The Occurrence of dsRNA Species in Apparently Healthy and Virus-infected Ribes Cultivars, and Evidence That One Such Species Originates from a Member of the Virus Family Totiviridae     

Sarah Cox  M.A. Mayo  A. Teifion Jones 《European journal of plant pathology / European Foundation for Plant Pathology》2000,106(4):353-364

Analysis was made of dsRNA in 37 cultivars and species of Ribes, that were healthy, naturally affected with the virus-like diseases, blackcurrant yellows, blackcurrant infectious variegation, gooseberry veinbanding or blackcurrant reversion, or graft-inoculated with scions from such diseased plants. Various dsRNA species, differing in size (from ca. 2 to 11kbp), number and staining intensity in gels, were detected in some or all assays of all plants, including those held as virus-tested stock. In different plant tissues from individual plants, the dsRNA species were usually similar in size and number but, in some sources, the dsRNA profile from flowers and/or bark differed greatly from the profiles of dsRNA obtained from leaves. No dsRNA species were associated consistently with any of these diseases. A 499kbp cDNA probe was obtained that in Northern blot analysis was specific to a ca. 5kbp dsRNA species present in the blackcurrant cv. Baldwin. It also detected a similarly sized dsRNA species in plants of many other blackcurrant cultivars, but it did not react with a similarly sized dsRNA species in redcurrant and gooseberry tissues. The 156 amino acid sequence encoded by the cDNA was very similar to sequences in the RNA-directed RNA polymerases of virus species in the family Totiviridae, especially Saccharomyces cerevisiae viruses L-1 and L-A. The significance of these findings and the possible origin of these dsRNA species are discussed.  相似文献   

Historical Perspectives of Rabies in Europe and the Mediterranean Basin     

Dr Sarah Cleaveland 《Tropical animal health and production》2006,38(2):169-170

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Searching for veterinary evidence: strategies and resources for locating clinical research.     

Sarah Anne Murphy 《Veterinary Clinics of North America: Small Animal Practice》2007,37(3):433-445

This article offers information regarding selected veterinary information resources, along with basic search strategies for locating clinical evidence within these resources. No one database provides adequate indexing and abstracting to all literature relevant to the veterinary clinical question. An understanding of a database's syntax and field structure is necessary to formulate a functional search strategy and evaluate the outcome of search results. Flexibility when identifying, selecting, and combining search terms is also required to avoid overlimiting a search.  相似文献   

Evidence-Based Equine Nutrition     

Sarah L. Ralston 《Veterinary Clinics of North America: Equine Practice》2007

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Ecological Issues in a Changing World     

Sarah Goslee 《Landscape Ecology》2006,21(4):629-630

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Testing assumptions of cost surface analysis—a tool for invasive species management   总被引：1，自引：0，他引：1  

Emily K. Gonzales  Sarah E. Gergel 《Landscape Ecology》2007,22(8):1155-1168

Applied ecology could benefit from new tools that identify potential movement pathways of invasive species, particularly where data are sparse. Cost surface analysis (CSA) estimates the permeability (friction) across a landscape and can be applied to dispersal modelling. Increasingly used in a diversity of applications, several fundamental assumptions that might influence the outputs of CSA (cost surfaces and least-cost pathways) have yet to be systematically examined. Thus, we explore two issues: the presumed relationship between habitat preferences and dispersal behaviour as well as the degree of landscape fragmentation through which an organism moves by modelling a total of 18 sensitivity and dispersal scenarios. We explored the effect of fragmentation by altering the friction values (generally assigned using expert opinion) associated with patch and linear features. We compared these sensitivity scenarios in two sites that differed in fragmentation. We also used eastern grey squirrels (Sciurus carolinensis) as an example invading species and compared diffusion models and two contrasting cost surface dispersal scenarios. The diffusion model underestimated spread because squirrels did not move randomly through the landscape. Despite contrasting assumptions regarding dispersal behaviour, the two cost surfaces were strikingly similar while the least-cost paths differed. Furthermore, while the cost surfaces were insensitive to changes in friction values for linear features, they were sensitive to assumptions made for patch features. Our results suggest that movement in fragmented landscapes may be more sensitive to assumptions regarding friction values than contiguous landscapes. Thus, the reliability of CSA may depend not only on the range of friction values used for patches but also the degree of contiguity in the landscape.  相似文献   

The spore coat of the bean anthracnose fungus Colletotrichum lindemuthianum is required for adhesion, appressorium development and pathogenicity     

Sarah L. Rawlings  Richard J. O&#x;Connell  Jonathan R. Green 《Physiological and Molecular Plant Pathology》2007,70(4-6):110-119

The spores (conidia) of the bean anthracnose fungal pathogen, Colletotrichum lindemuthianum, adhere to the aerial parts of plants to initiate the infection process. In previous studies we have shown that the Colletotrichum spores are surrounded by a fibrillar spore coat, comprising several major glycoproteins. Previous evidence showed that a monoclonal antibody (UB20) that recognised these glycoproteins was able to inhibit adhesion of spores to a hydrophobic surface. In this paper we have further studied the role of the spore coat in adhesion, germination and fungal development by studying the effects of UB20 and protease treatment of spores. The latter treatment has previously been shown to remove the spore coat. Spores germinate on glass, polystyrene and water agar, however, appressoria only develop on glass or polystyrene, showing a requirement for a hard surface. Removal of the spore coat with protease inhibits adhesion at 30 min, before the secretion of ECM glycoproteins. Protease treatment also inhibits the development of appressoria and reduces pathogenicity on leaves. Incubation of spores with the MAb UB20 inhibits adhesion at 30 min, but does not affect appressorium formation or pathogenicity. The results suggest that an intact spore coat has two functions; it is required for adhesion to a hydrophobic surface and for the detection of a hard surface necessary for appressorium formation. We suggest that contact with a hard surface, rather than adhesion, is the key event leading to appressorium formation.  相似文献   

Density and Organic Matter Influence on Egg‐laying and Hatching of Branchiura sowerbyi (Oligochaeta)     

Karine Cristiane Rech  Renata Maria Guereschi  Alex Pires de Oliveira Nuñer  Sarah Carvalho Sticca 《Journal of the World Aquaculture Society》2013,44(2):267-272

This study aimed to assess the combined effects of density of adults of Branchiura sowerbyi and the source of organic matter on the production of eggs and young species. The experimental units used were 250‐mL beakers with 100 mL of fine sand (0.074–0.210 mm) and 150 mL of chlorine‐free water with constant aeration at the temperature 25 C. The experiment was conducted based on a two‐factor model with six treatments and three repetitions, applied in a completely random design. The densities 5 individuals/38.5cm² (D5; 1298/m²) and 8 individuals/38.5cm² (D8; 2078/m²) were assessed with commercial fish feed (FF), commercial poultry feed (PF), and turkey manure (TM) as sources of organic matter. A total of 1223 cocoons and 2138 eggs were produced, with average hatching of 40.0 ± 15.1%. The highest number of cocoons and eggs was found with the use of PF, D8 having produced the highest number of cocoons and eggs. The hatching rate was not influenced by the source of organic matter or density and no influence was registered from the density of adults on the survival. The PF provided the highest growth of adults, and generally the use of TM provided the worst performance.  相似文献   

Physiological Responses of Rainbow Trout Oncorhynchus mykiss to Crowding and Anesthesia with AQUI-S™     

Glen W.  Davidson Peter S.  Davie Graham  Young Reece T.  Fowler 《Journal of the World Aquaculture Society》2000,31(1):105-114

Abstract.— Following exposure to the anesthetic AQUI-S™, plasma cortisol concentration in immature rainbow trout was measured as (mean) 293 ± 48 ng/ mL, which was significantly ( P > 0.05) higher than the mean concentration in resting fish. Cortisol concentrations remained significantly ( P > 0.05) elevated for at least 24 h after treatment. This was accompanied by a significant increase and decrease in hematocrit and plasma potassium, respectively. These perturbations continued for at least 48 h following recovery from anesthesia. Plasma concentrations of total protein and sodium remained unchanged following anesthesia with AQUI-S™. Crowding stress is commonly encountered by fish during manipulation in aquaculture situations. Anesthetising fish prior to, and during, manipulation may reduce the associated stress. Changes in cortisol values resulting from crowding (30 min; 0.1 kg/L) during anesthesia with AQUI-S™ were not appreciably different from those in fish crowded without anesthesia. Thus, anesthesia with AQUI-S™ at the recommended dose of 17 mg/L did not appear to be effective for alleviating the stress of crowding under the conditions of our experiments.  相似文献   

Red cell population distributions in healthy dogs     

G M Bell  J S Fowler 《Research in veterinary science》1985,38(2):220-225

Red blood cells population distributions were studied in puppies and in mature beagle dogs using the Coulter Channelyzer C-1000. Weekly measurements over a period of six months indicated that only minor fluctuations in population distribution indices occurred. Normal range studies showed that although mean cell volume was similar in young and older dogs, young dogs showed an approximately 12.5 per cent greater volume range due to an increased presence of both larger and smaller cells. The red cell population distributions conformed to a single log normal distribution. A mild anaemia was induced in mature dogs. Compensation for this led to transient changes from the usual log normal shape of the red cell population distribution.  相似文献