290 research outputs found
New abundance measurements in UKS 1927-177, a very metal-poor galaxy in the Local Group
We present new results from optical spectroscopy of the brightest Hii region
in the dwarf irregular galaxy UKS 1927-177 in Sagittarius (SagDIG). From high
signal-to-noise spectra, reddening-corrected line flux ratios have been
measured with typical uncertainties of a few percent, from which the oxygen
abundance is rediscussed, and new abundance estimates are derived for N and Ne.
The O abundance in SagDIG, estimated with the empirical abundance indicator R23
and other methods, is in the range 12+log(O/H)=7.26 to 7.50. The fact that
SagDIG is ~10 times closer than IZw18 makes it an ideal target to test the
hypothesis of the existence of young galaxies in the present-day universe.
Indeed, stellar photometry suggests that this galaxy may harbor a stellar
population older than a few Gyr, and possibly an old stellar component as well.
The case of SagDIG therefore supports the view that very low chemical
abundances can be maintained throughout the life of a dwarf stellar system,
even in the presence of multiple star formation episodes.Comment: 6 pages, 3 figures, accepted for publication in A&A, main journa
Ascites induces modulation of α6β1 integrin and urokinase plasminogen activator receptor expression and associated functions in ovarian carcinoma
Interactions between cancer cells and the surrounding medium are not fully understood. In this study, we demonstrate that ascites induces selective changes in the expression of integrins and urokinase plasminogen activator/urokinase plasminogen activator receptor (uPA/uPAR) in ovarian cancer cells. We hypothesise that this change of integrin and uPA/uPAR expression triggers signalling pathways responsible for modulating phenotype-dependent functional changes in ovarian cancer cells. Human ovarian surface epithelial (HOSE) cell lines and epithelial ovarian cancer cell lines were treated with ascites for 48 h. Ascites induced upregulation of α6 integrin, without any change in the expression of αv, β1 and β4 integrin subunits. Out of the four ovarian cancer cell lines studied, ascites induced enhancement in the expression of uPA/uPAR in the more invasive OVCA 433 and HEY cell lines without any change in the noninvasive OVHS1 and moderately invasive PEO.36 cell lines. On the other hand, no change in the expression of α6 integrin or uPAR, in response to ascites, was observed in HOSE cells. In response to ascites, enhancement in proliferation and in adhesion was observed in all four ovarian cancer cell lines studied. In contrast, no significant increase in proliferation or adhesion by ascites was observed in HOSE cells. Ascites-induced expression of uPA/uPAR correlated with the increased invasiveness of HEY and OVCA 433 cell lines but was not seen in OVHS1, PEO.36 and HOSE cell lines. Upregulation of α6 integrin and uPA/uPAR correlated with the activation of Ras and downstream Erk pathways. Ascites-induced activation of Ras and downstream Erk can be inhibited by using inhibitory antibodies against α6 and β1 integrin and uPAR, consistent with the inhibition of proliferation, adhesion and invasive functions of ovarian cancer cell lines. Based on these findings, we conclude that ascites can induce selective upregulation of integrin and uPA/uPAR in ovarian cancer cells and these changes may modulate the functions of ovarian carcinomas
Effects of hypoxia on anabolic and catabolic gene expression and DNA methylation in OA chondrocytes
Metal release from contaminated estuarine sediment under pH changes in the marine environment
The contaminant release from estuarine sediment due to pH changes was investigated using a modified CEN/TS 14429 pH-dependence leaching test. The test is performed in the range of pH values of 0-14 using deionised water and seawater as leaching solutions. The experimental conditions mimic different circumstances of the marine environment due to the global acidification, carbon dioxide (CO2) leakages from carbon capture and sequestration technologies, and accidental chemical spills in seawater. Leaching test results using seawater as leaching solution show a better neutralisation capacity giving slightly lower metal leaching concentrations than when using deionised water. The contaminated sediment shows a low base-neutralisation capacity (BNCpH 12 = -0.44 eq/kg for deionised water and BNCpH 12 = -1.38 eq/kg for seawater) but a high acid-neutralisation capacity when using deionised water (ANCpH 4 = 3.58 eq/ kg) and seawater (ANCpH 4 = 3.97 eq/kg). Experimental results are modelled with the Visual MINTEQ geochemical software to predict metal release from sediment using both leaching liquids. Surface adsorption to iron- and aluminium- (hydr)oxides was applied for all studied elements. The consideration of the metal-organic matter binding through the NICA-Donnan model and Stockholm Humic Model for lead and copper, respectively, improves the former metal release prediction. Modelled curves can be useful for the environmental impact assessment of seawater acidification due to its match with the experimental values.This work was supported by the Spanish Ministry of Economy and Competitiveness, Project No. CTM 2011-28437-C02-01, ERDF included. M. C. Martı´n-Torre was funded by the Spanish Ministry of Economy and Competitiveness by means of FPI. Fellowship No. BES-2012-053816
Uncovering the complex genetics of human temperament
Experimental studies of learning suggest that human temperament may depend on the molecular mechanisms for associative conditioning, which are highly conserved in animals. The main genetic pathways for associative conditioning are known in experimental animals, but have not been identified in prior genome-wide association studies (GWAS) of human temperament. We used a data-driven machine learning method for GWAS to uncover the complex genotypic-phenotypic networks and environmental interactions related to human temperament. In a discovery sample of 2149 healthy Finns, we identified sets of single-nucleotide polymorphisms (SNPs) that cluster within particular individuals (i.e., SNP sets) regardless of phenotype. Second, we identified 3 clusters of people with distinct temperament profiles measured by the Temperament and Character Inventory regardless of genotype. Third, we found 51 SNP sets that identified 736 gene loci and were significantly associated with temperament. The identified genes were enriched in pathways activated by associative conditioning in animals, including the ERK, PI3K, and PKC pathways. 74% of the identified genes were unique to a specific temperament profile. Environmental influences measured in childhood and adulthood had small but significant effects. We confirmed the replicability of the 51 Finnish SNP sets in healthy Korean (90%) and German samples (89%), as well as their associations with temperament. The identified SNPs explained nearly all the heritability expected in each sample (37-53%) despite variable cultures and environments. We conclude that human temperament is strongly influenced by more than 700 genes that modulate associative conditioning by molecular processes for synaptic plasticity and long-term memory.Peer reviewe
Fungal Endophyte Diversity in Sarracenia
Fungal endophytes were isolated from 4 species of the carnivorous pitcher plant genus Sarracenia: S. minor, S. oreophila, S. purpurea, and S. psittacina. Twelve taxa of fungi, 8 within the Ascomycota and 4 within the Basidiomycota, were identified based on PCR amplification and sequencing of the internal transcribed spacer sequences of nuclear ribosomal DNA (ITS rDNA) with taxonomic identity assigned using the NCBI nucleotide megablast search tool. Endophytes are known to produce a large number of metabolites, some of which may contribute to the protection and survival of the host. We speculate that endophyte-infected Sarracenia may benefit from their fungal associates by their influence on nutrient availability from within pitchers and, possibly, by directly influencing the biota within pitchers
Fungal endophytes from arid areas of Andalusia: high potential sources for antifungal and antitumoral agents
Native plant communities from arid areas present distinctive characteristics to survive in extreme
conditions. The large number of poorly studied endemic plants represents a unique potential
source for the discovery of novel fungal symbionts as well as host-specific endophytes not yet
described. The addition of adsorptive polymeric resins in fungal fermentations has been seen to
promote the production of new secondary metabolites and is a tool used consistently to generate
new compounds with potential biological activities. A total of 349 fungal strains isolated from 63
selected plant species from arid ecosystems located in the southeast of the Iberian Peninsula, were
characterized morphologically as well as based on their ITS/28S ribosomal gene sequences. The fungal
community isolated was distributed among 19 orders including Basidiomycetes and Ascomycetes,
being Pleosporales the most abundant order. In total, 107 different genera were identified being
Neocamarosporium the genus most frequently isolated from these plants, followed by Preussia and
Alternaria. Strains were grown in four different media in presence and absence of selected resins to
promote chemical diversity generation of new secondary metabolites. Fermentation extracts were
evaluated, looking for new antifungal activities against plant and human fungal pathogens, as well
as, cytotoxic activities against the human liver cancer cell line HepG2. From the 349 isolates tested,
126 (36%) exhibited significant bioactivities including 58 strains with exclusive antifungal properties
and 33 strains with exclusive activity against the HepG2 hepatocellular carcinoma cell line. After LCMS
analysis, 68 known bioactive secondary metabolites could be identified as produced by 96 strains,
and 12 likely unknown compounds were found in a subset of 14 fungal endophytes. The chemical
profiles of the differential expression of induced activities were compared. As proof of concept, ten
active secondary metabolites only produced in the presence of resins were purified and identified. The
structures of three of these compounds were new and herein are elucidated.This work was supported by Fundación MEDINA and the Andalusian Government grant
RNM-7987 ‘Sustainable use of plants and their fungal parasites from arid regions of Andalucía for new molecules
useful for antifungals and neuroprotectors’
Analysis of single nucleotide polymorphisms in the FAS and CTLA-4 genes of peripheral T-cell lymphomas
Angioimmunoblastic T-cell lymphoma (AILT) represents a subset of T-cell lymphomas but resembles an autoimmune disease in many of its clinical aspects. Despite the phenotype of effector T-cells and high expression of FAS and CTLA-4 receptor molecules, tumor cells fail to undergo apoptosis. We investigated single nucleotide polymorphisms (SNPs) of the FAS and CTLA-4 genes in 94 peripheral T-cell lymphomas. Although allelic frequencies of some FAS SNPs were enriched in AILT cases, none of these occurred at a different frequency compared to healthy individuals. Therefore, SNPs in these genes are not associated with the apoptotic defect and autoimmune phenomena in AILT
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