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1.
Hyena disease was first reported in France in 1975 and since then has been recognized in many countries. It is currently regarded as a disorder of skeletal development, mainly localised in the pelvic limbs of young cattle. Some investigators consider that it is a metabolic disease but the authors believe that it may be caused by a virus. Their hypothesis, according to which bovine virus diarrhoea-mucosal disease virus is involved, is based on epidemiological, histopathological and immunological evidence. 相似文献
2.
Lesnoff M Laval G Bonnet P Abdicho S Workalemahu A Kifle D Peyraud A Lancelot R Thiaucourt F 《Preventive veterinary medicine》2004,64(1):27-40
Contagious bovine pleuropneumonia (CBPP) is a major threat for cattle health and production in Africa. This disease is caused by the small-colony type of Mycoplasma mycoides subspecies mycoides (MmmSC). Transmission occurs from direct and repeated contacts between sick and healthy animals. Veterinary services recently reported a resurgence of CBPP in the province of West Wellega, in the Ethiopian highlands. A research program was set up to estimate the epidemiological parameters of the within-herd infection spread. A follow-up survey was implemented in 71 sampled herds of the Boji district (West Wellega province). Fifteen herds were classified as newly infected and used in a serological- and clinical-incidence study. The overall 16-month cumulative sero-incidence risk was 34%. Clinical cases were recorded for 39% of the seropositive cattle; case-fatality risk was 13%. There was no evidence of benefit on infection spread of CBPP-control measures used locally by farmers (isolation or antibiotic treatments of sick animals). This might be related to a lack of power in the statistical analyses or to a quality problem for the medications used (and more generally, for health-care delivery in the Boji district). 相似文献
3.
Chaouachi M El Malki R Berard A Romaniuk M Laval V Brunel D Bertheau Y 《Journal of agricultural and food chemistry》2008,56(6):1818-1828
The labeling of products containing genetically modified organisms (GMO) is linked to their quantification since a threshold for the presence of fortuitous GMOs in food has been established. This threshold is calculated from a combination of two absolute quantification values: one for the specific GMO target and the second for an endogenous reference gene specific to the taxon. Thus, the development of reliable methods to quantify GMOs using endogenous reference genes in complex matrixes such as food and feed is needed. Plant identification can be difficult in the case of closely related taxa, which moreover are subject to introgression events. Based on the homology of beta-fructosidase sequences obtained from public databases, two couples of consensus primers were designed for the detection, quantification, and differentiation of four Solanaceae: potato (Solanum tuberosum), tomato (Solanum lycopersicum), pepper (Capsicum annuum), and eggplant (Solanum melongena). Sequence variability was studied first using lines and cultivars (intraspecies sequence variability), then using taxa involved in gene introgressions, and finally, using taxonomically close taxa (interspecies sequence variability). This study allowed us to design four highly specific TaqMan-MGB probes. A duplex real time PCR assay was developed for simultaneous quantification of tomato and potato. For eggplant and pepper, only simplex real time PCR tests were developed. The results demonstrated the high specificity and sensitivity of the assays. We therefore conclude that beta-fructosidase can be used as an endogenous reference gene for GMO analysis. 相似文献
4.
Comparative pathogenicity of sexual and asexual spores of Zymoseptoria tritici (septoria tritici blotch) on wheat leaves 
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下载免费PDF全文 Zymoseptoria tritici ascospores and pycnidiospores are considered the main forms of primary and secondary inoculum, respectively, in septoria tritici blotch epidemics. The pathogenicity of the two types of spores of the same genotypic origin were compared through a two‐stage inoculation procedure in controlled conditions. Adult wheat leaves were inoculated with ascospores collected from field sources, yielding 119 lesions; pycnidiospores collected from 12 lesions resulting from these ascospore infections were then used for inoculation. Lesion development was assessed for 5 weeks; latent period, lesion size, and pycnidium density were estimated for different isolates. The latent period was calculated as the maximum likely time elapsed between inoculation and either the appearance of the majority of the sporulating lesions (leaf scale) or the appearance of the first pycnidia (lesion scale). The latent period was significantly longer (c. 60 degree‐days, i.e. 3–4 days) after infection with ascospores than with pycnidiospores. No difference was established for lesion size and density of pycnidia. A comparison with other ascomycete fungi suggested that the difference in latent period might be related to the volume of spores and their ability to cause infection. Fungal growth before the appearance of lesions may be slower after inoculation with an ascospore than with a pycnidiospore. The mean latent period during the very beginning of epidemics, when first lesions are mainly caused by ascospores, may be longer than during spring, when secondary infections are caused by pycnidiospores. Disease models would be improved if these differences were considered. 相似文献
5.
Fusarium oxysporum f. sp. radicis‐vanillae is the causal agent of root and stem rot of vanilla 下载免费PDF全文
下载免费PDF全文 S. Koyyappurath T. Atuahiva R. Le Guen H. Batina S. Le Squin N. Gautheron V. Edel Hermann J. Peribe M. Jahiel C. Steinberg E. C. Y. Liew C. Alabouvette P. Besse M. Dron I. Sache V. Laval M. Grisoni 《Plant pathology》2016,65(4):612-625
Root and stem rot (RSR) is a very detrimental disease of vanilla worldwide. Fusarium oxysporum is frequently associated with the disease but other Fusarium species are also reported. In this international study, 52 vanilla plots were surveyed in three of the most important vanilla producing countries (Madagascar, Reunion Island and French Polynesia) in order to determine the aetiology of RSR disease. Subsets from the 377 single‐spored Fusarium isolates recovered from rotten roots and stems in the surveys were characterized by molecular genotyping (EF1α and IGS gene sequences) and pathogenicity assays on Vanilla planifolia and V. ×tahitensis, the two commercially grown vanilla species. Fusarium oxysporum was shown to be the principal species responsible for the disease, representing 79% of the isolates recovered from the RSR tissues, 40% of which induced severe symptoms on inoculated plantlets. Fusarium oxysporum isolates were highly polyphyletic regardless of geographic origin or pathogenicity. Fusarium solani, found in 15% of the samples and inducing only mild symptoms on plantlets, was considered a secondary pathogen of vanilla. Three additional Fusarium species were occasionally isolated in the study (F. proliferatum, F. concentricum and F. mangiferae) but were nonpathogenic. Histopathological preparations observed in wide field and multiphoton microscopy showed that F. oxysporum penetrated the root hair region of roots, then invaded the cortical cells where it induced necrosis in both V. planifolia and V. ×tahitensis. The hyphae never invaded the root vascular system up to 9 days post‐inoculation. As a whole, the data demonstrated that RSR of vanilla is present worldwide and that its causal agent should be named F. oxysporum f. sp. radicis‐vanillae. 相似文献
6.
Jean Trap Wassila Riah Marthe Akpa-Vinceslas Caroline Bailleul Karine Laval Isabelle Trinsoutrot-Gattin 《Soil biology & biochemistry》2012
We tested the relevance of the microplate fluorimetric (F) assay for five enzymes in contrasting land uses, including woodland, grassland, cultivated and contaminated lands, as compared to the standard spectrophotometric (P) method. Enzymatic activity measured by the P method ranged from 0 to 56.04 nmol-pNP g?1 min?1 (median = 4) while the F method revealed lower values ranging from 0 to 6.22 nmol-MUB g?1 dry soil min?1 (median = 1). The values obtained by the P method were around 8 times higher than those revealed by the F method. However, the F method revealed significant differences in enzyme activity in orchard parcels (land use with low variations in soil properties). We concluded that the F method improves the effectiveness and the efficiency of measuring universal soil quality indicators using enzymes. 相似文献
7.
Essenberg M Bayles MB Samad RA Hall JA Brinkerhoff LA Verhalen LM 《Phytopathology》2002,92(12):1323-1328
ABSTRACT The development and genetic characterization of four near-isogenic lines (NILs) of cotton (Gossypium hirsutum) is described herein. Each line contains a single, but different, gene for resistance to bacterial blight caused by Xanthomonas campestris pv. malvacearum. The lines were derived using at least six backcrosses to the susceptible recurrent parent 'Acala 44', followed by single plant-progeny row selection for uniformity. The NILs are homozygous for the B(2), B(4), B(In), or b(7) genes and are designated as AcB(2), AcB(4), AcB(In), and Acb(7), respectively. In the 'Acala 44' background, B(2), B(4), and B(In) are partially dominant genes; b(7) is partially recessive. Relative strengths of resistance conferred by those genes toward race 1 of the pathogen were B(4) b(7)>B(In) B(2). B(4), B(In), and b(7) each conferred resistance toward X. campestris pv. malvacearum carrying a single avirulence gene, whereas B(2) was less specific. 相似文献
8.
猪呼吸道病综合征(PRDC)是一种由多种传染性因子和环境因子互相作用导致的多因子疾病,在生长肥育猪阶段常见,表现为生长迟缓和死亡率增加。其关键性病原为猪肺炎支原体,同时普遍存在 相似文献
9.
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
10.
Risk factors for high sow mortality in French swine herds 总被引：1，自引：0，他引：1
N. Abiven H. Seegers F. Beaudeau A. Laval C. Fourichon 《Preventive veterinary medicine》1998,33(1-4):109-119
Episodes of high sow mortality rates affect profitability of swine farms. However, relevant control actions are difficult to implement. The objective of this study was to identify the risk factors for high levels of sow mortality rate (HM) in French swine herds. A case-control study was carried out in 102 swine herds located in Brittany (western France). Level of sow mortality of a herd was quantified by the annual mortality rate using sow-days as denominator. Fifty-five (53.9%) herds which experienced a sow mortality rate over 5% were classified as HM herds. Logistic regression was used to assess associations of managerial practices and disease prevalence with the odds of HM. High prevalence of urinary tract infections, metritis or lameness were significantly associated with a HM herd status (P < 0.10, OR ranging from 3.4 to 5.2). Multiplying herds were herds at higher risk for sow mortality than commercial farrow-to-finish herds. Providing three meals per day instead of two to dry sows decreased the odds of HM. Feeding plans where the maximum daily amount of feed provided to lactating sows was lower than 8 kg and was reached before 15 d in lactation were related to lower odds of HM (P < 0.10). Average age at weaning of 28 d or more and/or small average litter size at birth (12 piglets or less) were associated with higher odds of experiencing HM. 相似文献