Réponse de la communauté de mollusques aux perturbations physiques et chimiques dans un grand lac fluvial (Lac Saint-Pierre, Fleuve Saint-Laurent, QC)

Les mollusques sont des indicateurs de perturbations anthropiques et environnementales. Ce groupe de macroinvertébrés représente en outre une source importante de nourriture pour les poissons et les oiseaux aquatiques du littoral. Les hypothèses de cette étude sont que la communauté de mollusques est influencée indirectement par les tributaires agricoles et/ou par des variables environnementales (comme la dessiccation et l'exposition aux vagues) puisque ces perturbations sont susceptibles de modifier leurs sources alimentaires et leur habitat. Les indicateurs de la réponse des mollusques aux agents perturbateurs sont la composition, la diversité, la densité, ainsi que la biomasse des espèces. En septembre 2013, des mesures de paramètres physico-chimiques de l'eau ont été réalisées, et des échantillons de mollusques et de végétation aquatique ont été prélevés à 14 sites le long des rives du lac Saint-Pierre (Fleuve Saint-Laurent, Québec, Canada). Le long de la rive nord, les sites fortement exposés à l'action du vent, situés à de plus grandes élévations, affichaient une plus faible densité, biomasse et richesse spécifique de mollusques que les sites de la rive sud, en milieu plus abrité et profond. Les sites physiquement perturbés étaient caractérisés par de faibles biomasses en macrophytes submergés. Les sphaeriidae apparaissent comme des exceptions à ces patrons, montrant une abondance plus élevée aux sites presque dépourvus de macrophytes. Bien que les variables physiques et l'habitat exercent une influence déterminante sur les communautés de mollusques, les gastéropodes et les moules unionidés étaient également affectés par la dégradation de la qualité de l'eau dans le panache des tributaires agricoles. La richesse, la densité et la biomasse des gastéropodes étaient négativement influencées par des teneurs élevées de matières en suspension et de fer dissous. Les résultats de notre étude montrent que la communauté de mollusques du lac Saint-Pierre est directement affectée par l'émersion périodique, l'exposition au vent, et indirectement par l'effet de ces variables physiques sur les macrophytes qui constituent leur habitat.

Saint-Maron : une paroisse diasporique : église et fidèles maronites à Montréal (1969-2015)

L’immigration maronite à Montréal date de la fin du XIXe siècle, mais c’est dans les années 1970 et 1990, à la suite des guerres au Liban, qu’il y a eu les plus grandes vagues. De rite syriaque antiochien, mais d’obédience catholique romaine, les immigrants maronites n’avaient pas d’église paroissiale propre. Les autorités diocésaines montréalaises avaient rassemblé les catholiques orientaux dans une même église dont le service était assuré par l’ordre melkite du Saint-Sauveur. En 1969, le père de l’ordre maronite mariamite Élias Najjar fonde avec des Égyptiens maronites la première paroisse. Cette étude se penche sur le processus qui a mené à la naissance de cette paroisse, son évolution à travers le temps et la vie de ses paroissiens. L’approche est narrative et descriptive, elle s’inscrit dans le cadre de l’histoire sociale et religieuse. Les résultats de l’analyse mettent en lumière une église nationale et un nouveau modèle de paroisse diasporique, différent du modèle classique, recelant des diversités infranationale, internationale et interconfessionnelle.

Valores del capital humano y las competencias del líder que facilitan la implantación de la estrategia organizacional

La obtención de una ventaja competitiva, el desarrollo, el crecimiento, la perdurabilidad, entre otros, son los aspectos que buscan las organizaciones a través de las estrategias que se definen. Sin embargo, no es suficiente con diseñar las metas y los objetivos que se quieren alcanzar, es necesario aterrizar estos propósitos en planes de acción e involucrar a todos los miembros de la organización, lo cual se consigue a través de la implantación de la estrategia. En este sentido, la etapa de implantación de la estrategia en una organización, da curso al camino establecido en la etapa de formulación de la estrategia, por lo tanto, se relaciona directamente con su éxito o su fracaso. No obstante, este proceso no depende de algunos pocos miembros de la organización, de directivos o de funcionarios, sino que depende de la buena sincronización y armonía de todos aquellos que hacen parte de ella. La presente investigación a través de la revisión teórica y de evidencias empíricas, busca poner de manifiesto la incidencia de dos aspectos clave en la organización sobre la implantación de la estrategia, por un lado, los líderes, a partir de sus competencias interpersonales y por otro el capital humano, a partir de sus valores. Los resultados obtenidos muestran que tanto las competencias del líder como los valores del capital humano son determinantes para la adecuada implantación de la estrategia organizacional.

Demand of children in Colombia : guessing or planning

El artículo analiza los determinantes de la presencia de hijos no deseados en Colombia. Se utiliza la información de la Encuesta Nacional de Demografía y Salud (ENDS, 2005), específicamente para las mujeres de 40 años o más. Dadas las características especiales de la variable que se analiza, se utilizan modelos de conteo para verificar si determinadas características socioeconómicas como la educación o el estrato económico explican la presencia de hijos no deseados. Se encuentra que la educación de la mujer y el área de residencia son determinantes significativos de los nacimientos no planeados. Además, la relación negativa entre el número de hijos no deseados y la educación de la mujer arroja implicaciones clave en materia de política social.

Dual citizenship or dual identity? Does 'transnationalism' supplant 'nationalism' among returning Trinidadians?

In this article we focus on the dual identities of relatively young Trinidadians who have decided to return to the island of their birth, or of their parents, while still in their thirties and forties. Highly-educated professional transnational migrants mostly make tip our sample of 36; 26 possess dual citizenship. We focus on our informants' narratives about their transnational experiences, self-appraisals of their dual identities and how they value dual citizenship. More generally, we ask does transnationalism supplant nationalism among our returning informants? Unsurprisingly, the diverse responses we document do not support the commonly held explanatory relationship between return adaptations, 'national belonging' and the expected dominance of 'transnational belonging'. Family, relations intervene significantly, both to encourage transnationalism and to strengthen nationalism. Feelings of notional belonging often accompany transnationalism. Notably, we view dual citizenship strategically and pragmatically as advantageous to the continuation of transnational practices.

In vitro evaluation of fibrolytic enzymes as additives for maize (Zea mays L.) silage - III. Comparison of enzymes derived from psychrophilic, mesophilic or thermophilic sources

A completely randomised study was completed to examine the influence of fibrolytic enzymes derived from psychrophilic, (F), mesophilic, (L) or thermophilic (Ta) sources, applied at ensiling, on the chemical characteristics and in vitro rumen fermentation of maize silage, assessed using the Reading Pressure Technique (RPT). Treatments, all in triplicate, consisted of untreated maize forage or treated with preparations F, L, Ta or a mixture (1: 1, v/v) of F and L (FL), at two levels each, and ensiled for 210 days in plastic mini-silos. Addition of enzymes L decreased (P < 0.05) silage pH relative to the control, whereas enzyme Ta tended (P < 0.10) to reduce it. Preparations F, L and Ta tended to reduce (P < 0.10) the fibre contents of the silages, with effects being attributable to a decrease in the cellulose fraction. Starch contents were reduced (P < 0.05) in the treatments including enzyme F. End-point (96 h) gas production (GP) values did not differ among treatments, suggesting that enzymes did not change the total amount of fermentable substrate. However, consistent with the decrease in starch contents, adding enzyme F reduced (P < 0.05) GP at most incubation times. Addition of enzymes increased (P < 0.05) the initial (6 h) organic matter degradation (OMD) levels in all but one treatment (F), with increases of 14, 19, and 26% for preparations L, Ta, and FL, respectively, averaged across levels. Furthermore, the addition of enzymes increased (P < 0.05) the soluble OM losses, however, these increases did not fully account for the initial increase in OMD. The latter suggests that enzymes increased solubility and also altered silage structure, making it more amenable to degradation by ruminal microorganisms. As a result of the increase in OMD, without a concomitant increase in GP, the fermentation efficiency was greatly increased (P < 0.05) in enzyme treatments. Addition of enzymes to maize at ensiling, particularly those from the mesophilic and thermophilic sources used here, have the potential to increase the initial rate of silage OMD. (C) 2003 Elsevier B.V. All rights reserved.

Effects of cottonseed cake-based diets supplemented with blood meal, alone or with lysine, on the growth of pigs

An experiment was carried out to establish the effect on the growth of pigs of including blood meal or lysine in diets containing gossypol from cottenseed cake. Forty Landrace x Large White pigs (20 of each sex) were randomly allocated to 5 treatments of 8 pigs each in a 2x2 factorial design with two levels of lysine or two levels of blood meal in the diets plus a control diet. The pigs were fed different diets and slaughtered at 75.0+/-2.0 kg live weight for carcase analysis. Supplementing the diets with blood meal resulted in higher live weight gains (p<0.001) and improved feed conversion ratios (p<0.001) than supplementing with lysine. Pigs fed the higher level of cottonseed cake showed a significant (p<0.001) depression in live weight gain and feed conversion ratio compared to those fed a low level of the cake. There was no significant difference (p>0.05) in intake in the pigs fed diets with cottonseed cake including blood meal or synthetic lysine. The kidney and liver weights of the pigs fed the diets with a higher level of cottonseed cake were significantly greater (p<0.001) than in those fed the lower level, but when the diets containing cottonseed cake were supplemented with blood meal or lysine at the same level there was no significant difference (p>0.05) in the weights of these organs. Lysine or other factors derived from blood meal appear to be more efficient than synthetic lysine in reducing the adverse effects of gossypol.

Expression of SOD1 G93A or wild-type SOD1 in primary cultures of astrocytes down-regulates the glutamate transporter GLT-1: lack of involvement of oxidative stress

Glutamate excitotoxicity is implicated in the aetiology of amyotrophic lateral sclerosis (ALS) with impairment of glutamate transport into astrocytes a possible cause of glutamate-induced injury to motor neurons. It is possible that mutations of Cu/Zn superoxide dismutase (SOD1), responsible for about 20% of familial ALS, down-regulates glutamate transporters via oxidative stress. We transfected primary mouse astrocytes to investigate the effect of the FALS-linked mutant hSOD1(G93A) and wild-type SOD1 (hSOD1(wt)) on the glutamate uptake system. Using western blotting, immunocytochemistry and RT-PCR it was shown that expression of either hSOD1(G93A) or hSOD1(wt) in astrocytes produced down-regulation of the levels of a glutamate transporter GLT-1, without alterations in its mRNA level. hSOD1(G93A) or hSOD1(wt) expression caused a decrease of the monomeric form of GLT-1 without increasing oxidative multimers of GLT-1. The effects were selective to GLT-1, since another glutamate transporter GLAST protein and mRNA levels were not altered. Reflecting the decrease in GLT-1 protein, [H-3]D-aspartate uptake was reduced in cultures expressing hSOD1(G93A) or hSOD1(wt). The hSOD1-induced decline in GLT-1 protein and [H-3]D-aspartate uptake was not blocked by the antioxidant Trolox nor potentiated by antioxidant depletion using catalase and glutathione peroxidase inhibitors. Measurement of 2',7'-dichlorofluorescein (DCF)-induced fluorescence revealed that expression of hSOD1(G93A) or hSOD1(wt) in astrocytes does not lead to detectable increase of intracellular reactive oxygen species. This study suggests that levels of GLT-1 protein in astrocytes are reduced rapidly by overexpression of hSOD1, and is due to a property shared between the wild-type and G93A mutant form, but does not involve the production of intracellular oxidative stress.

Lack of effect of foods enriched with plant- or marine-derived n-3 fatty acids on human immune function

Background: Greatly increasing dietary flaxseed oil [rich in the n-3 polyunsaturated fatty acid (PUFA) alpha-linolenic acid (ALA)] or fish oil [rich in the long-chain n-3 PUFAs eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids] can reduce markers of immune cell function. The effects of more modest doses are unclear, and it is not known whether ALA has the same effects as its long-chain derivatives. Objective: The objective was to determine the effects of enriching the diet with ALA or EPA+DHA on immune outcomes representing key functions of human neutrophils, monocytes, and lymphocytes. Design: In a placebo-controlled, double-blind, parallel study, 150 healthy men and women aged 25-72 y were randomly assigned to I of 5 interventions: placebo (no additional n-3 PUFAs), 4.5 or 9.5 g ALA/d, and 0.77 or 1.7 g EPA+DHA/d for 6 mo. The n-3 PUFAs were provided in 25 g fat spread plus 3 oil capsules. Blood samples were taken at 0, 3, and 6 mo. Results: The fatty acid composition of peripheral blood mononuclear cell phospholipids was significantly different in the groups with higher intakes of ALA or EPA+DHA. The interventions did not alter the percentages of neutrophils or monocytes engaged in phagocytosis of Escherichia coli or in phagocytic activity, the percentages of neutrophils or monocytes undergoing oxidative burst in response to E. coli or phorbol ester, the proliferation of lymphocytes in response to a T cell mitogen, the production of numerous cytokines by monocytes and lymphocytes, or the in vivo delayed-type hypersensitivity response. Conclusion: An intake of f less than or equal to9.5 g ALA/d or less than or equal to1.7 g EPA+DHA/d does not alter the functional activity of neutrophils, monocytes, or lymphocytes, but it changes the fatty acid composition of mononuclear cells.