Multiple species-specific controls of root-feeding nematodes in natural soils     

Anna M. Piśkiewicz  Henk Duyts  Wim H. van der Putten 《Soil biology & biochemistry》2008,40(11):2729-2735

One of the major limitations to enhance sustainability of crop production systems is the inability to control root-feeding nematodes without using chemical biocides. In soils under wild vegetation, however, root-feeding nematodes affect plant performance and plant community composition varying from substantially to insignificantly. Previous studies in natural ecosystems have already shown that mutualistic symbionts, such as arbuscular mycorrhizal fungi and endophytes, may influence plant exposure to root-feeding nematodes. In order to learn more from natural systems, we examined nematode control in the root zone of a wild coastal foredune grass by microorganisms, other nematodes and microarthropods. We cultured all eight root-feeding nematode species that occur in the root zone of marram grass (Ammophila arenaria) in coastal foredunes of the Netherlands. Then, in an indoor growth experiment we exposed each nematode species to the potential natural antagonists collected from the same dune soil. Most of the eight dominant root-feeding nematode species could be controlled to some extent by more than one group of soil organisms added. The effectiveness of control varied among nematode species, which seemed to be controlled in a species-specific way. We conclude that in a natural soil the effectiveness of control by microorganisms, other nematodes or microarthropods varies among root-feeding nematode species. Most are controlled, at least to some extent, by soil microbes. However, some root-feeding nematode species are controlled only by microarthropods. Our results strongly suggest that sustainable agriculture will benefit from using a range of biological control mechanisms when controlling root-feeding nematodes, rather than relying on single control agents. Our suggestion also implies that conserving soil biodiversity is crucial in order to enhance the reliability of biological crop protection against soil-borne pests and diseases.  相似文献   

Comparison of serological assays for the diagnosis of canine visceral leishmaniasis in animals presenting different clinical manifestations   总被引：1，自引：0，他引：1  

Ferreira Ede C  de Lana M  Carneiro M  Reis AB  Paes DV  da Silva ES  Schallig H  Gontijo CM 《Veterinary parasitology》2007,146(3-4):235-241

Three serological methods, indirect fluorescent immunoassay (IFI), enzyme-linked immunosorbent assay (ELISA) and direct agglutination test (DAT) that are commonly employed in the diagnosis of canine visceral leishmaniasis (CVL), have been assessed. A total of 234 domestic dogs, drawn from an area in the municipality of Belo Horizonte, Minas Gerais, Brazil, endemic for visceral leishmaniasis, were submitted to clinical and parasitological examinations and serological assay. Sera collected from confirmed non-infected dogs (n=20), and from dogs with other parasitic diseases including Trypanosoma cruzi (n=7), Leishmania braziliensis (n=5), Toxoplasma gondii (n=5) and Ehrlichia canis (n=3), were also included in the study. IFI presented a lower sensitivity (72%) than ELISA (95%), although the specificities of these assays were low (52 and 64%, respectively) and both exhibited cross-reactivity with sera from dogs infected with T. cruzi, L. braziliensis and E. canis. In contrast, DAT exhibited a high sensitivity (93%) and a high specificity (95%) and cross-reacted with only one serum sample derived from an E. canis-infected dog. The reproducibilities of the ELISA and DAT assays were excellent, whilst that of IFI was considered to be acceptable. The results produced by ELISA and DAT were in complete agreement, those between ELISA and IFI were at an acceptable level of agreement, whilst the concurrence between the IFI and DAT results were either acceptable or poor depending on the clinical conditions of the group of dogs examined. Since there is no readily accessible method for the diagnosis of CVL that offers 100% specificity and sensitivity, the choice of technique employed must depend on the aim of the investigation.  相似文献   

Identification of candidate genes required for susceptibility to powdery or downy mildew in cucumber     

Henk J. Schouten  Julian Krauskopf  Richard G. F. Visser  Yuling Bai 《Euphytica》2014,200(3):475-486

Powdery mildew (PM, caused by Podosphaera fusca) and downy mildew (DM, caused by Pseudoperonospora cubensis) are important diseases of cucumber (Cucumis sativus). Breeding for resistance has been undertaken since the 1940s, but underlying resistance genes have not been functionally analysed yet. The published genome sequence of cucumber catalyses the search for such genes. Genetic studies have indicated that resistances to PM and DM in cucumber are often inherited recessively, which indicates the presence of susceptibility genes (S-genes). Therefore we analyzed the cucumber genome for homologs of functionally proven S-genes known from other plant species. We identified 13 MLO-like genes in cucumber, three of which cluster in Clade V, the clade that contains all known MLO-like susceptibility genes to powdery mildews in other dicots. The expression of one of these three genes, CsaMLO1, located on chromosome 1, was upregulated after PM inoculation. It co-localizes with a QTL for PM resistance previously identified. Also homologs of the susceptibility genes PMR4 and PMR5 are located at this QTL. The second MLO-like gene from Clade V (CsaMLO8) resides in a recessively inherited major QTL for PM resistance at the bottom of chromosome 5, together with a PMR6-like gene. Two major QTL for DM recessive resistance at the top of chromosome 5 co-localize with CsaDMR6-2, which is homologous to the DMR6 susceptibility gene in Arabidopsis. This study has identified several candidate genes for susceptibility to PM and DM in cucumber that may explain QTL for recessively inherited resistance, reported earlier.  相似文献   

Attitudes of different stakeholders toward pig husbandry: a study to determine conflicting and matching attitudes toward animals,humans and the environment     

Tamara J. Bergstra  Henk Hogeveen  Elsbeth N. Stassen 《Agriculture and Human Values》2017,34(2):393-405

The pig sector is struggling with negative attitudes of citizens. This may be the result of conflicting attitudes toward pig husbandry between citizens and other stakeholders. To obtain knowledge about these attitudes, the objectives of this study were (1) to determine and compare attitudes of various stakeholders toward animals, humans and the environment in the context of pig husbandry and (2) to determine and compare the acceptability of publically discussed issues related to pig husbandry of various stakeholders. A questionnaire was distributed to citizens, conventional pig farmers, organic pig farmers, pig husbandry advisors and pig veterinarians. Respondents could indicate their attitude toward aspects related to animals, humans and the environment in the context of pig husbandry and they could indicate their opinion about the acceptability of issues of pig husbandry, e.g. piglet mortality and inside pig housing. Based on measured attitudes and the acceptability of issues, the studied stakeholders could be divided into three distinctive groups. The group of citizens and organic pig farmers showed negative attitudes toward all aspects of pig husbandry, the group of conventional pig farmers and pig husbandry advisors only showed negative attitudes toward aspects related to economics and the group of pig veterinarians showed negative attitudes to specific aspects of pig husbandry. This indicates that stakeholders have different interests and different perspectives with regard to pig husbandry. The pig sector should learn to understand citizens’ perspectives and take these into account in their line of work, the implementation of animal welfare measures and in their communication.  相似文献   

Pleuritis in slaughter pigs: Relations between lung lesions and bacteriology in 10 herds with high pleuritis     

Pichai Jirawattanapong  Norbert Stockhofe-Zurwieden  Henk Wisselink  Toine Cruijsen  Mirjam Nielen 《Research in veterinary science》2010,88(1):11-15

Pleuritis in slaughter pigs has increased in recent years in the Netherlands. The aim of the present study was to determine what respiratory pathogens were involved in pleuritis.In total, lungs of 968 slaughter pigs from 10 herds with high prevalence of pleuritis were morphologically examined for size, location, and type of lesions. Moreover, histology and bacteriology were performed.Examination of gross lung lesions showed 45% pleuritis, 14% pleuropneumonia and 38% catarrhal pneumonia. Peribronchiolar cuffing was found in 61 of 142 samples. Actinobacillus pleuropneumoniae was cultured from 22 lung samples from four herds. Pasteurella multocida was cultured from 55 lung samples in eight herds. No specific pattern with respect to the causal pathogens was found.In conclusion, no single infectious cause of pleuritis was found. A variety of infectious agents combined with environmental factors should be considered as a cause of pleuritis.  相似文献   

Qualitative aspects in the analysis of pesticide residues in fruits and vegetables using fast, low-pressure gas chromatography-time-of-flight mass spectrometry     

Lehotay SJ  Koesukwiwat U  van der Kamp H  Mol HG  Leepipatpiboon N 《Journal of agricultural and food chemistry》2011,59(14):7544-7556

Quantitative method validation is a well-established process to demonstrate trueness and precision of the results with a given method. However, an assessment of qualitative results is also an important need to estimate selectivity and devise criteria for chemical identification when using the method, particularly for mass spectrometric analysis. For multianalyte analysis, automatic instrument software is commonly used to make initial qualitative identifications of the target analytes by comparison of their mass spectra against a database library. Especially at low residue levels in complex matrices, manual checking of results is typically needed to correct the peak assignments and integration errors, which is very time-consuming. Low-pressure gas chromatography-mass spectrometry (LP-GC-MS) has been demonstrated to increase the speed of analysis for GC-amenable residues in various foods and provide more advantages over the traditional GC-MS approach. LP-GC-MS on a time-of-flight (ToF) instrument was used, which provided high sample throughput with <10 min analysis time. The method had already been validated to be acceptable quantitatively for nearly 150 pesticides, and in this study of qualitative performance, 90 samples in total of strawberry, tomato, potato, orange, and lettuce extracts from the QuEChERS sample preparation approach were analyzed. The extracts were randomly spiked with different pesticides at different levels, both unknown to the analyst, in the different matrices. Automated software evaluation was compared with human assessments in terms of false-positive and -negative results. Among the 13590 possible permutations with 696 blind additions made, the automated software approach yielded 1.2% false presumptive positives with 23% false negatives, whereas the analyst achieved 0.8% false presumptive positives and 17% false negatives for the same analytical data files. False negatives frequently occurred due to challenges at the lowest concentrations, but 70% of them involved certain pesticides that degraded (e.g., captafol, folpet) or otherwise could not be detected. The false-negative rate was reduced to 5-10% if the problematic analytes were excluded. Despite its somewhat better performance in this study, the analyst approach was extremely time-consuming and would not be practical in high sample throughput applications for so many analytes in complicated matrices.  相似文献   

Effect of saccharide structure and size on the degree of substitution and product dispersity of α-lactalbumin glycated via the Maillard reaction     

ter Haar R  Schols HA  Gruppen H 《Journal of agricultural and food chemistry》2011,59(17):9378-9385

The course of the Maillard reaction between α-lactalbumin and various mono- and oligosaccharides in the solid state was studied using UPLC-ESI-TOF-MS. Individual reaction products were monitored for their degree of substitution per protein molecule (DSP). The Maillard reaction rate depended on the saccharide type and decreased when the saccharide size increased. Conjugation with charged saccharides was hindered when a specific average DSP was reached, probably resulting from electrostatic repulsion. The DSP varied between 0 and 15, and the standard deviation of the average DSP, which is a measure for product dispersity, increased to 1.9. Similar experiments were performed with a dipeptide. Relative reaction rates in these experiments were 1 for glucose, 0.28 for maltose, and 0.16 for maltotriose. Comparison of the results obtained using α-lactalbumin and the dipeptide made clear that the Maillard reaction rate is determined by a number of factors, including saccharide reactivity and lysine accessibility.  相似文献   

Recent human‐induced salinity changes in Ramsar‐listed Orielton Lagoon,south‐east Tasmania,Australia: a new approach for coastal lagoon conservation and management     

Krystyna M. Saunders  Andrew Mcminn  Donna Roberts  Dominic A. Hodgson  Henk Heijnis 《水产资源保护:海洋与淡水生态系统》2007,17(1):51-70

• 1. Many coastal lagoons in eastern Australia have changed as a result of recent human activities. However, it is often difficult to determine the extent of change and the ecological implications. A palaeoecological approach allows a quantitative assessment of how an aquatic ecosystem changes and responds to human impacts beyond what is possible with historical data or monitoring programmes.
• 2. Orielton Lagoon (south‐east Tasmania, Australia) is a Ramsar‐listed coastal wetland of international importance for conservation. This study was undertaken at the site to determine whether recent anthropogenic hydrological modifications to the lagoon had influenced its ecology, particularly salinity, and compromised its Ramsar status.
• 3. A diatom–salinity transfer function was constructed from a training data set of 96 diatom taxa from 34 sampling sites in 19 lagoons along the east coast of Tasmania.
• 4. The salinity of Orielton Lagoon has changed in response to a causeway constructed across its mouth, which has transformed the lagoon from an open marine environment to an enclosed, virtually stagnant, brackish water body.
• 5. These changes have compromised the protected coastal wetland status of Orielton Lagoon. Environmental remediation attempts have since partially restored the natural hydrology of the lagoon and it is now returning towards the state it was in prior to causeway construction.
• 6. A palaeoecological approach using diatoms was found to be successful in reconstructing recent salinity changes and investigating human impacts on Orielton Lagoon over the last 50–55 years.

Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Comparative morphology of esophageal mucosa and submucosa in dogs from 1 to 337 days of age   总被引：1，自引：0，他引：1  

W G Henk  J D Hoskins  Y Z Abdelbaki 《American journal of veterinary research》1986,47(12):2658-2665

Scanning electron microscopy, light microscopy, and morphometric analyses were used to examine the morphology of the tunica mucosa-tela submucosa of the cervical, thoracic, and abdominal parts of the esophagus of healthy dogs from birth to 337 days of age from 3 litters of dogs whelped and reared under controlled conditions. Apart from the absence of a lamina muscularis mucosae from the cervical part of the esophagus of all dogs examined, little regional variation was detected. However, morphologic variation associated with age was observed. The number and complexity of microplicae on surface epithelial cells, as observed with the scanning electron microscope, increased with age, particularly between 1-day-old and 21-day-old dogs. Although scanning electron microscopy revealed typical duct openings from the submucosal glands in 1-day-old dogs, light microscopy revealed few functional glands. These glands gradually developed into a complex strata of tubules and acini during the time that secretory activity and the volume fraction of the tunica mucosa-tela submucosa occupied by glands increased with age. The presence of ciliated cells in the esophagus of 1-day-old dogs was apparent with scanning electron and light microscopes. Ciliated cells were always most abundant in the abdominal part of the esophagus. Finally, morphometric analyses revealed a significant increase in epithelial and connective tissue compartment thicknesses, as well as a marked increase in the volume fraction occupied by glands between 1 day and 161 days after dogs were whelped. A smaller decrease in all 3 measures occurred between 161 and 337 days after the dogs were whelped.  相似文献   

Targets for pathology research in protected crops     

Henk Rattink 《Pest management science》1992,36(4):385-388

Due to the need to diminish the amount of pesticides used, alternative ways of controlling fungal diseases have to be developed. Foliar diseases have been managed mainly by chemicals, but research has been started to develop integrated control programmes. Data from studies on epidemiology, in combination with nutritional and climatic management and use of partial resistant cultivars will lead to a reduced use of chemicals. Models used are: Botrytis cinerea in gerbera and roses, and powdery mildew in roses and cucumbers. Research has been intensified on biological control of these pathogens. In closed systems, with recirculation of the nutrient solution, soil-borne fungi can cause serious problems. Not only do diseases known from traditional cultural systems, like fusarium wilt of carnation, fusarium crown and root rot of tomato and Phytophthora and Pythium spp. in several crops occur, but also new problems like a new Phytophthora sp. and Gnomonia sp. in roses and a Cylindrocladium sp. in Spathiphyllum spp. To prevent introduction of pathogens in recirculation systems, emphasis is put on developing an integrated disease management programme by using disease-free planting material, disease-free irrigation water, strict hygienic measures, resistant cultivars, methods of disinfecting the nutrient solution and biological control. Research over the last 5–6 years has revealed good prospects for biological control, especially in closed systems with a limited amount of substrate. Wilt in carnation, caused by Fusarium oxysporum f.sp. dianthi can be prevented effectively by adding a non-pathogenic isolate of F. oxysporum and/or Pseudomonas spp. There are indications that non-pathogenic isolates of F. oxysporum are also effective against wilt disease in other crops. An isolate of Trichoderma harzianum appears to be very effective against fusarium crown and root rot of tomato. More applications of this, and other, biocontrol agents seem possible. However, translation of the results of research to practical application and registration is still very difficult.  相似文献