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.     

Cell proliferation and apoptosis in the pathogenesis of oesophagogastric lesions in pigs

Recent studies have stressed the importance of epithelial hyperproliferation in the pathogenesis of early lesions (parakeratotic hyperkeratosis) of the porcine gastric pars oesophagea (PO). In this study, immunohistochemical staining with Ki67 (clone MIB1) and AgNOR proteins silver staining were used to evaluate, by means of image analysis, cell proliferation in normal and parakeratotic (parakeratotic hyperkeratosis) epithelia of the PO. Apoptotic activity was also assessed with the TUNEL assay and compared with cell proliferative parameters. Early lesions of the PO were characterised by a significant increase in epithelial proliferative activity while there was no difference in the apoptotic activity between normal and parakeratotic epithelia.Our data confirm the hyperproliferative nature of epithelial changes preceding degeneration and erosion/ulcer of the PO and suggest that an underlying feature of gastric ulcers in pigs is an imbalance between cell proliferation and programmed cell death.     

Influence of dietary palm oil on growth, tissue fatty acid compositions, and fatty acid metabolism in liver and intestine in rainbow trout (Oncorhynchus mykiss)

This study aimed to investigate the effects of dietary crude palm oil (CPO) on fatty acid metabolism in liver and intestine of rainbow trout. Triplicate groups of rainbow trout for 10 weeks at 13 °C were fed on diets in which CPO replaced fish oil (FO) in a graded manner (0–100%). At the end of the trial, fatty acid compositions of flesh, liver and pyloric caeca were determined and highly unsaturated fatty acid (HUFA) synthesis and fatty acid oxidation were estimated in isolated hepatocytes and caecal enterocytes using [1‐¹⁴C]18:3n‐3 as substrate. Growth performance and feed efficiency were unaffected by dietary CPO. Fatty acid compositions of selected tissues reflected the dietary fatty acid composition with increasing CPO resulting in increased proportions of 18:1n‐9 and 18:2n‐6 and decreased proportions of n‐3HUFA, 20:5n‐3 and 22:6n‐3. Palmitic acid, 16:0, was also increased in flesh and pyloric caeca, but not in liver. The capacity of HUFA synthesis from 18:3n‐3 increased by up to threefold in both hepatocytes and enterocytes in response to graded increases in dietary CPO. In contrast, oxidation of 18:3n‐3 was unaffected by dietary CPO in hepatocytes and reduced by high levels of dietary CPO in enterocytes. The results of this study suggest that CPO can be used at least to partially replace FO in diets for rainbow trout in terms of permitting similar growth and feed conversion, and having no major detrimental effects on lipid and fatty acid metabolism, although flesh fatty acid compositions are significantly affected at an inclusion level above 50%, with n‐3HUFA reduced by up to 40%.     

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.     

Molecular characterization and marker based chemotaxonomic studies of Podophyllum hexandrum Royle

Detailed chemical studies and RAPD analysis were done in different populations of Podophyllum hexandrum collected from high altitude regions of North Western Himalayas. Random amplified polymorphic DNA (RAPD) analysis revealed a high degree of genetic diversity among the 12 collected accessions, attributed to their geographical and climatic conditions. HPLC analysis also revealed variation in the concentration of two major marker compounds which lead to the identification of a chemotype. The study demonstrated that RAPD and chemical markers are very useful tools to compare the genetic relationship and pattern of variation among such prioritized and endangered medicinal plants.     

THE EFFECTS OF HEAVY DRESSINGS OF POTASH APPLIED TO THE SEEDBED OF A LEY COMPARED WITH ANNUAL DRESSINGS

Two experiments were established to compare the effect on the yield of continuously cut herbage of varying amounts of potassium fertilizer applied either in one large dose to the seedbed, or as 3 equal dressings applied to the seedbed and in the summer of the 2 following years. Responses in dry–matter yield were recorded up to the higher rates of potassium fertilizer applied. Establishment and yield in the first 12 months were improved by seedbed applications of up to 4 cwt/ac of muriate of potash (60% K₂O). Although total yields over the whole period were similar, whether the potassium was applied to the seedbed only or in annual dressings, yields from "all–in–seedbed" dressings declined towards the end of the period. Soil analysis indicated that annual dressings left behind higher residues of K.     

THE INFLUENCE OF PHOSPHATE AND LIME ON THE GROWTH AND N FIXATION OF LOTUS ULIGINOSUS AND TRIFOLIUM REPENS UNDER GREENHOUSE CONDITIONS

Shoot dry weight, leaf area, leaf lamina dry weight and N-fixation of L. uliginosus cv. Grasslands 4705 were compared with those of T. repens S184 over a 90-day period frotn sowing, in pots in a greenhouse. Three P and three pH levels were imposed and there were three destructive harvests at 30-day intervals. N-fixation was estimated by the acetylene reduction technique prior to the last harvest. L. uliginosus had higjier means than T. repens for all characters measured under all treatments at all harvests. Large increases in shoot weight and leaf area were associated with addition of P, particularly with the first increment of P to L. uliginosus. High P reduced the contribution of lamina to total shoot weight in T. repens more than in L. uliginosus at the second harvest. Raising pH increased shoot weight and leaf area in both species. N-fixation was low in both species at low pH and low P. This was increased by addition of P, a smaller quantity being necessary for the same response in L. uliginosus compared with T. repens. At the higher P levels, the high pH gave rise to lower N-fixation than at the medium pH. Results are discussed in relation to field trials of other workers and the possible suitability of L. uliginosus for low fertility upland conditions.