Larval Distribution and Histopathology of Experimental Strongyloides ransomi Infection in Young Swine

Necropsy at various intervals of three week old pigs following experimental infection with larvae of Strongyloides ransomi showed distribution of the larvae through the body during the first 24 hours. Quiescent larvae at the 24 hour necropsy, as indicated by higher recovery before and after this period may be an indication of physiological changes preceding a moult. Whether or not a moult occurs in the lung prior to migration of the larvae to the intestine has not been determined. At the 72 hour necropsy, larvae were largely confined to the lung and juvenile worms were beginning to appear in the small intestine. Migration to the small intestine was completed by the 96 hour necropsy. Lesions were observed in the skin and lungs up to the 96 hour necropsy, and lymphocytic accumulations were observed in the skin and lungs to this point and lymphocytic accumulations were observed in the liver to the 72 hour necropsy. At 28 days post-application lung lesions were still evident and the duodenum and jejunum were heavily parasitized.

Egg passage began on the sixth day post-application and peaked on the 12th day.

     

METABOLIC MANAGEMENT OF THE HORSE WITH ACUTE ABDOMINAL CRISIS*

The horse with an abdominal crisis caused by acute gastro-intestinal tract obstruction develops hypovolemia, hemoconcentration, electrolyte depletion, metabolic acidosis and shock. During preparation for operation, treatment with fluids, antibiotics and bicarbonate will impede metabolic imbalance. Stomach decompression may slow the passage of sodium, water and potassium to the gut lumen, reduce pain and minimize the risk of stomach rupture. Selected laboratory determinations and the monitoring of arterial and venous pressures will provide a measure of severity and serve as a guide to replacement therapy. In the post surgical period, vigilance must be directed towards potassium and bicarbonate imbalanc and adequate hydration.     

A gas-chromatographic method for the determination of dichlorvos in air

A sensitive, specific and convenient method for the determination of dichlorvos in air is described. The method involves the use of glass tubes containing potassium nitrate for trapping dichlorvos vapour from the air and flame-photometric gas chromatography for the determination of dichlorvos. The recovery of dichlorvos is 80% and the coefficient of variation for the method is 10%. The method gives results which compare favourably with those obtained by the Drechsel bottle procedure. In addition, the method requires only low sample volumes and can be applied to determine levels of dichlorvos in confined spaces. The sampling flow rate is not critical but storage of the sampling tubes below room temperature prior to analysis is necessary.     

Peroxidative protection of parenteral admixture by D-alpha-tocopherol

High lipid:low dextrose (HL:LD) parenteral admixtures (PAs) are becoming commonplace in the nutritional support of veterinary patients. Lipid peroxidation before administration appears to be an unwanted sequela of high lipid content in PAs that can lead to oxidative injury of biologic membranes in vivo. The purpose of this in vitro study was to measure hydroperoxides in HL:LD PAs and to determine the optimal dose of d-alpha-tocopherol to minimize peroxidation in these PAs during a 24-hr period. Detectable concentrations of hydroperoxides were present in all PAs. D-alpha-tocopherol appeared to significantly minimize peroxidation of HL:LD PAs in vitro. These results have clinical implications for parenteral feeding in critically ill patients.     

Qualification of a Plant Disease Simulation Model: Performance of the LATEBLIGHT Model Across a Broad Range of Environments

ABSTRACT The concept of model qualification, i.e., discovering the domain over which a validated model may be properly used, was illustrated with LATEBLIGHT, a mathematical model that simulates the effect of weather, host growth and resistance, and fungicide use on asexual development and growth of Phytophthora infestans on potato foliage. Late blight epidemics from Ecuador, Mexico, Israel, and the United States involving 13 potato cultivars (32 epidemics in total) were compared with model predictions using graphical and statistical tests. Fungicides were not applied in any of the epidemics. For the simulations, a host resistance level was assigned to each cultivar based on general categories reported by local investigators. For eight cultivars, the model predictions fit the observed data. For four cultivars, the model predictions overestimated disease, likely due to inaccurate estimates of host resistance. Model predictions were inconsistent for one cultivar and for one location. It was concluded that the domain of applicability of LATEBLIGHT can be extended from the range of conditions in Peru for which it has been previously validated to those observed in this study. A sensitivity analysis showed that, within the range of values observed empirically, LATEBLIGHT is more sensitive to changes in variables related to initial inoculum and to weather than to changes in variables relating to host resistance.     

Genetic Diversity and Structure of the Apiosporina morbosa Populations on Prunus spp

ABSTRACT Populations of Apiosporina morbosa collected from 15 geographic locations in Canada and the United States and three host species, Prunus virginiana, P. pensylvanica, and P. padus, were evaluated using the sequence-related amplified polymorphism (SRAP) technique to determine their genetic diversity and population differentiation. Extensive diversity was detected in the A. morbosa populations, including 134 isolates from Canada and the United States, regardless of the origin of the population. The number of polymorphic loci varied from 6.9 to 82.8% in the geographic populations, and from 41.4 to 79.3% in the populations from four host genotypes based on 58 polymorphic fragments. In all, 44 to 100% of isolates in the geographic populations and 43.6 to 76.2% in populations from four host genotypes represented unique genotypes. Values of heterozygosity (H) varied from 2.8 to 28.3% in the geographic populations and 10.2 to 26.1% in the populations from four host genotypes. In general, the A. morbosa populations sampled from wild chokecherry showed a higher genetic diversity than those populations collected from other host species, whereas the populations isolated from cultivated chokecherry, P. virginiana 'Shubert Select', showed a reduction of genetic diversity compared with populations from wild P. virginiana. Significant population differentiation was found among both the geographic populations (P < 0.05) and populations from different host genotypes (P < 0.02). In the geographic populations, most of populations from cultivated and wild P. virginiana were closely clustered, and no population differentiation was detected except for the populations from Morris, Morden, and Winnipeg, Manitoba, Canada. Furthermore, the populations from P. virginiana in the same geographic locations had higher genetic identity and closer genetic distance to each other compared with those from different locations. Four populations from P. virginiana, P. pensylvanica, and P. padus, were significantly differentiated from each other (P < 0.02), except there was no differentiation between the Shubert Select and wild chokecherry populations (>P> = 0.334). Indirect estimation of gene flow showed that significant restricted gene flow existed between populations from different regions and host species. Gene flow rates (Nm) varied from <1 to 12.5, with higher gene flow rates among population pairs from the same host species (P = 1.000). The analysis of molecular variance revealed that a major genetic variance source came from the genetic variation among isolates within populations regardless of the origin and host genotype of the population. Although some locations had a limited number of isolates, the results of this study clearly showed that the genetic diversity and population differentiation of A. morbosa were closely associated with host genotypes and geographic locations, but mostly with the former.     

Transient expression vectors for functional genomics,quantification of promoter activity and RNA silencing in plants

Background  

We describe novel plasmid vectors for transient gene expression using Agrobacterium, infiltrated into Nicotiana benthamiana leaves. We have generated a series of pGreenII cloning vectors that are ideally suited to transient gene expression, by removing elements of conventional binary vectors necessary for stable transformation such as transformation selection genes.