First record of Pseudomonas syringae pv. viburni in the UK     

D. E. Stead  H. Stanford  A. Aspin  S. A. Weller 《Plant pathology》2006,55(4):571-571

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Improved methods for quantifying potential nutrient interception by riparian buffers   总被引：1，自引：0，他引：1  

Matthew E. Baker  Donald E. Weller  Thomas E. Jordan 《Landscape Ecology》2006,21(8):1327-1345

Efforts to quantify the effects of riparian buffers on watershed nutrient discharges have been confounded by a commonly used analysis, which estimates buffer potential as the percentage of forest or wetland within a fixed distance of streams. Effective landscape metrics must instead be developed based on a clear conceptual model and quantified at the appropriate spatial scale. We develop new metrics for riparian buffers in two stages of increasing functional specificity to ask: (1) Which riparian metrics are more distinct from measures of whole watershed land cover? (2) Do functional riparian metrics provide different information than fixed-distance metrics? (3) How do these patterns vary within and among different physiographic settings? Using publicly available geographic data, we studied 503 watersheds in four different physiographic provinces of the Chesapeake Bay Drainage. In addition to traditional fixed-distance measures, we calculated mean buffer width, gap frequency, and measures of variation in buffer width using both “unconstrained” metrics and “flow-path” metrics constrained by surface topography. There were distinct patterns of relationship between watershed and near-stream land cover in each physiographic province and strong correlations with watershed land cover confounded fixed-distance metrics. Flow-path metrics were more independent of watershed land cover than either fixed-distance or unconstrained measures, but both functional metrics provided greater detail, interpretability, and flexibility than the fixed-distance approach. Potential applications of the new metrics include exploring the potential for land cover patterns to influence water quality, accounting for buffers in statistical nutrient models, quantifying spatial patterns for process-based modeling, and targeting management actions such as buffer restoration.  相似文献   

The arthroscopic approach and intra-articular anatomy of the equine temporomandibular joint     

Weller R  Maierl J  Bowen IM  May SA  Liebich HG 《Equine veterinary journal》2002,34(4):421-424

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Comparison of Three Methods for Monitoring Populations of Different Genotypes of 2,4-Diacetylphloroglucinol-Producing Pseudomonas fluorescens in the Rhizosphere     

Landa BB  de Werd HA  McSpadden Gardener BB  Weller DM 《Phytopathology》2002,92(2):129-137

ABSTRACT Pseudomonas fluorescens strains producing the antibiotic 2,4-diacetylphloroglucinol (DAPG) have biocontrol activity against a broad spectrum of root and seedling diseases. In this study, we determined the effect of genotype on the ability to isolate and quantify introduced 2,4-DAPG producers from the rhizosphere of wheat using three different methods: traditional dilution plating on selective media, colony hybridization followed by polymerase chain reaction (PCR), and phlD-specific PCR-based dilution endpoint assay. Regression analysis of the population densities of 10 2,4-DAPG-producing P. fluorescens, representing five genotypes, determined by the three different methods demonstrated that the relationship was linear (P < 0.001) and the techniques were very similar (i.e., slopes equal to 1.0). The phlD-specific PCR-based assay had a slightly lower limit of detection than the other two methods (log 3.3 versus log 4.0 CFU/g of fresh root weight). With the colony hybridization procedure, we observed that the phlD probe, derived from strain P. fluorescens Q8r1-96, hybridized more strongly to colonies of BOX-PCR genotypes D (strains W2-6, L5.1-96, Q8r1-96, and Q8r2-96) and K (strain F113) compared with strains of genotypes A (Pf-5 and CHA0), B (Q2-87), and L (1M1-96 and W4-4). Colony hybridization alone overestimated the actual densities of some strains, thus requiring an additional PCR step to obtain accurate estimates. In contrast, population densities estimated for three of the bacterial treatments (strains CHA0, W2-6, and Q8r2-96) with the PCR-based assay were significantly (P < 0.041) smaller by 7.6 to 9.2% and 6.4 to 9.4% than population densities detected by the dilution plating and colony hybridization techniques, respectively. In this paper, we discuss the relative advantages of the different methods for detecting 2,4-DAPG producers.  相似文献   

Regionalisation of the muscle fascicle architecture in the equine longissimus dorsi muscle     

Ritruechai P  Weller R  Wakeling JM 《Equine veterinary journal》2008,40(3):246-251

REASON FOR PERFORMING STUDY: The longissimus dorsi is the largest muscle in the equine back and plays an important role in locomotor ability and performance in the horse. In vivo studies suggest that the mechanical function varies between different muscle segments, in part determined by anatomy. It is possible therefore that variations in function reflect variations in the anatomy of the longissimus dorsi along its length. OBJECTIVES: To identify if there are regional variations in muscle architecture of the longissimus dorsi. METHODS: Computed tomography scans were obtained from 8 cadaver backs to identify the cross-sectional area and volume of the muscle. The 3D orientations of the muscle fascicles were quantified in situ by their direction cosines using a magnetic digitisation system. RESULTS: Mean +/- s.e. volume of the muscle was 2.34 +/- 0.18 l for each side and mean length of the vertebral column from T4 to L6 dorsal spinous processes was 56.57 +/- 2.0 cm. There were significant differences in the cross-sectional area and the moment arm lengths between muscle segments (P<0.05). In the lumbar region, the mediolateral moment arms were 2-3 times greater than the dorsoventral moment arms. There were significant variations in the direction cosines (n = 7129) between muscle segments and between different regions within each segment (P<0.05). POTENTIAL RELEVANCE: These observations indicate that the muscle fascicle architecture predisposes the longissimus dorsi to different functions both along its length and between different regions within each segment. Detailed 3D anatomical measures of the structure with in vivo measures of function (back motion and muscle activity) will be investigated in further studies.  相似文献   

The Nature of the Iron Compounds in Red and Yellow Sandstone     

Hofer LJ  Weller S 《Science (New York, N.Y.)》1947,106(2759):470

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Assessment of the potential toxicity of a poison for rabbits, pindone (2-pivalyl 1, 3 indandione), to domestic animals     

GR MARTIN  RJ SUTHERLAND†  ID ROBERTSON†  WE KIRKPATRICK  DR KING  PJ HOOD† 《Australian veterinary journal》1991,68(7):241-243

The toxicity of pindone, a rabbit poison, to horses, cattle, goats, chickens, dogs and cats was investigated, using extension of prothrombin time (PT) as an index of poisoning. The daily dose of pindone, administered for 5 days, ranged from 0.3 mg/kg for dogs to 2.5 mg/kg for chickens. This range of dose rates was considered to be indicative of the worst possible case that could arise following a campaign of baiting for rabbits. Although significant elevations in PT (more than double baseline values) were noted in all species other than horses, clinical signs of anticoagulant poisoning were not observed in any of the species tested. From the observed PT, cattle and cats appeared to be the most susceptible, and horses the least susceptible, to pindone toxicity. The half-lives of the elevated PT were calculated as 3.1 days for cattle, 2.8 days for goats and chickens, 1.9 days for horses and dogs and less than one day for cats. It is proposed that these half-lives can be used as a guide for determining the duration of treatment of pindone-affected animals.  相似文献   

Trichophyton verrucosum infections in sheep     

P Kielstein  W Weller 《Monatshefte für Veterin?rmedizin》1965,20(16):671-675

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Rhizogenic Agrobacterium biovar 1 and cucumber root mat in the UK     

Weller  Stead  O'neill  Hargreaves  & McPherson 《Plant pathology》2000,49(1):43-50

An unusual root disease of cucumbers has affected an increasing number of hydroponic crops in the UK since 1993. Symptoms include upward growth of roots, root proliferation sufficient to distort the shape of rockwool cubes and slabs, thickened roots and occasionally reduced root production and an increase in bent fruit. Rhizogenic Agrobacterium biovar 1 has previously been associated with the problem. In a survey of 37 nurseries in 1997, rhizogenic Agrobacterium bv. 1 isolates were obtained from 17 of 22 nurseries with symptoms and only occasionally from nurseries without symptoms. Young cucumber plants inoculated with rhizogenic Agrobacterium bv. 1 isolates, previously obtained from cucumber roots with symptoms, developed typical symptoms. The survey data and pathogenicity test support rhizogenic Agrobacterium bv. 1 as the primary causal agent of root mat in the UK. Although Agrobacterium bv. 1 isolates that do not harbour an Ri-plasmid are considered avirulent, their abundance in rockwool slabs as potential vectors of the Ri-plasmid may be a major factor in the epidemiology of the disease.  相似文献   

Extraction and Characterization of Lipids from the Kernels,Leaves, and Stalks of Nine Grain Sorghum Parent Lines     

K. L. Christiansen  C. L. Weller  V. L. Schlegel  S. L. Cuppett  T. P. Carr 《Cereal Chemistry》2007,84(5):463-470

The objectives of this study were to identify and quantify lipid classes extracted from the stalk, leaves, and the whole kernels of nine different sorghum parent lines. All extractions were performed with a Soxtec using n-hexane as the extraction solvent. Analytical methods including high-performance liquid chromatography (HPLC), gas chromatography (GC), and thin-layer chromatography (TLC) were used to identify and quantify the extracted lipid classes: triacylglycerides (TAG), diglycerides (DG), policosanols (PA), free sterols (FS), phytosterols (PS), free fatty acids (FFA), tocopherols (T), and fatty aldehydes. Overall, extracts from the leaves had higher amounts of soluble matter. Extracts from leaves contained more alcohols and sterols, whereas extracts from the stalks and the whole kernels contained the greatest amount of free fatty acids and fatty aldehydes, respectively. Trace amounts of tocopherol were detected by HPLC in all 27 samples. The lipid profiles of extracts from the whole kernels, leaves, and stalks from the same plant differed. The lipid profiles of extracts from each anatomical part of the sorghum plant differed between the nine parent lines.  相似文献