Processes controlling the fate of chloroethenes emanating from dnapl aged sources in river-aquifer contexts

This work dealt with the physical and biogeochemical processes that favored the natural attenuation of chloroethene plumes of aged sources located close to influent rivers in the presence of co-contaminants, such as nitrate and sulfate. Two working hypotheses were proposed: i) Reductive dechlorination is increased in areas where the river-aquifer relationship results in the groundwater dilution of electron acceptors, the reduction potential of which exceeds that of specific chloroethenes; ii) zones where silts predominate or where textural changes occur are zones in which biodegradation place preferentially takes place. A field site on a Quaternary alluvial aquifer at Torelló, Catalonia (Spain) was selected to validate these hypotheses. This aquifer is adjacent to an influent river and its redox conditions favor reductive dechlorination. The main findings showed that the low concentrations of nitrate and sulfate due to dilution caused by the input of surface water diminish the competition for electrons between microorganisms that reduce co-contaminants and chloroethenes. Under these conditions, the most bioavailable electron acceptors were PCE and metabolites, which meant that their biodegradation was favored. This led to the possibility of devising remediation strategies based on bioenhancing natural attenuation. The artificial recharge with water that is low in nitrates and sulfates may favor dechlorinating microorganisms if the redox conditions in the mixing water are sufficiently maintained as reducing and if there are nutrients, electron donors and carbon sources necessary for these microorganisms

Temporal hydrochemical and microbial variations in microcosm experiments from sites contaminated with chloromethanes under biostimulation with lactic acid

The objective of our research is to identify the sequence of degradation processes leading to microbial speciation of microorganisms involved in degradation of CT and CF under natural attenuation and lactic acid biostimulation conditions. To this end, a comparative study of two types of microcosm experiments was carried out to analyze two scenarios: natural attenuation and lactic acid biostimulation. Experiments were carried out with water and sediment from a field site located at a petrochemical complex whose hydrochemical background inhibited the natural attenuation of carbon tetrachloride and chloroform. A significant result of our work was that these experiments allowed us to identify the CT abiotic degradation processes, among which the abiotic degradation induced by the biogenic activity of Dechlorosoma suillum should be noted. Although this is an abiotic degradation, the metabolism of this microorganism generates green rust precipitates, which in turn favor the abiotic reductive dechlorination of CT. Other relevant result was the identification of the biotic reductive dechlorination of CF by a bacterium of the Clostridiales order. This result presented the particularity that an apparent absence of isotopic fractionation was observed because a mixture of chloroform of different origins was produced. Our research showed that these processes were more efficient, in terms of faster degradation rates, when biostimulation with lactic acid was carried out. This biostimulation could therefore be an efficient remediation strategy at sites contaminated by chloromethanes, especially in cases where a complex pollution history results in a rich hydrochemical background that makes it difficult natural attenuation

Genome-Wide Analysis of Factors Affecting Transcription Elongation and DNA Repair: A New Role for PAF and Ccr4-Not in Transcription-Coupled Repair

RNA polymerases frequently deal with a number of obstacles during transcription elongation that need to be removed for transcription resumption. One important type of hindrance consists of DNA lesions, which are removed by transcription-coupled repair (TC-NER), a specific sub-pathway of nucleotide excision repair. To improve our knowledge of transcription elongation and its coupling to TC-NER, we used the yeast library of non-essential knock-out mutations to screen for genes conferring resistance to the transcription-elongation inhibitor mycophenolic acid and the DNA-damaging agent 4-nitroquinoline-N-oxide. Our data provide evidence that subunits of the SAGA and Ccr4-Not complexes, Mediator, Bre1, Bur2, and Fun12 affect transcription elongation to different extents. Given the dependency of TC-NER on RNA Polymerase II transcription and the fact that the few proteins known to be involved in TC-NER are related to transcription, we performed an in-depth TC-NER analysis of a selection of mutants. We found that mutants of the PAF and Ccr4-Not complexes are impaired in TC-NER. This study provides evidence that PAF and Ccr4-Not are required for efficient TC-NER in yeast, unraveling a novel function for these transcription complexes and opening new perspectives for the understanding of TC-NER and its functional interconnection with transcription elongation

Toxoplasma gondii Lysine Acetyltransferase GCN5-A Functions in the Cellular Response to Alkaline Stress and Expression of Cyst Genes

Parasitic protozoa such as the apicomplexan Toxoplasma gondii progress through their life cycle in response to stimuli in the environment or host organism. Very little is known about how proliferating tachyzoites reprogram their expressed genome in response to stresses that prompt development into latent bradyzoite cysts. We have previously linked histone acetylation with the expression of stage-specific genes, but the factors involved remain to be determined. We sought to determine if GCN5, which operates as a transcriptional co-activator by virtue of its histone acetyltransferase (HAT) activity, contributed to stress-induced changes in gene expression in Toxoplasma. In contrast to other lower eukaryotes, Toxoplasma has duplicated its GCN5 lysine acetyltransferase (KAT). Disruption of the gene encoding for TgGCN5-A in type I RH strain did not produce a severe phenotype under normal culture conditions, but here we show that the TgGCN5-A null mutant is deficient in responding to alkaline pH, a common stress used to induce bradyzoite differentiation in vitro. We performed a genome-wide analysis of the Toxoplasma transcriptional response to alkaline pH stress, finding that parasites deleted for TgGCN5-A fail to up-regulate 74% of the stress response genes that are induced 2-fold or more in wild-type. Using chromatin immunoprecipitation, we verify an enrichment of TgGCN5-A at the upstream regions of genes activated by alkaline pH exposure. The TgGCN5-A knockout is also incapable of up-regulating key marker genes expressed during development of the latent cyst form, and is impaired in its ability to recover from alkaline stress. Complementation of the TgGCN5-A knockout restores the expression of these stress-induced genes and reverses the stress recovery defect. These results establish TgGCN5-A as a major contributor to the alkaline stress response in RH strain Toxoplasma

Ptc6 is required for proper rapamycin-induced down-regulation of the genes coding for ribosomal and rRNA processing proteins in S. cerevisiae

Ptc6 is one of the seven components (Ptc1-Ptc7) of the protein phosphatase 2C family in the yeast Saccharomyces cerevisiae. In contrast to other type 2C phosphatases, the cellular role of this isoform is poorly understood. We present here a comprehensive characterization of this gene product. Cells lacking Ptc6 are sensitive to zinc ions, and somewhat tolerant to cell-wall damaging agents and to Li+. Ptc6 mutants are sensitive to rapamycin, albeit to lesser extent than ptc1 cells. This phenotype is not rescued by overexpression of PTC1 and mutation of ptc6 does not reproduce the characteristic geneti

Regulation of the Na+/K+-ATPase Ena1 Expression by Calcineurin/Crz1 under High pH Stress: A Quantitative Study

[EN] Regulated expression of the Ena1 Na+-ATPase is a crucial event for adaptation to high salt and/or alkaline pH stress in the budding yeast Saccharomyces cerevisiae. ENA1 expression is under the control of diverse signaling pathways, including that mediated by the calcium-regulatable protein phosphatase calcineurin and its downstream transcription factor Crz1. We present here a quantitative study of the expression of Ena1 in response to alkalinization of the environment and we analyze the contribution of Crz1 to this response. Experimental data and mathematical models substantiate the existence of two stress-responsive Crz1-binding sites in the ENA1 promoter and estimate that the contribution of Crz1 to the early response of the ENA1 promoter is about 60%. The models suggest the existence of a second input with similar kinetics, which would be likely mediated by high pH-induced activation of the Snf1 kinase.This work was supported by grants BFU2011-30197-C3-01, BFU2014-54591-C2-1-P and EUI2009-04147 (SysMo2) to JA. (Ministry of Industry and Competitivity, Spain, and Fondo Europeo de Desarrollo Regional [FEDER]). JA is the recipient of an Ajut 2014SGR-4 award (Generalitat de Catalunya). DC was recipient of a predoctoral fellowship from the Spanish Ministry of Education. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Petrezsélyová, S.; López-Malo, M.; Canadell, D.; Roque, A.; Serra-Cardona, A.; Marques Romero, MC.; Vilaprinyó, E.... (2016). Regulation of the Na+/K+-ATPase Ena1 Expression by Calcineurin/Crz1 under High pH Stress: A Quantitative Study. PLoS ONE. 11(6):e0158424-e0158424. https://doi.org/10.1371/journal.pone.0158424Se0158424e015842411

DSIF and RNA Polymerase II CTD Phosphorylation Coordinate the Recruitment of Rpd3S to Actively Transcribed Genes

Histone deacetylase Rpd3 is part of two distinct complexes: the large (Rpd3L) and small (Rpd3S) complexes. While Rpd3L targets specific promoters for gene repression, Rpd3S is recruited to ORFs to deacetylate histones in the wake of RNA polymerase II, to prevent cryptic initiation within genes. Methylation of histone H3 at lysine 36 by the Set2 methyltransferase is thought to mediate the recruitment of Rpd3S. Here, we confirm by ChIP–Chip that Rpd3S binds active ORFs. Surprisingly, however, Rpd3S is not recruited to all active genes, and its recruitment is Set2-independent. However, Rpd3S complexes recruited in the absence of H3K36 methylation appear to be inactive. Finally, we present evidence implicating the yeast DSIF complex (Spt4/5) and RNA polymerase II phosphorylation by Kin28 and Ctk1 in the recruitment of Rpd3S to active genes. Taken together, our data support a model where Set2-dependent histone H3 methylation is required for the activation of Rpd3S following its recruitment to the RNA polymerase II C-terminal domain

Prospección geoquímica en las redes de drenaje de los materiales cambro-ordovícicos del Macizo del Montseny-Guilleries (Noreste de España)

Catalonian Coastal Ranges (Northeast Spain) are a fragment of the Hercynian orogen in Europe placed south to the Pyrennes along the Mediterranean coast; early Palaeozoic materials crop out mainly in the Northern sector, in the Montseny-Guilleries massif, near Girona city. These materials (locally called 'Cambro-Ordovician") are composed of a thick serie of siliciclastic rocks, with important gneiss intercalations, and minor presence of carbonic rocks, amphibolites, and stratiform polimetallic sulphide ores. A geochemical stream sediment survey was developed over these materials, in the context of a regional miultielemental geochemical survey covering all the Palaeozoic materials in Northern Catalonian Coastal Ranges. Geochemical data were studied by uni-, bi- and multivariate statistical procedures, and afterwards mapped and interpreted. Secondary geochemical anomalies show a clustered pattern over most of the Cambro-Ordovician materials, in c!ear correspondence to stratiform ores. Vein-type post-Hercynian are well represented by highly manifested secondary anomalies oi local distribution. A comparison between total and sectorial results obtained after statistical producers ls made in order to obtain criteria of ore-prospecting interpretation.Peer reviewe

Prospección estratégica de la cuenca hidrográfica superior del río Garona (Vall d'Arán, Lleida)

Fernández Turiel J.L., Viladevall M., Gimeno D., Durán M.E., Prospección estratégica de la cuenca hidrográfica superior del río Garona (Vall d'Arán, Lleida). Revista d'Investig. Geol., 1986, 42/43: 121-130.[EN] The present work was conducted as part of a pilot experiment of a research project on the mineral resources of the NE the Iberian Peninsula. lts aim is to test a method for regional exploration in alpine zones. Accordingly, the hydrographic basin of t[he River Garona in the Vall d'Aran (Lleida, Spain) in the Pyrenean axial zone was chosen since the occurrences and ancient mining activity there are abundant and it is typical of the kind of zone to be studied. Two hundred and sixty-eight stream sediments and 64 panned concentrates were obtained from an area of 550 km2 of the hydrographic network. ln Ihe below-80 mesh fraction (ASTM) of the sediments Ihe contents in Pb, Zn, Cu, Fe, Mn, Ni, Ca, Cd, Ag, Mo, and V were analyzed whereas the concentrates were employed for the mineralogical determination and count of the grains of scheelite present. The statistical treatment of geochemical information (log-probabilistic graphs, bivariate analysis, principal component analysis, discriminant analysis and multiple linear regression), together with the mapping of the different parameters, has allowed us to determine the anomalies of the study area.[ES] Este trabajo se ha realizado como parte de la experiencia piloto de un proyecto de investigación de los recursos minerales del NE de la Península Ibérica. Su propósito es el de probar una metodología de prospección estratégica en zonas alpinas, por lo que se eligió para este fin la cuenca hidrográfica del río Garona en la Vall d'Aran (Lleida) en la zona axial pirenaica, pues en ella son numerosos los indicios y labores mineras antiguas y su orografía es característica del tipo de zona a estudiar. Sobre la red hidrográfica de una área de 550 km2 se recogieron 268 sedimentos de arroyo y 64 concentrados a la batea. En la fracción inferior a 80 mesh (ASTM) de los sedimentos, se analizaron los contenidos en Pb, Zn, Cu, Fe, Mn, Ni, Ca, Cd, Ag, Mo y V; mientras que los concentrados se usaron para la determinación mineralógica y contaje de los granos de scheelita presentes. El tratamiento estadístico de la información geoquímica (gráficos log-probabilísticos, análisis bivariante, análisis de componentes principales, análisis discriminante y regresión lineal múltiple), junto con la cartografía de los diferentes parámetros, ha permitido determinar correctamente las anomalías existentes en el área estudiada.Universitat de BarcelonaPeer reviewe