Identification of blackeye cowpea mosaic virus from germplasm of yard-long bean and from soybean,and the relationships between blackeye cowpea mosaic virus and cowpea aphid-borne mosaic virus     

Jeanne Dijkstra  L. Bos  H. J. Bouwmeester  Tutung Hadiastono  H. Lohuis 《European journal of plant pathology / European Foundation for Plant Pathology》1987,93(3):115-133

Two potyvirus isolates, one from germplasm of yard-long bean (Vigna unguiculata ssp.sesquipedalis) introduced into the Netherlands, and another one from soybean plants (Glycine max) in Indonesia, were compared with two virus isolates of blackeye cowpea mosaic virus (BICMV) from the USA and a Moroccan isolate of cowpea aphid-borne mosaic virus (CAMV). It is proposed that all five isolates be now considered BICMV on the basis of host ranges, symptoms and serology. From our results, and a reassessment of the literature it is suggested to drop the name CAMV in favour of BICMV.Samenvatting Twee potyvirussen, de een in Nederland ingevoerd met genenmateriaal vanVigna unguiculata ssp.sesquipedalis en de ander uit planten van sojaboon (Glycine max) in Indonesië, werden vergeleken met twee isolaten van blackeye cowpea mosiac virus (BICMV) en een Marokkaans isolaat van cowpea aphid-borne mosaic virus (CAMV). Op grond van waardplantenreeksen, symptomen en serologie stellen de auteurs voor om alle vijf isolaten te beschouwen als BICMV. Gebaseerd op de verkregen resultaten en een kritische beschouwing van de literatuur wordt de aanbeveling gedaan om de naam CAMV te laten vallen ten gunste van BICMV.  相似文献   

Do public attitudes affect conservation effort? Using a questionnaire-based survey to assess perceptions,beliefs and superstitions associated with frogs in South Africa     

Jeanne Tarrant  Donnavan Kruger  Louis H du Preez 《African Zoology》2016,51(1):13-20

Globally, amphibians are among the least appreciated vertebrates and are often negatively perceived by the general public. Such attitudes are particularly prevalent in South Africa, where fear, superstitions and myths associated with frogs are pervasive in some cultures. These attitudes could have harmful consequences both for the animals concerned and conservation efforts. This study aimed to investigate attitudes to frogs throughout South Africa across multiple age and ethnic groups. We used a multi-language survey in both hard-copy and online versions. Respondents (n = 2 295) comprised both genders across six age groups and five ethnic groups. A functionalist approach using structural equation modelling was used to assess how liking of frogs and cultural beliefs varied with socio-demographic factors. Attitudes varied significantly between groups, with males more likely to like frogs than females and age and level of education also significantly linked to liking. The influence of cultural beliefs and lack of knowledge also directly influenced negative attitudes towards frogs. More than 60% of respondents expressed an interest in learning more about frogs, indicating an opportunity for improving attitudes through educational outreach. The findings of this study can be used to inform current efforts to protect amphibians in South Africa through social interventions.  相似文献   

Factors associated with variation in Neospora caninum bulk-milk S/P ratios in initially bulk-milk negative testing Dutch dairy herds     

Bartels CJ  van Schaik G  van Maanen K  Wouda W  Dijkstra T 《Preventive veterinary medicine》2007,81(4):265-273

We conducted a study on 81 initially bulk-milk ELISA negative dairy herds taken from a random sample of Dutch dairy herds to evaluate variation in bulk-milk S/P ratios and to study reasons for bulk-milk conversion. These herds were repeatedly (3-month intervals) tested between April 2004 and August 2005 and serostatus of all animals had previously been established as negative (N), low-positive (LP) or high-positive (HP). Of these herds, herd- and test-related factors associated with variation in sample over positive (S/P) ratios were analysed using a multivariable linear-mixed model with ‘herd’ as random effect. In addition, changes of animal serostatus in converting herds were described. S/P ratios were calculated as the optical density of the bulk-milk sample minus the optical density of the negative serum control divided by the difference in optical density between the positive and negative serum control.

Sixteen bulk-milk conversions in 12 dairy herds were seen with few indications of serological conversion in lactating cattle except for one herd in which recrudescence of infection appeared likely in nine cows. The effect of HP serostatus on bulk-milk S/P ratio was 2–3 times stronger compared with LP serostatus. In addition, bulk-milk S/P-ratio increased when the proportion of HP animals between 1 and 60 days in milk increased and decreased when the average milk-production level of the herd increased. Besides these herd-related factors, the use of different ELISA-testkits between test rounds had a significant effect on the S/P-ratio in bulk-milk samples.  相似文献   

Use of detached tomato leaves to test for resistance to tomato mosaic virus     

Pim Lindhout  Wanda Korta  Jeanne Dijkstra 《European journal of plant pathology / European Foundation for Plant Pathology》1988,94(6):307-310

Samenvatting Een methode werd ontwikkeld om de resistentie van in de kas geteelde tomateplanten tegen tomatemozaïek virus (ToMV) te bepalen. Bladeren van een vatbare en een resistente cultivar werden afgesneden en geïnoculeerd met ToMV. Na 6, 10 en 17 dagen werden de geïnoculeerde bladeren getoetst op de aanwezigheid van virus met ELISA en door inoculatie van bladeren vanNicotiana glutinosa. Met beide toetsmethoden kon de virustoename in de vatbare cultivar al vroeg na inoculatie duidelijk worden aangetoond. In de bladeren van de resistente cultivar was een zeer kleine hoeveelheid virus pas laat na de inoculatie aantoonbaar. Met deze methode is het mogelijk om de resistentie tegen ToMV te bepalen, tevens zaad te winnen en landbouwkundige eigenschappen te evalueren, zonder de plant te infecteren.  相似文献   

Evaluating Sugarcane Diets for Dairy Cows Using a Digestion Model     

Kebreab E  Assis AG  Dijkstra J  France J 《Tropical animal health and production》2001,33(2):127-139

To eliminate unnecessary feeding trials, a mechanistic model of sugarcane digestion was used in the search for suitable supplements to improve milk production. Milk production simulated by the model was compared with data observed in four feeding trials published in the tropical literature where crossbred dairy cows were fed sugarcane/urea diets with different types of supplements. The predicted effects of the supplements on the ruminal microbial population, concentrations of ammonia and volatile fatty acids were also compared with the published results in one experiment. The model indicated the nutrient most limiting milk production for the different feeding situations. The addtion of Leucaena to the basal sugarcane/urea improved the availability of amino acids and long-chain fatty acids, with energy becoming the limiting factor. Supplementation with rice bran increased the availability of energy and long-chain fatty acids, but amino acids then became the limiting factor. Supplementation with both Leucaena and rice bran further improved the milk yield, but availability of energy now limited milk production. Supplementation with Leucaena increased milk production more than supplementation with king grass. The main reason for this increase was increased amino acid absorption due to increased microbial outflow. In all feeding situations, the average difference between the predicted milk production and that observed experimentally was 0.57 kg/d (ranging from 0.08 to 1 kg/d).  相似文献   

Electron microscopical investigations of mosaic diseased wheat plants found in Italy     

J. Dijkstra  P. Grancini 《European journal of plant pathology / European Foundation for Plant Pathology》1960,66(5):301-304

Summary For some years past at several places in the province of Brescia a mosaic disease of wheat has been detected which probably must be attributede to a virus (Grancini, 1959). Presumably the same disease has recently been constatated in other provinces of North Italy.Electron microscopical study of diseased wheat leaves showed that the preparations which were obtained with the dipping method ofBrandes (1957) all contained rod-shaped virus particles with a length of 300 m. These particles were absent from healthy plants. Whether or not this virus is directly responsible for the mosaic disease could not be established, since we did not succeed in transmitting the virus artificially.Samenvatting Sedert einige jaren wordt op verschillende plaatsen in de provincie Brescia een mozaïekziekte bij de tarwe gevonden, waarvna de oorzaak waarschijnlijk aan een virus moet worden toegeschreven (Grancini, 1959).Bij elektronemicroscopisch onderzoek van zieke bladeren is gevonden, dat de preparaten, welke met de doop-methode vanBrandes (1957) verkregen waren, alle staafvormige virusdeeltjes ter lengte van 300 m bevatten (fig. 1). In preparaten van gezond bladmateriaal kwamen deze deeltjes niet voor. Of dit virus direct aansprakelijk is voor de mozaïekziekte kon nog niet aangetoond worden, aangezien het tot nu toe niet gelukt is het virus langs kunstmatige weg over te brengen.  相似文献   

A dynamic model of N metabolism in the lactating dairy cow and an assessment of impact of N excretion on the environment   总被引：1，自引：0，他引：1  

Kebreab E  France J  Mills JA  Allison R  Dijkstra J 《Journal of animal science》2002,80(1):248-259

Improving N utilization in dairy cows and especially reducing N output in excreta is desirable due to global concerns of agricultural contribution of N to environmental pollution, particularly as ammonia. Data from five N balance experiments were used to develop a dynamic model that was evaluated with independent data. Model predictions of feces, urine, and milk outputs were close to observed values. Statistical analysis showed that 96% of mean square prediction error for feces and urine N output predictions was due to random variation. However, the model tends to overpredict milk N output, especially at higher N intake levels. Evaluation of model predictions for independent experimental observations from Agricultural Development Advisory Service at Bridgets (U.K.) showed good agreement between predicted and observed urine N output (95% due to random variation). However, there was a slight underprediction for fecal N output (14% mean square prediction error due to bias) and overprediction of milk N output (22% of mean square prediction error due to bias). The model predictions of N outputs in excreta were sensitive to changes in energy concentration of the diet. Dietary protein degradability had only a small influence on predicted fecal N output. However, the model was sensitive in its predictions of urine N when protein degradability was varied. Application of the model to assess reduction in ammonia emissions from dairy cows showed that increasing the energy concentration could potentially reduce ammonia emissions by up to 25% per cow. Similarly, reducing CP concentration in the diet to about 16% could reduce ammonia production by 20% and lower degradability of CP to match microbial requirement by 19% per cow. The model is a first step toward a mechanistic approach of nutrient modeling, and it is a valuable method for predicting N excretions and estimating N emissions from dairy systems.  相似文献   

Germinal pore number in pollen grains as a selection basis in the production of tetraploid clover     

J. Dijkstra  G. J. Speckmann 《Euphytica》1965,14(3):244-248

Experiments with the variety Fahl of Berseem clover and with different material of red clover have shown that the occurrence of tetraploid and diploid tissues can be detected in a rapid and reliable way by determining the number and arrangement of germinal pores of the pollen. The advantages over the conventional methods are mentioned and described.The determination of the germinal pore pattern, which is combined with pair crossing of the tetraploid heads, makes it possible to obtain in an efficient way completely tetraploid material with a great genetic variability.Samenvatting Proeven met het ras Fahl van Alexandrijnse klaver en met verschillend materiaal van rode klaver hebben uitgewezen dat het voorkomen van tetraploide en diploide weefsels op een snelle en betrouwbare wijze aangetoond kan worden door middel van bepaling van het kiemporiënbeeld van het stuifmeel.De bepaling van het kiemporiënbeeld gevolgd door paarsgewijze kruising van de tetraploide hoofdjes maakt het mogelijk op een efficiënte wijze te komen tot zuiver tetraploid materiaal met een grote genetische variabiliteit.  相似文献   

Relation between lipid and fatty acid composition of eggs and larval survival in white pacific shrimp (Penaeus vannamei, Boone, 1931)     

Elena Palacios  Ilie S. Racotta  Horacio Heras  Yanic Marty  Jeanne Moal  Jean-François Samain 《Aquaculture International》2001,9(6):531-543

In this study, lipid classes and fatty acid composition were determinedin eggs of P. vannamei as a function of survival to zoeaIII stage. Spawns were reared individually to zoea III and grouped, accordingtotheir final survival to this larval stage, into spawns of high and lowsurvival.Eggs of individual spawns were analyzed for lipid and fatty acid composition ofneutral and polar lipids and the results were then grouped according tosurvivalto zoea III. The lipids within each group (high and low survival to zoea III)were pooled for the separation of phospholipids and the analysis of their fattyacid composition.Higher levels of triglycerides, carotenoids, and linoleic (18:2n-6) acid ineggs were associated with improved survival to zoea III. Linoleic acid washigher in spawns from the high survival group in both neutral and polarfractions and in most of the phospholipid classes analyzed. Docosahexanoic acid(DHA) was not related to survival to zoea, probably because its content washighenough (> 15% of total fatty acids) to satisfy embryo and early larvaldevelopment needs. A high content of eicosapentaenoic acid (EPA) was found inphosphatidylethanolamine, lysophosphatidylethanolamine, phosphatidylserine, andphosphatidylinositol compared to other phospholipid classes, suggesting aspecific role of EPA in these lipids. These results describe the specificphospholipid composition of penaeid eggs and could (potentially) be used aspredictive indicators of larval quality for research and production purposes.  相似文献   

In vitro modulation of reactive oxygen and nitrogen intermediate (ROI/RNI) production in Crassostrea gigas hemocytes     

Christophe Lambert  Philippe Soudant  Marine Jegaden  Maryse Delaporte  Yannick Labreuche  Jeanne Moal  Jean-Franois Samain 《Aquaculture (Amsterdam, Netherlands)》2007,270(1-4):413-421

Bivalve hemocyte competence has been measured by quantifying functional characteristics, including reactive oxygen intermediate (ROI) production after activation with zymosan or phorbol myristate acetate (PMA). However, untreated oyster hemocytes also produce ROI and RNI (reactive nitrogen intermediates) after bleeding even if not stimulated by zymosan or PMA. Extensive investigation of this parameter by flow cytometry showed that, in vitro, ROI/RNI production by untreated hemocytes maintained in seawater appeared to be independent of both bacterial burden in the serum and non-self particle phagocytosis. ROI/RNI production in granulocytes was higher than in hyalinocytes and could be intensified when activated by zymosan but not by PMA. Both cell types used NADPH-oxidase- and NO-synthase-like pathways to produce these molecules; the NO-synthase pathway seemed relatively more dominant in hyalinocytes and NADPH-oxidase appeared more effective in granulocytes. These results provide new insights for interpreting the modulation of ROI/RNI production by untreated hemocytes shown by other studies, relative to environmental conditions or physiological status of the oysters.  相似文献