Epidemiology of dark leaf spot caused by Alternaria brassicicola and A. brassicae in organic seed production of cauliflower     

J. Köhl  C. A. M. Van Tongeren  B. H. Groenenboom‐de Haas  R. A. Van Hoof  R. Driessen  L. Van Der Heijden 《Plant pathology》2010,59(2):358-367

In organic seed production of Brassica vegetables, infections by Alternaria brassicicola and A. brassicae can cause severe losses of yield and seed quality. Four field experiments with or without artificial inoculation with A. brassicicola were conducted in organically managed seed‐production crops of cauliflower cv. Opaal RZ in 2005 and 2006 in the Netherlands. The development of A. brassicicola and A. brassicae on pod tissues and developing seeds was followed and seed quality was assessed. Alternaria brassicicola was externally present on 1·2% of the seeds 14 days after flowering and observed internally within 4 weeks after flowering. In both seasons, seed colonization by the pathogen increased slowly until maturation but sharply increased during maturation. A similar pattern was found for the colonization of pod tissues by A. brassicicola as quantified by TaqMan‐PCR. The incidence of A. brassicicola on mature seeds reached 70–90%. Internal colonization was found for 62–80% of the seeds. External and internal seed colonization by A. brassicae was much lower, with incidences below 3%. The quality of harvested seeds was generally low, with less than 80% of seeds able to germinate. Seed quality was not affected by warm water treatments. It was concluded that A. brassicicola and A. brassicae have the potential to infect pods and seeds soon after flowering. For the production of high quality seeds, producers must prevent such early infections. Therefore, new control measures are needed for use in organic cropping systems.  相似文献   

Microcyclic conidiogenesis in powdery mildews and its association with intracellular parasitism by <Emphasis Type="Italic">Ampelomyces</Emphasis>     

Levente Kiss  Alexandra Pintye  Györgyi Zséli  Tünde Jankovics  Orsolya Szentiványi  Yaser M. Hafez  Roger T. A. Cook 《European journal of plant pathology / European Foundation for Plant Pathology》2010,126(4):445-451

Microcyclic conidiogenesis (MC), a process defined as the production of conidia on a spore without any, or only a minimal, involvement of hyphal growth, has recently been reported in a little known powdery mildew species, Oidium longipes. To investigate whether this was an isolated case or it is a more general phenomenon in powdery mildew fungi, germinating conidia of eight species of the Erysiphales were examined using light microscopy. The following species were included in this work: Erysiphe necator on grapevine, Blumeria graminis f. sp. hordei on barley, Podosphaera xanthii on cucumber, Erysiphe sp. on Ligustrum vulgare, O. longipes on Petunia x grandiflora, O. neolycopersici on tomato, Golovinomyces cichoracearum on Rudbeckia laciniata and Sawadaea sp. on Acer negundo. In all these species, up to 4% of the germinated conidia exhibited MC. Moreover, when colonies of E. necator and O. neolycopersici, on detached grapevine and tomato leaves, respectively, were treated with a conidial suspension of Ampelomyces, the intracellular pycnidia of these mycoparasites appeared in microcyclic conidiophores. This represents a yet undescribed method of accelerating asexual reproduction in this mycoparasite. In the life cycle of powdery mildews, the importance of MC is still not clear but it should be taken into consideration when conidial germination is studied on the host surface for purposes such as epidemiology or species identification.  相似文献   

Seawater exposure effect on the fracture toughness of low-density woods/GRP sandwich systems     

Gökdeniz Neşer 《Journal of Wood Science》2010,56(2):154-159

The effect of seawater exposure on the fracture toughness of balsa (Ochroma pyramidale L.) and end-grain balsa cores that are widely used in small-craft constructive members has been investigated experimentally in this study. The interfacial fracture toughness was determined using mode I cracked sandwich beam (CSB) tests. Additionally, the same tests were performed for poplar (Populus tremula L.), easily available because of its natural distribution along the coast of Turkey and more cost-effective than balsa and its derivatives, to see if it is a proper alternative. It was found that balsa and poplar cores that can be classified as low-density cores have much lower fracture toughness values than end-grain balsa cores. Additionally, there was a positive effect of seawater exposure on their fracture toughness as opposed to that of the end-grain core. From the aspect of fracture toughness, the poplar core can be considered much more reliable than the balsa core where delamination loads occur.  相似文献   

Safety of a non-adjuvanted therapeutic vaccine for the treatment of feline dermatophytosis     

Westhoff D  Orveillon FX  Farnow D  Klös MC  Elbers K 《The Veterinary record》2010,167(23):899-903

The safety of a non-adjuvanted inactivated fungal vaccine for the treatment of dermatophytosis in cats was investigated in two studies: a controlled laboratory study, and a placebo-controlled double-blind field study with a cross-over design in Europe. In the laboratory study, two groups of 10 cats each were administered an intramuscular twofold overdose, followed by five single 1 ml doses, of either vaccine or control product at 14-day intervals. In the field study, cats were treated with three intramuscular injections of 1 ml vaccine administered at 14-day intervals, as recommended by the manufacturer. A total of 89 cats were enrolled in the field study and divided into two groups to receive either vaccine or placebo for the first three treatments, followed by the opposite product for the final three treatments. The cats enrolled in the two studies were 12 weeks of age or older, as recommended by the manufacturer. All the cats were monitored closely for possible injection site reactions, systemic reactions (including changes in rectal body temperature) and adverse events. The results from both studies showed no significant differences between the vaccinated cats and the control or placebo-treated cats with regard to local or systemic reactions. A few mild to moderate local reactions were noted, but these were evenly distributed between the vaccinated and placebo-treated cats and resolved within a few days. No severe or serious adverse events related to the vaccinations were observed.  相似文献   

Slaughter findings feedback systems--its use for farms of origin?     

Eckhardt P  Fuchs K  Kornberger B  Köfer J 《Berliner und Münchener tier?rztliche Wochenschrift》2010,123(11-12):468-476

Over a period of 22 months 13 official meat inspection authorities examined a number of 152 520 swine at an Austrian slaughterhouse for pathologic-anatomic changes (five parameters). Of those veterinarians whose reliability in the recording of findings was a given, the results were analysed by employing a mathematical model which assessed whether the activities of 25 attending veterinarians and 223 farmers actually lead to an improvement of animal health in their livestock. Mild pneumonia was registered in 14.5% of swine; no attending veterinarians had any influence whatsoever on the occurrence of this parameter. Farmers' activities improved animal health on two farms (0.9%), six farms of origin (2.69%) showed significantly lower findings than the average of all farms. Pleurisy was ascertained in 22% of all slaughter pigs. Through measures taken, four attending veterinarians (16%) caused a reduction of incidents, two works managers (0.9%) made worse, six farmers (2.69%) improved animal health of their live stock. Seven farmers (3.14%) showed significantly (p < 0.05) higher, 28 farms (12.6%) lower prevalence. Pericarditis affected 4.5% of the animals in question. On all farms of origin the condition of health remained unchanged by measures taken by veterinarians. On two farms (0.9%) the influence exercised by farmers led to a deterioration of the health of swine, six businesses (2.69%) showed higher, one (0.45%) lower prevalence than on average. 6.2% of swine showed white spots. Attending veterinarians did not influence this parameter at all. With preventive measures taken five farms (2.24%) showed less, three farms (1.35%) higher prevalence by the end of the 22 month term. Mange concerned 2.2% of all slaughter pigs. The activities of one veterinarian (4%) caused the number of incidents to double; on six farms (2.69%) a significantly higher prevalence was registered. Whatever influence exercised, the status of health of slaughter pigs remained unchanged throughout the duration of the study.  相似文献   

Pathogenicity determinants in smut fungi revealed by genome comparison     

Schirawski J  Mannhaupt G  Münch K  Brefort T  Schipper K  Doehlemann G  Di Stasio M  Rössel N  Mendoza-Mendoza A  Pester D  Müller O  Winterberg B  Meyer E  Ghareeb H  Wollenberg T  Münsterkötter M  Wong P  Walter M  Stukenbrock E  Güldener U  Kahmann R 《Science (New York, N.Y.)》2010,330(6010):1546-1548

Biotrophic pathogens, such as the related maize pathogenic fungi Ustilago maydis and Sporisorium reilianum, establish an intimate relationship with their hosts by secreting protein effectors. Because secreted effectors interacting with plant proteins should rapidly evolve, we identified variable genomic regions by sequencing the genome of S. reilianum and comparing it with the U. maydis genome. We detected 43 regions of low sequence conservation in otherwise well-conserved syntenic genomes. These regions primarily encode secreted effectors and include previously identified virulence clusters. By deletion analysis in U. maydis, we demonstrate a role in virulence for four previously unknown diversity regions. This highlights the power of comparative genomics of closely related species for identification of virulence determinants.  相似文献   

Spin transfer torques in MnSi at ultralow current densities     

Jonietz F  Mühlbauer S  Pfleiderer C  Neubauer A  Münzer W  Bauer A  Adams T  Georgii R  Böni P  Duine RA  Everschor K  Garst M  Rosch A 《Science (New York, N.Y.)》2010,330(6011):1648-1651

Spin manipulation using electric currents is one of the most promising directions in the field of spintronics. We used neutron scattering to observe the influence of an electric current on the magnetic structure in a bulk material. In the skyrmion lattice of manganese silicon, where the spins form a lattice of magnetic vortices similar to the vortex lattice in type II superconductors, we observe the rotation of the diffraction pattern in response to currents that are over five orders of magnitude smaller than those typically applied in experimental studies on current-driven magnetization dynamics in nanostructures. We attribute our observations to an extremely efficient coupling of inhomogeneous spin currents to topologically stable knots in spin structures.  相似文献   

Tachypnea and Antipyresis in Febrile Horses after Sedation with α2‐Agonists     

A. Kendall  C. Mosley  J. Bröjer 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2010,24(4):1008-1011

Background: Signs of tachypnea after sedation of febrile horses with α₂‐agonists have been noted previously but have not been further investigated. Objectives: To examine the effects of xylazine and detomidine on respiratory rate and rectal temperature in febrile horses and to investigate if either drug would be less likely than the other to cause changes in these variables. Animals: Nine febrile horses and 9 healthy horses were included in the study. Methods: Horses were randomly assigned to sedation with xylazine 0.5 mg/kg or detomidine 0.01 mg/kg. Heart rate and respiratory rate were recorded before sedation and at 1, 3, and 5 minutes after injection. Hourly measurements of rectal temperature were performed starting before sedation. Results: All febrile horses experienced an episode of tachypnea and antipyresis after sedation. Rectal temperature in the febrile group was significantly lower at 1, 2, and 3 hours after sedation. In several measurements, the decrease was >1°C. Respiratory rate in the febrile group was significantly increased after sedation. All febrile horses were breathing >40 breaths/min and 3 horses >100 breaths/min 5 minutes after sedation. No differences were noted between the 2 treatments. No significant changes in respiratory rate or temperature were noted in the reference group. Conclusions and Clinical Importance: Febrile horses can become tachypneic after sedation with detomidine or xylazine. The antipyretic properties of α₂‐agonists need consideration when evaluating patients that have been sedated several hours before examination.  相似文献   

Effects of toxic and non‐toxic blue mussel meal on health and product quality of laying hens     

L. Jönsson  L. Holm 《Journal of animal physiology and animal nutrition》2010,94(3):405-412

Blue mussels (Mytilus edulis) are a potential protein source in poultry feeds because of their high methionine and cystein content. However, mussels may temporarily be contaminated with the toxin, okadaic acid. The aim of this small scale study was to evaluate the effects on animal health and morphology of the digestive tract of laying hens fed three different diets; a commercial feed and diets containing 15% normal or 15% toxic mussel meal, i.e. a concentration of 198.6 μg toxin per kg feed. Twelve laying hens were divided into six groups and fed the experimental diets for 8 weeks. Animal health, production performance and egg quality were recorded. At sacrifice, tissue samples were prepared for histological evaluation using light microscopy. Okadaic acid did not have any adverse effects on animal health or production parameters and no histological changes indicating disturbances in the digestive tract was observed. Internal egg quality was improved as eggs from hens fed either of the two mussel meal diets had an increased yolk colour. These results show that mussel meal functions as a novel protein source for laying hens and those toxic mussels at this level may be included in the feed without negative effects on parameters evaluated in this study.  相似文献   

Comparisons of 3‐, 2‐Dimensional,and M‐Mode Echocardiographical Methods for Estimation of Left Chamber Volumes in Dogs with and without Acquired Heart Disease     

A. Tidholm  A.B. Westling  K. Höglund  I. Ljungvall  J. Häggström 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2010,24(6):1414-1420

Background: Real‐time 3‐dimensional echocardiography (RT3D) is a recent technique based on volumetric scanning, eliminating the need for geometric modeling of the cardiac chambers and minimizing the errors caused by foreshortened views. Hypothesis: Estimations of left ventricular (LV) end‐diastolic (EDV) and end‐systolic volume (ESV), and left atrial (LA) size, differ depending on the echocardiographic technique of estimation. Animals: Fifty‐one dogs with acquired heart disease and 34 healthy control dogs. Methods: Prospective observational study by M‐mode (Teichholz method), Simpson's modified 2‐dimensional (2D) method, and RT3D methods for estimation of LV volumes. LA size was evaluated by 2D and RT3D methods. Results: RT3D showed good agreement with 2D for EDV and ESV, whereas Teichholz method overestimated LV volumes in comparison with the other 2 methods by approximately a factor 2. There were no statistically significant differences among the 3 methods in estimating ejection fraction. Comparison between RT3D assessment of LA end‐systolic volume per kilogram (LAs/kg) and LA to aortic ratio (LA/Ao) measured by 2D relative to each other showed that the RT3D method underestimated LAs/kg at lower values, and overestimated it at higher values. The difference between methods increased with increasing LA size. Conclusions and Clinical Importance: There was good agreement between RT3D and 2D methods of estimating EDV and ESV, whereas the Teichholz method overestimated LV volumes by approximately a factor 2. In comparison with RT3D, LA/Ao underestimated LA size, especially when LA was enlarged.  相似文献