Comparative infectivity for axenic and specific-pathogen-free chickens of O2 Escherichia coli strains with or without virulence factors   总被引：1，自引：0，他引：1  

A Brée  M Dho  J P Lafont 《Avian diseases》1989,33(1):134-139

Adhesion to epithelial respiratory cells, iron acquisition, and production of K1 polysaccharide capsules have been proposed as potential virulence factors of avian Escherichia coli. These factors were studied by inoculating groups of axenic or specific-pathogen-free (SPF) chickens intratracheally with O2 E. coli strains after previous challenge with a wild strain of infectious bronchitis virus (IBV). In all experiments, the association between IBV and an E. coli strain endowed with the three virulence factors previously mentioned resulted in the most severe pathological effects, as measured by mortality, weight gains, lesions, and reisolation of E. coli from internal organs. An E. coli strain devoid of virulence factors was able only to induce mild pathological effects restricted to the respiratory tract when combined with IBV. Both E. coli strains were more invasive in axenic chickens than in SPF chickens. These results confirm the probable involvement of the three factors studied in the pathogenic properties of avian E. coli. This model can be used to assess the role of virulence factors, by comparing pairs of positive and negative isogenic strains.  相似文献   

Tentative description of Hippeastrum latent virus in Hippeastrum hybridum plants and differentiation from Hippeastrum mosaic virus     

J. E. Brölman-Hupkes 《European journal of plant pathology / European Foundation for Plant Pathology》1975,81(6):226-236

In mosaic-diseased plants ofHippeastrum hybridum two viruses were found. One virus with a normal length of 706 nm caused local lesions onHyoscyamus niger test plants and mosaic symptoms in the leaves ofH. hybridum. This virus was identified with theHippeastrum mosaic virus (HMV) (*/*∶*/*∶E/E∶S/*) and had a dilution end point between 10^?3 and 10^?4, a thermal inactivation point between 55–60°C and a longevity at room temperature of 28–32 hours. The second virus had a normal length between 584 and 611 nm depending on the method used. It caused local lesions onGomphrena globosa andChenopodium quinoa leaves, and after inoculation ofH. hybridum was found to be present without showing symptoms. It was readily purified from inoculated leaf tissue ofC. quinoa andNicotiana clevelandii by differential centrifugation and ofH. hybridum by density-gradient centrifugation. Purified virus had an absorption minimum at 242 nm, a maximum at 262 nm and a 260/280 absorption ratio of 1.19. The dilution end point was between 10^?3 and 10^?4, the thermal inactivation point between 70 and 80°C and the longevity in vitro at room temperature 28–32 hours. Although no direct comparisons have been made with other members of the potexvirus group, the virus seems to be a new one now namedHippeastrum latent virus. Both viruses were not seed-borne.  相似文献   

Bedeutung von Regenwurmröhren für die Verlagerung des Herbizids Diuron in Böden von Obstanlagen     

S. Pätzold  G. W. Brümmer 《Erwerbs-Obstbau》2004,46(3):74-80

Herbicide translocation was investigated in a Haplic Luvisol from loess (clayey silt; Klein-Altendorf near Bonn, Germany) and a Eutric Cambisol (sandy loam; fluvial sediments on the lower Rhine terrace north of Bonn) using the herbicide diuron as an example. diuron was applied once a year in May at the recommended dose of 2.4 kg/ha. It rapidly degraded in the topsoil: the “time for 50% disappearance” (DT₅₀) was 14–30 days. A population of adapted soil micro-organisms, which is repeatedly exposed to applications of the same compound every year, is thought to be responsible for this fast degradation. Remaining Diuron residues were largely degraded in the loess soil during the subsequent summer and became less mobile due to increasing binding strength. As a result, residue levels and leaching in the loess soil during the winter were negligible, with diuron traces of less than 10 µg/kg below the topsoil 11 months after application. Comparison of the translocation in a sandy loam soil showed—as expected—that diuron was leached to the subsoil to a higher extent than in clayey silt (loess). However, in the loess soil, diuron leached to the subsoil via macropores after 20 mm of natural precipitation within 1 week after herbicide application due to macropore flow. Colour tracer and analysis of the linings of earthworm burrows identified these macropores as preferred pathways of herbicide leaching. Macropore flow occurred in wet soil and moist soil with a sealed surface or crust but not in dry soil. Superficial mechanical soil cultivation before the herbicide application is discussed as one possibility to interrupt macropore entries and reduce herbicide leaching after its application in the spring.  相似文献   

Segment-based coancestry,additive relationship and genetic variance within and between the Norwegian and the Swedish Fjord horse populations     

Hanne Fjerdingby Olsen  Saija Tenhunen  Nils Ivar Dolvik  Dag Inge Våge  Gunnar Klemetsdal 《Acta Agriculturae Scandinavica, Section A - Animal Sciences》2020,69(1-2):118-126

ABSTRACT

The Fjord horse originates from Norway but forms a global population due to several small populations in foreign countries. There exists no information about the additive relationship and the genetic variance between these subpopulations. By collecting blood samples from Norwegian and Swedish Fjord horses, a sample of 311 Norwegian and 102 Swedish horses gave 485,918 SNPs available for analysis. Their inbreeding coefficients were calculated and compared to the pairwise coancestry and the shared genomic segments. The effective population size was almost similar with the two methods in the Norwegian Fjord horse population (63 and 71), but very different in the Swedish population (269 and 1136) and unprecise due to a much smaller number of observations. The study showed that coancestry from shared genomic segments can be used to estimate additive genetic relationship and genetic variation within and between the global populations of the Fjord horse.  相似文献   

The Influence of Organic and Integrated Production on Nutritional,Sensory and Agricultural Aspects of Vegetable Raw Materials for Food Production     

Stina Fjelkner-Modig  Håkan Bengtsson  Stig Nystrõm  Rolf Stegmark 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(3):102-113

In a six-year crop rotation trial organically and integrated grown vegetables were produced according to current good agricultural practices, taking quality and quantity aspects into consideration. The raw materials assessed focussed on materials used for industrial food production. Nutritional, sensory and agricultural aspects were evaluated. Carrot, cabbage, onion, pea and potato are possible to grow organically for industrial purposes. Depending on crop, the yield was lower (65-90%) for organically grown compared to integrated grown. Cultivation of organic spinach and dill turned out to be difficult due to problems with weed and discoloration. The chemical analyses included pesticide residues, nitrate, glycoalkaloid, dry matter, vitamin C and 25 different minerals and trace elements. Overall, the organically grown crops had higher dry matter content than the integrated grown. However, when examining the data for the different crops contradictory results were noted. No significant differences due to growing system were noticed for vitamin C and the other nutrients except for 4 of the trace elements. The growing system did not influence the sensory properties.  相似文献   

Describing Human–Wildlife Interaction from a European Perspective     

Maria Johansson  Sabrina Dressel  Emma Kvastegård  Göran Ericsson  Anke Fischer  Bjørn P. Kaltenborn 《Human Dimensions of Wildlife》2016,21(2):158-168

European researchers from both the natural and social sciences show growing interest in studying interactions between society and wildlife. A wealth of theoretical frameworks, concepts, and methods are used, but an integration of perspectives is lacking. This research note summarizes results from two workshops that included 63 delegates from 25 European countries, as well as a follow-up survey of 41 respondents. Two main theoretical approaches to the study of human–wildlife interactions were identified. One approach focuses on the collective societal level relying on theories of governance, social representation, deliberative procedures, and commons theory. The other approach targets individuals or groups, and is based on theories such as the cognitive hierarchy, theory of reasoned action, and theory of planned behavior. Interdisciplinary collaboration is needed to identify the best options for wildlife conservation and management in a more politically integrated Europe.  相似文献   

Breeding Restrictions Decrease the Prevalence of Myxomatous Mitral Valve Disease in Cavalier King Charles Spaniels over an 8‐ to 10‐Year Period          下载免费PDF全文

A.C. Birkegård  M.J. Reimann  T. Martinussen  J. Häggström  H.D. Pedersen  L.H. Olsen 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2016,30(1):63-68

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Evaluation of the effectiveness of selected measures against bovine spongiform encephalopathy (BSE) in Switzerland by use of the basic reproduction ratio R0     

Schwermer H  Brülisauer F  De Koeijer A  Heim D 《Berliner und Münchener tier?rztliche Wochenschrift》2007,120(5-6):189-196

The effectiveness of two measures against Bovine Spongiform Encephalopathy (BSE), the compulsory processing of animal by products to meat and bone meal (MBM) at 133 degrees C under 3 bars of pressure for 20 minutes in February 1993 and the exclusion of fallen stock, heads with eyes and spinal cord of cattle older than 30 month from MBM production in April 1996, was evaluated in a process model. The transmission of BSE by calculation of the basic reproduction ratio R0 was modelled.The results were verified by use of a cohort model, based on observed surveillance data. Prior to 1990, before the ban of feeding MBM to ruminants, R0, as calculated in the process model, was above 1, coherent with a slowly progressing BSE epidemic. Since 1991, values of R0 were low at 0.06.The corresponding R0 values derived from the cohort model were higher, the lowest value 0.13 calculated for 1996. Given such low R0 values, the epidemic should have died out. Additionally, no influence of the two measures was obvious at that time given the low level of R0. The discrepancy between the results of the two models is evidence for a dependency of the BSE epidemic from an infection source not considered in the process model. This infection source is most likely importation of feed ingredients and MBM.  相似文献   

Grid keratotomy as a treatment for superficial nonhealing corneal ulcers in 10 horses     

Brünott A  Boevé MH  Velden MA 《Veterinary ophthalmology》2007,10(3):162-167

OBJECTIVE: To describe the clinical symptoms of 10 cases of superficial nonhealing corneal ulcers in horses and to evaluate the results of grid keratotomy in these patients. DESIGN: Retrospective study. ANIMALS: Ten horses with superficial nonhealing corneal ulceration in one eye. PROCEDURE: The signalment, history and clinical symptoms are reported of 10 patients with superficial nonhealing corneal ulcers during the period from August 2003 to February 2005. Grid keratotomy was performed in all cases. In addition, the surgical procedure of grid keratotomy and response to therapy are described. RESULTS: Horses generally responded well to grid keratotomy (eight cases healed after one grid keratotomy and one horse healed after a second grid keratotomy; one case was not available for follow-up). Only 2/10 had discomfort after treatment and only 2/9 had some degree of scarring after treatment. The healing time, which was known in seven cases, averaged 8.4 days (+/- SD 4). CONCLUSIONS AND CLINICAL RELEVANCE: Grid keratotomy is an appropriate option for treatment of superficial nonhealing corneal ulcers in horses. The procedure is simple to perform. It generally induces a rapid and uncomplicated healing of the cornea. Only in a limited number of cases does a small amount of scarring occur.  相似文献   

In vivo confocal microscopy in the normal corneas of cats, dogs and birds   总被引：1，自引：1，他引：0  

Kafarnik C  Fritsche J  Reese S 《Veterinary ophthalmology》2007,10(4):222-230

OBJECTIVE: To evaluate the applicability of in vivo confocal microscopy (IVCM) in veterinary ophthalmology and analyze the morphology of living, healthy cornea. ANIMALS EXAMINED: Thirty-seven dogs, 34 cats and five birds. PROCEDURE: Various corneal sublayers were visualized in the central region using an in vivo confocal corneal microscope (HRTII/RCM). RESULTS: An investigation method was developed and adapted for use on animals with varying skull forms and eye positions. Real-time images of the epithelial cells, the corneal stroma and the endothelial layer were obtained. The corneal stromal nerve trunks and the subepithelial and basal epithelial nerve plexus were visualized. In dogs, full corneal thickness (FCT) was 585 +/- 79 microm (mean +/- SD) and endothelial cell density (ECD) 3175 +/- 776 cells/mm(2) (mean +/- SD). In cats, FCT was 592 +/- 80 microm and ECD 2846 +/- 403 cells/mm(2). There were no significant differences between canine and feline FCT and ECD and no morphologic differences could be seen between dogs and cats. The bird images revealed a number of structural differences. CONCLUSION: Noninvasive IVCM allows accurate detection of corneal sublayers, corneal pachymetry, endothelial cell density and corneal innervation in various animal species. For clinical usage, patients must be under general anesthesia. The confocal images provided anatomic reference images of various healthy corneal structures in dogs, cats and birds.  相似文献