A comparison of mortality rates between top height trees and average site trees

? Although comparisons between methods of selecting trees for site index estimates are well documented in the literature, little is known on mortality rates of different canopy tree cohorts used for that purpose.

? This study was initiated to test the hypothesis that the mortality rates of top height trees are lower than those of codominants only or a combination of codominant and dominant trees. To test this hypothesis, we used records from a network of permanent sample plots in Québec and studied the fate of different cohorts of site trees for five different species.

? Our results did not show clear evidence of lower mortality rates for top height trees. Instead we found that depending on the species, top height trees have lower (Populus tremuloides, Pinus banksiana), higher (Picea mariana, Abies balsamea) or equal mortality rates (Betula papyrifera) than codominant trees or codominant and dominant trees combined.

? These results suggest a tendency for shade intolerant species to maintain lower top height tree mortality rates over time when compared to shade tolerant species. In the latter case, it is also shown that spruce budworm epidemics (Choristoneura fumiferana) did not change the pattern of mortality rates of site trees of A. balsamea.

     

Phenoloxidase and peroxidase activities in Sphagnum-dominated peatland in a warming climate

Peatlands still suffer from the scarcity of available data about the characterization and the response to climate forcing of the main oxidative enzymes that occur over the seasons. In the present study, phenoloxidase and peroxidase activities were examined in Sphagnum lawns along a narrow fen-bog gradient under experimental elevated temperatures. We showed that peroxidase activities from Sphagnum mosses were 1000-fold higher than those of phenoloxidases irrespective of seasons and sampling areas. Peroxidase activities increased (+30%) with the rise of air temperatures (an average of 1 °C), while warming did not alter phenoloxidase activities. These results suggest that the monitoring of peroxidase activities in peatlands may represent a suitable and forward indicator of the impact of climate warming on carbon cycle in peatlands.     

Phenolics, phytic acid, and phytase in Canadian-grown low-tannin faba bean (Vicia faba L.) genotypes

Thirteen low-tannin faba bean genotypes grown at two locations in north central Alberta in 2009 were evaluated to investigate the variation in seed characteristics, phenolic and phytate contents, and phytase and antioxidant activities and to elucidate the relationship of these components as a breeding strategy. Seed characteristics including color were predominantly genotype dependent. The faba bean genotypes with total phenolic content ranging from 5.5 to 41.8 mg of catechin equiv/g of sample was linearly related to tannin content and the best predictor of antioxidant activity. Phytic acid content and phytase activity varied significantly among genotypes and between locations, ranging from 5.9 to 15.1 g/kg and from 1606 to 2154 FTU/kg sample, respectively. Multivariate data analysis performed on 19 components analyzed in this study using principal component analysis (PCA) and cluster analysis demonstrate that differences in seed characteristics, phenolic components, phytic acid, and phytase are major factors in segregating faba bean genotypes. The relatively low phytic acid content and high phytase activity of these low-tannin faba bean genotypes are beneficial/essential traits for their use in human and animal nutrition.     

Postprandial kinetics of gene expression of proteins involved in the digestive process in rainbow trout (<Emphasis Type="Italic">O. mykiss</Emphasis>) and impact of diet composition

The impact of increased incorporation of plant ingredients on diets for rainbow trout was evaluated in terms of gene expression of gastric (gastric lipase, pepsinogen) and intestinal (prolidase, maltase, phospholipase A2) digestive enzymes and nutrient transporters (peptide and glucose transporters), as well as of postprandial levels of plasma glucose, triglycerides and total free amino acids. For that purpose, trout alevins were fed from the start of exogenous feeding one of three different experimental diets: a diet rich in fish meal and fish oil (FM–FO), a plant-based diet (noFM–noFO) totally free from fish meal and fish oil, but containing plant ingredients and a Mixed diet (Mixed) intermediate between the FM–FO and noFM–noFO diets. After 16 months of rearing, all fish were left unfed for 72 h and then given a single meal to satiation. Blood, stomach and anterior intestine were sampled before the meal and at 2, 6 and 12 h after this meal. The postprandial kinetics of gene expression of gastric and intestinal digestive enzymes and nutrient transporters were then followed in trout fed the FM–FO diet. The postprandial profiles showed that the expression of almost all genes studied was stimulated by the presence of nutrients in the digestive tract of trout, but the timing (appearance of peaks) varied between genes. Based on these data, we have focused on the molecular response to dietary factors in the stomach and the intestine at 6 and 12 h after feeding, respectively. The reduction in FM and FO levels of dietary incorporation induced a significant decrease in the gene expression of gastric lipase, GLUT2 and PEPT1. The plasma glucose and triglycerides levels were also reduced in trout fed the noFM–noFO diet. Consequently, the present study suggests a decrease in digestive capacities in trout fed a diet rich in plant ingredients.     

A conserved p38 MAP kinase pathway in Caenorhabditis elegans innate immunity

A genetic screen for Caenorhabditis elegans mutants with enhanced susceptibility to killing by Pseudomonas aeruginosa led to the identification of two genes required for pathogen resistance: sek-1, which encodes a mitogen-activated protein (MAP) kinase kinase, and nsy-1, which encodes a MAP kinase kinase kinase. RNA interference assays and biochemical analysis established that a p38 ortholog, pmk-1, functions as the downstream MAP kinase required for pathogen defense. These data suggest that this MAP kinase signaling cassette represents an ancient feature of innate immune responses in evolutionarily diverse species.     

Induction of a barrier membrane to facilitate reconstruction of massive segmental diaphyseal bone defects: an ovine model

OBJECTIVES: To report an ovine model that can be used to evaluate the efficacy of bone substitutes for repair of segmental diaphyseal bone defects. STUDY DESIGN: Experimental study. ANIMALS: Eleven 2-year-old Pré-Alpes Sheep. METHODS: Mid-diaphyseal metatarsal bone defects (25 mm long) were stabilized by a dynamic compression plate over a polymethylmethacrylate (PMMA) cement spacer, and by external coaptation. The PMMA spacer was removed at 6 weeks by incising the encapsulating membrane. The defect remained unfilled (Group 1; n=5) or was filled with morselized autologous corticocancellous graft (Group 2; n=6), the membrane sutured closed, and external coaptation applied for 6 months, when healing was evaluated. RESULTS: Radiographic, computed tomographic, and histologic examinations at 6 months after the 2nd surgery revealed non-union in ungrafted defects whereas grafted defects showed bone healing. The induced membrane had blood vessels, CBFA1+ cells, and very few macrophages entrapped in a collagenous tissue positive for type I collagen. CONCLUSION: This ovine metatarsal defect model resulted in a critical-size defect (non-union) that healed when grafted. The PMMA-induced membrane constrained the graft, was well vascularized, and may have osteogenic properties. CLINICAL RELEVANCE: This model may be useful to evaluate new strategies in bone tissue engineering because the PMMA-induced membrane may help confine bone morphogenetic proteins, skeletal stem cells, or other agents to the defect cavity where they could be useful to enhance bone formation.     

Understanding veterinary practitioners' decision-making process: implications for veterinary medical education

Understanding how veterinary practitioners make clinical decisions, and how they use scientific information to inform their decisions, is important to optimize animal care, client satisfaction, and veterinary education. We aimed to develop an understanding of private practitioners' process of decision making. On the basis of a grounded-theory qualitative approach, we conducted a telephone survey and semi-structured face-to-face interviews. We identified a decision-making framework consisting of two possible processes to make decisions, five steps in the management of a clinical case, and three influencing factors. To inform their decision, veterinary surgeons rarely take the evidence-based medicine (EBM) approach. They consult first-opinion colleagues, specialists, laboratories, and the Internet rather than scientific databases and peer-reviewed literature, mainly because of limited time. Most interviewees suggested the development of educational interventions to better develop decision-making skills in veterinary schools. Adequate information and EBM tools are needed to optimize the time spent in query and assessment of scientific information, and practitioners need to be trained in their use.     

Masitinib decreases signs of canine atopic dermatitis: a multicentre, randomized, double-blind, placebo-controlled phase 3 trial

This study investigated the efficacy and safety of masitinib, a selective tyrosine kinase inhibitor capable of downregulating mast cell functions, for treatment of canine atopic dermatitis (CAD). Dogs with confirmed CAD received masitinib at 12.5 mg/kg/day (n = 202) or control (n = 104) for 12 weeks. A reduction in CAD Extent and Severity Index (CADESI-02) score of ≥ 50% at week 12 was observed in 61% of masitinib-treated dogs versus 35% of control dogs (P < 0.001), according to the modified intent-to-treat population. For dogs resistant to ciclosporin and/or corticosteroids (60% of the study population), CADESI-02 response rates were 60 versus 31%, respectively (P = 0.004). The mean reduction in pruritus score of severely pruritic dogs was 46 versus 29%, respectively (P = 0.045). Furthermore, 65% of owners with severely pruritic dogs assessed masitinib efficacy as good/excellent versus 35% control (P = 0.05). Overall, 63% of investigators assessed masitinib efficacy as good/excellent versus 35% control (P < 0.001). Premature discontinuations from the modified intent-to-treat population (28.2% masitinib versus 26.0% control) were mainly due to adverse events (13.4 versus 4.8%, respectively) or lack of efficacy (12.4 versus 18.3%, respectively). In total, 13.2% dogs presented with severe adverse events (16.0% masitinib versus 7.7% control). Masitinib showed a risk of reversible protein loss, although regular surveillance of blood albumin and proteinuria allowed for discontinuation of treatment while the dog was still clinically asymptomatic. Masitinib proved to be an effective and mostly well-tolerated treatment of CAD, including severe and refractory cases, with medically manageable adverse effects.     

Biocontrol of soil-borne fungal plant diseases by 2,4-diacetylphloroglucinol-producing fluorescent pseudomonads with different restriction profiles of amplified 16S rDNA

Fluorescent pseudomonads producing the antimicrobial compound 2,4-diacetylphloroglucinol (Phl) are being studied extensively for use as biocontrol agents of soil-borne fungal diseases. Some of them can produce pyoluteorin (Plt) in addition to Phl, whereas others synthesise only Phl. Here, a collection of seven Phl⁺ Plt^- pseudomonads, seven Phl⁺ Plt⁺ pseudomonads and seven Phl^- biocontrol pseudomonads were compared for protection of plant roots against fungal pathogens. The seven Phl⁺ Plt⁺ pseudomonads were identical by restriction analysis of amplified spacer ribosomal DNA (spacer ARDRA), whereas the Phl⁺ Plt^- pseudomonads and especially the Phl^- biocontrol pseudomonads were quite diverse by spacer ARDRA. Collectively, the Phl⁺ Plt^- pseudomonads proved superior to the Phl⁺ Plt⁺ pseudomonads and the Phl^- biocontrol pseudomonads for protection of tomato against Fusarium crown and root rot (in rockwool microcosms) or cucumber against Pythium damping-off (in non-sterile soil microcosms). There was no correlation between protection in vivo and inhibition of the corresponding fungal pathogen on plates. However, there was a significant correlation between the amount of Phl produced on plates and protection of tomato against Fusarium crown and root rot, but not with protection of cucumber against Pythium damping-off. Interestingly, the minority of strains unable to produce HCN, an extracellular protease, or both, were among those unable to protect plants in both pathosystems. A seedling assay was developed to compare pseudomonads for suppression of Fusarium crown and root rot in vitro, and a significant correlation was found between disease severity in vitro and in vivo. Overall, results suggest that promising biocontrol pseudomonads may be identified based on the ability to produce Phl and/or specific ARDRA-based fingerprints.