ONG internationales environnementalistes et politiques forestières tropicales : L’exemple de Greenpeace en Amazonie

L’analyse critique de la campagne de Greenpeace consacrée à la protection de l’Amazonie, entre le milieu des années 1990 et le début des années 2000, révèle l’impact contradictoire des ONG internationales sur les politiques forestières tropicales. D’un côté, l’ONG participe avec succès au maintien sur les agendas nationaux et internationaux de la question de la bonne gestion des forêts tropicales. Elle réussit aussi à apporter une aide conséquente à certaines populations locales, tout en étant l’un des principaux promoteurs de nouveaux concepts, de nouvelles normes et de nouvelles politiques. De l’autre, certaines logiques internes entraînent des choix stratégiques qui conduisent Greenpeace à engager et porter des normes et des représentations n’intégrant pas toujours la complexité inhérente aux milieux forestiers tropicaux. Cela peut amenuiser les débats visant à mettre à jour les meilleurs modes de conservation et de gestion de ces espaces forestiers. Ces dynamiques peuvent aussi produire les effets inverses de ceux qui sont escomptés.A critical analysis of Greenpeace’s conservation campaign in Amazonia, from the mid 1990s to today reveals the contradictory impact of international NGOs on tropical forest policies. On one hand, Greenpeace succeeds in maintaining the question of tropical forest management on national and international political agendas. The organisation also contributes by providing a substantial aid to local populations, whilst being at the forefront of new concepts and norms in local participation and promoting new policies. On the other hand, internal logics induce strategic decision-making which, at times, leads Greenpeace to adopt norms and representations that do not always adequately represent the complexity inherent to tropical forest environments. This in turn can restrict debates concerning appropriate conservation modalities and the management of forest spaces. Such dynamics can also produce contrary effects to those desired.El análisis de la campaña de Greenpeace consagrada a la protección de la Amazonía, entre mediados de los años 1990 y principios de los años 2000, muestra el impacto contradictorio de las ONG internacionales sobre las políticas forestales tropicales. Por un lado, la ONG participa con éxito al mantenimiento de la cuestión de la buena gestión de los bosques tropicales en las agendas nacionales e internacionales. Esta organización logra asimismo aportar la ayuda requerida por ciertas poblaciones locales, sin perder su rol de promotor de nuevos conceptos, nuevas normas y nuevas políticas. Por otra parte, ciertas dinámicas internas inducen decisiones estratégicas que conducen a Greenpeace a comprometerse y promover normas y representaciones que no siempre integran la complejidad inherente a los medios forestales tropicales. Eso puede simplificar los debates que tratan de actualizar los mejores modos de conservación y de gestión de los espacios forestales. Estas dinámicas pueden asimismo producir efectos contrarios a lo que se buscan

La réserve extractiviste de Ciriaco : babaçu durable pour les petits producteurs?

L'expérience de développement durable étudiée, la réserve extractiviste de Ciriaco a été implantéedans le municipe de Cidelândia, localisé dans la région dite du Bico do Papagaio, à l'extrême sudouestde l'État du Maranhão. La zone s'insère dans la région écologique de la "Pré-Amazonie"(SEPLAN), qui correspond à une bordure forestière de transition du massif amazonien

Le délicat apprentissage d’une préservation conjointe des écosystèmes et des sociétés (Maranhão, Brésil)

À travers l’analyse de la mise en place et du fonctionnement de la réserve extractiviste (« résex ») de Ciriaco, située dans un ancien front pionnier amazonien (Maranhão, Brésil), nous montrons comment certains dispositifs de protection de la nature s’associent à un processus de démocratisation et d’apprentissage social, essentiel à la survie des populations locales et de leurs écosystèmes. Mais ces mesures environnementales s’avèrent aussi souvent déconnectées de processus socio-territoriaux plus larges conduisant alors à une forte dichotomie entre les discours structurant l’action de préservation et les réalités économiques et sociales locales, d’autant plus qu’il est extrêmement difficile de donner aux populations traditionnelles la capacité de résister aux effets délétères d’une intégration anarchique au marché. Néanmoins, la mise en place de la « résex » a permis aux populations concernées de se structurer en communauté autour d’un projet fondé sur la préservation de la nature et d’engager un processus permettant d’entrevoir la construction d’un modèle de développement pouvant conduire à une préservation conjointe des milieux naturels et des sociétés.Through an analysis of the extractive reserve (resex) of Ciriaco, located on an old Amazonian pioneer front (Maranhão, Brazil), we show the important role this resex model of conservation plays in the promotion of local sustainable development and democratization. However, we argue that these environmental measures do not necessarily entail positive changes. They are often disconnected from broader territorial and social dynamics – extensive cattle breeding, in the case of Ciriaco – leading to tensions between the logics structuring preservation practices and local socio-economic realities. Regardless of which sustainable development model is implemented, it is extremely difficult to assist local communities in gaining the capacity to resist the wider detrimental effects of an anarchistic integration into the market. Nevertheless, the resex model allows local families to organise themselves into a community around a nature conservation project. This is an essential step in the construction of new development models that integrate ecosystem conservation and social development

Differential Interactions of Na+ Channel Toxins with T-type Ca2+ Channels

Two types of voltage-dependent Ca2+ channels have been identified in heart: high (ICaL) and low (ICaT) voltage-activated Ca2+ channels. In guinea pig ventricular myocytes, low voltage–activated inward current consists of ICaT and a tetrodotoxin (TTX)-sensitive ICa component (ICa(TTX)). In this study, we reexamined the nature of low-threshold ICa in dog atrium, as well as whether it is affected by Na+ channel toxins. Ca2+ currents were recorded using the whole-cell patch clamp technique. In the absence of external Na+, a transient inward current activated near −50 mV, peaked at −30 mV, and reversed around +40 mV (HP = −90 mV). It was unaffected by 30 μM TTX or micromolar concentrations of external Na+, but was inhibited by 50 μM Ni2+ (by ∼90%) or 5 μM mibefradil (by ∼50%), consistent with the reported properties of ICaT. Addition of 30 μM TTX in the presence of Ni2+ increased the current approximately fourfold (41% of control), and shifted the dose–response curve of Ni2+ block to the right (IC50 from 7.6 to 30 μM). Saxitoxin (STX) at 1 μM abolished the current left in 50 μM Ni2+. In the absence of Ni2+, STX potently blocked ICaT (EC50 = 185 nM) and modestly reduced ICaL (EC50 = 1.6 μM). While TTX produced no direct effect on ICaT elicited by expression of hCaV3.1 and hCaV3.2 in HEK-293 cells, it significantly attenuated the block of this current by Ni2+ (IC50 increased to 550 μM Ni2+ for CaV3.1 and 15 μM Ni2+ for CaV3.2); in contrast, 30 μM TTX directly inhibited hCaV3.3-induced ICaT and the addition of 750 μM Ni2+ to the TTX-containing medium led to greater block of the current that was not significantly different than that produced by Ni2+ alone. 1 μM STX directly inhibited CaV3.1-, CaV3.2-, and CaV3.3-mediated ICaT but did not enhance the ability of Ni2+ to block these currents. These findings provide important new implications for our understanding of structure–function relationships of ICaT in heart, and further extend the hypothesis of a parallel evolution of Na+ and Ca2+ channels from an ancestor with common structural motifs

Multiple Potential Molecular Contributors to Atrial Hypocontractility Caused by Atrial Tachycardia Remodeling in Dogs

Background-Atrial fibrillation impairs atrial contractility, inducing atrial stunning that promotes thromboembolic stroke. Action potential (AP)-prolonging drugs are reported to normalize atrial hypocontractility caused by atrial tachycardia remodeling (ATR). Here, we addressed the role of AP duration (APD) changes in ATR-induced hypocontractility. Methods and Results-ATR (7-day tachypacing) decreased APD (perforated patch recording) by approximate to 50%, atrial contractility (echocardiography, cardiomyocyte video edge detection), and [Ca2+](i) transients. ATR AP waveforms suppressed [Ca2+](i) transients and cell shortening of control cardiomyocytes; whereas control AP waveforms improved [Ca2+](i) transients and cell shortening in ATR cells. However, ATR cardiomyocytes clamped with the same control AP waveform had approximate to 60% smaller [Ca2+](i) transients and cell shortening than control cells. We therefore sought additional mechanisms of contractile impairment. Whole-cell voltage clamp revealed reduced I-CaL; I-CaL inhibition superimposed on ATR APs further suppressed [Ca2+](i) transients in control cells. Confocal microscopy indicated ATR-impaired propagation of the Ca2+ release signal to the cell center in association with loss of t-tubular structures. Myofilament function studies in skinned permeabilized cardiomyocytes showed altered Ca2+ sensitivity and force redevelopment in ATR, possibly due to hypophosphorylation of myosin-binding protein C and myosin light-chain protein 2a (immunoblot). Hypophosphorylation was related to multiple phosphorylation system abnormalities where protein kinase A regulatory subunits were downregulated, whereas autophosphorylation and expression of Ca2+-calmodulin-dependent protein kinase II delta and protein phosphatase 1 activity were enhanced. Recovery of [Ca2+](i) transients and cell shortening occurred in parallel after ATR cessation. Conclusions-Shortening of APD contributes to hypocontractility induced by 1-week ATR but accounts for it only partially. Additional contractility-suppressing mechanisms include I-CaL current reduction, impaired subcellular Ca2+ signal transmission, and altered myofilament function associated with abnormal myosin and myosin-associated protein phosphorylation. The complex mechanistic basis of the atrial hypocontractility associated with AF argues for upstream therapeutic targeting rather than interventions directed toward specific downstream pathophysiological derangements. (Circ Arrhythm Electrophysiol. 2010;3:530-541.

F.A.R.O.G. FORUM, Vol. 5 No. 5

Contains a supplément littéraire.https://digitalcommons.library.umaine.edu/francoamericain_forum/1063/thumbnail.jp

Imaging the nanoscale organization of peptidoglycan in living Lactococcus lactis cells

Peptidoglycans provide bacterial cell walls with mechanical strength. The spatial organization of peptidoglycan has previously been difficult to study. Here, atomic force microscopy, together with cells carrying mutations in cell-wall polysaccharides, has allowed an in-depth study of these molecules