1,693 research outputs found

    A grid of Synthetic Spectra for Hot DA White Dwarfs and Its Application in Stellar Population Synthesis

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    In this work we present a grid of LTE and non-LTE synthetic spectra of hot DA white dwarfs (WDs). In addition to its usefulness for the determination of fundamental stellar parameters of isolated WDs and in binaries, this grid will be of interest for the construction of theoretical libraries for stellar studies from integrated light. The spectral grid covers both a wide temperature and gravity range, with 17,000 K <= T_eff <= 100,000 K and 7.0 <= log(g) <= 9.5. The stellar models are built for pure hydrogen and the spectra cover a wavelength range from 900 A to 2.5 microns. Additionally, we derive synthetic HST/ACS, HST/WFC3, Bessel UBVRI and SDSS magnitudes. The grid was also used to model integrated spectral energy distributions of simple stellar populations and our modeling suggests that DAs might be detectable in ultraviolet bands for populations older than ~8 Gyr.Comment: to be published in The Astrophysical Journal Supplement Serie

    Antileishmanial activity and evaluation of the mechanism of action of strychnobiflavone flavonoid isolated from Strychnos pseudoquina against Leishmania infantum

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    © 2015, Springer-Verlag Berlin Heidelberg. The present study aimed to investigate the in vitro antileishmanial activity of strychnobiflavone flavonoid against Leishmania infantum, as well as its mechanism of action, and evaluate the ex vivo biodistribution profile of the flavonoid in naive BALB/c mice. The antileishmanial activity (IC50 value) of strychnobiflavone against stationary promastigote and amastigote-like stages of the parasites was of 5.4 and 18.9 μM, respectively; with a 50% cytotoxic concentration (CC50) value of 125.0 μM on murine macrophages, resulting in selectivity index (SI) of 23.2 and 6.6, respectively. Amphotericin B, used as a positive control, presented SI values of 7.6 and 3.3 for promastigote and amastigote-like stages of L. infantum, respectively. The strychnobiflavone was also effective in reducing in significant levels the percentage of infected macrophages, as well as the number of amastigotes per macrophage, after the treatment of infected macrophages using the flavonoid. By using different fluorescent probes, we investigated the bioenergetics metabolism of L. infantum promastigotes and demonstrated that the flavonoid caused the depolarization of the mitochondrial membrane potential, without affecting the production of reactive oxygen species. In addition, using SYTOX® green as a fluorescent probe, the strychnobiflavone demonstrated no interference in plasma membrane permeability. For the ex vivo biodistribution assays, the flavonoid was labeled with technetium-99m and studied in a mouse model by intraperitoneal route. After a single dose administration, the scintigraphic images demonstrated a highest uptake by the liver and spleen of the animals within 60 min, resulting in low concentrations after 24 h. The present study therefore demonstrated, for the first time, the antileishmanial activity of the strychnobiflavone against L. infantum, and suggests that the mitochondria of the parasites may be the possible target organelle. The preferential distribution of this compound into the liver and spleen of the animals could warrant its employ in the treatment of visceral leishmaniasis.This work was supported by grants from Instituto Nacional de Ciência e Tecnologia em Nanobiofarmacêutica (INCT-Nanobiofar), FAPEMIG (CBB-APQ-00819-12), CNPq (APQ-472090/2011-9, APQ- 482976/2012-8, and APQ-488237/2013-0) and São Paulo State Research Fundation (FAPESP 2012/18756-1). MACF is a grant recipient of FAPEMIG/CAPES. EAFC, VNC and AGT are grant recipient of CNPqPeer Reviewe

    Assessment of Wild Rocket (Diplotaxis tenuifolia (L.) DC.) Germplasm accessions by NGS identified SSR and SNP markers

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    Rocket is the common designation for two baby-leaf salad crops of the Brassicaceae family: Eruca sativa (L.) Cav., usually referred to as annual garden rocket, and Diplotaxis tenuifolia (L.) DC. commonly named to as perennial wild rocket. E. sativa is used for human consumption since antiquity. However, the growing consumer preference for D. tenuifolia is being accompanied by the fast increase in its production area and commercialization of new cultivars. Nevertheless, the worldwide number of wild rocket accessions maintained in germplasm collections is very reduced, the solution for which situation the project “REMIRucula” intends to contribute, establishing a germplasm collection at the INIAV, Oeiras, Portugal. Herein, we report on the establishment via next generation sequencing (NGS) of the first genome assembly of D. tenuifolia and the identification of specific single sequence repeat (SSR) and single nucleotide polymorphisms (SNP) loci for the establishment of specific DNA-markers for this species. A representative set of 87 D. tenuifolia and 3 E. sativa accessions were assessed by 5 SSR and 9 SNP-CAPS markers, allowing a drastic discrimination between both species and the establishment of unequivocal molecular fingerprints for the analyzed accessions. The non-discrimination within six pairs and one trio of D. tenuifolia accessions is discussed.info:eu-repo/semantics/publishedVersio

    Optimization of oil recovery from Japonica luna rice bran by supercritical carbon dioxide applying design of experiments: characterization of the oil and mass transfer modeling

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    This study presents an optimization strategy for recovery of oil from Japonica Luna rice bran using supercritical carbon dioxide (scCO2), based on design of experiments (DoE). Initially, a 24−1 two level fractional factorial design (FFD) was used, and pressure, temperature, and scCO2 flow rate were determined as the significant variables; while the yield, total flavonoids content (TFC), and total polyphenols content (TPC) were the response functions used to analyze the quality of the extracts recovered. Subsequently, central composite design (CCD) was applied to examine the effects of the significant variables on the responses and create quadratic surfaces that optimize the latter. The following values of pressure = 34.35 MPa, temperature = 339.5 K, and scCO2 flow rate = 1.8 × 10−3 kg/min were found to simultaneously optimize the yield (6.83%), TPC (61.28 μmol GAE/g ext), and TFC (1696.8 μmol EC/g ext). The fatty acid profile of the oils was characterized by GC-FID. It was demonstrated that the acids in largest quantities are C16:0 (15–16%), C18:1 (41%), and C18:2 (38–39%). Finally, three mass transfer models were applied to determine the mass transfer coefficients and assess the cumulative extraction curves, with an AAD% of 4.16, for the best model.info:eu-repo/semantics/publishedVersio

    Downy mildew resistance and genetic variability in a wild rocket germplasm collection

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    One hundred accessions of a "core collection" of Diplotaxis tenuifolia (L.) DC. and Eruca spp. were screened at seedling stage for resistance to downy mildew. Accessions tested at the seedling stage were assigned to 0-6 interaction phenotypes. All cultivated rocket (Eruca spp.) accessions exhibited a resistant (R) response both in cotyledons and in young leaves. The wild rocket (D. tenuifolia) accessions exhibited higher susceptibility in cotyledons than in the 1st and 2nd leaves, with 16 and 47 accessions classified as resistant or partially resistant (PR) in the cotyledon and in leaves stages, respectively. Only three wild rocket accessions displayed an R phenotype in cotyledons and leaves. The most frequent response in cotyledons vs. leaves was the highly susceptible/susceptible (HS/S) combination (33 accessions), followed by the S/PR combination (18 accessions). A significant correlation (r = 0.917, P < .000) was observed between the disease index in cotyledons and leaves. The molecular markers analyses revealed a wide genetic distance between Diplotaxis and Eruca, which gather in two clearly separated species clusters. The molecular variability is accompanied by a wide diversity of interactions with the pathogen isolate. The closest similarities among D. tenuifolia accessions were found in accessions provided by the same breeding company. Future studies will be focused on two main objectives: (a) the assessment of the accessions behavior that have evidenced an R/R, S/PR, and HS/PR cotyledon and leaf response under greenhouse or field production and (b) the genome mapping of genetic features that provide downy mildew resistance.info:eu-repo/semantics/publishedVersio

    Sustained data access and tools as key ingredients to strengthening EO capacities : examples from land application perspective + powerpoint

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    Sustainably managing agriculture and forests is key for development, in particular in Africa, and for facing global challenges such as climate change or food security, but requires reliable information. As Earth Observation (EO) satellite data can contribute to these information needs, more and more institutes integrate this technology into their daily work. Facing ever-growing and evolving EO data sources (e.g. new satellites and sensors) and access technology (both online and via EUMETCast satellite broadcast), their applications require software tools to particularly facilitate (i) the exchange of data between the analysis tools, so users can take advantage of each tool’s strengths, and (ii) the processing and analysis of time series. A first example is the Land Surface Analysis Satellite Application Facility (LSA-SAF), that entered the second part of the Continuous Development and Operations Phase (CDOP-2), under the lead of the Portuguese Institute for Sea and Atmosphere (IPMA), in 2011. VITO, joining the LSA-SAF network for the first time and building on previous experiences (e.g. http://www.metops10.vito.be), aims to contribute by producing and delivering operational, 10-daily vegetation indicators based on MetOp-AVHRR. Furthermore, a software tool is developed to aid exploitation of LSA-SAF products, provisionally called “MSG Toolbox”. A second example is the AGRICAB project, that receives funding from the European Union’s 7th Framework Programme for Research (FP7) and aims to build a comprehensive framework for strengthening capacities in the use of EO for agriculture and forestry management in Africa. This framework starts from sustained access to relevant satellite data (e.g. CBERS-3, DEIMOS) and derived products, such as those from the European Copernicus Global Land service, the 15 year time series of SPOT-VEGETATION (and its transition to PROBA-V) and Meteosat Second Generation (e.g. rainfall estimates). It combines local and EO data with tools and training into applications on crop monitoring, area statistics and yield forecasting, livestock insurance and modelling, forest and fire management, all fitted to the needs of stakeholders in the African focus countries

    Tissue distribution of DNA-Hsp65/TDM-loaded PLGA microspheres and uptake by phagocytic cells

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    This study aimed to demonstrate that microspheres, used as delivery vehicle of DNA-Hsp65/TDM [plasmid DNA encoding heat shock protein 65 (Hsp65) coencapsulated with trehalose dimycolate (TDM) into PLGA microspheres], are widely spread among several organs after intramuscular administration in BALB/c mice. In general, we showed that these particles were phagocytosed by antigen presenting cells, such as macrophages and dendritic cells. Besides, it was demonstrated herein that draining lymph node cells presented a significant increase in the number of cells expressing costimulatory molecules (CD80 and CD86) and MHC class II, and also that the administration of the DNA-Hsp65/TDM and vector/TDM formulations resulted in the up-regulation of CD80, CD86 and MHC class II expression when compared to control formulations (vector/TDM and empty). Regarding the intracellular trafficking we observed that following phagocytosis, the microspheres were not found in the late endosomes and/or lysosomes, until 15 days after internalization, and we suggest that these constructions were hydrolysed in early compartments. Overall, these data expand our knowledge on PLGA [poly (lactic-co- glycolic acid)] microspheres as gene carriers in vaccination strategies, as well as open perspectives for their potential use in clinical practice

    Crop Type Exerts Greater Influence Upon Rhizosphere Phosphohydrolase Gene Abundance and Phylogenetic Diversity than Phosphorus Fertilization.

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    Rock phosphate is considered as an alternative form of phosphorus fertilizer in acidic, nutrient depleted soils of the Brazilian Cerrado. However, there is no information regarding the influence of phosphorus fertilizer sources in Cerrado soils upon microbial genes coding for phosphohydrolase enzymes in crop rhizospheres. Here, we analyse a field experiment comparing phosphorus fertilization (rock phosphate and triple superphosphate) of maize and sorghum upon crop performance, phosphatase activity and rhizosphere microbiomes at three levels of diversity: small subunit rRNA marker genes of bacteria, archaea and fungi; a suite of alkaline and acid phosphatase and phytase genes; and ecotypes of individual genes. We showed that there is no significant difference in crop performance between the fertilizers sources. Differences in rhizosphere microbiomes were observed at all levels of biodiversity due to crop type, but not fertilization. Inspection of phosphohydrolase gene ecotypes responsible for differences between the crops suggests a role for lateral genetic transfer in establishing ecotype distributions. Our results suggest development of inocula of microorganisms harbouring the gene ecotypes identified in this study, or selective breeding of crops with an enhanced capacity to attract beneficial microorganisms to the rhizosphere may prove useful to optimizing rock phosphate fertilizer in Cerrado soils

    Pathotypic diversity of Hyaloperonospora brassicae collected from Brassica oleracea

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    Downy mildew caused by Hyaloperonospora brassicae is an economically destructive disease of brassica crops in many growing regions throughout the world. Specialised pathogenicity of downy mildews from different Brassica species and closely related ornamental or wild relatives has been described from host range studies. Pathotypic variation amongst Hyaloperonospora brassicae isolates from Brassica oleracea has also been described; however, a standard set of B. oleracea lines that could enable reproducible classification of H. brassicae pathotypes was poorly developed. For this purpose, we examined the use of eight genetically refined host lines derived from our previous collaborative work on downy mildew resistance as a differential set to characterise pathotypes in the European population of H. brassicae. Interaction phenotypes for each combination of isolate and host line were assessed following drop inoculation of cotyledons and a spectrum of seven phenotypes was observed based on the level of sporulation on cotyledons and visible host responses. Two host lines were resistant or moderately resistant to the entire collection of isolates, and another was universally susceptible. Five lines showed differential responses to the H. brassicae isolates. A minimum of six pathotypes and five major effect resistance genes are proposed to explain all of the observed interaction phenotypes. The B. oleracea lines from this study can be useful for monitoring pathotype frequencies in H. brassicae populations in the same or other vegetable growing regions, and to assess the potential durability of disease control from different combinations of the predicted downy mildew resistance genes
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