Comparative evaluation of virulence and pathology of Streptococcus suis serotypes 2 and 9 in experimentally infected growers     

Beineke A  Bennecke K  Neis C  Schröder C  Waldmann KH  Baumgärtner W  Valentin-Weigand P  Baums CG 《Veterinary microbiology》2008,128(3-4):423-430

Streptococcus (S.) suis is an invasive porcine pathogen causing meningitis, septicemia, arthritis and other diseases. Studies on pathogenesis as well as vaccine trials have focused on serotype 2 strains, which are worldwide the most prevalent among invasive isolates. However, in Europe serotype 9 strains also contribute substantially to S. suis-associated invasive diseases of piglets. The objective of this study was to determine the virulence of an MRP* SLY+ serotype 9 S. suis strain in comparison to an MRP+ EF+ SLY+ serotype 2 strain. Experimental intranasal and intravenous infections of 7-8 weeks old SPF piglets were investigated with regard to clinic and pathology. In contrast to the virulent serotype 2 strain, the serotype 9 strain did not cause disease with clinical manifestations after intranasal administration. However, histological screenings of these animals revealed pathological lesions, such as mild focal suppurative meningitis. Clinical manifestations related to meningitis, arthritis and serositis could be induced by intravenous application of this serotype 9 strain. Bacteriological culture and immunohistochemistry of the brain confirmed association with the S. suis challenge strains in all cases with clinical manifestations. Interestingly, expression of MRP within meningitis lesions was demonstrated for both pathotypes via immunohistochemistry. In conclusion, this study demonstrates that MRP* SLY+ serotype 9 strains are less virulent for growers than MRP+ EF+ SLY+ serotype 2 strains. Thus, intravenous application of this serotype 9 strain is required to evaluate heterologous protection in the course of vaccine development based on serotype 2 strains in the future.  相似文献   

Antibiotic resistance in Lactococcus species from bovine milk: presence of a mutated multidrug transporter mdt(A) gene in susceptible Lactococcus garvieae strains     

Walther C  Rossano A  Thomann A  Perreten V 《Veterinary microbiology》2008,131(3-4):348-357

A total of 72 Lactococcus strains (41 Lactococcus lactis and 31 Lactococcus garvieae) isolated from bovine milk were tested for susceptibility to 17 antibiotics and screened for the presence of antibiotic resistance genes using a microarray. Resistance to tetracycline, clindamycin, erythromycin, streptomycin, nitrofurantoin were found. The tetracycline-resistant L. garvieae and L. lactis harbored tet(M) and tet(S). L. lactis that were resistant to clindamycin were also resistant to erythromycin and possessed the erm(B) gene. The multidrug transporter mdt(A), originally described in L. lactis, was detected for the first time in L. garvieae and does not confer decreased susceptibility to erythromycin nor tetracycline in this species. Mdt(A) of L. garvieae contains one mutation in each antiporter motif C, which is known to play an essential role in drug efflux antiporters. This suggests that the mutations found in the C-motifs of Mdt(A) from L. garvieae may be responsible for susceptibility. The study revealed the presence of antibiotic resistance genes in non-pathogenic and pathogenic lactococci from bovine milk, including a mutated multidrug transporter in L. garvieae.  相似文献   

追踪沙门菌病暴发的起源     

Billy M.Hargis  Renee M.Tsolis  徐仕忠 《中国家禽》2008,30(21)

在1980年代,欧洲和美洲的卫生官员们就注意到由肠炎沙门菌（SE）引起的人类食物源性疾病明显增加,发现这种沙门菌存在于鸡胴体、鸡蛋和蛋产品中。这提示,作为公共卫生问题,SE的出现可能是现代家禽养殖实践和家禽遗传多样性下降的结果。但是,这些假设没有说明为什么其它沙门菌血清型,如鼠伤寒沙门菌（ST）,感染人的数量没有增加。  相似文献   

Physiological and behavioural responses of grazing dairy cows to an acute metabolic challenge          下载免费PDF全文

Esther Müller  Andreas Münger  Roi Mandel  Lukas Eggerschwiler  Ann‐Catherine Schwinn  Josef J. Gross  Rupert M. Bruckmaier  H. Dieter Hess  Frigga Dohme‐Meier 《Journal of animal physiology and animal nutrition》2018,102(5):1120-1130

Due to seasonal changes in the quality and quantity of herbage, the nutrient supply to grazing dairy cows is not always sufficient, which may increase their metabolic load. To investigate the temporal pattern of behavioural changes in relation to concomitant metabolic alterations, we subjected 15 multiparous early lactating Holstein dairy cows (24 (SD 7.4) days in milk) to a short‐term metabolic challenge, which we provoked by abruptly withdrawing concentrate for 1 week. Cows grazed full‐time and were supplemented with concentrate in experimental week (EW) 1 and EW 3, whereas concentrate was withdrawn in EW 2. We analysed milk and blood samples to characterise the metabolic changes and found that the total yield of milk and protein decreased (p < 0.05) and fat yield, fat‐to‐protein ratio and acetone content increased (p < 0.05) from EW 1 to EW 2. Plasma glucose and insulin concentrations were lower (p < 0.05), and concentrations of nonesterified fatty acids and beta‐hydroxybutyrate were higher (p < 0.05) in EW 2 compared with EW 1. Apart from ingestive and rumination behaviour and activity, we also monitored the use of an automated brush on pasture. While time spent eating and ruminating increased (p < 0.05) in EW 2 compared with EW 1, time spent idling decreased (p < 0.05). Concomitantly, while time standing and moving increased (p < 0.05) from EW 1 to EW 2, walking time decreased (p < 0.05). The daily proportion of cows using the automated brush decreased (p < 0.05) in EW 2 compared with EW 1, as did the duration of brushing per day. In conclusion, grazing cows experiencing a metabolic challenge try to compensate for the nutrient deficiency by increasing eating time, a behavioural element important for short‐term survival. Due to the strong impact of weather conditions, we cannot currently recommend observation of outdoor brushing activity to address short‐term alterations in the metabolic state of grazing cows.  相似文献   

PhenoFly Planning Tool: flight planning for high-resolution optical remote sensing with unmanned areal systems     

Lukas?Roth  Andreas?HundView author&#;s OrcID profile  Helge?AasenView author&#;s OrcID profile 《Plant methods》2018,14(1):116

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Histology-guided high-resolution AP-SMALDI mass spectrometry imaging of wheat-<Emphasis Type="Italic">Fusarium graminearum</Emphasis> interaction at the root–shoot junction     

Dhaka Ram Bhandari  Qing Wang  Bin Li  Wolfgang Friedt  Andreas Römpp  Bernhard Spengler  Sven Gottwald 《Plant methods》2018,14(1):103

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Spatial Estimation of Soil Erosion Risk by Land‐cover Change in the Andes OF Southern Ecuador     

Pablo Ochoa‐Cueva  Andreas Fries  Pilar Montesinos  Juan A. Rodríguez‐Díaz  Jan Boll 《Land Degradation \u0026amp; Development》2015,26(6):565-573

Ecuador has the highest deforestation rate in South America, causing large‐scale soil erosion. Inter‐Andean watersheds are especially affected by a rapid increase of the population leading to the conversion of large areas of montane forest into pasture and cropland. In this study, we estimate soil erosion risk in a small mixed land‐use watershed in the southern Andes of Ecuador. Soil loss was estimated at a spatial resolution of 30 m, using the Revised Universal Soil Loss Equation (RUSLE) where the RUSLE factors were estimated on the basis of limited public available data. Land‐cover maps for 1976, 2008 and 2040 were created assuming increasing deforestation rates over the ensuing decades. Greater erosion rates are estimated for succession areas with agricultural cropland and pasture with maximum values of 936 Mg ha⁻¹ y⁻¹, where slopes and precipitation amounts are the greatest. Under natural forest vegetation, the estimated soil erosion rates are negligible (1·5 to 40 Mg ha⁻¹ y⁻¹) even at steep slopes and higher elevations where rainfall amounts and intensities are generally higher. When the entire watershed has undergone substantial deforestation in 2040, erosion values may reach 2,021 Mg ha⁻¹ y⁻¹. Vegetation cover is the most important factor for potential soil erosion. Secondary factors are related to rainfall (R‐factor) and topography (LS factors). Although the spatial predictions of potential soil erosion have only limited meaning for erosion risk, this method provides an important screening tool for land management and assessment of land‐cover change. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Argyrophilic nucleolar organizing regions and Ki67 equally reflect proliferation in fine needle aspirates of normal, hyperplastic, inflamed, and neoplastic canine lymph nodes (n = 101)   总被引：1，自引：0，他引：1  

Bauer NB  Zervos D  Moritz A 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2007,21(5):928-935

BACKGROUND: The count of argyrophilic nucleolar organizing regions (AgNOR) has been considered a useful variable that reflects cellular proliferation in canine lymph nodes, but it has not been compared with other markers of proliferation. Hypothesis: Ki67 and AgNORs are equally useful as markers of tissue proliferation in fine needle aspirates of canine lymph nodes. ANIMALS: A total of 101 dogs. MATERIAL AND METHODS: Prospective, observational study of a convenience sample of dogs. Two smears were prepared for a May-Gruenwald-Giemsa stain and a Ki67/AgNOR double stain. In addition, CD3/CD79a immunostaining was performed when cytologic examination revealed a lymphoma. The dogs were grouped as normal (n = 26), reactive hyperplasia (n = 25), lymphadenitis (n = 31), and lymphoma (n = 19), based on the physical examination and the cytologic findings. The AgNOR count/cell, AgNOR area/cell and the percentage of cells staining positive for Ki67 were evaluated in 100-167 cells (median, 113 cells) by using automatic image analysis. RESULTS: Mean (SD) AgNOR counts/cell were 1.36 +/- 0.19 in normal dogs, 1.55 +/- 0.26 in lymphadenitis, 1.65 +/- 0.32 in reactive hyperplasia, and 3.67 +/- 1.08 in lymphoma. The percentage of Ki67 positive cells was 2.67 +/- 0.99% in normal lymph nodes, 5.04 +/- 3.34% in lymphadenitis, 5.36 +/- 2.14% in reactive hyperplasia, and 30.2 +/- 10.8% in lymphoma. All variables were significantly higher in dogs with lymphoma compared with the other groups (P < .0001). The sensitivity and the specificity of the AgNOR count for diagnosing lymphoma were 95 and 96% at a cutoff value of >2.04 AgNORs/cell. The cutoff value for the Ki67 positive cells was >10.40% (sensitivity, 95%; specificity, 98%). CONCLUSION AND CLINICAL IMPORTANCE: The results indicated that both AgNOR and Ki67 counts were good diagnostic tools for assessment of proliferation in aspirates of canine lymph nodes.  相似文献   

Multifunctionality of floodplain landscapes: relating management options to ecosystem services     

Stefan Schindler  Zita Sebesvari  Christian Damm  Katrin Euller  Volker Mauerhofer  Anna Schneidergruber  Marianna Biró  Franz Essl  Róbert Kanka  Sophie G. Lauwaars  Christiane Schulz-Zunkel  Theo van der Sluis  Michaela Kropik  Viktor Gasso  Andreas Krug  Martin T. Pusch  Klaus Peter Zulka  Werner Lazowski  Christa Hainz-Renetzeder  Klaus Henle  Thomas Wrbka 《Landscape Ecology》2014,29(2):229-244

The concept of green infrastructure has been recently taken up by the European Commission for ensuring the provision of ecosystem services (ESS). It aims at the supply of multiple ESS in a given landscape, however, the effects of a full suite of management options on multiple ESS and landscape multifunctionality have rarely been assessed. In this paper we use European floodplain landscapes as example to develop an expert based qualitative conceptual model for the assessment of impacts of landscape scale interventions on multifunctionality. European floodplain landscapes are particularly useful for such approach as they originally provided a high variety and quantity of ESS that has declined due to the strong human impact these landscapes have experienced. We provide an overview of the effects of floodplain management options on landscape multifunctionality by assessing the effects of 38 floodplain management interventions on 21 relevant ESS, as well as on overall ESS supply. We found that restoration and rehabilitation consistently increased the multifunctionality of the landscape by enhancing supply of provisioning, regulation/maintenance, and cultural services. In contrast, conventional technical regulation measures and interventions related to extraction, infrastructure and intensive land use cause decrease in multifunctionality and negative effects for the supply of all three aspects of ESS. The overview of the effects of interventions shall provide guidance for decision makers at multiple governance levels. The presented conceptual model could be effectively applied for other landscapes that have potential for a supply of a high diversity of ESS.  相似文献   

Sap flow characteristics and whole-tree water use of Pinus cembra across the treeline ecotone of the central Tyrolean Alps     

Gerhard Wieser  Andreas Gruber  Walter Oberhuber 《European Journal of Forest Research》2014,133(2):287-295

Whole-tree water use of nine Pinus cembra trees was estimated in the treeline ecotone of the Central Austrian Alps. Sap flow density using Granier-type thermal dissipation probes and environmental parameters was monitored along an elevational gradient from the forest limit up to treeline and finally mediating the krummholz limit throughout two growing seasons. Normalized sap flow density (Q _s) was significantly correlated with solar radiation (R _s) and vapor pressure deficit (D) throughout the treeline ecotone. Multiple regression analysis indicated that at the forest limit and at treeline, D had a similar effect on Q _s than R _s. At the krummholz limit by contrast, D had a greater effect on Q _s than R _s due to partially stomatal closure and wind-induced clustering of the needles, which impaired their response to available irradiance. Whole-tree water use scaled to crown surface area estimated for an entire growing (172 days) declined from 449 mm at the forest limit to 274 mm at treeline and was 251 mm at the krummholz limit, which is within the values estimated for other European forest ecosystems. Nevertheless, the observation above the forest limit in the central Tyrolean Alps tree transpiration scaled to crown surface area is comparable to the water use of adjacent low-stature vegetation, which should also be taken into account when forecasting potential effects of global change on the water balance of the treeline ecotone.  相似文献