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Jessica J. Buss Kathryn H. Wiltshire Thomas A. A. Prowse James O. Harris Marty R. Deveney 《Journal of fish diseases》2019,42(1):63-74
Bonamia spp. parasites threaten flat oyster (Ostrea spp.) farming worldwide. Understanding test performance is important for designing surveillance and interpreting diagnostic results. Following a pilot survey which found low Bonamia sp. intensity in farmed Ostrea angasi, we tested further oysters (n = 100–150) from each of three farms for Bonamia sp. using heart smear, histology and qPCR. We used a Bayesian Latent Class Model to assess diagnostic sensitivity (DSe) and specificity (DSp) of these tests individually or in combination, and to assess prevalence. Histology was the best individual test (DSe 0.76, DSp 0.93) compared to quantitative polymerase chain reaction (qPCR) (DSe 0.69, DSp 0.93) and heart smear (DSe 0.61, DSp 0.60). Histology combined with qPCR and defining a positive from either test as an infected case maximized test performance (DSe 0.91, DSp 0.88). Prevalence was higher at two farms in a high‐density oyster growing region than at a farm cultivating oysters at lower density. Parasite intensities were lower than in New Zealand and European studies, and this is probably contributed to differences in the performance of test when compared to other studies. Understanding diagnostic test performance in different populations can support the development of improved Bonamia surveillance programs. 相似文献
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Gene flow between introduced and native Eucalyptus species 总被引：2，自引：0，他引：2
Barbour Robert C. Potts Brad M. Vaillancourt René E. Tibbits Wayne N. Wiltshire Robert J.E. 《New Forests》2002,23(3):177-191
The first evidence of in situ F1 hybridisation between an introduced eucalypt plantation species, Eucalyptus nitens, and a native eucalypt species is presented. Open-pollinated seed was collected from a mature E. nitens trial and from the adjacent native species, E. ovata and E. viminalis on the island of Tasmania. Nearly 70 000 seedlings were grown to a size at which hybrids could be clearly distinguished from pure species seedlings on the basis of morphology and a nearly species-specific isozyme allele. Hybridisation was observed between E. nitens and E. ovata, but no hybrids involving E. viminalis were found. This pattern of hybridisation was consistent with the flowering time overlap between the E. ovata and E. nitens. Eucalyptus nitens progenies displayed a low and relatively homogeneous level of hybridisation, averaging 0.15% per tree. In comparison, the proportion of hybrids obtained from the adjacent E. ovata trees varied from 0.04 to 16% per tree. Whether progeny arising from such hybridisation will survive and grow in nature to allow for backcrossing and introgression of the exotic genes into the native population is not yet known. 相似文献
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Teeling H Fuchs BM Becher D Klockow C Gardebrecht A Bennke CM Kassabgy M Huang S Mann AJ Waldmann J Weber M Klindworth A Otto A Lange J Bernhardt J Reinsch C Hecker M Peplies J Bockelmann FD Callies U Gerdts G Wichels A Wiltshire KH Glöckner FO Schweder T Amann R 《Science (New York, N.Y.)》2012,336(6081):608-611
Phytoplankton blooms characterize temperate ocean margin zones in spring. We investigated the bacterioplankton response to a diatom bloom in the North Sea and observed a dynamic succession of populations at genus-level resolution. Taxonomically distinct expressions of carbohydrate-active enzymes (transporters; in particular, TonB-dependent transporters) and phosphate acquisition strategies were found, indicating that distinct populations of Bacteroidetes, Gammaproteobacteria, and Alphaproteobacteria are specialized for successive decomposition of algal-derived organic matter. Our results suggest that algal substrate availability provided a series of ecological niches in which specialized populations could bloom. This reveals how planktonic species, despite their seemingly homogeneous habitat, can evade extinction by direct competition. 相似文献
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Agronomic evaluation of precise mechanical hoeing and chemical weed control in sugar beet 总被引：1，自引：0，他引：1
Most herbicide applications to sugar beet (Beta vulgaris L.) are made to the whole crop area, but there is the opportunity to restrict applications to the crop row, decreasing the usage of herbicide by up to 70%. However, this would require greater use of mechanical weed control between rows. Experiments were performed in two seasons to evaluate the weed control performance of a novel, vision‐guided, inter‐row hoe in sugar beet crops grown on a peat fen soil. Hoe lateral placement was within ±30 mm. A precise hoeing and band spraying treatment was compared with overall herbicide use, and with treatments in which the herbicide applications were replaced by hand weeding to minimize competition between crop and weeds. Two hoe passes were made in each season, at crop growth stages of two and 10–12 true leaves in the first season and four and eight true leaves in the second season. Plant population density was not affected by treatment, indicating that none of the treatments caused crop plant loss. Use of the guided hoe controlled weeds better than overall spraying. Crop yields were not significantly different between treatments, indicating that weed control prevented competition with the crop in all treatments. 相似文献
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A morphological abnormality occurring in micro-propagated strawberry plants is described and illustrated. The condition is recognised in established micro-propagated plants by an abnormal phyllotaxy which results typically in 2 or more young leaves emerging together rather than singly and by an excessive number of small branch crowns being produced. Dissection shows that the abnormality originates at the apex and is manifest as a linear (or less often as a circular) arrangement of multiple apices. Such multi-apexing plants “bud-off” normal single-apexed crowns from time to time but the abnormality can persist in the main shoot for 2 years (the limit of our observations). The multi-apexing differs fundamentally from clusters of single apices which, when removed from culture and separated, give rise to normal single-crowned plants.Similarities between the multi-apexing condition and fasciation in other plant species are discussed. Changes in growth regulator constituents of the culture media are shown to control the incidence of multi-apexing. In the presence of indole-3-butyric acid (IBA), higher 6-benzyl-aminopurine (BA) concentration increases the frequency, while adding gibberellin (GA3) decreases the incidence of affected plantlets. The frequency of abnormality varies greatly between different cultivars.It is suggested that conditions favouring greater proliferation rates in culture may also favour multi-apexing. Results indicate that multi-apexing can be avoided by using appropriate concentrations of growth regulators in culture media which will concomitantly maintain a good proliferation rate. 相似文献
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Wiltshire MC Pendry JB Young IR Larkman DJ Gilderdale DJ Hajnal JV 《Science (New York, N.Y.)》2001,291(5505):849-851
Magnetic resonance imaging and spectroscopy systems use coils, either singly or as arrays, to intercept radio-frequency (RF) magnetic flux from regions of interest, often deep within the body. Here, we show that a new magnetic material offers novel possibilities for guiding RF flux to the receiver coil, permitting a clear image to be obtained where none might otherwise be detectable. The new material contains microstructure designed according to concepts taken from the field of photonic band gap materials. In the RF range, it has a magnetic permeability that can be produced to specification while exhibiting negligible direct-current magnetism. The latter property is vital to avoid perturbing the static and audio-frequency magnetic fields needed to obtain image and spectral data. The concept offers a new paradigm for the manipulation of RF flux in all nuclear magnetic resonance systems. 相似文献
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D D Morris J N Moore N Wiltshire K Fischer 《American journal of veterinary research》1989,50(5):747-750
A study was performed to determine the effect of proadifen hydrochloride on prostacyclin (prostaglandin I2 [PGI2]) and thromboxane A2 (TxA2) synthesis by equine peritoneal macrophages and the effect of proadifen on endotoxin-induced synthesis of PGI2 and TxA2 by equine macrophages. Peritoneal macrophages (2.5 x 10(6)/ml) were incubated for 6 hours in tissue culture media containing 1) nothing (nontreated control), 2) proadifen hydrochloride (20, 100, 250, and 500 mumol/L, 3) endotoxin (5 ng/ml), or 4) the calcium ionophore A23187 (0.95 mumol/L). In a second series of experiments, peritoneal macrophages were incubated with endotoxin (5 ng/ml) and proadifen (250 umol/L), for 6 hours. Concentrations of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) and thromboxane B2, the stable metabolites of PGI2 and TxA2, were determined in the incubation media by radioimmunoassay. Proadifen caused increased synthesis of PGI2 by equine macrophages, without affecting TxA2 production. The increased PGI2 production was similar to that induced by endotoxin and calcium ionophore; however, the latter 2 agents significantly stimulated TxA2 production as well (P less than 0.05). There were no significant differences among mean concentrations of 6-keto-PGF1 alpha in media from macrophages treated with 100, 250, or 500 mumol/L proadifen, but there was a significant curvilinear regression between their concentrations. The ratio of thromboxane B2 to 6-keto-PGF1 alpha was significantly lower than baseline in incubation media from macrophages exposed to proadifen, endotoxin, and calcium ionophore. Proadifen hydrochloride did not significantly change equine peritoneal macrophage production of PGI2 or TxA2 in response to endotoxin. 相似文献
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D.L. Barnes M. Swart M.F. Smith G.H. Wiltshire 《African Journal of Range and Forage Science》2013,30(3):92-98
Forty systematically‐placed observation points were established in a 1.5‐ha area of floristically unifoim veld in which productivity varied spatially. At each point grass yields were determined by harvesting quadrats at eight‐week intervals during the growing season, and the volumetric water content of the soil was measured weekly. In addition, root mass and root‐N content, and soil variables involving C and N contents, extractable P, K, Ca and Mg, cation exchange capacity and base saturation, pH, clay content and soil depth, were determined. The data were examined using linear correlations between variables, principal components analysis and multiple regression. The major factors associated with variations in yield were, in order of importance, soil water content, the N supply (as expressed by root‐N content or root‐N mass) and the cation supply (as expressed by the topsoil variables, extractable Ca or cation exchange capacity or percentage base saturation). There was a relatively weak positive association between yields and the H+ concentration in the subsoil, and a weak negative association between yields and the clay content of the topsoil. A multiple regression function involving all five factors accounted for 77.3% of the variation in dry matter yield. 相似文献