Development of a semi-selective medium and an immunofluorescence colony-staining procedure for the detection of Clavibacter michiganensis subsp. sepedonicus in cattle manure slurry

Various compounds and basal media were tested for their suitability to create a semi-selective medium for isolation ofClavibacter michiganensis subsp.sepedonicus (Cms) from cattle manure slurry containing c. 10⁸ colony forming units (cfu) per ml.Plating efficiency of Cms in yeast glucose mineral medium (YGM) was 104% compared with yeast peptone glucose medium. Nalidixic acid, polymyxin B sulphate and the experimental disinfectant S-0208 inhibited colony growth of cattle slurry bacteria as compared with Cms in YGM. The optimal concentration of these inhibitors in combination was determined by modified agar diffusion tests and by pour plating in 24-well tissue culture plates. The semi-selective medium YGMI consisted of YGM supplemented with nalidixic acid (2 mg/l), polymyxin B sulphate (30 mg/l) and S-0208 (125 mg/l). Plating efficiency varied for Cms between 50.9 and 69.6%, for cattle slurry bacteria between 1.8 and 2.5% and for saprophytes from potato heel end extracts between 11.5 and 27.4%.Differentiation of Cms colonies from other colonies was based on their small and bluish colony morphology in pour plates and on immunofluorescence colony-staining (IFC). IFC of a pure culture of micro colonies of Cms in YGM was possible after one day incubation (colonies c. 5 cells). Green background fluorescence in the agar gels was prevented by addition of Tween 20 (0.1%) to the washing buffer and the use of 1% agar gels. IFC of macro colonies of Cms in YGMI, visible with 4x objective magnification, was possible after 4 days. The detection level of the target organism in artificially inoculated cattle slurry in YGMI based on colony morphology varied between 1.4×10³ and 2.3×10⁴ cfu per ml of cattle slurry. Miniaturized plating combined with IFC, using wells in tissue culture plates (=16 mm), proved suitable for detection, but was c. 30 times les sensitive. The recovery of Cms was negatively correlated with the number of saprophytic colonies in the agar plates (R ²=0.74).     

Transmission of the agent causing a melon yellowing disease by the greenhouse whitefly Trialeurodes vaporariorum in southeast Spain

The agent causing a yellowing disease of melon (Cucumis melo), which results in severe losses in crops under plastic on the coastal plains of southeast Spain, was shown to be transmitted in a semipersistent manner by the greenhouse whitefly (Trialeurodes vaporariorum Westwood). The agent was transmitted by grafting, but not by mechanical inoculation or through seeds. The agent was acquired in the minimum period tested (2 h) and could infect plants in an infection feeding interval of 6 h. Capsella bursa-pastoris, Cucumis melo, C. sativus, Cucurbita moschata, Cichorium endivia, Lactuca sativa andTaraxacum officinale were found susceptible.Results suggest that the yellowing disease affecting melon crops in the southeast of Spain is due to a pathogen similar to beet pseudo yellows virus, but this has to be confirmed by serology.     

Survey of faba bean (Vicia faba L.) for viruses in Morocco

A total of 52 faba-bean (Vicia faba L.) fields, located in the main growing areas in Morocco were surveyed for viruses. From 240 samples with symptoms suggestive of virus infection, the following viruses were detected using electron microscopy, serology, and biological indexing: Alfalfa mosaic virus (AMV), bean yellow mosaic virus (BYMV), broad bean mottle virus (BBMV), broad bean stain virus (BBSV), broad bean true mosaic virus (BBTMV), pea earlybrowning virus (PEBV), pea enation mosaic virus (PEMV), pea seed-borne mosaic virus (PSbMV), and a complex of luteoviruses including bean leafroll virus (BLRV). This is the first report of the occurrence of BBTMV, PEMV, PSbMV, and the luteoviruses (including BLRV) of faba bean in Morcco. The luteoviruses and BBMV were found to be the most prevalent. They were detected in 56 and 50%, respectively, of the surveyed fields; while AMV, BBSV, and PEBV were found in single fields only. The remaining viruses were less prevalent, and were detected in a range of 4 to 15% of the fields surveyed. The incidences per field of the prevalent viruses varied and ranged from 1 to 33% for BBMV and up to 20% in the case of luteoviruses. BBMV was found confined to the central and northern parts of the country, BBTMV and PEMV mainly occurred in the central area, while the luteoviruses and BYMV were spread over the faba-bean growing regions of the country.     

Landscape-ecological mapping of the Netherlands

The Landscape-ecological Mapping of the Netherlands project (LMN project) started in 1983 with the aim of establishing a landscape-ecological database for use in developing and evaluating national land-use plans. The project, working with grid cells of 1 km², has four working objectives: a) development of mapping potential for basic landscape-ecological data, b) assessment of susceptibility to interventions, c) evaluation of significance for nature conservation and d) production of vulnerability maps, as a combination of susceptibility and significance. In addition to information on soil, groundwater, ecotopes, flora and fauna, the database also incorporates information on physiographical features and entire landscapes. The resulting database is a geographic information system (GIS). This article describes the second phase of the project (1985–1989), covering the Randstad area, and focusses on the methods and the applications potential of the database.     

Pathophysiologic mechanism of cardiac dysfunction in experimentally induced heartworm caval syndrome in dogs: an echocardiographic study

In dogs with experimentally induced heartworm infection, the onset of caval syndrome (CS) was characterized by a murmur, loudest over the tricuspid valve, and a large worm mass in the right ventricular lumen detectable during diastole by use of M-mode echocardiography. Two-dimensional echocardiography indicated that the worm mass was located in the right atrium and venae cavae and was "flowing" into the right ventricle during rapid diastolic filling. Paradoxical septal motion and vigorous right ventricular cranial wall motion also were observed. Other echocardiographic changes included decreased size of the left atrium and ventricle, aortic root, and ratio of left-to-right ventricular diastolic luminal diameter, compared with values obtained 6 months after experimentally induced heartworm infection. Right ventricular end diastolic diameter increased considerably. Most echocardiographic indices of left ventricular function (fractional shortening, velocity of circumferential fiber shortening, ejection fraction, and preejection period) were not altered appreciably, but estimates of cardiac index and stroke volume were markedly decreased. Electrocardiography revealed ventricular and supraventricular premature complexes in 7 of the 8 dogs studied, evidence of right ventricular enlargement in 6 of the 8 dogs studied, and increased mean heart rate, compared with that measured 6 months after inoculation of infective larvae, before the onset of CS. Cardiac catheterization was performed in 3 days at the onset of CS. Severe pulmonary arterial and right ventricular hypertension and decreased cardiac index (compared with values obtained before inoculation) were observed. Evidence of right ventricular inflow obstruction was not detected. Mean aortic blood pressure decreased with the onset of CS, but right ventricular end diastolic pressure increased.(ABSTRACT TRUNCATED AT 250 WORDS)     

Estimation of the costs of mastitis, using National Animal Health Monitoring System and milk somatic cell count data

Data collected by the National Animal Health Monitoring System in Ohio for a 12-month period during 1986 and 1987 were used to determine the relative magnitude of costs associated with mastitis in the following categories: milk production loss, veterinary services, drugs, producer labor, and "other" factors. The cost of milk loss associated with mastitis that was reported by producers cooperating in the National Animal Health Monitoring System program was compared with estimates based on bulk tank somatic cell counts and individual cow milk somatic cell counts. Using producer-reported estimates, milk loss accounted for about one third of the total cost associated with mastitis. When estimates of milk loss were replaced by estimates based on bulk tank somatic cell counts, milk loss accounted for over 80% of the total cost of mastitis. Estimates of the cost of milk loss based on studies relating milk yield to somatic cell counts differed considerably. Consequently, it was unclear how to best estimate the relative magnitude of the milk loss component of mastitis costs.