DNA synthesis in spinal ganglia of rabbit after Herpes suis infection. Findings obtained by electron microscopy and autoradiography]

The mulitplication of herpes suis virus in neurons, amphicytes, gliocytes, as well as Schwann's and endothelial cells of the spinal ganglion of rabbit was traced by electron microscopy and autoradiography, using tritium-labelled thymidine. Marking of nuclear zone margin, quite common when it comes to ganglion cells, was observed also in the context of mesenchymal cells beyond expectation on the basis of light microscopy, but in the case under review it had no direct relationship with virus synthesis. Repeated markings were recorded from the nucleoli of apparently unchanged ganglion cells which suggested the suitability of the technique for early detection of infectious attack on intact cells. Exogenous 3H-thymidine was supplied three hours and absorbed with specificity by the DNA-forming centres of the nuclei, but the growing virus drew into itself additional cellular or inactive thymidine. The method proved to be highly significant, as in comparison to the nuclear environment there were ten times as many lemnici in the DNA production centres of neurons and Schwann's cells and about six times as many in the amphicytes and gliocytes. Now, there is definite justification in rejecting as unfounded all doubt expressed repeatedly and more recently in the specificity of herpes-dependent intranuclear inclusions.     

Serologic correlation of suspected Leptospira interrogans serovar pomona-induced uveitis in a group of horses

After the observation of 2 horses with uveitis on a horse farm in the Minnesota River valley, 100 horses from this geographic area were given ophthalmologic examinations and were evaluated serologically for leptospirosis. A statistically significant (P less than 0.001) association was observed between the finding of antibodies against Leptospira interrogans serovar pomona and uveitis.     

Spatial variations of rainwash and runoff within apparently homogeneous areas

The magnitude and causes of rainwash and runoff variability within small and supposedly “homogeneous” areas were investigated. Artificial rainfall (at 50 mm hr⁻¹ for 30 minutes) was applied to twenty identical 0.0929 m² (1 ft²) mini-plots arranged within a wetted annular 16.5 m² in area. Despite the uniformity of techniques used for data collection, there was considerable variability in the rainwash and runoff data (coefficient of variation= 21 to 35% and 20 to 75% respectively) at the three locations in southern Ontario. In comparison with laboratory data, field rainwash variability was similar but field runoff variability was substantially higher. Soil strength parameters, surface roughness and microtopography, as well as aggregation indices, are considered to be the potential causes of the observed variabilities. Operator variance was found to be extremely significant in our study. It is suggested, therefore, that comparison of erosion data collected by different researchers must be conducted with great caution.     

Field release of a non-toxigenic Aspergillus flavus L strain in central Benin

Journal of Plant Diseases and Protection - Non-toxigenic strains of Aspergillus flavus (Link) can be used as biological control agents to reduce the contamination of grains such as maize with...