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排序方式: 共有987条查询结果,搜索用时 15 毫秒
141.
Michel AL Hlokwe TM Coetzee ML Maré L Connoway L Rutten VP Kremer K 《Veterinary microbiology》2008,126(1-3):151-159
The genetic diversity among South African Mycobacterium bovis isolates from cattle was determined by genetic fingerprinting. The restriction fragment length polymorphism (RFLP) markers IS6110 and polymorphic GC-rich sequence (PGRS) as well as spoligotyping and determination of variable number of tandem repeats (VNTR) were used to characterize sub samples of 91 M. bovis field isolates. PGRS RFLP was the single most discriminatory method and combinations of typing methods, which included IS6110 and/or PGRS had the highest discriminatory power, able to reveal 29 distinct genotypes among 35 farms with no epidemiological link. Three of the farms were co-infected with two genetically unrelated strains. In contrast to reports from European and also other colonised countries on the African continent our findings are suggestive of a high genetic diversity of M. bovis in South Africa's cattle population, implying a variety of unrelated ancestor strains. Despite effective intervention through test-and-slaughter campaigns no indication of a 'founder effect' was apparent in the panel of isolates derived from all infected provinces. 相似文献
142.
Duchêne S Audouin E Crochet S Duclos MJ Dupont J Tesseraud S 《Domestic animal endocrinology》2008,34(1):63-73
In mammals, insulin regulates S6K1, a key enzyme involved in the control of protein synthesis, via the well-documented phosphoinositide-3'kinase (PI3K) pathway. Conversely, S6K1 is activated by insulin in avian muscle despite the relative insulin insensitivity of the PI3K pathway in this tissue. Mitogen-activated protein kinase (MAPK) cascade is another insulin sensitive pathway. The aim of this study was to explore the potential involvement of the ERK1/2 MAPK pathway in the control of p70 S6 kinase (S6K1) in avian species. Firstly, we characterized ERK1/2 MAPK in various chicken tissues. ERK2 was the only isoform detected in avian species whatever the tissue studied. We also showed that ERK2 is activated in vivo by insulin in chicken muscle. The regulation and the role of ERK2 in insulin signaling were next investigated in chicken hepatoma cells (LMH) and primary myoblasts. Insulin stimulation led to ERK2 and S6K1 phosphorylation, and concomitantly increased kinase activity. U0126, an inhibitor of the ERK MAPK pathway, completely abolished insulin-induced S6K1 phosphorylation and activity in chicken myoblasts, whereas its effect was only partial in LMH cells. In conclusion, these results show that ERK1/2 MAPK is involved in the control of S6K1 by insulin in chicken cells, particularly myoblasts. 相似文献
143.
Adenosine A2A receptor agonists inhibit lipopolysaccharide-induced production of tumor necrosis factor-alpha by equine monocytes 总被引:1,自引:1,他引:0
Sun WC Moore JN Hurley DJ Vandenplas ML Linden J Cao Z Murray TF 《Veterinary immunology and immunopathology》2008,121(1-2):91-100
Adenosine is an endogenous nucleoside that regulates many physiological processes by activating one or more adenosine receptor subtypes, namely A1, A2A, A2B and A3. The results of previous studies indicate that adenosine analogues inhibit lipopolysaccharide (LPS)-induced production of reactive oxygen species (ROS) by equine neutrophils primarily through activation of A2A receptors. Because peripheral blood monocytes produce cytokines that are responsible for many of the deleterious effects of LPS, the current study was performed to evaluate the effects of an array of novel adenosine receptor agonists on LPS-induced production of tumor necrosis factor-alpha (TNF-alpha), and to assess the selectively of these agonists for equine adenosine A2A over the A1 receptor. Radioligand binding studies performed with equine tissues expressing adenosine A1 and A2A receptor subtypes yielded a rank order of affinity for the equine A2A receptor of ATL307>ATL309 approximately ATL310 approximately ATL313>ATL202 approximately ATL361 approximately ATL376>ATL372>CGS21680>NECA. Co-incubation of equine peripheral blood monocytes with LPS and these agonists resulted in inhibition of TNF-alpha production with a rank order of potency that strongly correlated with their binding affinities for equine adenosine A2A receptors. Results of experiments performed with one of the adenosine receptor agonists (ATL313) and selective adenosine receptor antagonists confirmed that inhibition of LPS-induced production of TNF-alpha occurred via stimulation of A2A receptors. Although incubation of monocytes with IB-MECA, a compound purported to act as an adenosine A3 receptor agonist, reduced LPS-induced TNF-alpha production, this effect of IB-MECA was inhibited by the A2A selective antagonist ZM241385 but not by the A3 receptor antagonist MRS1220. These results indicate that the adenosine receptor subtype responsible for regulation of LPS-induced cytokine production by equine monocytes is the A2A receptor. To address the signal transduction mechanism responsible for the anti-inflammatory effects of ATL313 in equine monocytes, production of cAMP was compared in the presence and absence of either the adenosine A2A receptor antagonist ZM241385 or the adenosine A2B receptor antagonist MRS1706. In the absence of the antagonists, ATL313 increased production of cAMP; ZM241385 inhibited this effect of ATL313, whereas MRS1706 did not. Furthermore, incubation of monocytes with either the stable analogue of cAMP, dibutyryl cAMP, or forskolin, an activator of adenylyl cyclase, also inhibited LPS-induced production of TNF-alpha production by equine monocytes. Collectively, the results of the current study indicate that adenosine analogues inhibit LPS-induced production of TNF-alpha by equine monocytes primarily via activation of adenosine A2A receptors and do so in a cAMP-dependent manner. The results of this study indicate that stable adenosine analogues that are selective for adenosine A2A receptors may be suitable for development as anti-inflammatory drugs in horses. 相似文献
144.
145.
Chafika Mouhoub-Sayah Hafsa Djoudad-Kadji Florian Kletty André Malan Jean-Patrice Robin Michel Saboureau 《African Zoology》2018,53(1):1-10
The Algerian hedgehog Atelerix algirus is an insectivorous species. However, the exact composition of its natural diet remains largely undetermined, especially in relation to seasonal variations in food availability. From March to November, we simultaneously analysed the composition of 180 hedgehog faecal samples and food availability in the Soumman Valley, Algeria to assess food selection in this species. The faeces contained 196 different prey species, of which 92% belonged to the class Insecta. The highest prey species diversity was found in the Coleoptera order (100 species recorded) and the highest species occurrence was found in Hymenoptera (65% of the prey items, mainly represented by the harvester ant Messor barbarus, a crop-ravaging species). This study shows that the Algerian hedgehog is mainly a generalist species with a diet that is strongly linked to food availability. However, seasonal variations were observed in prey selection, and a notable shift in food preference was observed during autumn. The exact nature of these changes in feeding behaviour remains to be investigated, notably in relation to changes in energy requirements of this species before hibernation, in terms of quantity and/or quality. 相似文献
146.
Michel Guillaume 《猪业科学》2018,(4):95-96
正如今,由于基因科技和品种选育技术的不断提高,母猪品种无论是从环境适应度和营养需求都与过去的品种有非常大的差别。现代母猪的高繁殖力需要充足的营养来支持:从动物各种阶段的营养需求到各种阶段的饲喂方式及采食量,母猪的高繁殖潜力必须通过精确的营养来发挥。不同的营养方案根据不同的品种来制定;不同阶段的采食量根据其背膘和体重来决定。决定采食量的因素有:环境温度、霉菌毒素含量、饮水质量、饲料适口性等。 相似文献
147.
Anne Villemey William E. Peterman Murielle Richard Annie Ouin Inge van Halder Virginie M. Stevens Michel Baguette Philip Roche Frédéric Archaux 《Landscape Ecology》2016,31(7):1629-1641
Context
Anthropogenic activities readily result in the fragmentation of habitats such that species persistence increasingly depends on their ability to disperse. However, landscape features that enhance or limit individual dispersal are often poorly understood. Landscape genetics has recently provided innovative solutions to evaluate landscape resistance to dispersal.Objectives
We studied the dispersal of the common meadow brown butterfly, Maniola jurtina, in agricultural landscapes, using a replicated study design and rigorous statistical analyses. Based on existing behavioral and life history research, we hypothesized that the meadow brown would preferentially disperse through its preferred grassy habitats (meadows and road verges) and avoid dispersing through woodlands and the agricultural matrix.Methods
Samples were collected in 18 study landscapes of 5 × 5 km in three contrasting agricultural French regions. Using circuit theory, least cost path and transect-based methods, we analyzed the effect of the landscape on gene flow separately for each sex.Results
Analysis of 1681 samples with 6 microsatellites loci revealed that landscape features weakly influence meadow brown butterfly gene flow. Gene flow in both sexes appeared to be weakly limited by forests and arable lands, whereas grasslands and grassy linear elements (road verges) were more likely to enhance gene flow.Conclusion
Our results are consistent with the hypothesis of greater dispersal through landscape elements that are most similar to suitable habitat. Our spatially replicated landscape genetics study allowed us to detect subtle landscape effects on butterfly gene flow, and these findings were reinforced by consistent results across analytical methods.148.
Corgozinho KB de Souza HJ Pereira AN Belchior C da Silva MA Martins MC Damico CB 《Journal of Feline Medicine and Surgery》2007,9(6):481-486
Fifteen cats were evaluated with urethral obstruction. Penile trauma by catheterization was the major indication for perineal urethrostomy. Ten cats had developed a urethral stricture and five had rupture of the urethra following medical management. All cats had abnormalities in penis and/or prepuce and/or scrotal sacs including hyperemia or swelling. Perineal urethrostomy was performed in all cases and they were evaluated for 6 months after surgery. Few complications were noted. Urinary tract infection was the most frequent complication observed. The clients considered their cats to have a good quality of life following surgery. 相似文献
149.
A dielectric omnidirectional reflector 总被引:3,自引:0,他引:3
Y Fink JN Winn S Fan C Chen J Michel JD Joannopoulos EL Thomas 《Science (New York, N.Y.)》1998,282(5394):1679-1682
A design criterion that permits truly omnidirectional reflectivity for all polarizations of incident light over a wide selectable range of frequencies was used in fabricating an all-dielectric omnidirectional reflector consisting of multilayer films. The reflector was simply constructed as a stack of nine alternating micrometer-thick layers of polystyrene and tellurium and demonstrates omnidirectional reflection over the wavelength range from 10 to 15 micrometers. Because the omnidirectionality criterion is general, it can be used to design omnidirectional reflectors in many frequency ranges of interest. Potential uses depend on the geometry of the system. For example, coating of an enclosure will result in an optical cavity. A hollow tube will produce a low-loss, broadband waveguide, whereas a planar film could be used as an efficient radiative heat barrier or collector in thermoelectric devices. 相似文献
150.
Luc Doyen Christophe Béné Michel Bertignac Fabian Blanchard Abdoul Ahad Cissé Catherine Dichmont Sophie Gourguet Olivier Guyader Pierre‐Yves Hardy Sarah Jennings Lorne Richard Little Claire Macher David Jonathan Mills Ahmed Noussair Sean Pascoe Jean‐Christophe Pereau Nicolas Sanz Anne‐Maree Schwarz Tony Smith Olivier Thébaud 《Fish and Fisheries》2017,18(6):1056-1072
Reconciling food security, economic development and biodiversity conservation is a key challenge, especially in the face of the demographic transition characterizing many countries in the world. Fisheries and marine ecosystems constitute a difficult application of this bio‐economic challenge. Many experts and scientists advocate an ecosystem approach to manage marine socio‐ecosystems for their sustainability and resilience. However, the ways by which to operationalize ecosystem‐based fisheries management (EBFM) remain poorly specified. We propose a specific methodological framework—viability modelling—to do so. We show how viability modelling can be applied using four contrasted case‐studies: two small‐scale fisheries in South America and Pacific and two larger‐scale fisheries in Europe and Australia. The four fisheries are analysed using the same modelling framework, structured around a set of common methods, indicators and scenarios. The calibrated models are dynamic, multispecies and multifleet and account for various sources of uncertainty. A multicriteria evaluation is used to assess the scenarios’ outcomes over a long time horizon with different constraints based on ecological, social and economic reference points. Results show to what extent the bio‐economic and ecosystem risks associated with the adoption of status quo strategies are relatively high and challenge the implementation of EBFM. In contrast, strategies called ecoviability or co‐viability strategies, that aim at satisfying the viability constraints, reduce significantly these ecological and economic risks and promote EBFM. The gains associated with those ecoviability strategies, however, decrease with the intensity of regulations imposed on these fisheries. 相似文献