Modeling the interannual variability in Maipo and Rapel river plumes off central Chile

River plumes have a direct influence on coastal environments, impacting coastal planktonic and benthic communities, including fishery resources. In general, the main drivers of river plume dynamics are the river discharge and the alongshore wind stress, whereas the tides and topography play a secondary role. In central Chile, rivers flowing into the eastern Pacific have a relatively short path on land, with a high slope and a mixed snow–rain regime. This study aims to understand the interannual variability in the plumes of the Maipo and Rapel rivers in the coastal/shelf area off central Chile and their influence on local ocean dynamics. We used the Coastal and Regional Ocean Community (CROCO) model, with 1 km horizontal resolution and 20 sigma levels, to simulate the ocean dynamics for the period 2003–2011. The results show that the plume's area coverage and coastal ocean salinity are strongly correlated with the river discharges. The predominant northeastward winds control the plumes' orientation toward the northwest. However, episodes of southeastward winds in winter can reverse the plumes' direction, promoting their attachment to the coast and southward transport. Results also show a salification trend linked to the severe droughts hitting central Chile during the studied period. This salification determines a change in local dynamics which could be more frequent in future scenarios of climate change with a significant lack of rain and river discharges along central Chile.</p

Continental shelf off northern Chilean Patagonia: A potential risk zone for the onset of Alexandrium catenella toxic bloom?

Harmful Algal Blooms (HAB) pose a severe socio-economic problem worldwide. The dinoflagellate species Alexandrium catenella produces potent neurotoxins called saxitoxins (STXs) and its blooms are associated with the human intoxication named Paralytic Shellfish Poisoning (PSP). Knowing where and how these blooms originate is crucial to predict blooms. Most studies in the Chilean Patagonia, were focused on coastal areas, considering that blooms from the adjacent oceanic region are almost non-existent. Using a combination of field studies and modelling approaches, we first evaluated the role of the continental shelf off northern Chilean Patagonia as a source of A. catenella resting cysts, which may act as inoculum for their toxic coastal blooms. This area is characterized by a seasonal upwelling system with positive Ekman pumping during spring-summer, and by the presence of six major submarine canyons. We found out that these submarine canyons increase the vertical advection of bottom waters, and thus, significantly enhance the process of coastal upwelling. This is a previously unreported factor, among those involved in bloom initiation. This finding put this offshore area at high risk of resuspension of resting cysts of A. catenella. Here, we discuss in detail the physical processes promoting this resuspension.Harmful Algal Blooms (HAB) pose a severe socio-economic problem worldwide. The dinoflagellate species Alexandrium catenella produces potent neurotoxins called saxitoxins (STXs) and its blooms are associated with the human intoxication named Paralytic Shellfish Poisoning (PSP). Knowing where and how these blooms originate is crucial to predict blooms. Most studies in the Chilean Patagonia, were focused on coastal areas, considering that blooms from the adjacent oceanic region are almost non-existent. Using a combination of field studies and modelling approaches, we first evaluated the role of the continental shelf off northern Chilean Patagonia as a source of A. catenella resting cysts, which may act as inoculum for their toxic coastal blooms. This area is characterized by a seasonal upwelling system with positive Ekman pumping during spring-summer, and by the presence of six major submarine canyons. We found out that these submarine canyons increase the vertical advection of bottom waters, and thus, significantly enhance the process of coastal upwelling. This is a previously unreported factor, among those involved in bloom initiation. This finding put this offshore area at high risk of resuspension of resting cysts of A. catenella. Here, we discuss in detail the physical processes promoting this resuspension.Postprint2,35

Filosofía ambiental de campo: Educación e investigación para la valoración ecológica y ética de los insectos dulceacuícolas (Field environmental philosophy: education and research for the ecological and ethical appreciation of freshwater insects)

In a rapidly changing world, to confront biodiversity losses and the lack of appreciation for and knowledge about the most diverse groups of organisms, it is urgently necessary to stimulate cultural shifts that transcend purely scientific and technological domains. This paper addresses this problem by focusing on one of the least known groups of organisms, and in one of the most remote regions of the planet: freshwater insects in the sub-Antarctic Magellanic ecoregion. The work of this thesis included scientific-ecological and environmental philosophical research that was integrated into formal and non-formal environmental education practices that value freshwater insects, particularly as indicators of climate change. The integration of science and philosophy was done adapting the Field Environmental Philosophy methodology that includes a four-step cycle. Transdisciplinary research on freshwater insects and their sub-Antarctic ecosystems served as a basis for the composition of metaphors and educational activities with schoolchildren, other members of the local community and visitors to Omora Park, in Puerto Williams, Chile. Based on this work, new outdoor educational activities were designed with the objective of awakening the interest of citizens for insects, and nurturing their perceptions about these organisms, their habitats and life habits. In this way, at a local scale this work aims to contribute to greater knowledge, appreciation and conservation of this unique sub-Antarctic biodiversity, and at a global scale it aims to contribute overcoming the under-appreciation for the most diverse group of organisms: the insects

Burkholderia cenocepacia BC2L-C Is a Super Lectin with Dual Specificity and Proinflammatory Activity

Lectins and adhesins are involved in bacterial adhesion to host tissues and mucus during early steps of infection. We report the characterization of BC2L-C, a soluble lectin from the opportunistic pathogen Burkholderia cenocepacia, which has two distinct domains with unique specificities and biological activities. The N-terminal domain is a novel TNF-α-like fucose-binding lectin, while the C-terminal part is similar to a superfamily of calcium-dependent bacterial lectins. The C-terminal domain displays specificity for mannose and l-glycero-d-manno-heptose. BC2L-C is therefore a superlectin that binds independently to mannose/heptose glycoconjugates and fucosylated human histo-blood group epitopes. The apo form of the C-terminal domain crystallized as a dimer, and calcium and mannose could be docked in the binding site. The whole lectin is hexameric and the overall structure, determined by electron microscopy and small angle X-ray scattering, reveals a flexible arrangement of three mannose/heptose-specific dimers flanked by two fucose-specific TNF-α-like trimers. We propose that BC2L-C binds to the bacterial surface in a mannose/heptose-dependent manner via the C-terminal domain. The TNF-α-like domain triggers IL-8 production in cultured airway epithelial cells in a carbohydrate-independent manner, and is therefore proposed to play a role in the dysregulated proinflammatory response observed in B. cenocepacia lung infections. The unique architecture of this newly recognized superlectin correlates with multiple functions including bacterial cell cross-linking, adhesion to human epithelia, and stimulation of inflammation

Optical, morphological and photocatalytic properties of biobased tractable films of chitosan/donor-acceptor polymer blends

Biobased tractable films consisting of blends of chitosan (CS) with polymer bearing carbazole derivatives as pendant groups and fluorene-thiophene as donor-acceptor units (referred to as DA) were prepared, and their optical, morphological and photocatalytic properties were studied. DA was dissolved in tetrahydrofuran (THF) and mixed with an acidified aqueous solution containing chitosan to obtain chitosan/DA (CS/DA) films by solution casting. The fabricated biobased films were characterized using spectroscopic techniques (FT-IR and UV–vis), thermogravimetry, mechanical assays, contact angle analysis, and atomic force microscopy (AFM). The effects of varying DA compositions and the results of exposure to visible-light irradiation of the films were also analyzed. The results indicated the existence of interactions between chitosan and DA and a potentially profitable light-driven response of these biobased films. This behavior was reflected in the optical, topographical, and contact angle properties of the films, which exhibited different characteristics before and after visible-light exposure. Finally, the photocatalytic performance of the biobased films was tested via the decomposition of methyl orange (MO), as a reaction model system. Our results revealed a significant photocatalytic activity (according to biobased film composition, approximately 64 % and 87 % of methyl orange were degraded under continuous visible-light irradiation for 120 min) of the films which is attributed to the combined presence and synergetic effects of the film-forming ability of chitosan and the photoproperties of DA

Comparative analyses imply that the enigmatic sigma factor 54 is a central controller of the bacterial exterior

Contains fulltext : 95738.pdf (publisher's version ) (Open Access)BACKGROUND: Sigma-54 is a central regulator in many pathogenic bacteria and has been linked to a multitude of cellular processes like nitrogen assimilation and important functional traits such as motility, virulence, and biofilm formation. Until now it has remained obscure whether these phenomena and the control by Sigma-54 share an underlying theme. RESULTS: We have uncovered the commonality by performing a range of comparative genome analyses. A) The presence of Sigma-54 and its associated activators was determined for all sequenced prokaryotes. We observed a phylum-dependent distribution that is suggestive of an evolutionary relationship between Sigma-54 and lipopolysaccharide and flagellar biosynthesis. B) All Sigma-54 activators were identified and annotated. The relation with phosphotransfer-mediated signaling (TCS and PTS) and the transport and assimilation of carboxylates and nitrogen containing metabolites was substantiated. C) The function annotations, that were represented within the genomic context of all genes encoding Sigma-54, its activators and its promoters, were analyzed for intra-phylum representation and inter-phylum conservation. Promoters were localized using a straightforward scoring strategy that was formulated to identify similar motifs. We found clear highly-represented and conserved genetic associations with genes that concern the transport and biosynthesis of the metabolic intermediates of exopolysaccharides, flagella, lipids, lipopolysaccharides, lipoproteins and peptidoglycan. CONCLUSION: Our analyses directly implicate Sigma-54 as a central player in the control over the processes that involve the physical interaction of an organism with its environment like in the colonization of a host (virulence) or the formation of biofilm

O Bom, o Mau e o Feio: Um enfoque pragmático para a revisão de uma ética e uma política para Internet

The article stems from a broader ongoing research project on Internet, Global Constitutionalism and Ethics. We attempt to brisk up traditional ethical thinking against the background of urgent questions concerning the Internet. By revisiting the perspective of cosmopolitanism that was inspired by Kant's thesis of a universal rationality, reflecting upon Hanna Arendt's critical analysis of moral claims and political outcome, and building on Capurro's "net ethics", we introduce a perspective aiming at an intercultural understanding that might guide our actions in global politics in times of the so called digital era. The article advances the idea by Hannah Arendt that a concrete example as such has moral relevance and therefore makes a case to foster this approach using "best practices" as explicit examples to follow.Este artículo deriva de un proyecto de investigación mayor sobre Internet, Constitucionalismo Global y Ética. En él intentamos avivar el pensamiento ético tradicional a la luz de preguntas urgentes relativas a Internet. Pasamos revista a la perspectiva del cosmopolitismo, reflexionando sobre el análisis crítico de aseveraciones morales y los resultados políticos, y, finalmente, construyendo sobre la "net ethics" de Capurro, presentamos una perspectiva que apunta a un entendimiento intercultural capaz de guiar nuestras acciones en la política global en tiempos de la denominada "era digital". El artículo utiliza de idea de Hannah Arendt que afirma que un ejemplo concreto, como tal, tiene relevancia moral y, por ende, propone este enfoque relativo a las "mejores prácticas" como un ejemplos explícitos a seguir.Este artigo deriva de um projeto de investigação maior sobre Internet, Constitucionalismo Global e Ética. Nele tentamos avivar o pensamento ético tradicional à luz de preguntas urgentes relativas à Internet. Passamos em revista a perspectiva do cosmopolitismo, refletindo sobre a análise crítica de asseverações morais e os resultados políticos, e, finalmente, construindo sobre a "net ethics" de Capurro, apresentamos uma perspectiva que aponta para um entendimento intercultural capaz de guiar nossas ações na política global em tempos da denominada "era digital". O artigo utiliza da ideia de Hannah Arendt que afirma que um exemplo concreto, como tal, tem relevância moral e, por fim, propõe este enfoque relativo às "melhores práticas" como um exemplos explícitos a seguir.