anatomy traits and size-related traits in laboratory-grown seedlings were analyzed across 55 woody European species from cool-temperate and Mediterranean climates. As hypothesized, conduit D max of each organ showed similar scaling with plant size and consistent basipetal widening from the leaf midvein via the stem to the main root across species, independently of growth form, RGR and leaf habit. We also found a strong correlation between D max and average leaf area, and between stem xylem area and whole-plant leaf area. We conclude that seedlings of ecologically wide-ranging woody species converge in their allometric scaling of conduit diameters within and across plant organs. These relationships will contribute to modeling of water transport in woody vegetation that accounts for the whole life history from the trees’ regeneration phase to adulthood.

A novel method of measuring leaf epidermis and mesophyll stiffness shows the ubiquitous nature of the sandwich structure of leaf laminas in broad-leaved angiosperm species
Onoda, Y. ; Schieving, F. ; Anten, N.P.R. - \ 2015
Journal of Experimental Botany 66 (2015)9. - ISSN 0022-0957 - p. 2487 - 2499.
herbaceous plants - tissue stresses - mechanical-properties - maize leaf - biomechanics - organs - growth - perspective - irradiance - sunflower
Plant leaves commonly exhibit a thin, flat structure that facilitates a high light interception per unit mass, but may increase risks of mechanical failure when subjected to gravity, wind and herbivory as well as other stresses. Leaf laminas are composed of thin epidermis layers and thicker intervening mesophyll layers, which resemble a composite material, i.e. sandwich structure, used in engineering constructions (e.g. airplane wings) where high bending stiffness with minimum weight is important. Yet, to what extent leaf laminas are mechanically designed and behave as a sandwich structure remains unclear. To resolve this issue, we developed and applied a novel method to estimate stiffness of epidermis- and mesophyll layers without separating the layers. Across a phylogenetically diverse range of 36 angiosperm species, the estimated Young’s moduli (a measure of stiffness) of mesophyll layers were much lower than those of the epidermis layers, indicating that leaf laminas behaved similarly to efficient sandwich structures. The stiffness of epidermis layers was higher in evergreen species than in deciduous species, and strongly associated with cuticle thickness. The ubiquitous nature of sandwich structures in leaves across studied species suggests that the sandwich structure has evolutionary advantages as it enables leaves to be simultaneously thin and flat, efficiently capturing light and maintaining mechanical stability under various stresses.
Spike-Interval Triggered Averaging Reveals a Quasi-Periodic Spiking Alternative for Stochastic Resonance in Catfish Electroreceptors
Lankheet, M.J.M. ; Klink, P.C. ; Borghuis, B.G. ; Noest, A.J. - \ 2012
PLoS ONE 7 (2012)3. - ISSN 1932-6203 - 11 p.
white-noise analysis - interspike intervals - binocular-rivalry - nervous-system - organs - responses - neuron - input - motoneurons - cells
Catfish detect and identify invisible prey by sensing their ultra-weak electric fields with electroreceptors. Any neuron that deals with small-amplitude input has to overcome sensitivity limitations arising from inherent threshold non-linearities in spike-generation mechanisms. Many sensory cells solve this issue with stochastic resonance, in which a moderate amount of intrinsic noise causes irregular spontaneous spiking activity with a probability that is modulated by the input signal. Here we show that catfish electroreceptors have adopted a fundamentally different strategy. Using a reverse correlation technique in which we take spike interval durations into account, we show that the electroreceptors generate a supra-threshold bias current that results in quasi-periodically produced spikes. In this regime stimuli modulate the interval between successive spikes rather than the instantaneous probability for a spike. This alternative for stochastic resonance combines threshold-free sensitivity for weak stimuli with similar sensitivity for excitations and inhibitions based on single interspike intervals.
Haemocyte reactions in WSSV immersion infected Penaeus monodon
Arts, J.A.J. ; Taverne-Thiele, J.J. ; Savelkoul, H.F.J. ; Rombout, J.H.W.M. - \ 2007
Fish and Shellfish Immunology 23 (2007)1. - ISSN 1050-4648 - p. 164 - 170.
spot syndrome virus - monoclonal-antibodies - baculovirus wsbv - shrimp - emphasis - organs
White spot syndrome virus (WSSV) has been a major cause of shrimp mortality in aquaculture worldwide in the past decades. In this study, WSSV infection (by immersion) and behaviour recruitment of haemocytes is investigated in gills and midgut, using an antiserum against the viral protein VP28 and a monoclonal antibody recognising haemocytes (WSH8) in a double immunohistochemical staining and in addition transmission electron microscopy was applied. More WSH 8+ haemocytes were detected at 48 and 72 h post-infection in the gills of infected shrimp compared to uninfected animals. Haemocytes in the gills and midgut were not associated with VP28-immunoreactivity. In the gills many other cells showed virus replication in their nuclei, while infected nuclei in the gut cells were rare. Nevertheless, the epithelial cells in the midgut showed a clear uptake of VP28 and accumulation in supranuclear vacuoles (SNV) at 8 h post-infection. However, epithelial nuclei were never VP28-immunoreactive and electron microscopy study suggests degradation of viral-like particles in the SNV. In contrast to the gills, the midgut connective tissue shows a clear increase in degranulation of haemocytes, resulting in the appearance of WSH8-immunoreactive thread-like material at 48 and 72 h post-infection. These results indicate recruitment of haemocytes upon immersion infection in the gills and degranulation of haemocytes in less infected organs, like the midgut.
Sensitive detection of Myobacterium avium subsp paratuberculosis in bovine semen by real-time PCR
Herthnek, D. ; Englund, S. ; Willemsen, P.T.J. ; Bolske, G. - \ 2006
Journal of Applied Microbiology 100 (2006)5. - ISSN 1364-5072 - p. 1095 - 1102.
polymerase-chain-reaction - mycobacterium-paratuberculosis - crohns-disease - johnes-disease - diagnosis - organs - is900 - milk - dna - herpesvirus
Aims: To develop a fast and sensitive protocol for detection of Mycobacterium avium subsp. paratuberculosis (MAP) in bovine semen and to make a critical evaluation of the analytical sensitivity. Methods and Results: Processed semen was spiked with known amounts of MAP. Semen from different bulls as well as semen of different dilutions was tested. The samples were treated with lysing agents and beadbeating and the DNA was extracted with phenol and chloroform. Real-time PCR with a fluorescent probe targeting the insertion element IS900 detected as few as 10 organisms per sample of 100 ¿l semen. PCR-inhibition was monitored by inclusion of an internal control. Pre-treatment with immunomagnetic separation was also evaluated, but was not shown to improve the overall sensitivity. Conclusions: Real-time PCR is a sensitive method for detection of MAP in bovine semen. Lysis by mechanical disruption followed by phenol and chloroform extraction efficiently isolated DNA and removed PCR-inhibitors. Significance and Impact of the Study: The high sensitivity of the applied method allows reliable testing of bovine semen used for artificial insemination to prevent the spread of Johne's disease, caused by MAP.
Mortality and growth performance of broilers given drinking water supplemented with chicken-specific probiotics
Timmerman, H.M. ; Veldman, A. ; Rombouts, F.M. ; Beynen, A.C. - \ 2006
Poultry Science 85 (2006)8. - ISSN 0032-5791 - p. 1383 - 1388.
lactobacillus-cultures - fed diets - acidophilus - exclusion - weight - organs - flora
For application in broiler production, we developed a multispecies (MSPB) and a chicken-specific (CSPB) probiotic preparation in fluid form. The MSPB contained different probiotic species of human origin, whereas the CSPB consisted of 7 Lactobacillus species isolated from the digestive tract of chickens. In a field trial with broilers, MSPB treatment resulted in a slight increase (by 1.84%) in broiler productivity based on an index taking into account daily weight gain, feed efficiency, and mortality. The CSPB treatment reduced mortality in 2 subsequent field trials and raised productivity by 2.94 and 8.70%. In a controlled trial with broilers showing a high index of productivity, probiotic treatment further raised productivity by 3.72%. Based on the present 4 studies in combination with 9 studies published earlier, it is suggested that with higher productivity rates of the broilers the effect of probiotics becomes smaller
Ontwikkeling van een screeningsmethode voor [beta]2 - agonisten in weefsel : residuen van clenbuterol in vlees en organen van slachtkuikens en kalveren
Haasnoot, W. ; Hamers, A.R.M. ; Kan, C.A. ; Schilt, R. ; Huf, F.A. - \ 1991
Wageningen : RIKILT (Rapport / RIKILT 91.03) - 24
clenbuterol - pluimveevlees - kippenvlees - rundvlees - kalfsvlees - organen - poultry meat - chicken meat - beef - veal - organs
In verband met de controle op het oneigenlijk gebruik van clenbuterol en andere [beta]2 - agonisten is het noodzakelijk over gegevens te beschikken over de wijze van toediening aan en het voorkomen van residuen bij pluimvee. In de literatuur zijn gegevens over een mogelijke residuvorming van o.a. clenbuterol in vlees en organen van pluimvee niet beschreven. Over de toepassing van clenbuterol en andere [beta]2 - agonisten bij pluimvee zijn wel enkele gegevens bekend. Om deze reden werd een dierexperiment uitgevoerd, waarbij aan kuikens gedurende vijf dagen clenbuterolhoudend voeder (1 mg/kg) werd verstrekt. Direct volgend op de toediening en één dag daarna werden de kuikens gedood en werden monsters van vlees, nier, lever, spiermaaginhoud en blindedarminhoud genomen. Voor de bepaling van clenbuterol werd een, recent ontwikkelde, muili-screeningsmethode voor [beta]2 - agonisten toegepast, welke gebaseerd is op een enzym-immunologische test (EIA).
Resultaten onderzoek bestrijdingsmiddelen, chloorbifenylen, zware metalen en diergeneesmiddelen in vlees, organen, vetten en urine (Nationaal Plan Overige Stoffen/ VREK) : jaaroverzicht 1990
Roos, A.H. ; Frijns, L.M.H. ; Rutjes, B.P.M. ; Pauw, C.G. van der; Haasnoot, W. ; Horstman, H.J. ; Keukens, H.J. ; Tuinstra, L.G.M.Th. ; Huf, F.A. - \ 1991
Wageningen : DLO-Rijks-Kwaliteitsinstituut voor Land- en Tuinbouwprodukten (Rapport / RIKILT-DLO 91.20) - 20
pesticiden - zware metalen - gechloreerde koolwaterstoffen - polychloorbifenylen - veterinaire producten - vlees - organen - vetten - urine - voedselveiligheid - monitoring - pesticides - heavy metals - chlorinated hydrocarbons - polychlorinated biphenyls - veterinary products - meat - organs - fats - food safety
De in 1990 in het kader van het Nationaal Plan "Overige Stoffen" en VREK programma uitgevoerde onderzoeken zijn samengevat en vergeleken met onderzoeksresultaten van voorgaande jaren. Op verzoek van de directie Voedings- en Kwaliteitsaangelegenheden worden in dit rapport de resultaten van het Nationaal Plan "Overige Stoffen" en tevens de resultaten van het onderzoek uitgevoerd in het kader van het VREK-programma samengevat ten behoeve van de beleidsvorming op het gebied van de bestrijdingsmiddelen, zware metalen en diergeneesmiddelen. Het rapport geeft een samenvatting van de resultaten van het in 1990 uitgevoerde onderzoek naar sulfonamiden in vlees, furazolidon in vlees, desoxycarbadox in nier, p-blokkers en tranquillizers in nier, clenbuterol in urine, chlooramfenicol in urine en vlees, uitgevoerd door het Centraal Laboratorium RVV, van het onderzoek naar zware metalen in vlees, lever, nier en organochloorverbindingen in dierlijk vet en eiprodukten uitgevoerd door het RIKILT en CIVO-TNO (alleen in pluimveeprodukten) en vergelijkt de verkregen data met de resultaten van de afgelopen jaren.
The development of an in vitro model for studying mechanisms of nephrotoxicity as an alternative for animal experiments
Mertens, J.J.W.M. - \ 1991
Agricultural University. Promotor(en): J.H. Koeman; J.H.M. Temmink. - S.l. : Mertens - 143
nefrotoxiciteit - alternatieven voor dierproeven - organen - weefsels - in vitro - nephrotoxicity - animal testing alternatives - organs - tissues - in vitro
SUMMARY

Presently in our society animal tests still form the main starting point for the assessment of the possible risks of chemicals with regard to human and animal health. For scientific. economic, and ethical reasons. attempts are undertaken continuously to develop cell models as alternatives to animal testing. However, the predictive value of in vitro test systems is often limited due to the unawareness about the mechanisms of toxicity and the complexity of organisms. As a consequence, a strategy increasingly used is one of studying mechanisms of toxicity evolving in rational cell models. Following this strategy, this thesis aims at contributing to the development of cell models as an alternative to animal testing.

A usefull cell model for studying mechanisms of toxicity requires the presence of characteristics which may play a role in this toxicity in vivo. and the possibility to demonstrate their involvement. The organ of our choice was the kidney. Since very often the cortex. more in particular the proximal tubule. is affected by chemicals. cortical cells of different origin have been used: A renal cell line derived from a Hamshire pig (LLC-PK1) and primary cultures of rat renal cortical cells (Chapter 2). The applicability of these cells in a cell model was tested considering two major aspects of importance for nephrotoxicity: Firstly. the functional polarity of the proximal tubular cell, and secondly the presence of specific biotransformation processes and transport systems (Chapter 1).

In vivo luminal (apical) as well as serosal (basolateral) exposure of the proximal tubular cell can occur. However. when monolayers are cultured in a conventional way, i.e. on a solid support, only the apical side is accessible for the compounds to be investigated. To overcome this problem a new system for nephrotoxicological in vitro studies has been developed. Cells were cultured on porous substrates, which enables exposure of monolayers on either side (Chapter 2).

The nephrotoxic effects of haloalkenes and halobenzenes seem to be mediated via the formation of glutathione conjugates (Chapter 1). In part II of this thesis a glutathione conjugate of hexachlorobutadiene and its derivatives are used as model compounds to investigate the possibilities of the cell systems described in chapter 2. LLC-PK1monolayers possess the most important characteristics necessary for cytotoxicity of S-(1.2,3,4,4-pentachlorobutadienyl)glutathione (PCBD- GSH) to occur (Chapter 3). Via the use of acivicin, an irreversible inhibitor of γ-glutamyltranspeptidase (γGT). and aminooxyacetic acid. an inhibitor of β-lyase, the importance of these enzymes in the activation of PCBD-GSH was demonstrated. After metabolism by γGT and dipeptidase S-(1,2,3,4,4-pentachlorobutadienyl)-L-cysteine (PCBD-CYS) is formed extracellularly. This is taken up and converted by β-lyase into a reactive thiol resulting in toxicity. In vivo and in the LLC-PK1cell line γGT is predominantly present on the luminal and apical membrane respectively. In agreement with this. apical exposure of LLC-PK1monolayers to PCBD-GSH caused a stronger toxicity than basolateral exposure . In the nephrotoxicity of the corresponding mercapturate N-acetyl-S-(1,2,3,4,4-pentachlorobutadlenyl)-L-cysteine (PCBD-NAC), which is deacetylated intracellularly into PCBD-CYS, a serosally located probenecid sensitive organic anion transporter has been suggested to be of importance (Chapter 1). Apical exposure of LLC-PK1monolayers to PCBD-NAC caused hardly any toxicity; only at relatively high concentrations a toxic effect was detected. Surprisingly, basolateral exposure and consequently administration of the compound to the possible transporter, did not cause substantial toxicity either. Further investigations revealed that this is probably caused by the absence of an organic anion transporter in the LLC-PK1cell line: The model organic anion para-aminohippurate (PAH) was not transported by LLC-PK1cells. In contrast, LLC-PK1monolayers are in the possession of an organic cation transporter. A quinine and ouabalne inhibitable transcellular transport of the cation tetraethylammonium (TEA) was demonstrated (Chapter 3).

The organic anion transporter was also postulated (Lash and Anders, 1986) to play a role in the cytotoxicity of cysteine conjugates . However, in spite of the demonstrated absence of an organic anion transporter , PCBD-CYS causes toxicity in the LLC-PK1monolayer. In contrast to PCBD-GSH, basolateral exposure to PCBD-CYS resulted in a stronger toxic effect than apical exposure (Chapter 4). A possible candidate for the transport of PCBD-CYS in LLC-PK1cells is an amino acid transporter. The inhibitory effect of D-tryptophan and histidine on the toxicity of PCBD-CYS strongly suggests the involvement of the amino acid transport System T (Chapter 4).

Culturing primary cultures of rat renal cortical cells resulted in confluent monolayers (Chapter 2 and 5). However, investigating transcellular transport of organic ions in a similar way as with the LLC- PK1 monolayers was not possible, because a non-leaking monolayer on a porous support was not obtained. This may be due to the diversity of the cell population in the culture, and the concomitant differences in junctional complexes necessary for complete sealing of the monolayer. The presence of both PAH and TEA transporters was demonstrated by measuring intracellular accumulation, which could be inhibited by probenecid and quinine respectively. Inhibition of γGT and/or β-lyase decreased the toxic effect of PCBD-GSH, PCBD-CYS, and PCBD-NAC. In contrast to the experiments with LLC- PK1 monolayers, no effect of amino acid transporter substrates or probenecid on the toxicity was observed. Apparently uptake of PCBD-CYS or PCBD-NAC in primary cultures of rat renal cortical cells is not the rate-limiting step in the toxicity. The probenecid sensitivity of toxicity observed by others thus must be caused by other mechanisms.

In part II, glutathione conjugated halohydroquinones are the subject of investigation. These conjugates resemble the bromohydroquinone glutathione conjugates which are supposed to be responsible for the nephrotoxic effects of bromobenzene. The exact mechanism of nephrotoxicity is not known. In vivo experiments indicate that γGT is an important factor, as in the case of PCBD-GSH. However, β-lyase mediated metabolism appears to be of lesser importance than oxidative metabolism resulting in quinone conjugates (Chapter 1). In a first attempt to validate the in vitro test system and to see whether the mechanism of nephrotoxicity of glutathione conjugated bromohydroquinones is more generally valid, dichloro(glutathion-S-yl)hydroquinone (DC-(GSyl)HQ) and trichloro(glutathion-S-yl)hydroquinone (TC-(GSyl)HQ) were studied in vivo (Chapter 6). Administration (i.v.) of these compounds in the quinone form caused nephrotoxicity evidenced by elevations in blood urea nitrogen (BUN) , an increase in the urinary excretion of glucose, lactate dehydrogenase and γGT, and by the pathological changes in the kidney slices. Reducing the glutathione conjugated quinones with ascorbic acid caused a drastic increase in nephrotoxicity . This protocol may result in an increased delivery of DC-(GSyl)HQ and TC-(GSyl)HQ to the kidney , by preventing their interaction with nucleophilic sites on plasma proteins and/or with other extra-renal macromolecules. Surprisingly, inhibition of γGT increased the nephrotoxicity.

Apparently γGT has a dual role in the nephrotoxicity of halogenated hydroquinone glutathione conjugates. This was further investigated in vitro in chapter 7. The LLC-PK1cell line was chosen, since the apical presence of γGT makes this cell line a very suitable model for this purpose. However, in contrast to the experiments with PCBD-GSH and its derivatives, the in vitro experiments did not completely clarify the mechanism of activation of halogenated hydroquinone-glutathione conjugates. In a postulated scheme (Fig.7.7) the reactions that can occur with halogenated GSyl-HQ conjugates are summarized , and an explanation for the results obtained in vitro as well as in vivo is offered. The results indicate that γGT is not the rate-limiting step in the toxicity. They suggest that γGT on the one hand initiates a detoxication by 1.4-benzothiazine formation and/or polymerization, and on the other hand activates by targetting the oxidation that causes the toxicity. In addition, without metabolism by γGT these compounds are not stable and can be detoxified via air-oxidation and presumably polymerization. Further studies will be necessary to elucidate the exact site and mechanism of oxidation.

CONCLUDING REMARKS

The studies described in this thesis demonstrate that exposing of monolayers on porous substrates closely resembles the in vivo luminal and serosal exposure of a renal proximal tubular cell. In the future this system offers the possibility to investigate and compare the relative importance of polarized functions of epithelial cells of different organs and origin.

By using model compounds it could be demonstrated that the LLC-PK1cell may be a relatively simple model for determining a specific nephrotoxic potential of glutathione and cysteine conjugates. For this purpose, the absence of an organic anion transporter in the LLC-PK1cell line proved not to be a handicap. However, for investigating the nephrotoxic potential of other chemicals, the presence of an organic anion transporter may be a prerequisite. Consequently, further characterization of other cell lines as the Opussum Kidney cell fine (Koyama et al, 1978) or the recently established human renal cell line (KRC/Y) (Yano et al. 1988) should focus on the presence of this transporter.

Finally. the experiments on the role of γGT in the nephrotoxicity of glutathione conjugated halogenated hydroquinones underline once more the importance of in vivo validation. Differences of a more physical natures between in vivo and in vitro, as e.g. oxygen pressure and pH, may cause different or additional effects of compounds in vivo. which may be missed in vitro when these differences are not taken into account.

Evaluatie van het, in 1985 in het kader van het VREKprogramma, uitgevoerde onderzoek naar de cadmium-, lood-, kwik- en arseengehalten in vlees en organen van runderen, varkens, schapen en pluimvee
Vos, G. ; Roos, A.H. - \ 1986
Wageningen : RIKILT (Rapport / RIKILT 86.16)
vlees - vleeskwaliteit - vleessamenstelling - kwaliteitscontroles - cadmium - lood - kwik - arsenicum - organen - meat - meat quality - meat composition - quality controls - lead - mercury - arsenic - organs
Doel van dit onderzoek is: Het Ministerie van Landbouw en Visserij en met name de LAG-stuurgroep "Vee, vlees en eieren" en de LAG-werkgroep "zware metalen" te informeren omtrent het gehalte aan lood, cadmium, kwik en arseen in vlees en organen van consumptiedieren; ondersteuning van de Nederlandse exportbelangen ten aanzien van dierlijke produkten. De in 1985 in het kader van het LAC-signaleringsprogramma VREK gevonden lood-, cadmium-, kwik- en arseengehalten zijn geëvalueerd en vergeleken met de resultaten van voorgaande jaren. De gevonden gehalten zijn getoetst aan geldende aktiegrenzen en ontwerpnormen.
Evaluatie van het, in 1984 in het kader van het VREKprogramma, uitgevoerde onderzoek naar de cadmium-, lood-, kwik- en arseengehalten in vlees en organen van runderen, varkens, schapen en pluimvee
Vos, G. ; Roos, A.H. - \ 1985
Wageningen : RIKILT (Rapport / RIKILT 85.20)
rundvlees - varkensvlees - schapenvlees - pluimveevlees - vleeskwaliteit - vleessamenstelling - organen - kwaliteitscontroles - cadmium - lood - kwik - arsenicum - beef - pigmeat - sheepmeat - poultry meat - meat quality - meat composition - organs - quality controls - lead - mercury - arsenic
De in 1984, in het kader van het LAC-signaleringsprogramma VREK, gevonden cadmium-, lood-, kwik- en arseengehalten zijn geëvalueerd en vergeleken met de resultaten van voorgaande jaren. De gevonden gehalten zijn getoetst aan geldende actiegrenzen en richtnormen.
Manual for root-box system
Bosch, A.L. - \ 1985
Wageningen : LH - 11
experimenten - bosbouw - handboeken - meting - organen - plantenontwikkeling - plantenfysiologie - wortels - simulatie - bodem - statistiek - weefsels - waterrelaties - experiments - forestry - handbooks - measurement - organs - plant development - plant physiology - roots - simulation - soil - statistics - tissues - water relations
Gehalten aan lood, cadmium, kwik en arseen in monsters vlees en organen van runderen, varkens, schapen en pluimvee, alsmede eieren
Veen, N.G. van der; Roos, A.H. ; Berghmans-van Megen, E.H.J. ; Betteray-Kortekaas, A.M.G. ; Driessen, A.C.M. ; Hoff, A.W. ; Horstman, H.J. ; Hovens, J.P.C. ; Moraal, J.C. ; Teeuwen, J.J.M.H. ; Werdmuller, G.A. - \ 1982
Wageningen : RIKILT (Verslag / RIKILT 82.30) - 21
vlees - organen - lood - kwik - cadmium - arsenicum - eieren - vleessamenstelling - eiersamenstelling - voedselanalyse - meat - organs - lead - mercury - arsenic - eggs - meat composition - egg composition - food analysis
Doel van dit onderzoek is: Het Ministerie van Landbouw en Visserij en met name de LAC-Werkgroep "Zware metalen" en de LAG-Stuurgroep Vee, Vlees en Eieren informeren omtrent het gehalte van lood, cadmium, kwik en arseen in vlees en organen van runderen, varkens, schapen en pluimvee, alsmede in eieren. De monsters zijn in 1981 genomen in het kader van het LAC-signaleringsprogramma VREK. De analyseresultaten zijn vergeleken met die uit 1980. In het kader van het signaleringsprogramma VREK zijn de analyseresultaten voor lood, cadmium, kwik en arseen verkregen in 1981, vergeleken met die uit 1980. Ten aanzien van overschrijdingen van aktiegrenzen en toleranties zijn de resultaten verkregen over 1978 t/m 1981 met elkaar vergeleken.
Bepaling van chlooramphenicol in urine, gal, lever etc.
Beek, W.M.J. ; Buizer, F.G. - \ 1982
Wageningen : RIKILT (Verslag / RIKILT 82.81) - 3
chlooramfenicol - bloedplasma - bloedserum - hplc - analytische methoden - vloeistofchromatografie - organen - urine - chloramphenicol - blood plasma - blood serum - analytical methods - liquid chromatography - organs
Het bepalen van chlooramphenicol in monsters urine, gal, nier etc , welke afkomstig zijn van de Vleeskeuringsdient Nijmegen, met behulp van Interne Analysemethoden. De monsters werden onderzocht volgens intern analysevoorschrift nr. Dgm 26: Bepaling van chlooramphenicol in bloed, plasma, serum etc. door middel van HPLC. Met enige wijzigingen konden ook hiermede vlees, lever etc. onderzocht worden.
Histologische technieken t.b.v. uierweefselkweken
Wijs, M. de; Versluijs, F. - \ 1974
Hoorn : [s.n.] (Intern rapport / Instituut voor veevoedingsonderzoek "Hoorn" no. 65) - 16
anatomie - rundvee - celkweek - experimenten - melkklieren - organen - tepels - weefselkweek - weefsels - uiers - diergeneeskunde - anatomy - cattle - cell culture - experiments - mammary glands - organs - teats - tissue culture - tissues - udders - veterinary science
Germination of powdery mildew conidia in vitro on cellulose membranes
Waard, M.A. de - \ 1970
Wageningen : [s.n.] (Mededeling / Laboratorium voor phytopathologie no. 269) - 8
experimenten - kieming - organen - plantenziekteverwekkende schimmels - kiemrust - zaadkieming - weefsels - experiments - germination - organs - plant pathogenic fungi - seed dormancy - seed germination - tissues
Insektenhormonen en insektenbestrijding
Wilde, J. de - \ 1970
Wageningen : Veenman - 16
insecten - entomologie - hormonen - ongewervelde dieren - gewasbescherming - insecticiden - acariciden - mollusciciden - voortbeweging - organen - insects - entomology - hormones - invertebrates - plant protection - insecticides - acaricides - molluscicides - locomotion - organs
Evolutionary trends in Heteroptera
Cobben, R.H. - \ 1968
Wageningen University. Promotor(en): J. de Wilde. - S.l. : s.n. - ISBN 9789022001691 - 475
rassen (dieren) - evolutie - genetische variatie - heteroptera - overerving - organen - rassen (taxonomisch) - weefsels - breeds - evolution - genetic variation - heteroptera - inheritance - organs - races - tissues - cum laude

1. This work, the first volume of a series dealing with evolutionary trends in Heteroptera, is concerned with the egg system of about 400 species. The data are presented systematically in chapters 1 and 2 with a critical review of the literature after each family.

2. Chapter 3 evaluates facts about each egg character. I have attempted to distinguish between anagenetic and cladogenetic processes of evolution.

3. The actual chorion reveals a wide range of types of architecture and of aeropylar systems (fig. 264-267). The aerostatic inner layer of the shell of most Geocorisae and of Hydrometra is not homologous with the porous inner layer of Saldidae, many Amphibicorisae and Hydrocorisae. A thin, entirely solid chorion is considered as a plesiomorphous condition (Hebrus, Mesovelia, Idiostolus, Embiophila, Oncylocotis). Some of the specific features of shells are: air clefts; respiratory horns on the rim or on the operculum; porous structures in different stages of evolution, ultimately acting as a plastron; regulation of respiration by movable slips of the rim.

4. The general trend of evolution of the micropylar system (fig. 268-270) represents multiplication and displacement of the micropyles, starting from a single micropyle in the centre of the cephalic pole; in some groups reduction and complete loss of the micropyles is associated with traumatic insemination. The structure and orientation of the micropyle(s) and their changes during evolution have been discussed. Monalocoris, Bryocoris and Oncylocotis are divergent from the general pattern.

5. The primitive longitudinal dehiscence of the shell has evolved independently and along different pathways into a cap in most major groups (schemes in fig. 270-272), sometimes intermediately on one of the lateral sides. The lygaeid-coreid types of eclosion are derived from a transitional, radial structure which has consolidated in Piesmatidae, and also in Malcidae after loss of a central polygon. The terms operculum and pseudoperculum are redefined on a more functional basis. The cap of the serosal cuticle has evolved more slowly than the cap of the chorion.

6. The progressive evolution in size is usually accompanied by some regularities as shown graphically in fig. 273, 274: small eggs have a spacious hexagonal pattern from the follicle; plesiomorphous species are usually small, have a long period of oviposition and few ovarioles in which a few, relatively large, eggs ripen simultaneously; apomorphous species have a larger body, smaller egg and follicle cells, more ovarioles, and synchronous egg maturation and deposition.

7. A survey is given of incubation periods, diapause phenomena and reproductive cycles; the phylogenetic consequences are limited. With one exception, diapause of the egg intervenes in embryonic development between the stages of the early germ band and revolution (fig. 275), but does not affect the formation of the serosal cuticle.

8. Family groups are distinguished by different types of embryogenesis. A wide range of progressive evolution of the embryonic development is apparent within most of the major phyletic lines. Altogether, the diversity of embryonic features and processes in Heteroptera is not equalled in any other Order of insects as far as is known.

9. The variable characteristics utilized in reconstructing the genealogy of embryogenic patterns (fig. 276) are: degree of visible development of the 'pregerm'; location of blastopore; growth, orientation, transformation in shape and displacement (mostly clockwise rotations) of the germ band, embryo and prolarva.

10. Since relations between the various ontogenies of the embryo appear to be independent of evolutionary adaptations, the phylogeny of the embryogenetic patterns gives a most reliable picture to contrast with quite different characters used for major classification.

11. The archetype of embryogenesis is distinguished by invagination of the embryo (morphologically at the caudo-ventral edge of the egg) along the longitudinal median axis of the yolk column without loss of contact between head lobes and serosa and by a 1800 rotation of the embryo before revolution. Hebrus most closely conforms to this type, followed by most Amphibicorisae and by cimicoid groups which tend to invaginate at the left side of the egg. Temporary complete invagination occurs in Saldidae, Gerris and Hesperoctenes, and in diapausing mirid eggs.

12. The variability in the type of egg rotation and embryo rotation in Gerridae, Hydrometridae, Cydnidae and Acanthosomatidae suggests that the egg system is not yet in equilibrium.

13. Pentatomomorpha reveal gradual loss of embryo rotation, while Hydrocorisae retain such rotation, sometimes with germ-band and prolarval rotations. Both groups show a transition (anagenetic intra se, cladogenetic inter se ) from the immersed towards the superficial type of embryogenesis.

14. The superficial condition of the hydrocorisous type prevails in Reduviidae after complete loss of rotations. The progression in embryonic evolution reached a high level in Harpactorinae; many perform semi-invagination, and species of Coranus entirely omit the invagination stage, and have no blastokinesis in the broadest sense. This deficiency is associated with early differentiation of the prospective germ band in the blastoderm stage. Similar early development occurs in some Hydrocorisae and, through cladistic divergence, also in evolved taxa of the Pentatomomorpha.

15. The standard of embryogenesis is not influenced by egg shape. The dimensions of the embryo do not foreshadow those of the future larva but allometry of the limbs appears already during bud formation.

16. In contrast to other Heteroptera, saldid embryos have the eyes differentiated before revolution. They possess a peculiar cephalic organ, possibly hydropic, extending through the serosal cuticle and underlying a great part of the chorion.

17. A survey is given of the various positions and fates of the serosal hydropyle. The revolution of the embryo is predominantly brought about by local contractions of the fused amnion and serosa, and not by intrinsic action of the embryo itself.

18. The remains of the contracted serosa, the serosal plug, is rapidly engorged in course of time into the future pronotal region to form the secondary dorsal organ. The involution is the result of a spectacular peristalsis, in the first instance caused by sudden contraction of cells close to the line of fusion between amnion and serosa.

19. In many Miridae, the serosal plug, with or without yolk content, persists till eclosion of the egg, apparently absorbing water from the outside in order to stretch the serosal cuticle. The subsequent lengthening of the egg enables the prolarva to escape out of the sunken oviposition slit.

20. The blackening of the egg is reducible to different principles, depending on whether suprachorionic, chorionic or subchorionic layers are involved. The blackish exudate of the serosal cuticle, restricted to some families of Heteroptera, may play a role in water regulation. Extra-embryonic envelopes of uncertain origin have been noticed in a few species.

21. The embryological data are compared with the literature dealing with other insect Orders. Because the evolution of embryonic development of insects seems to be largely governed by parallelism, a clearer distinction between cladogenetic and anagenetic phenomena in other Orders must be made first before relationships between Orders can be settled. The differences between the holometabolic and the hemimetabolic type of development may not be as fundamental as has been suggested.

22. The evolution of structures involved in four different methods of eclosion is outlined in fig. 278. A transverse, paired ruptor ovi forming part of the embryonic cuticle and delimiting the anteclypeus from the postclypeus is considered as the archetypical condition (as in Hebrus).

23. Cladogenesis of the eclosion process evolved within the Amphibicorisae. In Mesovelia, eclosion is caused by fluid pressure within the embryonic cuticle. The situation in the Nabidae represents a link between this procedure and that in the Cimicoidea sensu lato, but the function of pressure transfer is gradually taken over by the fluid-filled serosal cuticle.

24. The main device in eclosion of Reduviidae and Hydrocorisae is part of the serosal cuticle. Sudden forcing of extra-embryonic fluid anteriad explosively breaks the chorion in Hydrocorisae. Prolarval rotations may accelerate solution of the inner layer of the serosal cuticle, and the function of the pleuropodia is discussed in relation to this behaviour.

25. In Amphibicorisae other than Mesoveliidae, and in the Leptopodoidea the transverse clypeal ruptor developed into a longitudinal frontal ruptor; Saldidae have both a frontal and a clypeal ruptor.

26. Pentatomomorpha reveal anagenesis of the ruptor system resulting in displacement of the cephalic armature up to the pronotum through loss of the vertex.

27. An account is given of the many sorts of bilateral, mostly monostrophous asymmetries found in the heteropterous egg system. The typical flexing pattern of limbs and antennae of the prolarva (a characteristic of the hemipteroid Orders) is racemic. In Hydrocorisae this asymmetry is constant and either amphidromous or monostrophous (the reverse asymmetry occurs in Plea ).

28. The different orientations of the laid egg are reduced to three main types (Table 2, p. 332) the evolution of which is outlined in fig. 281. Some speculations are made on the selection factors involved in switching from one type to the other.

29. The archetypal Heteroptera did not possess a well developed ovipositor, and they were able both to deposit the eggs 'backwards' or 'forwards'. The theoretical possibilities of oviposition in ancestors are shown within the central circle of fig. 281.

30. Saldidae and Mesoveliidae have a firm 'concave' ovipositor; oviposition is such that 180° rotation of the longitudinal axis of the egg within the genital tract must be supposed. Gerris regulates delivery of rotated or non-rotated eggs according to the oviposition site selected. Pentatomids of the genera Aeliomorpha and Macrina exhibit 90° rotation of the eggs and the alteration in egg shape conforms with this mode of laying.

31. Comparison of embryogenic types (fig. 276), the egg types drawn in a standardized way (fig. 282-285), and the stance of the depositing female demonstrated that 180° rotation of the eggs is more common in Heteroptera and most probably also in other insects.

32. The side of the egg where the embryonic anlage develops into the blastoderm is taken as the ventral side. The following rules have been drafted for the dorsoventral polarity of the egg-system: 1. All eggs laid exposed, whether rotated or not, and whose embryo rotates through 180°, are attached with the ventral side against the substrate; the venter of the fully grown embryo lies below the dorsal side of the egg. 2. Eggs without embryo rotation are likewise ventrally attached to the substrate, except when the egg is rotated before laying; the morphological sides of the fully grown embryo correspond with those of the egg.

The same rules hold for erect or embedded eggs, when these are figured as being laid horizontally.

33. The data obtained from the study of heteropterous eggs have been compared with relevant data from other Orders of insects. The 'HALLEZ law' is redefined on pages 347- 348.

34. A preliminary discussion of the phylogeny of the Heteroptera is given. The group characters derived from the egg system are discussed on p. 350-363.

35. The Leptopodoidea forms a natural group sharply defined from others. It seems improbable that Amphibicorisae arose from a proto-saldid stock; the opposite direction of evolution, Saldidae from proto-amphibicorisae is more in accordance with our findings.

36. The Amphibicorisae appear more diverse than was assumed on the basis of other character complements, and comprise more than one superfamily. Mesoveliidae and Hydrometridae deviate considerably from the group type. Gerridae and Veliidae could be delimited more clearly from each other. Macrovelia and other aberrant genera show close affinity with Veliidae, not with Mesoveliidae.

37. Pentatomomorpha constitute a natural group of families but the Idiostolidae are remote. The families are distinguished by the height reached on the anagenetic scale. The origin of the Pentatomoidea dated further back and the anagenesis advanced further than in the other superfamilies. Stenocephalidae appear more lygaeid-like and Colobathristidae more coreid-like. Malcidae are cladogenetically derivable from Piesmatidae. Eggs of Pseudophloeinae and Hydara resemble those of Alydidae.

38. Reduvioidea, Thaumastocoroidea and Dipsocoroidea ought to be excluded from the Cimicomorpha which should contain only the families of the Cimicoidea sensu lato. On the basis of the eggs, Bryocorinae, excluding the Helopeltis group, merit family status. Several mirid genera seem to be classed under wrong subfamilies. The eggs of Velocipedidae and Pachynomidae are essentially nabid-like.

39. Thaumastocoridae, Dipsocoroidea and Enicocephalidae are all isolated groups. There seems to be no justification for combining the two latter in one group.

40. Hydrocorisae, inclusive of Corixidae and Ochteridae, share similar types of embryogenesis and eclosion dynamics but are heterogeneous in chorionic architecture. The common predecessors of Hydrocorisae probably must be found in the naucorid, not in the ochterid branch. Several taxa, considered as subfamilies, perhaps merit family rank (Potamocorinae, Aphelocheirinae, Diaprepocorinae, Micronectinae).

41. The unintentional nomenclatoral consequences of the new major classification of terrestrial Heteroptera (LESTON et al. 1954) are discussed. Terrestrial Heteroptera are widely polyphyletic. Hence, the taxonomic use of the name Geocorisae should be avoided.

42. The results of our study lead to the recognition of the following, more or less equivalent, major groups; Amphibicorisae, Leptopodoidea, Cimicomorpha sensu stricto, Dipsocoroidea, Enicocephaloidea, Reduvioidea, Thaumastocoroidea, Pentatomomorpha and Hydrocorisae (eggs of Joppeicidae were not available).

43. Fig. 306 presents a provisional scheme of the phylogeny of the Suborder. The terrestrial groups and the Hydrocorisae are presented as radiations from an extinct amphibicorisous stock.

44. The book concludes with a concise account of some new aspects of evolutionary morphology, which will be elaborated later. The subjects refer, among others, to: eye of egg larva, trichobothria, pretarsus, scent glands, internal and external genitalia, caryotypes, salivary glands, alimentary system, stigmata. These and other characters will be evaluated and compared in Parts 2 and 3 of the series in search of a basis for phylogenetic weighting.

Onderzoek naar enkele klauw - eigenschappen bij runderen
Badichi, Y. - \ 1967
Zeist : I.V.O. (Rapport / Instituut voor veeteeltkundig onderzoek Schoonoord no. B-91) - 29
botziekten - rundvee - klauwen - hoeven - voortbeweging - organen - beslaan - diergeneeskunde - bone diseases - cattle - claws - hooves - locomotion - organs - shoeing - veterinary science
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