Highly relaxing gadolinium based MRI contrast agents responsive to Mg2+ sensing

[Abstract] A Gd complex based on a polyphosphonated pyridyl ligand shows a very high stability in aqueous solution (logKEuL = 25.7), a high relaxivity (8.5 mM−1 s−1 at 25 °C and 20 MHz) and a marked and selective relaxivity enhancement (37%) in the presence of Mg2+, opening interesting perspectives for the design of cation responsive contrast agents

Oxygen-limited cellobiose fermentation and the characterization of the cellobiase of an industrial Dekkera/Brettanomyces bruxellensis strain

The discovery of a novel yeast with a natural capacity to produce ethanol from lignocellulosic substrates (second-generation ethanol) is of great significance for bioethanol technology. While there are some yeast strains capable of assimilating cellobiose in aerobic laboratory conditions, the predominant sugar in the treatment of lignocellulosic material, little is known about this ability in real industrial conditions. Fermentations designed to simulate industrial conditions were conducted in synthetic medium with glucose, sucrose, cellobiose and hydrolyzed pre-treated cane bagasse as a different carbon source, with the aim of further characterizing the fermentation capacity of a promising Dekkera bruxellensis yeast strain, isolated from the bioethanol process in Brazil. As a result, it was found (for the first time in oxygen-limiting conditions) that the strain Dekkera bruxellensis GDB 248 could produce ethanol from cellobiose. Moreover, it was corroborated that the cellobiase activity characterizes the enzyme candidate in semi-purified extracts (β-glucosidase). In addition, it was demonstrated that GDB 248 strain had the capacity to produce a higher acetic acid concentration than ethanol and glycerol, which confirms the absence of the Custer effect with this strain in oxygen-limiting conditions. Moreover, it is also being suggested that D. bruxellensis could benefit Saccharomyces cerevisiae and outcompete it in the industrial environment. In this way, it was confirmed that D. bruxellensis GDB 248 has the potential to produce ethanol from cellobiose, and is a promising strain for the fermentation of lignocellulosic substrates

Thermal regime and spatial variability of the active layer in Deception Island, Antarctica

El programa de monitoreo de capa activa (CALM) fue desarrollado en las últimas décadas con la finalidad de comprender el impacto del cambio climático sobre los ambientes con permafrost. Este trabajo analiza los resultados obtenidos, en los últimos seis años, de los sitios CALM-S Irizar, Cráter Lake y Refugio Chileno, ubicados en Isla Decepción. En ellos se ha medido el espesor, el estado térmico y la distribución espacial de la capa activa. En los sitios Irizar y Refugio Chileno la evolución del espesor de capa activa varió interanualmente sin una clara tendencia dentro del corto período analizado; por el contrario, el sitio Cráter Lake evidenció una tendencia a la disminución de espesor. La distribución espacial como el espesor de dicha capa en los tres sitios de monitoreo, mostraron estar condicionados principalmente por la potencia de la cubierta de nieve, la litología y la exposición a los vientos. El relieve, la topografía de detalle, la orientación de las laderas frente a la radiación solar incidente, ejercieron un control menor sobre esta distribución. El estado térmico de la capa activa evidenció el control ejercido sobre ella de la temperatura del aire y de la cubierta nival. Así bajo reducidos espesores de nieve, el modelo de penetración en profundidad de la isoterma de 0 ºC, ha permitido aproximar satisfactoriamente el espesor de capa activa.The Circumpolar Active Layer Monitoring (CALM) program developed over the last two decades has a leading edge in comprehensive efforts to study the impacts of climate change in permafrost environments. This paper describes results obtained during the last six years, on the active layer thickness, thermal regime and spatial patterns of thaw, at the CALM-S Irizar, Crater Lake and Refugio Chileno sites in Deception Island. In Irizar and Refugio Chileno CALM-S sites the active layer depth varied interannually without any clear trend over the short record available. By contrast, Crater Lake CALM-S showed a slight thinning trend. In all sites, the spatial patterns of thaw and active layer thickness were mainly controlled by snow cover conditions, lithology and the effect of aspect on wind. The relief, the detailed topography and the effect of aspect on solar radiation also exert a local control over its patterns. Air temperature and snow cover controlled the thermal state of active layer. In absence of snow, the use of depth penetration model of the 0 ºC isotherm allowed approximated satisfactorily active layer thickness.Fil: Goyanes, Gabriel Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Vieira, Gonçalo. Universidad de Lisboa; PortugalFil: Caselli, Alberto Tomás. Universidad Nacional de Río Negro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mora, Carla. Universidad de Lisboa; PortugalFil: Ramos, Miguel Esteban. Universidad de Alcalá; España. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: de Pablo, Miguel Angel. Universidad de Alcalá; EspañaFil: Neves, Mario. Universidad de Lisboa; PortugalFil: Santos, Fernando. Universidad de Lisboa; PortugalFil: Bernardo, Ivo. Universidad de Lisboa; PortugalFil: Gilichinsky, David. Academia Rusa de Ciencias; RusiaFil: Abramov, Andrey. Academia Rusa de Ciencias; RusiaFil: Batista, Vanessa. Universidad de Lisboa; PortugalFil: Melo, Raquel. Universidad de Lisboa; PortugalFil: Nieuwendam, Alexandre. Universidad de Lisboa; PortugalFil: Ferreira, Alice. Universidad de Lisboa; PortugalFil: Oliva, Marc. Universidad de Lisboa; Portuga

Aspergillus sección Nigri : estudio fisiológico y molecular de especies ocratoxígenas /

Descripció del recurs: 31 agost 2006Consultable des del TDXLa presente Memoria de Tesis Doctoral, presentada en forma de compendio de publicaciones, recoge el estudio fisiológico y molecular realizado con especies del género Aspergillus sección Nigri productoras de ocratoxina A (OTA). Esta micotoxina está recibiendo una especial atención en todo el mundo debido a su marcado carácter nefrotóxico. Además, es una sustancia carcinógena, teratógena e inmunotóxica y desde el año 2002, la UE ha comenzado a establecer niveles máximos de esta micotoxina en algunos alimentos. Estudios muy recientes han puesto claramente de manifiesto la implicación de algunas especies del género Aspergillus de la sección Nigri (A. carbonarius y las incluidas en el «agregado A. niger») en la presencia de OTA en alimentos como la uva, las pasas y el vino, entre otros. No obstante, no se conocen hasta el momento las condiciones ambientales que favorecen la producción de la micotoxina por estas especies. En los modelos fisiológicos utilizados, se han incluido cepas de A. carbonarius y del agregado A. niger, seleccionadas en base a su diferente origen y capacidad ocratoxígena. Se ha estudiado el efecto del sustrato (medios CYA y YES), la temperatura (5-45ºC), la actividad de agua (aw) (0,78-0,99) y el pH (2-10) en el crecimiento y la producción de OTA. Asimismo, se ha analizado la relación filogenética de las cepas estudiadas mediante diferentes técnicas de biología molecular (RFLP, RAPD, secuenciación, ERIC-PCR, AFLP y microsatélites). Los resultados obtenidos han permitido determinar las condiciones óptimas para la producción de OTA en las cepas del agregado A. niger (medio YES a 20-25ºC en el intervalo 0,96-0,99 aw y pH 5-10) y en las de A. carbonarius (medio CYA a 15-20ºC en el intervalo 0,98-0,99 aw y pH 5-7). En relación a la caracterización molecular de las cepas estudiadas, las técnicas de RAPD y secuenciación confirman la separación del agregado A. niger en dos grupos que se corresponden con los patrones de RFLP (N y T) establecidos previamente. En el caso de A. carbonarius estas técnicas han permitido la diferenciación molecular de una de las cepas estudiadas. Esta cepa pertenecería a la nueva especie propuesta dentro de la sección Nigri, denominada «A. ibericus». Las técnicas ERIC-PCR, AFLP y microsatélites han resultado útiles para la caracterización molecular de las especies estudiadas. Los resultados más significativos se han obtenido mediante AFLP y el análisis de microsatélites, permitiendo ambos la diferenciación de las cepas del agregado A. niger en dos grupos que se corresponden con los patrones de RFLP N y T. Los resultados obtenidos ponen de manifiesto la capacidad de las cepas del agregado A. niger y A. carbonarius para crecer y elaborar OTA en amplios márgenes de temperatura, pH y actividad de agua. Esta capacidad permite explicar el papel que juegan estas especies ocratoxígenas en la presencia de esta micotoxina en los alimentos y especialmente en aquellos donde constituyen la micobiota predominante.The present work, presented as compendium of publications, is focused on the physiology and molecular study of species within Aspergillus section Nigri (black aspergilli) able to produce ochratoxin A (OTA). This mycotoxin is achieving an increasing attention worldwide due to its acute nephrotoxicity. It is also carcinogenic, teratogenic and is clearly an immunosuppressive agent. Since 2002 the European Commission has established limits for OTA in some food commodities. Recently, several studies have highlighted the involvement of several species of black aspergilli (A. carbonarius and A. niger aggregate) in the presence of OTA in food commodities such as grapes, raisins and wine. However, the environmental conditions which support the production of this mycotoxin by these species are still unknown. Strains of A. carbonarius and A. niger aggregate, selected to include different sources and ochratoxigenic abilities, have been included in the physiology study. The effect of substrate (CYA and YES media), temperature (5-45ºC), water activity (aw) (0.78-0.99) and pH (2-10) has been studied. Analysis of genetic relationships within the studied strains has been also performed through different molecular techniques (RFLP, RAPD, sequencing, ERIC-PCR, AFLP and microsatellites). The results obtained show the optimal conditions for the production of OTA in A. niger aggregate strains (YES medium, 20-25ºC, 0.96-0.99 aw and pH 5-10) and in A. carbonarius strains (CYA medium 0.98-0.99 aw and pH 5-7). With regard to the molecular characterization of the studied strains, RAPD and sequencing techniques confirm the division of the A. niger aggregate into two groups which correspond with the previously described RFLP patterns (N and T). In the case of A. carbonarius one strain differs from the rest and it may belong to the new species proposed in section Nigri, «A. ibericus». The molecular markers ERIC-PCR, AFLP and microsatellites have been useful to characterize the studied species. The most significant results have been obtained through AFLP and microsatellites. Both markers make possible the differentiation of the A. niger aggregate strains in two groups which correspond with the two RFLP patters N and T. The results obtained state the ability of A. niger aggregate and A. carbonarius strains to grow and produce OTA in wide ranges of temperature, pH, and water activity. This ability let understand the role of these ochratoxigenic species in the presence of this mycotoxin in food commodities, especially in those where they are the predominant isolated fungi

Wild dogs at stake: deforestation threatens the only Amazon endemic canid, the short-eared dog (Atelocynus microtis)

The persistent high deforestation rate and fragmentation of the Amazon forests are the main threats to their biodiversity. To anticipate and mitigate these threats, it is important to understand and predict how species respond to the rapidly changing landscape. The short-eared dog Atelocynus microtis is the only Amazon-endemic canid and one of the most understudied wild dogs worldwide. We investigated short-eared dog habitat associations on two spatial scales. First, we used the largest record database ever compiled for short-eared dogs in combination with species distribution models to map species habitat suitability, estimate its distribution range and predict shifts in species distribution in response to predicted deforestation across the entire Amazon (regional scale). Second, we used systematic camera trap surveys and occupancy models to investigate how forest cover and forest fragmentation affect the space use of this species in the Southern Brazilian Amazon (local scale). Species distribution models suggested that the short-eared dog potentially occurs over an extensive and continuous area, through most of the Amazon region south of the Amazon River. However, approximately 30% of the short-eared dog's current distribution is expected to be lost or suffer sharp declines in habitat suitability by 2027 (within three generations) due to forest loss. This proportion might reach 40% of the species distribution in unprotected areas and exceed 60% in some interfluves (i.e. portions of land separated by large rivers) of the Amazon basin. Our local-scale analysis indicated that the presence of forest positively affected short-eared dog space use, while the density of forest edges had a negative effect. Beyond shedding light on the ecology of the short-eared dog and refining its distribution range, our results stress that forest loss poses a serious threat to the conservation of the species in a short time frame. Hence, we propose a re-assessment of the short-eared dog's current IUCN Red List status (Near Threatened) based on findings presented here. Our study exemplifies how data can be integrated across sources and modelling procedures to improve our knowledge of relatively understudied species

Improved Innate and Adaptive Immunostimulation by Genetically Modified HIV-1 Protein Expressing NYVAC Vectors.

Attenuated poxviruses are safe and capable of expressing foreign antigens. Poxviruses are applied in veterinary vaccination and explored as candidate vaccines for humans. However, poxviruses express multiple genes encoding proteins that interfere with components of the innate and adaptive immune response. This manuscript describes two strategies aimed to improve the immunogenicity of the highly attenuated, host-range restricted poxvirus NYVAC: deletion of the viral gene encoding type-I interferon-binding protein and development of attenuated replication-competent NYVAC. We evaluated these newly generated NYVAC mutants, encoding HIV-1 env, gag, pol and nef, for their ability to stimulate HIV-specific CD8 T-cell responses in vitro from blood mononuclear cells of HIV-infected subjects. The new vectors were evaluated and compared to the parental NYVAC vector in dendritic cells (DCs), RNA expression arrays, HIV gag expression and cross-presentation assays in vitro. Deletion of type-I interferon-binding protein enhanced expression of interferon and interferon-induced genes in DCs, and increased maturation of infected DCs. Restoration of replication competence induced activation of pathways involving antigen processing and presentation. Also, replication-competent NYVAC showed increased Gag expression in infected cells, permitting enhanced cross-presentation to HIV-specific CD8 T cells and proliferation of HIV-specific memory CD8 T-cells in vitro. The recombinant NYVAC combining both modifications induced interferon-induced genes and genes involved in antigen processing and presentation, as well as increased Gag expression. This combined replication-competent NYVAC is a promising candidate for the next generation of HIV vaccines