Nigribactin, a Novel Siderophore from Vibrio nigripulchritudo, Modulates Staphylococcus aureus Virulence Gene Expression     

Anita Nielsen  Maria Mansson  Matthias Wietz  Anders N. Varming  Richard K. Phipps  Thomas O. Larsen  Lone Gram  Hanne Ingmer 《Marine drugs》2012,10(11):2584-2595

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The ash dieback crisis: genetic variation in resistance can prove a long‐term solution     

L. V. McKinney  L. R. Nielsen  D. B. Collinge  I. M. Thomsen  J. K. Hansen  E. D. Kjær 《Plant pathology》2014,63(3):485-499

Over the last two decades, ash dieback has become a major problem in Europe, where the causative fungus has invaded the continent rapidly. The disease is caused by the invasive pathogenic fungus Hymenoscyphus pseudoalbidus (anamorph Chalara fraxinea), which causes severe symptoms and dieback in common ash, Fraxinus excelsior. It is becoming a significant threat to biodiversity in forest ecosystems and the economic and aesthetic impacts are immense. Despite the presence of the disease for at least 10 years in Scandinavia, a small fraction of F. excelsior trees have remained vigorous, and these trees exhibit no or low levels of symptoms even where neighbouring trees are very sick. This gives hope that a fraction of the ash trees will retain a sufficiently viable growth to survive. Following a period of high mortality in natural populations, selection and breeding of remaining viable ash trees could therefore provide a route for restoring the role of ash in the landscape. This paper reviews the available data on disease dissemination, and the consequences thereof in terms of symptom severity and mortality, and appraises studies that have tested the hypothesis that less‐affected trees have genetically based resistance. The implications of the results for the adaptive potential of common ash to respond to the disease through natural or assisted selection are discussed. The risks of adverse fitness effects of population fragmentation due to high mortality are considered. Finally, it is recommended that resistant trees (genotypes) should be selected to facilitate conservation of the species.  相似文献   

S. Bell,D. Apostol. Designing Sustainable Forest Landscapes. Taylor & Francis,Oxon (2008). 356pp., $90.00, ISBN:9780419256809     

Anders Busse Nielsen 《Urban Forestry & Urban Greening》2010,9(1):65-66

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Use of herd information for predicting Salmonella status in pig herds     

Baptista FM  Alban L  Nielsen LR  Domingos I  Pomba C  Almeida V 《Zoonoses and public health》2010,57(Z1):49-59

Salmonella surveillance-and-control programs in pigs are highly resource demanding, so alternative cost-effective approaches are desirable. The aim of this study was to develop and evaluate a tool for predicting the Salmonella test status in pig herds based on herd information collected from 108 industrial farrow-to-finish pig herds in Portugal. A questionnaire including known risk factors for Salmonella was used. A factor analysis model was developed to identify relevant factors that were then tested for association with Salmonella status. Three factors were identified and labelled: general biosecurity (factor 1), herd size (factor 2) and sanitary gap implementation (factor 3). Based on the loadings in factor 1 and factor 3, herds were classified according to their biosecurity practices. In total, 59% of the herds had a good level of biosecurity (interpreted as a loading below zero in factor 1) and 37% of the farms had good biosecurity and implemented sanitary gap (loading below zero in factor 1 and loading above zero in factor 3). This implied that they, among other things, implemented preventive measures for visitors and workers entering the herd, controlled biological vectors, had hygiene procedures in place, water quality assessment, and sanitary gap in the fattening and growing sections. In total, 50 herds were tested for Salmonella. Logistic regression analysis showed that factor 1 was significantly associated with Salmonella test status (P = 0.04). Herds with poor biosecurity had a higher probability of testing Salmonella positive compared with herds with good biosecurity. This study shows the potential for using herd information to classify herds according to their Salmonella status in the absence of good testing options. The method might be used as a potentially cost-effective tool for future development of risk-based approaches to surveillance, targeting interventions to high-risk herds or differentiating sampling strategies in herds with different levels of infection.  相似文献   

Next Generation Sequencing Bulk Segregant Analysis of Potato Support that Differential Flux into the Cholesterol and Stigmasterol Metabolite Pools Is Important for Steroidal Glycoalkaloid Content     

Kacper Piotr Kaminski  Kirsten Kørup  Mathias Neumann Andersen  Mads Sønderkær  Mette Sondrup Andersen  Hanne Grethe Kirk  Kåre Lehmann Nielsen 《Potato Research》2016,59(1):81-97

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Stringency of environmental regulation and aquaculture growth: A cross-country analysis     

Tenaw G. Abate  Rasmus Nielsen  Ragnar Tveterås 《Aquaculture Economics & Management (Blackwell Science)》2016,20(2):201-221

During the last three decades, aquaculture has been the fastest growing animal-food-producing sector in the world, accounting for half of the present seafood supply. However, there is a significant growth disparity among aquaculture-producing countries. The reasons why some countries have achieved remarkable growth in aquaculture while others have stagnated or even declined have not been determined. In this article, we investigate whether environmental regulations have an impact on aquaculture growth. Using a cross-country regression analysis, we show that stringent environmental regulations are negatively related to aquaculture growth, whereas GDP growth has a positive effect. Countries often face a difficult balancing act between growth and environmental considerations when devising regulations. Our empirical results suggest that stricter environmental regulations in developed countries have contributed to lower growth rates and that these countries are falling behind emerging and developing economies that have more lenient environmental regulations.  相似文献   

Restructuring European freshwater aquaculture from family‐owned to large‐scale firms – lessons from Danish aquaculture          下载免费PDF全文

Rasmus Nielsen  Frank Asche  Max Nielsen 《Aquaculture Research》2016,47(12):3852-3866

Aquaculture is the world's fastest growing animal food producing sector. Although its overall performance is very good, it is unevenly spread geographically. In particular, the growth in most EU countries has been stagnating over the past 20 years despite repeated policy initiatives to launch new growth in the industry. The lack of production growth in EU aquaculture is often explained by strict environmental regulation and bureaucracy. In this article, we argue that an additional important element is an industry structure that limits the innovation and use of new technologies. Historically, farms have been small and often co‐managed with larger agriculture production. However, to succeed in a market with global competition, technological innovation and sector‐wide specialization, it is necessary to continuously increase productivity and induce investments in larger production facilities to take advantage of economies of scale. In Denmark, a structural change was ‘kicked off’ in 2005. In just 6 years, 30% of Danish production in freshwater has been reallocated to larger and more technologically advanced recirculation farms. Labour productivity has increased and the environmental impact per kilo of fish produced has been reduced, improving future prospects for aquaculture in Denmark and Europe.  相似文献   

Molecular and biological characterization of Potato mop‐top virus (PMTV,Pomovirus) isolates from the potato‐growing regions of Colombia          下载免费PDF全文

J. F. Gil  I. Adams  N. Boonham  S. L. Nielsen  M. Nicolaisen 《Plant pathology》2016,65(7):1210-1220

Potato mop‐top virus (PMTV) causes necrotic flecks inside and on tubers in temperate countries. In South America, these symptoms have not been observed, although the presence of the virus has been confirmed in the Andes and in Central America. To characterize PMTV isolates from the Andes, soil samples were taken from the main potato‐producing regions in Colombia and virus was recovered by planting Nicotiana benthamiana as bait plants. The complete genomes of five isolates were sequenced and three of the isolates were inoculated to four different indicator plants. Based on sequence comparisons, three types of RNA‐CP (RNA2) and RNA‐TGB (RNA3) were found. The isolates from the centre of the country (CO3 and CO4) were similar to isolates from Europe. The genomes of CO1, CO2 and CO5 differ from other PMTV isolates, placing them in a separate clade in phylogenetic trees. The three Colombian isolates (CO1, CO2 and CO5) only induced slightly different symptoms in the indicator plants. However, the isolate from the northwest of the country (CO1) induced stronger symptoms in N. benthamiana including severe stunting. A correlation between the genotype of the isolates and the symptoms they induced on indicator plants was not found.  相似文献   

Pore‐size distribution and compressibility of coarse sandy subsoil with added biochar          下载免费PDF全文

C. T. Petersen  E. Hansen  H. H. Larsen  L. V. Hansen  J. Ahrenfeldt  H. Hauggaard‐Nielsen 《European Journal of Soil Science》2016,67(6):726-736

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二穗短柄草幼胚再生体系及农杆菌介导转化的初步研究   总被引：2，自引：1，他引：1  

吴雪莉  刘金星  Klaus K Nielsen  杨志民  高彩霞 《草业学报》2010,19(5):9-16

以二穗短柄草3个品系BDR018,BD21,BD21-3的幼胚为外植体,研究了幼胚大小对胚性愈伤组织诱导和再生的影响。采用携带gus和bar基因双元表达载体(pDM805)的根癌农杆菌菌株AGL1对BDR018品系的幼胚愈伤组织进行了遗传转化。本实验探讨了影响幼胚愈伤组织诱导再生及遗传转化的几个因素。结果发现,幼胚大小介于0.5～1.0mm之间的愈伤组织诱导率最高。随愈伤组织年龄的增加,BDR018,BD21,BD21-3愈伤组织的再生率下降,白化率上升。愈伤组织年龄在5～8周范围内转化效率较高,平均转化效率为38.5%。真空处理5min和0.01%的SilwetL-77处理均可提高转化效率。对转化植株进行GUS基因化学组织检测和PCR鉴定,初步证明外源基因已整合再生植株基因组中。  相似文献