Fluoroquinolone-resistant Campylobacter in animal reservoirs: dynamics of development, resistance mechanisms and ecological fitness     

Zhang Q  Lin J  Pereira S 《Animal health research reviews / Conference of Research Workers in Animal Diseases》2003,4(2):63-71

Thermophilic Campylobacter species, including Campylobacter jejuni and Campylobacter coli, are responsible for foodborne campylobacteriosis in humans and are increasingly resistant to fluoroquinolone (FQ) antimicrobials. The therapeutic use of FQ antimicrobial agents in food animal production, particularly in poultry, has become a concern for public health, because the practice may promote the emergence of FQ-resistant Campylobacter that can be transmitted to humans through the food chain. Recent studies have indicated that Campylobacter displays a hypermutable phenotype in response to in vivo treatment with FQ antimicrobials, resulting in the rapid emergence of resistant mutants. Distinct from other Gram-negative bacteria, the acquisition of FQ resistance in Campylobacter does not require stepwise accumulation of gyrA mutations and overexpression of efflux pumps, and is mainly mediated by single-step point mutations in gyrA in the presence of a constitutively expressed multidrug efflux pump, CmeABC. The simplicity of the resistance mechanisms may facilitate the rapid adaptation of Campylobacter to FQ treatment. The FQ-resistant Campylobacter mutants derived from chickens do not show a fitness cost in vivo and are ecologically competitive in the colonization of chickens even in the absence of antimicrobial selection pressure. These findings suggest that FQ-resistant Campylobacter may continue to persist regardless of antimicrobial usage, and highlight the need for extra effort to prevent the occurrence and spread of FQ-resistant Campylobacter in animal reservoirs.  相似文献   

Isolation and characterization of immortalized porcine aortic endothelial cell lines   总被引：6，自引：0，他引：6  

Carrillo A  Chamorro S  Rodríguez-Gago M  Alvarez B  Molina MJ  Rodríguez-Barbosa JI  Sánchez A  Ramírez P  Muñoz A  Domínguez J  Parrilla P  Yélamos J 《Veterinary immunology and immunopathology》2002,89(1-2):91-98

Primary porcine endothelial cells have a limited life span in culture. After four to five passages, they tend to de-differentiate and eventually reach senescence. The aim of this work was to establish immortalized porcine aortic endothelial cell lines (AOCs) to facilitate in vitro studies of different pathological process involving the endothelium. Primary porcine aortic endothelial cells (PAECs) were transfected with a plasmid containing the SV40 genome and selected on the basis of morphological and phenotypical features. Flow cytometry analysis demonstrated uptake of acetylated low density lipoproteins (Ac-LDL) and constitutive expression of SLA class I, CD29, CD31, CD41/61, CD80/86, CD46, SWC3, and LAMP-1 antigens by all analyzed lines and showed little differences to primary cells. The functional similarity between primary and immortalized endothelial cells was demonstrated in a cytotoxicity assay using a human natural killer cell line (NKL) as effector. The AOCs cell lines should be valuable tools for in vitro study of the human immune response against pig endothelial cells. In addition, they would be very useful to gain insight in the pathogenesis of some viral haemorrhagic diseases of pig such as African swine fever (ASF) or classical swine fever (CSF).  相似文献   

An Aqueous Extract of the Dry Mycelium of Penicillium chrysogenum Induces Resistance in Several Crops under Controlled and Field Conditions     

Barbara Thuerig  Andres Binder  Thomas Boller  Urs Guyer  Sonia Jiménez  Christina Rentsch  Lucius Tamm 《European journal of plant pathology / European Foundation for Plant Pathology》2006,114(2):185-197

We have examined the effect of Pen, an aqueous extract of the dry mycelium of Penicillium chrysogenum, on plant–pathogen interactions. Pen controlled a broad range of pathogens on several crop plants under greenhouse and field conditions. Pen protected grapevine from downy and powdery mildew (caused by Plasmopara viticola and Uncinula necator), tomato from early blight (caused by Phytophthora infestans), onion from downy mildew (Peronospora destructor) and apple trees from apple scab (caused by Venturia inaequalis) to a similar extent as fungicides such as copper and sulphur or well-known inducers such as benzothiadiazole or β-aminobutyric acid. Pen had no major direct fungicidal effect and is thus supposed to protect plants by activating their defense mechanisms. The raw material for extraction of Pen was available in constant quality, a prerequisite for commercial application. Under certain conditions, Pen caused phytotoxic side effects. The symptoms mostly consisted of small necrotic spots or, more rarely, of larger necrotic areas. The development of the symptoms was dependent on several parameters, including concentration of Pen, the number of applications, the persistence on the plant tissue, the plant species and variety and environmental conditions. In grapevine, a partially purified fraction of Pen was much less toxic than the crude Pen extract, but protected the plants to a similar extent against P. viticola. Our data show that Pen has interesting and unique properties as a plant protection agent, but more research is needed to further reduce its phytotoxic side effects.  相似文献   

Stomatal responses to drought at a Mediterranean site: a comparative study of co-occurring woody species differing in leaf longevity     

Mediavilla S  Escudero A 《Tree physiology》2003,23(14):987-996

We studied stomatal responses to decreasing predawn water potential (Psipd) and increasing leaf-to-air water vapor pressure difference (VPD) of co-occurring woody Mediterranean species with contrasting leaf habits and growth form. The species included two evergreen oaks (Quercus ilex subsp. ballota (Desf.) Samp. and Q. suber L.), two deciduous oaks (Q. faginea Lam. and Q. pyrenaica Willd.) and two deciduous shrubs (Pyrus bourgaeana Decne. and Crataegus monogyna Jacq.). Our main objective was to determine if stomatal sensitivity is related to differences in leaf life span and leaf habit. The deciduous shrubs had the least conservative water-use characteristics, with relatively high stomatal conductance and low stomatal sensitivity to soil and atmospheric drought. As a result, Psipd decreased greatly in both species during the growing season, resulting in early leaf abscission in the summer. The deciduous oaks showed intermediate water-use characteristics, having maximum stomatal conductances and CO2 assimilation rates similar to or even higher than those of the deciduous shrubs. However, they had greater stomatal sensitivity to soil drying and showed less negative Psipd values than the deciduous shrubs. The evergreen oaks, and especially the species with the greatest leaf longevity, Q. ilex, exhibited the most conservative water-use behavior, having lower maximum stomatal conductances and greater sensitivity to VPD than the deciduous species. As a result, Psipd decreased less during the growing season in the evergreens than in the deciduous species, which may contribute to greater leaf longevity by avoiding irreversible damage during the summer drought. However, the combination of low maximum CO2 assimilation rates and high stomatal sensitivity to drought must have a negative impact on the final carbon budget of leaves with a long life span.  相似文献   

Applied Behavior Analysis as a Development Tool: Examples from Agroforestry     

Sonia M. Goltz  Audrey L. Mayer 《Journal of Sustainable Forestry》2020,39(8):785-799

ABSTRACT

Applied behavior analysis can be used by development practitioners to improve the design and implementation of development programs. Programs are most successful when the goals and consequences of change agents, strategists, and adopters align, as we demonstrate with real-world examples from international agroforestry projects. We focus on the role of change agents acting as intermediaries between change strategists, such as large development agencies, and development adopters, the rural farmers who implement agroforestry projects. We describe three aspects that are particularly important for agroforestry projects: (1) identifying the rules being used, (2) assessing the roles and reinforcement contingencies of both individuals and larger groups, and (3) being flexible and able to respond to rapid change.  相似文献   

Irrigation effects on quality, phenolic composition, and selected volatiles of virgin olive oils cv. Leccino   总被引：1，自引：0，他引：1  

Servili M  Esposto S  Lodolini E  Selvaggini R  Taticchi A  Urbani S  Montedoro G  Serravalle M  Gucci R 《Journal of agricultural and food chemistry》2007,55(16):6609-6618

Field-grown olive trees (Olea europaea L. cv. Leccino) were used over two growing seasons to determine the effect of deficit irrigation regimes on virgin olive oil (VOO) quality. Drip irrigation was managed to maintain a predawn leaf water potential (PLWP): (a) higher than -1.1 MPa (full irrigation: FI); (b) between -1.0 and -3.3 MPa (deficit irrigation: DI); (c) higher than -4.2 MPa (severe deficit irrigation: SI). The fruit yield and oil yield of DI trees were over 90% of those of FI treatments in both years, respectively, whereas yields of SI trees ranged from 61 to 76%. The irrigation regime had minor effects on the free acidity, peroxide value, and fatty acid composition of VOO. The concentrations of phenols and o-diphenols in VOO were negatively correlated with PLWP. The concentrations of the dialdehydic form of decarboxymethyl elenolic acid linked to (3,4-dihydroxyphenyl)ethanol (3,4-DHPEA-EDA), the isomer of the oleuropein aglycon (3,4-DHPEA-EA), and the dialdehydic form of decarboxymethyl elenolic acid linked to (p-hydroxyphenyl)ethanol (p-HPEA-EDA) were lower in FI than in SI treatments. The concentrations of lignans (+)-1-acetoxipinoresinol and (+)-1-pinoresinol were unaffected by the irrigation regime. The tree water status had a marked effect on the concentration of volatile compounds, such as the C(6)-saturated and unsaturated aldehydes, alcohols, and esters.  相似文献   

Yucca gloriosa: a source of phenolic derivatives with strong antioxidant activity     

Bassarello C  Bifulco G  Montoro P  Skhirtladze A  Benidze M  Kemertelidze E  Pizza C  Piacente S 《Journal of agricultural and food chemistry》2007,55(16):6636-6642

On the basis of the biological activities exhibited by the phenolic constituents of Yucca schidigera, the antioxidant activity of the methanol extract of Yucca gloriosa roots was evaluated in the TEAC assay. The strong activity exerted by this extract prompted investigation of its phenolic constituents, yielding three new phenolic derivatives, gloriosaols C, D, and E, along with gloriosaols A and B previously isolated from Y. gloriosa roots and yuccaols C-E isolated from Y. schidigera. ESIMS and NMR data of gloriosaols C-E closely resembled those reported for gloriosaols A and B, two diasteroisomers characterized by unusual spirostructures. Careful inspection of ROESY spectra revealed that gloriosaols C-E are diastereoisomers of gloriosaols A and B. A possible assignment of the relative configuration of gloriosaols C-E, derived according to an integrated NMR-quantum mechanical (QM) approach, which was already applied to the determination of the stereostructures of gloriosaols A and B, is also proposed. Gloriosaols A-E exhibited potent antioxidant activity measured by the TEAC assay, showing the potential use of Y. gloriosa as a source of antioxidant principles.  相似文献   

Lipoxygenase distribution in coffee (Coffea arabica L.) berries     

Patui S  Peresson C  Braidot E  Tubaro F  Colussi A  Bonnländer B  Macrì F  Vianello A 《Journal of agricultural and food chemistry》2007,55(20):8223-8230

In this paper lipoxygenase (LOX) presence was investigated in coffee berries to determine its involvement in lipid degradative metabolism of plants grown in organic and conventional cultivations. An immunochemical analysis has evidenced a ca. 80 kDa protein, cross-reacting with an anti-LOX antibody, only in the pulp fraction of berries obtained from plants of both cultivations. LOX activity in this fraction could be monitored either as conjugated diene formation or reaction products (determined by HPLC) and was mainly associated with a heavy membrane fraction (HMF, enriched in tonoplast, endoplasmic reticulum, plasma membrane, and mitochondria) and a light membrane fraction (LMF, enriched in plasma membrane and endoplasmic reticulum, with low levels of tonoplast and mitochondria). The LOX activity of LMF from berries of both cultivations showed an optimum at pH 8.0. The HMF exhibited a different activity peak in samples from conventional (pH 8.0) and organic (pH 5.5) cultures, suggesting the presence of different isoenzymes. These findings were also confirmed by variation of the ratio of 9- and 13-hydroperoxides in organic (1:1) and conventional cultivations (1:10), indicating that the organic one was subjected to an oxidative stress in the coffee pulp fraction leading to the expression of an acidic LOX. Such de novo synthesized LOX activity could be responsible for the production of secondary metabolites, which may interfere with the organoleptic profile of coffee.  相似文献   

Radiographic evaluation of positional atelectasis in sedated dogs breathing room air versus 100% oxygen     

Michele Barletta  Donna Almondia  Jamie Williams  Sonia Crochik  Erik Hofmeister 《The Canadian veterinary journal. La revue veterinaire canadienne》2014,55(10):985-991

This study documents the degree of positional atelectasis in sedated dogs receiving 100% oxygen (O₂) versus room air. Initial lateral recumbency was determined by an orthopedic study and initial treatment (O₂ or room air) was randomized. Each dog was maintained in lateral recumbency for 15 min, at which time ventrodorsal (VD) and opposite lateral thoracic radiographs were obtained. Each dog was then maintained in the opposite lateral recumbency and received the other treatment for 15 min, followed by a VD and opposite lateral radiograph. Radiographs were scored for severity of pulmonary pattern and mediastinal shift by 3 radiologists. Dogs breathing O₂ had significantly higher scores than dogs breathing room air. If radiographically detectable dependent atelectasis is present, repeat thoracic images following manual positive ventilation and/or position change to the opposite lateral recumbency should be made to rule out the effect of O₂ positional atelectasis and avoid misdiagnosis.  相似文献   

Immune characterization of long pentraxin 3 in pigs infected with influenza virus     

Elisa Crisci  Lorenzo Fraile  Sonia Valentino  Laura Martínez-Guinó  Barbara Bottazzi  Alberto Mantovani  Maria Montoya 《Veterinary microbiology》2014

Long pentraxin 3 (PTX3) is a conserved pattern-recognition secreted protein and a host-defence-related component of the humoral innate immune system. The aim of the present study was to characterize swine PTX3 (SwPTX3) protein expression in influenza virus infected pigs. First, we performed in silico studies to evaluate the cross-reactivity of PTX3 human antibodies against SwPTX3. Secondly, we used in vitro analysis to detect SwPTX3 presence in swine bone marrow dendritic cells (SwBMDC) upon stimulation with different agents by Western blot and immunofluorescence. Finally, the levels of SwPTX3 were assessed in experimental infection of pigs with different strains of influenza virus. This is a novel study where the expression of SwPTX3 was evaluated in the context of a pathogen infection. The initial characterization of SwPTX3 in influenza virus infected pigs contributes to understand the role of PTX proteins in the immune response.  相似文献