Modelling nitrogen and phosphorus loads in a Mediterranean river catchment (La Tordera, NE Spain)

Human activities have resulted in increased nutrient levels in many rivers all over Europe. Sustainable management of river basins demands an assessment of the causes and consequences of human alteration of nutrient flows, together with an evaluation of management options. In the context of an integrated and interdisciplinary environmental assessment (IEA) of nutrient flows, we present and discuss the application of the nutrient emission model MONERIS (MOdelling Nutrient Emissions into River Systems) to the Catalan river basin, La Tordera (north-east Spain), for the period 1996-2002. After a successful calibration and verification process (Nash-Sutcliffe efficiencies E=0.85 for phosphorus and E=0.86 for nitrogen), the application of the model MONERIS proved to be useful in estimating nutrient loads. Crucial for model calibration, in-stream retention was estimated to be about 50 % of nutrient emissions on an annual basis. Through this process, we identified the importance of point sources for phosphorus emissions (about 94% for 1996-2002), and diffuse sources, especially inputs via groundwater, for nitrogen emissions (about 31% for 1996-2002). Despite hurdles related to model structure, observed loads, and input data encountered during the modelling process, MONERIS provided a good representation of the major interannual and spatial patterns in nutrient emissions. An analysis of the model uncertainty and sensitivity to input data indicates that the model MONERIS, even in data-starved Mediterranean catchments, may be profitably used by water managers for evaluating quantitative nutrient emission scenarios for the purpose of managing river basins. As an example of scenario modelling, an analysis of the changes in nutrient emissions through two different future scenarios allowed the identification of a set of relevant measures to reduce nutrient loads

Participatory scenario development for integrated assessment of nutrient flows in a Catalan river catchment

Rivers in developed regions are under significant stress due to nutrient enrichment generated mainly by human activities. Excess nitrogen and phosphorus emissions are the product of complex dynamic systems influenced by various factors such as demographic, socio-economic and technological development. Using a Catalan river catchment, La Tordera (North-East of Spain), as a case study of an integrated and interdisciplinary environmental assessment of nutrient flows, we present and discuss the development of narrative socio-economic scenarios through a participatory process for the sustainable management of the anthropogenic sources of nutrients, nitrogen and phosphorus. In this context, scenarios are an appropriate tool to assist nutrient emissions modelling, and to assess impacts, possible pathways for socio-economic development and associated uncertainties. Evaluated against the 1993–2003 baseline period, scenarios target the 2030 horizon, i.e. through the implementation process of the Water Framework Directive (Directive 2000/60/EC). After a critical examination of the methodology used in the participatory development of socio-economic scenarios, we present four possible futures (or perspectives) for the Catalan river catchment conceived by stakeholders invited to a workshop. Keys to the success of such a participatory process were trust, which enhanced openness, and disagreements, which fostered the group's creativity for scenario development. The translation of narrative socio-economic scenarios into meaningful nutrient emission scenarios is also discussed. By integrating findings of natural sciences and socio-economic analysis, we aim to assist decision makers and stakeholders in evaluating optimal management strategies for the anthropogenic sources of nitrogen and phosphorus

Functional significance of repressor element 1 silencing transcription factor (REST) target genes in pancreatic beta cells

Aims/hypothesis: The expression of several neuronal genes in pancreatic beta cells is due to the absence of the transcription factor repressor element 1 (RE-1) silencing transcription factor (REST). The identification of these traits and their functional significance in beta cells has only been partly elucidated. Herein, we investigated the biological consequences of a repression of REST target genes by expressing REST in beta cells. Methods: The effect of REST expression on glucose homeostasis, insulin content and release, and beta cell mass was analysed in transgenic mice selectively expressing REST in beta cells. Relevant target genes were identified in INS-1E and primary beta cells expressing REST. Results: Transgenic mice featuring a beta cell-targeted expression of REST exhibited glucose intolerance and reduced beta cell mass. In primary beta cells, REST repressed several proteins of the exocytotic machinery, including synaptosomal-associated protein (SNAP) 25, synaptotagmin (SYT) IV, SYT VII, SYT IX and complexin II; it impaired first and second phases of insulin secretion. Using RNA interference in INS-1E cells, we showed that SYT IV and SYT VII were implicated in the control of insulin release. Conclusions/interpretation: The data document the critical role of REST target genes in pancreatic beta cells. Specifically, we provide evidence that the downregulation of these genes is detrimental for the exocytosis of large dense core vesicles, thus contributing to beta cell dysfunction and impaired glucose homeostasi

Assessment of the interplay between blood and skin vascular abnormalities in adult purpura fulminans

RATIONALE: Purpura fulminans in adults is a rare but devastating disease. Its pathophysiology is not well known. OBJECTIVES: To understand the pathophysiology of skin lesions in purpura fulminans, the interplay between circulating blood and vascular alterations was assessed. METHODS: Prospective multicenter study in four intensive care units. Patients with severe sepsis without skin lesions were recruited as control subjects. MEASUREMENTS AND MAIN RESULTS: Twenty patients with severe sepsis and purpura fulminans were recruited for blood sampling, and skin biopsy was performed in deceased patients. High severity of disease and mortality rates (80%) was observed. Skin biopsies in purpura fulminans lesions revealed thrombosis and extensive vascular damage: vascular congestion and dilation, endothelial necrosis, alteration of markers of endothelial integrity (CD31) and of the protein C pathway receptors (endothelial protein C receptor, thrombomodulin). Elevated plasminogen activating inhibitor-1 mRNA was also observed. Comparison with control patients showed that these lesions were specific to purpura fulminans. By contrast, no difference was observed for blood hemostasis parameters, including soluble thrombomodulin, activated protein C, and disseminated intravascular coagulation markers. Bacterial presence at the vascular wall was observed specifically in areas of vascular damage in eight of nine patients tested (including patients with Streptococcus pneumoniae, Neisseria meningitidis, Escherichia coli, and Pseudomonas aeruginosa infection). CONCLUSIONS: Thrombi and extensive vascular damage with multifaceted prothrombotic local imbalance are characteristics of purpura fulminans. A "vascular wall infection" hypothesis, responsible for endothelial damage and subsequent skin lesions, can be put forward

Transferencia de tecnología para cocción energéticamente eficiente en ciudades de la Patagonia argentina

El presente trabajo describe el proceso de realización de taller de cajas térmicas y hornos solares en dos localidades de la Patagonia Argentina, Sierra Grande (Río Negro) y Puerto Madryn (Chubut). A través de la convocatoria efectuada por la Fundación Patagona Natural, se realizaron dos talleres de autoconstrucción de hornos solares de tacho y uno de cajas térmicas, esta actividad se llevó a cabo como complemento de un trabajo previo con las comunidades como lo es la fabricación de composteras. La radiación solar global diaria en verano en la zona en estudio es de 7 kWh/m2 día; con lo cual se podría utilizar el horno solar en esa época. Los talleres se desarrollaron a través de la intervención participativa entre los capacitadores y los participantes, futuros usuarios de los equipos. El seguimiento del los grupos se lleva a cabo por miembros de la Fundación Patagonia Natural y por el equipo capacitador a través de intervenciones de los propios usuarios en redes sociales. Se observan logros interesantes tanto en el uso de la tecnología como en la réplica posterior a la realización de los talleres, lo cual pone énfasis en las ventajas de la metodología empleada.Tema 10: Educación y capacitación en energías renovables y uso racional de la energía.Facultad de Arquitectura y Urbanism

Transferencia de tecnología para cocción energéticamente eficiente en ciudades de la Patagonia argentina

El presente trabajo describe el proceso de realización de taller de cajas térmicas y hornos solares en dos localidades de la Patagonia Argentina, Sierra Grande (Río Negro) y Puerto Madryn (Chubut). A través de la convocatoria efectuada por la Fundación Patagona Natural, se realizaron dos talleres de autoconstrucción de hornos solares de tacho y uno de cajas térmicas, esta actividad se llevó a cabo como complemento de un trabajo previo con las comunidades como lo es la fabricación de composteras. La radiación solar global diaria en verano en la zona en estudio es de 7 kWh/m2 día; con lo cual se podría utilizar el horno solar en esa época. Los talleres se desarrollaron a través de la intervención participativa entre los capacitadores y los participantes, futuros usuarios de los equipos. El seguimiento del los grupos se lleva a cabo por miembros de la Fundación Patagonia Natural y por el equipo capacitador a través de intervenciones de los propios usuarios en redes sociales. Se observan logros interesantes tanto en el uso de la tecnología como en la réplica posterior a la realización de los talleres, lo cual pone énfasis en las ventajas de la metodología empleada.Tema 10: Educación y capacitación en energías renovables y uso racional de la energía.Facultad de Arquitectura y Urbanism

Transferencia de tecnología para cocción energéticamente eficiente en ciudades de la Patagonia argentina

El presente trabajo describe el proceso de realización de taller de cajas térmicas y hornos solares en dos localidades de la Patagonia Argentina, Sierra Grande (Río Negro) y Puerto Madryn (Chubut). A través de la convocatoria efectuada por la Fundación Patagona Natural, se realizaron dos talleres de autoconstrucción de hornos solares de tacho y uno de cajas térmicas, esta actividad se llevó a cabo como complemento de un trabajo previo con las comunidades como lo es la fabricación de composteras. La radiación solar global diaria en verano en la zona en estudio es de 7 kWh/m2 día; con lo cual se podría utilizar el horno solar en esa época. Los talleres se desarrollaron a través de la intervención participativa entre los capacitadores y los participantes, futuros usuarios de los equipos. El seguimiento del los grupos se lleva a cabo por miembros de la Fundación Patagonia Natural y por el equipo capacitador a través de intervenciones de los propios usuarios en redes sociales. Se observan logros interesantes tanto en el uso de la tecnología como en la réplica posterior a la realización de los talleres, lo cual pone énfasis en las ventajas de la metodología empleada.Tema 10: Educación y capacitación en energías renovables y uso racional de la energía.Facultad de Arquitectura y Urbanism

Highly efficient xylem transport of arsenite in the arsenic hyperaccumulator Pteris vittata

The hyperaccumulator Pteris vittata translocates arsenic (As) from roots to fronds efficiently, but the form of As translocated in xylem and the main location of arsenate reduction have not been resolved. Here, P. vittata was exposed to 5 mu M arsenate or arsenite for 1-24 h, with or without 100 mu M phosphate. Arsenic speciation was determined in xylem sap, roots, fronds and nutrient solutions by high-performance liquid chromatography (HPLC) linked to inductively coupled plasma mass spectrometry (ICP-MS). The xylem sap As concentration was 18-73 times that in the nutrient solution. In both arsenate- and arsenite-treated plants, arsenite was the predominant species in the xylem sap, accounting for 93-98% of the total As. A portion of arsenate taken up by roots (30-40% of root As) was reduced to arsenite rapidly. The majority (c. 80%) of As in fronds was arsenite. Phosphate inhibited arsenate uptake, but not As translocation. More As was translocated to fronds in the arsenite-treated than in the arsenate-treated plants. There was little arsenite efflux from roots to the external solution. Roots are the main location of arsenate reduction in P. vittata. Arsenite is highly mobile in xylem transport, possibly because of efficient xylem loading, little complexation with thiols in roots, and little efflux to the external medium

Comparison of root absorption, translocation and tolerance of arsenic in the hyperaccumulator Pteris vittata and the nonhyperaccumulator Pteris tremula

Several fern species can hyperaccumulate arsenic, although the mechanisms are not fully understood. Here we investigate the roles of root absorption, translocation and tolerance in As hyperaccumulation by comparing the hyperaccumulator Pteris vittata and the nonhyperaccumulator Pteris tremula. The two species were grown in a pot experiment with 0-500 mg As kg(-1) added as arsenate, and in a short-term (8 h) uptake experiment with 5 pm arsenate under phosphorus-sufficient conditions. In the pot experiment, P. vittata accumulated up to 2500 mg As kg(-1) frond d. wt and suffered no phytotoxicity. P. tremula accumulated < 100 mg As kg(-1) frond d. wt and suffered severe phytotoxicity with additions of ! 25 mg As kg-1. In the short-term uptake experiment, P. vittata had a 2.2-fold higher rate of arsenate uptake than P. tremula, and distributed more As taken up to the fronds (76%) than did P. tremula (9%). Our results show that enhanced root uptake, efficient root-to-shoot translocation, and a much elevated tolerance through internal detoxification all contribute to As hyperaccumulation in P. vittata