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101.
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Cecilia Wolff Ulf Emanuelson Anna Ohlson Stefan Alenius Nils Fall 《Acta veterinaria Scandinavica》2015,57(1)
Background
Infections with bovine respiratory syncytial virus (BRSV) and bovine coronavirus (BoCV) are endemic to the cattle populations in most countries, causing respiratory and/or enteric disease. It has been demonstrated that herds can remain free from these infections for several years also in high prevalence areas. Organically managed (OM) dairy herds have been shown to have lower seroprevalence of both viruses compared to conventionally managed (CM) herds. The objective of this study was to challenge the hypothesis of a lower occurrence of BRSV and BoCV in OM compared to CM dairy herds.In November 2011, May 2012 and May 2013 milk samples from four homebred primiparous cows were collected in 75 to 65 OM and 69 to 62 CM herds. The antibody status regarding BRSV and BoCV was analysed with commercial indirect ELISAs. Herds were classified as positive if at least one individual sample was positive.Results
The prevalence of positive herds ranged from 73.4% to 82.3% for BRSV and from 76.8% to 85.3% for BoCV among OM and CM herds, over the three sampling occasions. There was no statistically significant difference between OM and CM herds at any sampling occasion. The incidence risk of newly infected herds did not differ statistically between OM and CM herds at any sampling occasion, neither for BRSV nor for BoCV. The incidence of herds turning sero-negative between samplings corresponded to the incidence of newly infected. Bulk tank milk (BTM) samples were also sampled in the herds and analysed. Several herds were negative on individual samples but positive in BTM. Herd-level data on production, health and reproduction were retrieved from VÄXA Sweden and the study herds were representative of the source population.Conclusion
There was no difference in prevalence of or incidence risk for BRSV or BoCV between Swedish OM and CM herds. Because the incidence of herds becoming seropositive was balanced by herds becoming seronegative it should be possible to lower the prevalence of these two infections among Swedish dairy cattle herds if biosecurity is improved.Electronic supplementary material
The online version of this article (doi:10.1186/s13028-014-0091-x) contains supplementary material, which is available to authorized users. 相似文献103.
104.
Sharpe J Ahlgren U Perry P Hill B Ross A Hecksher-Sørensen J Baldock R Davidson D 《Science (New York, N.Y.)》2002,296(5567):541-545
Current techniques for three-dimensional (3D) optical microscopy (deconvolution, confocal microscopy, and optical coherence tomography) generate 3D data by "optically sectioning" the specimen. This places severe constraints on the maximum thickness of a specimen that can be imaged. We have developed a microscopy technique that uses optical projection tomography (OPT) to produce high-resolution 3D images of both fluorescent and nonfluorescent biological specimens with a thickness of up to 15 millimeters. OPT microscopy allows the rapid mapping of the tissue distribution of RNA and protein expression in intact embryos or organ systems and can therefore be instrumental in studies of developmental biology or gene function. 相似文献
105.
Sun H Ringdahl U Homeister JW Fay WP Engleberg NC Yang AY Rozek LS Wang X Sjöbring U Ginsburg D 《Science (New York, N.Y.)》2004,305(5688):1283-1286
Group A streptococci, a common human pathogen, secrete streptokinase, which activates the host's blood clot-dissolving protein, plasminogen. Streptokinase is highly specific for human plasminogen, exhibiting little or no activity against other mammalian species, including mouse. Here, a transgene expressing human plasminogen markedly increased mortality in mice infected with streptococci, and this susceptibility was dependent on bacterial streptokinase expression. Thus, streptokinase is a key pathogenicity factor and the primary determinant of host species specificity for group A streptococcal infection. In addition, local fibrin clot formation may be implicated in host defense against microbial pathogens. 相似文献
106.
Büntgen U Tegel W Nicolussi K McCormick M Frank D Trouet V Kaplan JO Herzig F Heussner KU Wanner H Luterbacher J Esper J 《Science (New York, N.Y.)》2011,331(6017):578-582
Climate variations influenced the agricultural productivity, health risk, and conflict level of preindustrial societies. Discrimination between environmental and anthropogenic impacts on past civilizations, however, remains difficult because of the paucity of high-resolution paleoclimatic evidence. We present tree ring-based reconstructions of central European summer precipitation and temperature variability over the past 2500 years. Recent warming is unprecedented, but modern hydroclimatic variations may have at times been exceeded in magnitude and duration. Wet and warm summers occurred during periods of Roman and medieval prosperity. Increased climate variability from ~250 to 600 C.E. coincided with the demise of the western Roman Empire and the turmoil of the Migration Period. Such historical data may provide a basis for counteracting the recent political and fiscal reluctance to mitigate projected climate change. 相似文献
107.
Ehn BM Allmere T Telemo E Bengtsson U Ekstrand B 《Journal of agricultural and food chemistry》2005,53(9):3743-3748
The effect of fermentation by Lactobacilli and of proteolytic hydrolysis of whole milk on the IgE binding ability of beta-lactoglobulin was studied using an ELISA inhibition assay. Sera from nine adult milk allergic patients were tested. The individual sera showed a similar inhibition pattern in the changes during fermentation and proteolysis. The degradation of beta-lactoglobulin was studied with liquid chromatography. In general, fermentation with Lactobacilli gave little effect on IgE binding, even though chromatography data showed a gradual degradation of beta-lactoglobulin. Proteolysis with trypsin, however, gave extensive degradation of beta-lactoglobulin and strongly decreased IgE binding. In addition, we measured the inhibition pattern of beta-lactoglobulin in various selected commercially available fermented milk products. These showed an IgE binding capacity similar to that of nonfermented high pasteurized milk. 相似文献
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Summary The performance of transgenic varieties depends not only upon the stable and correctly-regulated expression of specific transgenes but also upon the agronomic potential of the background genotype. Ideally, transgenes should be introduced into agronomically-superior cultivars and transgenic varieties will become out-classed if their agronomic properties are not continually improved. It will often prove desirable to use conventional breeding techniques, as opposed to new cycles of transformation, to carry out this process of varietal improvement.Continuing advances in marker-assisted selection have made possible the selection and manipulation of an entire genetic background. This means that transgenes can be transferred to new and often untransformable varieties with relative ease. To carry out this process efficiently requires the correct choice of male and female parents, the use of appropriate marker-systems and the concentration of selection on the most appropriate generations.Efficient, phenotypically-neutral marker-systems have revolutionised the identification and manipulation of quantitative trait loci (QTLs). The loci which modify the expression of transgenes are a form of QTL. Desirable alleles at modifier QTLs can be transferred to new varieties along with the transgenes themselves, using marker-assisted breeding.The strategies for maker-assisted selection are becoming ever more sophisticated. A range of complementary marker systems allows the selection of desirable genotypes. In addition, the meiotic reassortment and recombination of chromosomes which produces new genotypes is becoming better understood. The most efficient plant breeding methods and the most powerful genetics will make optimal use of both markers and meiosis. 相似文献