A Large-Scale Survey of Races of Leptosphaeria  maculans Occurring on Oilseed Rape in France     

Marie-Hélène Balesdent  Karine Louvard  Xavier Pinochet  Thierry Rouxel 《European journal of plant pathology / European Foundation for Plant Pathology》2006,114(1):53-65

Nine avirulence genes (AvrLm1–AvrLm9) were identified in Leptosphaeria maculans, the causal agent of stem canker of oilseed rape (OSR), combinations of which could theoretically generate up to 512 different races of the fungus. L. maculans displays a high evolutionary potential to adapt to novel resistance genes as illustrated by the Rlm1 breakdown in France, where virulent populations became prevalent within three growing seasons. An improved knowledge of the race structure of the fungal population is therefore needed to ensure a better use of available major resistance genes. The objective of this study was to characterise the L. maculans population structure in France using a large-scale, rationalised sample of isolates. Experimental fields, planted with “trap plants” harbouring no major resistance gene, were sown at 20 locations. Single-pycnidium isolates were collected from leaf lesions that developed in early autumn and 1797 isolates were genotyped at Avr loci. The frequency of AvrLm6 and AvrLm7 was higher than 99%, whereas avrLm2 and avrLm9 alleles were fixed in the population. AvrLm1, AvrLm4, AvrLm5 and AvrLm8 were polymorphic. AvrLm3 isolates were detected at a very low frequency (less than 1%). Only 11 races were identified in France, with one race prevalent, namely Av5-6-7-(8) (i.e. virulent on Rlm1, Rlm2, Rlm3, Rlm4 and Rlm9), representing around 65% of the population. Disparities between the locations sampled were evident at all scales analysed. Some virulent races, such as those harbouring avrLm5, were present before the introduction of the corresponding resistance gene in the commercial OSR crop.  相似文献   

Reliable ELISAs showing differences between resistant and susceptible lines in hens orally inoculated with Salmonella Enteritidis     

Proux K  Jouy E  Houdayer C  Protais J  Dibb-Füller M  Boscher E  Gillard A  Gracieux P  Gilbert F  Beaumont C  Duchet-Suchaux M 《Veterinary research》2002,33(1):23-33

Reliable ELISAs were investigated with the aim to select hen lines resistant to Salmonella Enteritidis and producing high levels of antibodies. In the first experiment, the relation between the humoral response and the bacteriological results was assessed on hens from the Y11 resistant line and the L2 susceptible line, orally inoculated with 10(8) CFU S. Enteritidis per animal. Anti-lipopolysaccharide (LPS) IgG titres were higher but the liver and spleen were less contaminated in hens from the Y11 line than in hens from the L2 line (p = 0.013, 0.031 and 0.026 respectively). In the second experiment, the hens were inoculated orally with 1.7 x 10(8) CFU S. Enteritidis per animal in order to select the ELISA methods showing the more significant differences. ELISAs were based on LPS, flagella, LPS from rough (LPS-R) and smooth strains (LPS-S) and detected IgG and IgM antibodies from sera and yolks. No between-line host response variation was observed in the yolk, with LPS-S and R antigens nor with anti-LPS IgM in the sera. Otherwise, significant differences were encountered between hen lines with the ELISAs performed on the sera detecting anti-LPS IgG, anti-flagella IgG or IgM (p = 0.017, 0.017 and p < 0.001 respectively). When comparing the kinetics of the selected ELISAs, the IgG antibodies against LPS detected between-line variations as early as 1 to 4 weeks pi, whereas with IgG against flagella, the differences were only detected at 1 and 2 weeks pi and with IgM against flagella, the differences were significant at 1, 2, 4 and 8 weeks pi. In conclusion, resistant hen lines producing higher levels of antibodies than the susceptible hen lines may be selected with these ELISAs.  相似文献   

An unusual form of canine babesiosis     

Van de Maele I  Savary-Bataille K  Gielen I  Daminet S 《The Canadian veterinary journal. La revue veterinaire canadienne》2008,49(3):283-286

An Akita Inu, living in Belgium, was presented with unusual clinical manifestations of acute babesiosis that included neurological signs and pancytopenia. Diagnosis was made by identifying Babesia canis in the blood smear. Neurological signs resolved after treatment with imidocarb diproprionate. Normalization of hematological abnormalities was gradual over 5 months.  相似文献   

Distribution of equine infectious anemia in horses in the north of Minas Gerais State, Brazil.     

Dominique J Bicout  Regina Carvalho  Karine Chalvet-Monfray  Philippe Sabatier 《Journal of veterinary diagnostic investigation》2006,18(5):479-482

The paper examines the prevalence of equine infectious anemia (EIA) in horse populations in the northern part (comprising 89 cities) of Minas Gerais State, Brazil, from January 2002 to December 2004. Data on 8,981 agar gel immunodiffusion test results from the region were used as input for a statistical and autoregressive analysis model to construct a city-level map of the distribution of EIA prevalence. The following EIA prevalence (P) levels were found: 49 cities with 0 < P < or = 0.5%, 26 with 0.5% < P < or = 1.5%, 10 with 1.5% < P < or = 5%, and 4 with 5% < P < or = 25%.  相似文献   

A mathematical model of the effects of chronic carriers on the within-herd spread of contagious bovine pleuropneumonia in an African mixed crop-livestock system     

Lesnoff M  Laval G  Bonnet P  Chalvet-Monfray K  Lancelot R  Thiaucourt F 《Preventive veterinary medicine》2004,62(2):101-117

Contagious bovine pleuropneumonia (CBPP) is a respiratory disease of cattle; CBPP is caused by Mycoplasma mycoides subsp. mycoides small colony. CBPP is a major cause for concern for African countries (because of mortality, animal-production losses and cost of control). The clinical form of the disease is the more infectious (contagion occurs essentially through coughing). However, chronic lung lesions with viable mycoplasmas can persist in recovering cattle. Animals presenting these lesions might have a time-delimitated infectious phase. Such carriers are suspected to generate field outbreaks (although this hypothesis remains debated). We investigated the potential quantitative effects of these chronic carriers on the within-herd CBPP spread. Data were collected during a longitudinal field herd survey in a mixed crop-livestock system in the Ethiopian highlands. Two stochastic Markov-chain models' outputs (seroconversion dynamics, basic reproduction ratio R0, cumulative clinical incidence and risk of herd infection) were compared given different hypotheses on the carrier infectiousness. The late seroconversions observed in the field data were fitted correctly only for the highest carrier infectiousness we considered (mean chronic duration of 1 year and carriers 50-times less infectious than clinical cases). Although sensitivities (in terms of disease impact in the herd) were in general negligible when the carrier infectiousness was low (e.g. when carriers were assumed to be 1000-times less infectious than clinical cases), they rapidly became important when the infectiousness increased.  相似文献   

Impact of the Salmonella status of market-age pigs and the pre-slaughter process on Salmonella caecal contamination at slaughter     

Beloeil PA  Chauvin C  Proux K  Madec F  Fravalo P  Alioum A 《Veterinary research》2004,35(5):513-530

The aim of this study was to evaluate the impact of the pre-slaughter process on Salmonella caecal contamination of pigs at slaughter. An observational study was carried out in 2001 on 101 conventional farrow-to-finish pig farms. On each farm, one batch of contemporary pigs was followed from the end of the fattening period until slaughter. The Salmonella bacteriological status of the batches was assessed by environmental samples of faecal material. The serological Salmonella status was obtained on 30 individually identified market-age pigs using an indirect ELISA test. At the slaughterhouse, 25 g of caecal contents were taken from 10 of the identified pigs. Faecal and caecal material were analysed according to a classical bacteriological method. A questionnaire was designed to obtain information about the type of feeding during the fattening period (dry versus wet), the duration of fasting on the farm before leaving for the slaughterhouse, the duration of transport between the farm and the slaughterhouse, the holding time in lairage at the slaughterhouse and loading and unloading conditions on the farm and at the slaughterhouse. To assess the relationships between these factors and the Salmonella caecal status of the pigs and the batches, two logistic models were fitted at the individual and at the batch level, respectively. The first analysis was performed using a random effects logistic regression model. The second analysis was based on a cumulative logit model with a positive caecal rate classified into three classes as the outcome variable. The results showed that the Salmonella status of market-age pigs assessed on the farm either by serological or bacteriological examinations and the time spent in lairage before slaughtering played a crucial role on caecal contamination. In the light of these results, actions should be considered both on the farm and at the slaughterhouse to decrease the risk of Salmonella contamination of the caecal contents.  相似文献   

Wild boar rooting in a northern coniferous forest – minor silviculture impact     

Olav Haaverstad  Hilde Karine Wam 《Scandinavian Journal of Forest Research》2014,29(1):90-95

European wild boar (Sus scrofa) is expanding northwards beyond its preferred habitat of broadleaved forests. We studied wild boar habitat use in a northern coniferous forest, and noted whether their rooting damaged roots, thereby influencing timber quality and forest regeneration (n = 562 rootings). Overall, the animals selected older spruce (Picea abies L.) forest of higher soil fertility with sparse field vegetation for rooting. During winter, they rooted more in pine (Pinus sylvestris L.) forest on lower soil fertility, possibly because the lichen cover can easily be removed even on frozen ground. Average size and depth of rootings were 6 ± 0.6 m² and 10 ± 0.2 cm, respectively. Rooting occurred on <1% of the area and caused negligible damage to roots of trees with commercial value. Because the wild boar mainly rooted in older forest, rootings will do little to improve germination of seeds by scarification of the top soil layer.  相似文献   

Modeling the dynamics of backyard chicken flows in traditional trade networks in Thailand: implications for surveillance and control of avian influenza     

Anuwat Wiratsudakul  Mathilde Cécile Paul  Dominique Joseph Bicout  Thanawat Tiensin  Wannapong Triampo  Karine Chalvet-Monfray 《Tropical animal health and production》2014,46(5):845-853

In Southeast Asia, traditional poultry marketing chains have been threatened by epidemics caused by the highly pathogenic avian influenza H5N1 (HPAI H5N1) virus. In Thailand, the trade of live backyard chickens is based on the activities of traders buying chickens from villages and supplying urban markets with chicken meat. This study aims to quantify the flows of chickens traded during a 1-year period in a province of Thailand. A compartmental stochastic dynamic model was constructed to illustrate trade flows of live chickens from villages to slaughterhouses. Live poultry movements present important temporal variations with increased activities during the 15 days preceding the Chinese New Year and, to a lesser extent, other festivals (Qingming Festival, Thai New Year, Hungry Ghost Festival, and International New Year). The average distance of poultry movements ranges from 4 to 25 km, defining a spatial scale for the risk of avian influenza that spread through traditional poultry marketing chains. Some characteristics of traditional poultry networks in Thailand, such as overlapping chicken supply zones, may facilitate disease diffusion over longer distances through combined expansion and relocation processes. This information may be of use in tailoring avian influenza and other emerging infectious poultry disease surveillance and control programs provided that the cost-effectiveness of such scenarios is also evaluated in further studies.  相似文献   

COX-2-derived prostacyclin confers atheroprotection on female mice   总被引：1，自引：0，他引：1  

Egan KM  Lawson JA  Fries S  Koller B  Rader DJ  Smyth EM  Fitzgerald GA 《Science (New York, N.Y.)》2004,306(5703):1954-1957

Female gender affords relative protection from cardiovascular disease until the menopause. We report that estrogen acts on estrogen receptor subtype alpha to up-regulate the production of atheroprotective prostacyclin, PGI2, by activation of cyclooxygenase 2 (COX-2). This mechanism restrained both oxidant stress and platelet activation that contribute to atherogenesis in female mice. Deletion of the PGI2 receptor removed the atheroprotective effect of estrogen in ovariectomized female mice. This suggests that chronic treatment of patients with selective inhibitors of COX-2 could undermine protection from cardiovascular disease in premenopausal females.  相似文献   

Phenolics from commercialized grape extracts prevent early atherosclerotic lesions in hamsters by mechanisms other than antioxidant effect     

Auger C  Gérain P  Laurent-Bichon F  Portet K  Bornet A  Caporiccio B  Cros G  Teissédre PL  Rouanet JM 《Journal of agricultural and food chemistry》2004,52(16):5297-5302

The aim of this study was to evaluate the antiatherosclerotic effect of commercially available phenolic-rich extracts from grape seeds (ExGrape seeds, EGS; grape seed extract, GSE) and marc (ExGrape total, EGT) in cholesterol-fed hamsters and to investigate possible operating mechanisms. These extracts fed at a moderate dose mimicking two glasses of red wine per meal reduced plasma cholesterol (-11% on average) but did not affect plasma antioxidant capacity of hamsters. The extracts prevented the development of aortic atherosclerosis by 68% (EGS), 63% (EGT), and 34% (GSE). Elsewhere, in an ex vivo experiment using rat aortic rings, EGS (7 microg/mL) induced 77% endothelium-dependent relaxation, whereas EGT and GSE (30 microg/mL) induced 84 and 72%, respectively. These results suggests that phenolic extracts from grape seeds and marc are beneficial in inhibiting atherosclerosis by indirect mechanism(s).  相似文献