Prevalence of Mycoplasma agassizii and Chelonian herpesvirus in captive tortoises (Testudo sp.) in the United Kingdom.     

Jorge F Soares  Victoria J Chalker  Kerstin Erles  Sonya Holtby  Michael Waters  Stuart McArthur 《Journal of zoo and wildlife medicine》2004,35(1):25-33

During the months of April to August in 1999 and 2002, oral swabs were collected from 146 tortoises (Testudo sp.) in private collections in the United Kingdom and tested by polymerase chain reaction (PCR) for the presence of Mycoplasma agassizii and Chelonian herpesvirus (ChHV). The presence of M. agassizii was confirmed by restriction digestion of the PCR product. A 307-bp fragment of the ChHV UL5 homologue gene was sequenced and found to show most similarity to equine herpesvirus type 1. A prevalence of 15.8 and 8.2% was found for M. agassizii and ChHV, respectively. Comparison of the carriage of both M. agassizii and ChHV in different species of tortoises correlated the presence of M. agassizii with Testudo horsfieldii and ChHV with Testudo marginata and Testudo graeca iberia. An association of ChHV with stomatitis was also found. Mixed infections with both agents were detected. The findings further demonstrate this pathogen-tortoise association and the cross transmission of these infections if different tortoise species are housed together.  相似文献   

Intramedullary Intervertebral Disk Extrusion in a Cat     

J. Fraser McConnell BVM&S    Laurent S. Garosi DVM 《Veterinary radiology & ultrasound》2004,45(4):327-330

Intervertebral disk extrusion is rarely reported in the cat. In this case, the clinical, radiologic, and magnetic resonance imaging findings of an acute intramedullary intervertebral disk extrusion in a 5-year-old domestic shorthaired cat are described. Radiographically, there was mineralized disk material within the vertebral canal. On magnetic resonance images, the disk material was found to be within the spinal cord. A linear disk trail extending from the disk space into the spinal cord may be specific for intramedullary disk extrusion.  相似文献   

Molecular epidemiology of two fowl cholera outbreaks on a free-range chicken layer farm.     

P Zhang  N Fegan  I Fraser  P Duffy  R E Bowles  A Gordon  P J Ketterer  W Shinwari  P J Blackall 《Journal of veterinary diagnostic investigation》2004,16(5):458-460

Two outbreaks of fowl cholera on a multiage free-range egg farm were investigated. The outbreaks occurred in 1994 and 2002. A total of 22 strains of Pasteurella multocida were available for study, 11 from the 1994 outbreak and 11 from the 2002 outbreak. Lesions typical of acute fowl cholera were seen in the 1994 outbreak, whereas both acute and chronic fowl cholera occurred in the 2002 outbreak. The isolates were examined in an extended phenotypic typing methodology, by a P. multocida-specific polymerase chain reaction (PCR), by the Heddleston somatic serotyping scheme, and by restriction endonuclease analysis (REA) typing using the enzyme HpaII. All 22 strains had the same phenotypic properties, all were confirmed as P. multocida by PCR, all were Heddleston serovar 4, and all had the same REA pattern. The results indicate that these 2 outbreaks were caused by the same clone of P. multocida--despite the 8-year time period between the outbreaks.  相似文献   

Projecting future habitat quality of three midwestern reservoir fishes under warming conditions     

Richard R. Budnik  Joseph D. Conroy  Richard D. Zweifel  Stuart A. Ludsin  Elizabeth A. Marschall 《Ecology of Freshwater Fish》2021,30(1):31-47

Rising temperatures caused by climate change are likely to affect cool‐water and warm‐water fishes differently. Yet, forecasts of anticipated temperature effects on fishes of different thermal guilds are lacking, especially in freshwater ecosystems. Towards this end, we used spatially explicit, growth rate potential (GRP) models to project changes in seasonal habitat quality for a warm‐water piscivore (largemouth bass Micropterus salmoides), a cool‐water piscivore (walleye Sander vitreus) and a hybrid piscivore (saugeye S. vitreus × S. canadensis) in two Midwestern reservoirs. We assessed habitat quality for two periods (early and middle 21st century) under two realistic greenhouse gas emission scenarios (a mid‐century emissions peak and a rapid continuous increase in emissions). Largemouth bass were projected to experience enhanced or slightly reduced habitat during all seasons, and throughout the mid‐21st century. By contrast, walleye habitat was projected to decline with anticipated warming, except during the spring in the smaller of our two study reservoirs and during the fall in the larger of our two study reservoirs. Saugeye habitat was projected to either increase modestly or decline slightly during the spring and fall and declines in habitat quality and quantity that were smaller than those for walleye were identified during summer. Collectively, our findings indicate that climate warming will differentially alter habitat suitability for reservoir piscivores, favouring warm‐water species over cool‐water species. We expect these changes in habitat quality to impact the dynamics of reservoir fish populations to varying degrees necessitating the consideration of climate when making future management decisions.  相似文献   

An acute case of Pimelea elongata toxicity in cattle in western New South Wales     

C Cavanagh  S Parry  C Fraser  BC Dominiak 《Australian veterinary journal》2023,101(1-2):35-40

In May 2019, 96 cattle died from Pimelea toxicity in a period of 19 days after potential exposure, with the first deaths occurring within 5 days. After examining the circumstances, we suspect that several factors contributed to the deaths. These included that recently purchased stock and transported had access to flooded land containing Pimelea elongata. This weed species contains simplexin and 18 other compounds. Roots, flowers and seeds are significantly more toxic than the stem, branches and leaves. We suspect that thirsty and hungry stock consumed seed and roots from flooded pastures and consumed lethal doses of simplexin. Blood tests were not good indicators of the conditions. Management strategies are suggested.  相似文献   

Microhabitat use of the diamond darter     

Stuart A. Welsh  Dustin M. Smith  Nate D. Taylor 《Ecology of Freshwater Fish》2013,22(4):587-595

The only known extant population of the diamond darter (Crystallaria cincotta) exists in the lower 37 km of Elk River, WV, USA. Our understanding of diamond darter habitat use was previously limited, because few individuals have been observed during sampling with conventional gears. We quantified microhabitat use of diamond darters based on measurements of water depth, water velocity and per cent substrate composition. Using spotlights at night‐time, we sampled 16 sites within the lower 133 km of Elk River and observed a total of 82 diamond darters at 10 of 11 sampling sites within the lower 37 km. Glides, located immediately upstream of riffles, were the primary habitats sampled for diamond darters, which included relatively shallow depths (<1 m), moderate‐to‐low water velocities (often < 0.5 m·s^?1) and a smooth water surface. Microhabitat use (mean ± SE) of diamond darters was estimated for depth (0.47 ± 0.02 m), average velocity (0.27 ± 0.01 m·s^?1) and bottom velocity (0.15 ± 0.01 m·s^?1). Substrate used (mean ± SE) by diamond darters was predominantly sand intermixed with lesser amounts of gravel and cobble: % sand (52.1 ± 1.6), % small gravel (12.2 ± 0.78), % large gravel (14.2 ± 0.83), % cobble (19.8 ± 0.96) and % boulder (1.6 ± 0.36). Based on our microhabitat use data, conservation and management efforts for this species should consider preserving glide habitats within Elk River. Spotlighting, a successful sampling method for diamond darters, should be considered for study designs of population estimation and long‐term monitoring.  相似文献   

Virus recognition and pathogenicity: Implications for resistance mechanisms and breeding     

Ronald S. S. Fraser 《Pest management science》1988,23(3):267-275

The major method of control of virus diseases in crop plants is breeding for resistance. The genetics of resistance, and of matching virulence (the ability of a virus strain to overcome a specific host resistance gene) have been studied less for viruses than for fungal and bacterial pathogens. This paper draws on a survey of the genetics of resistance to a large number of viruses in cultivated crops, and makes some generalisations and predictions about mechanisms. Most resistance to viruses in crops is monogenic. Dominant alleles are associated with virus-localisation mechanisms, which are induced after infection. The nature of the ‘recognition event’ between plant- and virus-coded functions, which triggers resistance plus a cascade of secondary responses, is not yet known. Gene dosage-dependent alleles tend to be associated with non-localising resistance, which allows some virus spread, but inhibits multiplication. Recessive alleles may involve a negative type of resistance mechanism, whereby the resistant plant lacks some function normally required by the virus for pathogenesis. Such resistance tends to be expressed as complete immunity. Many resistance genes have been overcome by virulent isolates of viruses; only 10 % of the sample of resistance genes have proved exceptionally durable. Virulence may involve different viral functions. The production of infectious cDNA clones, and construction of chimaeric recombinants between clones of virulent and avirulent isolates, is now allowing detailed mapping of virulence determinants. Transformation of plants with ‘novel’ genes for virus resistance, based on coat proteins and viral satellites, may allow construction of more robust resistance systems.  相似文献   

Temperature effects on the action of acylurea insecticides against tobacco hornworm (Manduca sexta) larvae     

Darren R. Chandler  Robert G. King  Philip Jewess  Stuart E. Reynolds 《Pest management science》1991,31(3):295-304

The toxic effects of six acylurea insecticides on larvae of the tobacco hornworm were investigated at each of four environmental temperatures (20, 25, 30 and 35°C). This spans the range of temperatures which the insects can tolerate. For all the acylureas tested, mortality increased with temperature when either newly hatched or fourth-instar larvae were given insecticide in their food. Sub-lethal growth inhibition also became more pronounced at progressively higher environmental temperatures. This temperature dependence of acylurea action was not due to altered uptake of the insecticide, since there was no significant variation with temperature in the amount of [¹⁴C]flufenoxuron taken up by fifth-instar larvae when given a single meal containing labelled insecticide. Additionally, mortality of fourth-instar larvae given a single intra-haemocoelic injection of flufenoxuron was significantly greater at higher temperatures, implying that temperature affects a process that occurs after insecticide uptake. The intrinsic ability of acylureas to inhibit chitin synthesis is temperaturesensitive, since flufenoxuron inhibited the incorporation of [¹⁴C]N-acetylalucosamine into chitin by proleg epidermis in vitro significantly less well at 20°C than at the higher temperatures tested. However, there was no significant variation between the effectiveness of in-vitro chitin synthesis inhibition at 25, 30 and 35°C. These data show that the effectiveness of acylurea insecticides is subject to strong temperature effects in the range of temperatures likely to be experienced in the field.  相似文献   

The cuticle,growth and moulting in insects: The essential background to the action of acylurea insecticides     

Stuart E. Reynolds 《Pest management science》1987,20(2):131-146

The functions, structure and biochemistry of the insect cuticle in relation to the moulting cycle are briefly reviewed as an introduction to the actions of insecticides that act on the cuticle, particularly acylureas. The symptoms of poisoning with diflubenzuron (DFB) and other acylureas are consistent with ultra-structural and biochemical evidence that these insecticides inhibit the formation of chitin microfibrils in newly synthesised cuticle. It is probable that DFB acts at a late stage in chitin biosynthesis, perhaps inhibiting chitin synthase (CS) itself. However, the results of studies using cell-free preparations of CS have not, on the whole, supported this hypothesis. A number of alternative suggestions as to the mode of action of DFB are reviewed. Among the most attractive of these is the possibility that DFB may inhibit the transmembrane transport of chitin synthesis precursors from their site of production within the epidermal cells to the site of the final poly condensation reaction, presumably at the apical membrane of the epidermal microvilli.  相似文献   

A comparison of cypermethrin distribution on cattle hair after application of impregnated ear and tail tags     

Stuart M. Taylor  Christopher T. Elliott  William J. Blanchflower 《Pest management science》1987,21(1):39-43

Ten dairy cows were separated into two groups of five. One group was ear tagged with a PVC ear tag containing 8-5 g kg^?1 cypermethrin in each ear. A PVC strip impregnated with the same quantity of cypermethrin was attached to the tail of each cow in the other group. The concentration of cypermethrin in hair samples from the neck, flanks and the anterior, sides and the posterior of the udder was measured for a period of 10 weeks after application. Concentrations were found to be high in those body areas nearest to the points of application, moderate on the flanks but low on the front and sides of the udder.  相似文献