Activity against Ostertagia ostertagi of low doses of oxfendazole continuously released from intraruminal capsules in cattle.

Slow release from intraruminal capsules of 0.48 mg/kg oxfendazole per day for 5.5 days gave percentage efficiencies of 99 +/- 0.6, 86.6 +/- 6.3 and 93.1 +/- 4.5 for the removal of adult worms, developing 4th stages and inhibited larvae of Ostertagia ostertagi respectively. These efficiencies were not significantly different from those obtained from a single oral dose of 2.5 mg/kg. Peak plasma levels of oxfendazole were similar for the 2 types of administration but high levels were maintained longer in cattle given capsules.     

Influence of variety on the within-plant distribution of cassava green spider mite (Acari: Tetranychidae), and leaf anatomical characteristics and chemical components in relation to varietal resistance

The within-plant distribution of the cassava green spider mite, Mononychellus tanajoa Bondar, and the anatomical characteristics and the chemical components relating to varietal resistance of cassava, were studied using 11 cassava genotypes with varying levels of resistance for two dry seasons and one wet season. The results show that M. tanajoa aggregates on the top leaves of cassava at low levels of resistance as compared with a more even within-plant distribution at higher levels of resistance. Thus, for accurate sampling of mite populations, it might be important to consider young and old leaves, not just the young leaves, in fields containing resistant and susceptible cassava genotypes. Correlations between the anatomical characteristics and mite population density and damage scores were not consistent across months, either within or over seasons. This suggests that leaf anatomical characteristics may not be important in the varietal resistance of cassava to M. tanajoa. During the dry season, mite population density was positively correlated with leaf nitrogen, potassium and phosphorus and negatively correlated with leaf calcium and fat. Only calcium was negatively associated with mite damage at the peak of the dry season (January 1993 and 1994). Breeding cassava genotypes with high levels of leaf calcium and fat, and low levels of leaf nitrogen, potassium and phosphorus, may improve the level of resistance to M. tanajoa.     

Contamination of soil with Toxocara eggs in urban (Prague) and rural areas in the Czech Republic

Contamination of soil with feline and canine ascarid eggs in public parks, backyards and sand pits in Prague, Czech Republic was investigated in this work. Soil samples from shelters and rural areas were also collected. The comparison of soil from different areas (urban, rural, backyards and shelters) exhibited significant difference (chi(2)=32.16, d.f.=3 and p<0.0001). The highest rate of contamination (45%) was found in backyards inhabited by feral cats. The eggs of Toxocara spp. were found in 20.4% of parks, 10% of shelters and 5% of rural samples. Mean egg density per sample from Prague parks was 6.2 eggs/100g of soil. In 126 composite samples from children's and pits, the prevalence of Toxocara eggs was 11.90%. The number of eggs in positive samples varied from 2 to 22 (per 100g). A high proportion (46.9%) of eggs was fully embryonated. There was no difference between the sand pits with or without formal exclusion of dogs (chi(2)=0.6, d.f.=1 and p<0.0001).     

Estimation of the effect of lead and cadmium ions on fluctuating asymmetry in leaves of the common bean (Phaseolus vulgaris L.)

The effect of lead and cadmium ions on the fluctuating asymmetry of the side leaflets’ central veins of the common bean (Phaseolus vulgaris L.) was estimated. The impact of heavy metals on the parameter with the lead or cadmium content in the ground in the concentration of 650 mg/kg or 10 mg/kg respectively was not revealed.     

Ultrastructural features of Mycoplasma gallisepticum in tracheal explants under transmission and stereoscan electron microscopy

Ultrastructural features of Mycoplasma gallisepticum in tracheal explants were examined using the transmission and stereoscan electron microscope. The organisms were characteristically cocco-bacilliform except when in close contact with the host cells when they assumed an elongated and irregular form characteristically terminating in a bleb which was often embedded in the cell surface. In such organisms there were peripherally aligned fibrillar structures oriented towards the bleb which may have a functional relationship with a probing or moving habit of the mycoplasma.     

Assessment of salt tolerance of <Emphasis Type="Italic">Aegilops</Emphasis> L. from the VIR collection

The effect of high NaCl concentrations on accumulation of biomass and change in content of sodium and potassium ions in 17 accessions of nine species of Aegilops L. is studied. Three salt-tolerant accessions (Ae. tauschii k-677 and 674 and Ae. cylindrica k-676) containing the D genome and having a high K/Na ratio are identified.     

Using 3D animations to teach intracellular signal transduction mechanisms: taking the arrows out of cells

Traditional methods of teaching intracellular biological processes and pathways use figures or flowcharts with the names of molecules linked with arrows. Many veterinary students, presented with such material, simply memorize the names or chemical structures of the molecules and are then likely to forget the material once the examination is completed. To address this problem, the authors designed, created, and field-tested new teaching media that incorporate realistic three-dimensional (3D) animations depicting the dynamic changes that occur in intracellular molecules during cellular activation. Testing found that veterinary students taught using traditional teaching media (e.g., lectures, handouts, textbooks) are proficient in memorizing the names and order of intracellular molecules but unable to appreciate the interactions between these elements or their spatial relationships within cells. In contrast, more than 90% of veterinary students taught using 3D animations not only recall the facts about the intracellular elements but also develop accurate mental images of the interactions among these molecules and their spatial relationships. These findings strongly suggest that the comprehension of complex biological processes by veterinary students can be enhanced by the use of dynamic 3D depictions of these processes in the classroom.     

Physical Properties of Extruded Wheat Starch-Additive Mixtures

The effects of the addition of fatty acids, monoglycerides (MG), and wheat germ oil (WGO) on the level of crystallinity and the crystalline structure of extrusion-cooked wheat starch have been studied using twin-screw extruders. Measurements of water solubility and water absorption indices were made on the extrudates, together with specific mechanical energy (SME) consumption and die pressure for the extruder. MG and the fatty acids added to a level of 4% caused an increase in V_hydrate type crystallinity. WGO addition to a level of 8% caused no change in crystallinity, although the E_hydrate type was favored at lower moisture contents. All additives caused a decrease in SME and an increase or maximum in die pressure. WGO behaved differently than MG and fatty acids in that its addition caused the water solubility index and expansion to increase, as previously observed for other oils added to flours.     

Factors affecting the adoption of agroforestry practices by farmers in Cameroon

This paper presents empirical evidence on the impact of socio-economic factors on the adoption of agroforestry practices in Cameroon. The analysis uses primary farm-level data collected from June to December 1996. Three major provinces of the country were covered, namely Centre, Southwest and Northwest Several agroforestry technologies have been promoted among farmers in the zone, including alley farming, improved fallow, live fencing, cut-and-carry fodder and apiculture. The status of adoption of each agroforestry practice is described and factors that affect adoption identified. These are gender of farmer, household family size, level of education, farmer’s experience, membership within farmers’ associations, contact with research and extension, security of land tenure, agroecological zone, distance of the village from nearest town, village accessibility and income from livestock. Research findings indicate that since factors affecting farmers’ adoption of agroforestry practices differ across techniques, generalisation is to be avoided.