Polyphenol oxidase and peroxidase expression in four pineapple varieties (Ananas comosus L.) after a chilling injury

Pineapple internal browning (IB) is a chilling injury that produces enzymatic browning associated with flesh translucency. Pineapple biodiversity allowed the investigation of how polyphenol oxidase (PPO) and peroxidase (POD) activities with their different isoforms are involved in the IB mechanism. Fruits of four varieties that expressed IB symptoms differently, Smooth Cayenne (SCay) and the hybrids MD2, Flhoran 41 (Flh 41), and Flhoran 53 (Flh 53), were stressed by cold. The susceptible varieties showed classical brown spots but different patterns of IB, whereas MD2 and controls showed no IB. Enzymatic activities were measured on fruit protein extracts and PPO and POD isoforms separated on mini-gels (PhastSystem). Only PPO activity was significantly enhanced in the presence of IB. Up to six PPO isoforms were identified in the susceptible varieties. PPO was barely detectable in the nonsusceptible variety MD2 and in controls. The number of PPO isoforms and the total PPO activity after chilling are varietal characteristics.     

Furan formation from lipids in starch-based model systems, as influenced by interactions with antioxidants and proteins

The formation of furan upon sterilization of a lipid-containing starch gel was investigated in the presence of various antioxidants, namely, α-tocopherol, β-carotene, and ascorbic acid, with and without proteins. Results indicated that α-tocopherol did not significantly influence furan formation from oxidized lipids. β-Carotene, suggested previously to be a furan precursor itself, did influence the generation of furan in a concentration-dependent manner, although to a limited extent. Surprisingly, the presence of lipids seemed to limit the furan generation from β-carotene. Interestingly, the addition of ascorbic acid to the emulsions containing soybean or sunflower oils considerably enhanced the formation of furan from these oils. This was also the case when fresh oils were applied, shown previously to be nearly unable to generate furan. This observation can be explained by an intensified ascorbic acid degradation stimulated by the presence of lipids.     

Assessing the influence of resource covariates at multiple spatial scales: an application to forest-dwelling caribou faced with intensive human activity

Efforts in isolating the relative effects of resources and disturbances on animal-distribution patterns remain hindered by the difficulty of accounting for multiple scales of resource selection by animals with seasonally dynamic drivers. We developed multi-scale, seasonal models to explore how local resource selection by the threatened forest-dwelling woodland caribou (Rangifer tarandus caribou) was influenced by both broad-scale landscape context and local resource heterogeneity in the intensively managed region of Charlevoix, Québec, Canada, located on the southern border of the North American caribou range. We estimated resource selection functions using 23 GPS-collared caribou monitored from 2004 to 2006 and landscape data on vegetation classes, terrain conditions, and roads. We found evidence of thresholds in road “proximity” effects (up to 1.25 km), which underscores the importance of including landscape context variables in addition to locally measured variables, and of fitting seasonal-specific models given temporal variation in the magnitude of selection and optimal scale of measurement. Open lichen woodlands were an important cover type for caribou during winter and spring, whereas deciduous forests, wetlands, and even young disturbed stands became important during calving and summer. Caribou consistently avoided roads and rugged terrain conditions at both local and landscape levels. Landscape context fundamentally constrains the choices available to animals, and we showed that failing to consider landscape context, or arbitrarily choosing an inappropriate scale for measuring covariates, may provide biased inferences with respect to habitat selection patterns. Effective habitat management for rare or declining species should carefully consider the hierarchical nature of habitat selection.     

Application of Soil Fractionation Methods to the Study of the Distribution of Pollutant Metals

Three agricultural Fluvisols polluted by sewage sludge were dispersed by shaking in water or in organic solvent for particle size and density separations. The perturbations caused by the ultrasonic treatment were discussed. Only the carbonate particles were disrupted to very fine particles. The pollutant metals were not displaced by the treatments, except perhaps Cd that is partly soluble in water and in other solvents. We discussed the relationship between soil constitution and major element chemical analyses. We obtained enough different fractions by using the ultrasonic and other dispersion treatments and by fractionating versus two physical parameters (i.e. particle size and density), for a correlation study between the contents of major and trace elements. We found that Cu was the only element to be more concentrated in the “free” organic matter. Other metals were more concentrated within an organo-mineral compartment, containing evoluted organic matter, fine clay and hydrous oxides. No pollutant metals were associated with carbonates, feldspars, and quartz. Other less general features were discussed.     

Cytokine and chemokine gene expression of IL-1beta stimulated equine articular chondrocytes

OBJECTIVE: To evaluate mRNA expression of several proinflammatory and anti-inflammatory cytokines and chemokines in equine unstimulated and interleukin-1beta (IL-1beta)-stimulated chondrocytes. STUDY DESIGN: In vitro experiment using equine chondrocyte cultures. SAMPLE POPULATION: Whole articular cartilage from metacarpophalangeal joints (n=5 horses; 10 fetlocks). METHODS: Chondrocyte monolayer cultures were established from digested adult equine articular cartilage and stimulated with 5 ng/mL of recombinant human IL-1beta. RNA was extracted from the cells 24 hours after stimulation. IL-1beta, IL-4, IL-6, IL-8, tumor necrosis factor-alpha (TNF-alpha), and ubiquitin (house keeping gene) mRNA expression were investigated by real-time RT-PCR. RESULTS: IL-1beta, IL-6, and IL-8 mRNA were expressed in unstimulated chondrocytes from macroscopically normal joints and were significantly up-regulated after stimulation (5/5 horses). IL-4 mRNA was not detected in any samples (0/5 horses). TNF-alpha mRNA, by comparison, was expressed in 2/5 unstimulated samples and in all stimulated samples but a considerable sample variation in response to IL-1beta stimulation was observed. CONCLUSIONS: Equine chondrocytes express mRNA for several proinflammatory cytokines and chemokines and IL-1beta modulates their expression. CLINICAL RELEVANCE: Chondrocytes express proinflammatory cytokines and chemokines capable of modulating a local inflammatory cascade in articular cartilage, which could potentially lead to focal degradation and osteoarthritis.     

Teaching veterinary clinical pathology to undergraduate students: an integrated European project

BACKGROUND: Veterinary clinical pathology is a relatively new and emerging discipline in Europe that has gained momentum with the recent establishment of a specialty college. In this situation, veterinary faculties may face challenges in understanding and defining what clinical pathology is and how it can best be integrated into existing curricula. In addition, many schools in Europe may not yet have available a critical mass of suitably qualified faculty capable of teaching in all areas of clinical pathology. OBJECTIVE: The main purpose of this report is to describe the goals, procedures adopted, teaching material produced, and proposed future activities of a major European initiative designed to develop a veterinary clinical pathology curriculum. METHODS: Four working subgroups were formed to establish a list of course objectives and topics and prepare a series of lectures. These contents were reviewed and discussed several times at a series of general meetings. RESULTS: An undergraduate course on veterinary clinical pathology was designed with course objectives, a list of topics and a CD-ROM consisting of 24 lectures. CONCLUSIONS: The results of this project could be useful in the establishment or improvement of training programs in veterinary clinical pathology at the undergraduate level in Europe and in other places around the world. The provision of teaching resources for faculty could help to instill in veterinary students a strong understanding of the discipline and promote development of advanced training programs and career opportunities in clinical pathology in Europe.     

Variations saisonnieres des composantes de l'alcalinite des eaux dans le haut-estuaire du fleuve Saint-Laurent (Quebec)

Measurements of the total alkalinity and its components have been made on waters collected from the St.` Lawrence River during the year 1980–1981. Analyses of the total inorganic carbon, the borates, the phosphates and the silicates along with the pH and the total alkalinity permitted an evaluation of each component. In all seasons, the carbonate system was the major component (96%) of the total alkalinity. The residual alkalinity accounting for only 2 to 3% and obtained by the difference between the total alkalinity and the sum of the components appears attributable to weak organic acids. The saturation state of calcite coincided with a river saturated by dissolved calcium carbonate during the summer season and only 45% saturated during the winter season.