Isolement et caractérisation de la mycomembrane des mycobactéries

Les mycobactéries, dont les plus connues sont Mycobacterium tuberculosis et Mycobacterium leprae, agents étiologiques de la tuberculose et de la lèpre respectivement, présentent une enveloppe complexe et atypique faisant l'objet de nombreuses études dans le cadre de la lutte contre ces pathologies. Cette enveloppe est composée d'une couche externe aussi appelée capsule dans le cas de bactéries pathogènes, d'une paroi (mycomembrane - arabinogalactane (AG) - peptidoglycane (PG)) et d'une membrane plasmique. La membrane externe des mycobactéries, appelée mycomembrane est composée de protéines et majoritairement d'acides mycoliques, acides gras à très longues chaînes a-ramifiés et ß-hydroxylés. Ces derniers sont retrouvés covalemment liés, d'une part au complexe AG-PG dans le feuillet interne de la mycomembrane, et d'autre part au tréhalose au niveau du feuillet externe de la mycomembrane. On trouve également en fonction des mycobactéries des lipides complexes dont la localisation exacte dans l'enveloppe n'est à ce jour pas clairement connue et reste sujette à débats. Ce travail a permis de mettre au point un protocole, en deux étapes majeures, permettant le fractionnement cellulaire de deux espèces mycobactériennes, M. aurum et M. smegmatis. Le but étant d'isoler les deux membranes mycobactériennes afin de déterminer leur composition en terme de lipides mais aussi de protéines. Tout d'abord, des culots enrichis en mycomembranes (liées à l'AG-PG) ou en membranes plasmiques sont obtenus par ultracentrifugations différentielles puis purifiés sur gradients de densité discontinus de saccharose. L'absence de contaminations des membranes entre elles est vérifiée grâce à des marqueurs spécifiques. Il a été montré que les phospholipides qui sont les composants majoritaires de la membrane plasmique sont également présents dans la mycomembrane à côté des mycolates de tréhalose. De plus ce travail a permis de montrer que les lipoglycanes, lipoarabinomannanes et lipomannanes, lipides possédant des propriétés antigéniques, sont retrouvés dans les deux fractions membranaires. Ce travail de fractionnement a été le point de départ d'une étude de protéomique afin d'identifier les protéines retrouvées spécifiquement au niveau de la mycomembrane-AG-PG mais également les protéines de la membrane plasmique, les protéines sécrétées et les protéines solubles, provenant des cytosol et périplasme. Une étude de dynamique par RMN sur les fractions membranaires natives menée conjointement avec l'étude protéomique, devrait permettre de mieux comprendre l'organisation de l'enveloppe cellulaire des mycobactéries ainsi que certains des mécanismes impliqués dans la pathogénicité.Mycobacteria, including Mycobacterium tuberculosis and Mycobacterium leprae, etiological agents of tuberculosis and leprosy respectively, are composed of a complex and atypical cell wall, which is the focus of numerous studies in the context of the fight against these pathologies. This cell envelope, to which many biological properties have been attributed, is composed of three entities: an outer layer also called capsule in the case of pathogenic species, a cell wall and a plasma membrane. Within the mycobacterial cell wall, the outer membrane, called mycomembrane, is mainly composed of proteins and mycolic acids, very long chain a-branched and ß-hydroxylated fatty acids. These mycolic acids are found in the inner leaflet of the mycomembrane, covalently linked to the arabinogalactan-peptidoglycan complex (AG-PG), and in the outer leaflet where they are linked to trehaloses. Complex lipids are also known in mycobacteria, and may vary depending on the species, however their exact localization within the cell envelope is not yet clearly known and remains open to debate. In order to better delineate the composition of the two mycobacterial membranes, mycomembrane and plasma membrane, a two-step protocol was developed for cell fractionation of two mycobacterial species, M. aurum and M. smegmatis. Firstly, pellets enriched in mycomembranes (linked to AG-PG) or plasma membranes are obtained by differential ultracentrifugations. Then, these membrane pellets are purified using a sucrose step density gradient. To ensure the absence of cross-contaminations of the membranes, specific markers of each membranes are used. Phospholipids, which are the major components of the plasma membrane, are also found in the mycomembrane with trehalose mycolates. Moreover, this study allowed us to demonstrate that immunogenic lipoglycans, lipoarabinomannans and lipomannans, are found in the two mycobacterial membranes. Once the fractionation successfully achieved, it was possible to initiate proteomic studies in order to identify proteins that are specific of the mycomembrane-AG-PG but also those secreted or present in the soluble fraction, derived from the cytosol and periplasm compartments. Future NMR dynamic studies, to be performed on the native membranes, combined with the proteomic studies will help deciphering the organization of the mycobacterial cell envelope as well as the mechanisms involved in pathogenicity

The Altar porphyry Cu-(Au-Mo) deposit (Argentina): a complex magmatic-hydrothermal system with evidence of recharge processes

Altar (31º 29’ S, 70º 28’ W) is a large porphyry Cu-(Au-Mo) deposit with associated epithermal Au-(Ag-Cu) veins located in the Cordillera Principal of SW San Juan Province (Argentina). Altar is a complex magmatic-hydrothermal system formed from several magmatic and hydrothermal pulses during the middle-late Miocene. New LA-ICPMS U-Pb ages in zircons from the Altar porphyries indicate four discrete events of intrusions over an extended magmatic life time of ca. 3 m.y. It comprises a pre-mineralization porphyry (11.75 ± 0.24 Ma), three mineralized porphyries (11.62 ± 0.21 Ma and 11.68 ± 0.27 Ma, 11.13 ± 0.26 Ma, 10.35 ± 0.32 Ma) related to hydrothermal breccias, two post-mineralization intrusions, and a post-mineralization breccia (8.9 ± 0.4 Ma). The three mineralized porphyries (porphyries 2, 3 and 4) were emplaced within ~0.7-1.3 m.y. Amphibole phenocrysts from the porphyries crystallized from oxidized magmas (fO₂=NNO +1 to +2) at temperatures of 780 to 850°C and pressures between 0.9 and 1.8 kbar corresponding to depths of ~4-7 km. Anorthite and Fe- rich rims in the plagioclase phenocrysts suggest that the magmatic chambers were episodically recharged by a less evolved magma. The middle-late Miocene intrusions are interpreted to have been derived from a deeper and relatively large magmatic reservoir that supplied magmas to smaller chambers located in the upper crust. The focused magmatic output to shallow levels during a period of a few million years in the Altar area has been a main requirement in the formation of this large porphyry copper deposit

Inter-Individual Variability and Conspecific Densities: Consequences for Population Regulation and Range Expansion

The presence of conspecifics can strongly modulate the quality of a breeding site. Both positive and negative effects of conspecifics can act on the same individuals, with the final balance between its costs and benefits depending on individual characteristics. A particular case of inter-individual variation found in many avian species is chromatic variability. Among birds, plumage coloration can co-vary with morphology, physiology and behavior as well as with age. These relationships suggest that cost-benefit balances of conspecific presence may be different for individuals with different colorations. We investigated whether inter-individual variability affects population regulation and expansion processes by analyzing potential differences in density-dependent productivity and settlement patterns in relation to plumage coloration in a population of a long-lived avian species recently undergoing a notable increase in numbers and distribution range. Our results show strong variation in the effect of density on productivity of breeding pairs depending on plumage coloration of their members. Productivity of dark birds decreased along the breeding density gradient while that of lighter breeders remained unchanged with conspecific density. In a similar way, our results showed an uneven occupation of localities by individuals with different plumage coloration in relation to local densities, with the breeding of lighter harriers more aggregated than that of dark-brown ones. At a population scale, darker birds had higher probability of colonization of the most isolated, empty sites. Explanations for species range expansion and population regulation usually make the inferred assumption that species traits are similar among individuals. However, in most species, there could be individual variation in niche requirements or dispersal propensities among individuals with different traits. Our results contribute to the growing appreciation that the individual traits, but not the average trait at the level of species, are important during population regulation and expansion processes

Moving in the anthropocene: global reductions in terrestrial mammalian movements

Animal movement is fundamental for ecosystem functioning and species survival, yet the effects of the anthropogenic footprint on animal movements have not been estimated across species. Using a unique GPS-tracking database of 803 individuals across 57 species, we found that movements of mammals in areas with a comparatively high human footprint were on average one-half to one-third the extent of their movements in areas with a low human footprint. We attribute this reduction to behavioral changes of individual animals and to the exclusion of species with long-range movements from areas with higher human impact. Global loss of vagility alters a key ecological trait of animals that affects not only population persistence but also ecosystem processes such as predator-prey interactions, nutrient cycling, and disease transmission

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Isolation and characterization of the mycobacterial mycomembrane

Les mycobactéries, dont les plus connues sont Mycobacterium tuberculosis et Mycobacterium leprae, agents étiologiques de la tuberculose et de la lèpre respectivement, présentent une enveloppe complexe et atypique faisant l'objet de nombreuses études dans le cadre de la lutte contre ces pathologies. Cette enveloppe est composée d'une couche externe aussi appelée capsule dans le cas de bactéries pathogènes, d'une paroi (mycomembrane - arabinogalactane (AG) - peptidoglycane (PG)) et d'une membrane plasmique. La membrane externe des mycobactéries, appelée mycomembrane est composée de protéines et majoritairement d'acides mycoliques, acides gras à très longues chaînes a-ramifiés et ß-hydroxylés. Ces derniers sont retrouvés covalemment liés, d'une part au complexe AG-PG dans le feuillet interne de la mycomembrane, et d'autre part au tréhalose au niveau du feuillet externe de la mycomembrane. On trouve également en fonction des mycobactéries des lipides complexes dont la localisation exacte dans l'enveloppe n'est à ce jour pas clairement connue et reste sujette à débats. Ce travail a permis de mettre au point un protocole, en deux étapes majeures, permettant le fractionnement cellulaire de deux espèces mycobactériennes, M. aurum et M. smegmatis. Le but étant d'isoler les deux membranes mycobactériennes afin de déterminer leur composition en terme de lipides mais aussi de protéines. Tout d'abord, des culots enrichis en mycomembranes (liées à l'AG-PG) ou en membranes plasmiques sont obtenus par ultracentrifugations différentielles puis purifiés sur gradients de densité discontinus de saccharose. L'absence de contaminations des membranes entre elles est vérifiée grâce à des marqueurs spécifiques. Il a été montré que les phospholipides qui sont les composants majoritaires de la membrane plasmique sont également présents dans la mycomembrane à côté des mycolates de tréhalose. De plus ce travail a permis de montrer que les lipoglycanes, lipoarabinomannanes et lipomannanes, lipides possédant des propriétés antigéniques, sont retrouvés dans les deux fractions membranaires. Ce travail de fractionnement a été le point de départ d'une étude de protéomique afin d'identifier les protéines retrouvées spécifiquement au niveau de la mycomembrane-AG-PG mais également les protéines de la membrane plasmique, les protéines sécrétées et les protéines solubles, provenant des cytosol et périplasme. Une étude de dynamique par RMN sur les fractions membranaires natives menée conjointement avec l'étude protéomique, devrait permettre de mieux comprendre l'organisation de l'enveloppe cellulaire des mycobactéries ainsi que certains des mécanismes impliqués dans la pathogénicité.Mycobacteria, including Mycobacterium tuberculosis and Mycobacterium leprae, etiological agents of tuberculosis and leprosy respectively, are composed of a complex and atypical cell wall, which is the focus of numerous studies in the context of the fight against these pathologies. This cell envelope, to which many biological properties have been attributed, is composed of three entities: an outer layer also called capsule in the case of pathogenic species, a cell wall and a plasma membrane. Within the mycobacterial cell wall, the outer membrane, called mycomembrane, is mainly composed of proteins and mycolic acids, very long chain a-branched and ß-hydroxylated fatty acids. These mycolic acids are found in the inner leaflet of the mycomembrane, covalently linked to the arabinogalactan-peptidoglycan complex (AG-PG), and in the outer leaflet where they are linked to trehaloses. Complex lipids are also known in mycobacteria, and may vary depending on the species, however their exact localization within the cell envelope is not yet clearly known and remains open to debate. In order to better delineate the composition of the two mycobacterial membranes, mycomembrane and plasma membrane, a two-step protocol was developed for cell fractionation of two mycobacterial species, M. aurum and M. smegmatis. Firstly, pellets enriched in mycomembranes (linked to AG-PG) or plasma membranes are obtained by differential ultracentrifugations. Then, these membrane pellets are purified using a sucrose step density gradient. To ensure the absence of cross-contaminations of the membranes, specific markers of each membranes are used. Phospholipids, which are the major components of the plasma membrane, are also found in the mycomembrane with trehalose mycolates. Moreover, this study allowed us to demonstrate that immunogenic lipoglycans, lipoarabinomannans and lipomannans, are found in the two mycobacterial membranes. Once the fractionation successfully achieved, it was possible to initiate proteomic studies in order to identify proteins that are specific of the mycomembrane-AG-PG but also those secreted or present in the soluble fraction, derived from the cytosol and periplasm compartments. Future NMR dynamic studies, to be performed on the native membranes, combined with the proteomic studies will help deciphering the organization of the mycobacterial cell envelope as well as the mechanisms involved in pathogenicity

LA-ICP-MS zircon U-Pb geochronology in the Altar porphyry copper Project, Andes Main Cordillera of San Juan, Argentina

The “now amagmatic” Andean flat-slab segment (28-33ºS) (Cahill e Isacks, 1992) is known for its Cu-Mo-Au mineralization ‘fertility’ and hosts high-sulphidation epithermal deposits such as La Coipa (6 million ounces of Au equivalent,~24 to 17 Ma), Pascua (12 Moz Au, ~9 to 6 Ma) and El Indio (12 Moz Au,~9 to 6 Ma) and world-class porphyry Cu-Mo deposits such as Pachón-Los Pelambres (21 Mt Cu,~11 to 10 Ma), Los Bronces-Rio Blanco (49 Mt Cu,~6 to 4 Ma) and El Teniente (75 Mt Cu,~6 to 4 Ma). The Altar Porphyry Cu-(Au-Mo) project (31º 29' S, 70º 28´ W) occurs in the southern portion of the Andean flat-slab segment, within a “cluster” of Cu (Au) prospects including Piuquenes, La Coipa, Calderón, Rincones de Araya and Los Azules and next to the worldclass porphyry Cu deposits of Los Pelambres, in Chile, and Pachón, in Argentina. Despite the high economic value, the geology of this area is poorly known. This contribution presents new geological, geocronologic and isotopic data for Altar rocks that provide insights into the magmatic evolution of this region during Miocene times.Fil: Maydagán, Laura. Universidad Nacional del Comahue. Facultad de Ingeniería. Departamento de Geología y Petróleo; Argentina. Comisión Nacional de Investigación Científica y Tecnológica; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Sato, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; ArgentinaFil: Lanfranchini, Mabel Elena. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Recursos Minerales. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto de Recursos Minerales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Llambias, Eduardo Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; ArgentinaFil: Chiaradia, Massimo. University Of Geneva (ug);7th South American Symposium Isotope GeologyBrasiliaBrasilComité organizador del South American Symposium On Isotope Geolog

Las rocas volcánicas del Mioceno Temprano en la región de Altar, Cordillera Principal de San Juan, Argentina: Petrogénesis y geotectónica

El pórfido de Cu-Au-Mo Altar (31º 29? S, 70º 28? O) se localiza en la Cordillera Principal de San Juan, en la porción sur del segmento de subducción horizontal de los Andes Centrales (28-33ºS), 25 km al norte de los depósitos de Cu-Au-Mo de clase mundial Los Pelambres y El Pachón. Las rocas ígneas de Altar han sido clasificadas en el Complejo Volcánico Inferior (CVI) y la Suite Subvolcánica Superior (SSS) (Maydagán et al., 2010). En esta contribución se presentan recientes estudios sobre la petrografía, la geoquímica, una datación radimétrica y los datos de los isótopos radiogénicos de las rocas volcánicas del CVI de la región de Altar, que permiten precisar la evolución magmática y el ambiente geodinámico del segmento de subducción horizontal a los ~31º 30? de latitud sur, entre los cinturones de El Indio (~30°) y El Teniente (~34°). El CVI comprende una intercalación de niveles lávicos (andesita basáltica y dacita-andesita porfírica) y piroclásticos (toba lapillítica y brecha piroclástica de composición andesítica-dacítica) que gradan a una unidad superior de toba riolítica compacta. Toda la secuencia se encuentra afectada por deformación (plegamientos y fallamientos). Los planos de estratificación muestran rumbos (N 70°- N 340°) e inclinan entre 25° y 85° hacia el NO y SE. Estudios previos asignaron esta secuencia al Grupo Choiyoi (Almandoz et al., 2005). Una nueva edad U-Pb en circones de 20 ± 0,3 Ma (Maydagán et al., 2010) obtenida en una muestra de toba maciza asignaría estas rocas al MiocenoTemprano. En diagramas normalizados al manto primitivo, estas rocas muestran anomalías negativas de Nb y Ta típicas de arcos magmáticos. Su rango composicional variable (andesita basáltica poco evolucionada, lavas de andesita-dacita y rocas piroclásticas más evolucionadas) indica procesos de cristalización fraccionada, como lo expresa también el aumento de K2O y la disminución de MgO, CaO, Al2O3, MnO, Fe2O3, P2O5 y TiO2 con la diferenciación. La disminución del CaO, Al2O3, Sr y del MgO, Fe2O3, TiO2, V, Sc al aumentar el SiO2 señala el fraccionamiento de la plagioclasa y de olivino, clinopiroxeno y óxidos de Fe-Ti, respectivamente. La disminución de P2O5 y de Zr al aumentar el SiO2 indicaría el fraccionamiento de apatito y de circón. Los patrones subhorizontales de elementos de tierras raras intermedias y pesadas (Sm/Yb=1,49-3,17) y las anomalías negativas de Eu, indican un proceso de fraccionamiento dominado por plagioclasa y piroxeno. Las correlaciones observadas entre los isótopos radiogénicos y los índices geoquímicos de estas rocas, sugieren que el proceso de cristalización fraccionada estuvo acompañado por asimilación cortical (AFC). Sin embargo, el rango restringido de variación de los datos isotópicos implica un grado reducido de asimilación o la incorporación de rocas corticales isotópicamente similares a los fundidos derivados del manto. Los contenidos de SiO2 y las razones La/Yb, La/Sm y Sm/Yb de la andesita basáltica y andesita del CVI son similares a las rocas ígneas de la Formación Escabroso (21?18 Ma; Martin et al., 1997), mientras que estos valores en la dacita y en la riolita son similares a la Formación Tillito (27-23 Ma; Martin et al., 1997), ambas Formaciones del Grupo Doña Ana (Kay et al, 1987, 1991; Maksaev et al., 1984) del el Cinturón El Indio (30° S). Las rocas del CVI y el Grupo Doña Ana también tienen similares firmas isotópicas. Las razones La/Ta bajas en la Formación Tillito (Kay y Mpodozis, 2002), similares a las observadas en las tobas riolíticas de Altar, parecen obedecer a la influencia de componentes derivados de la corteza continental reciclada en sus magmas (Kay et al., 1987, 1991). Los contenidos de SiO2 y las razones La/Yb, La/Sm y Sm/Yb del CVI también son similares a las rocas de la Formación Abanico (37-15 Ma) (Aguirre, 1960; Klohn, 1960) de la Zona Central (32-34° S), a excepción de las tobas riolíticas del CVI que tienen razones La/Sm más elevadas. Las firmas istópicas de las rocas menos evolucionadas del CVI indican magmas más enriquecidos que la Formación Abanico (Hollings et al., 2005), salvo una muestra de andesita basáltica que tiene valores similares a los de la Formación Abanico Este (Muñoz et al., 2006). Los magmas del CVI tienen firmas de tierras raras levemente diferentes a los de la Formación Coya Machalí (20-27 Ma; Charrier et al., 2002) de la región de El Teniente (34° S). En resumen, las rocas volcánicas de Altar representan un arco magmático del Mioceno Temprano en el cual los magmas procedentes del manto evolucionaron a bajas presiones por procesos de cristalización fraccionada y por la asimilación de rocas corticales en niveles someros. De acuerdo con las reconstrucciones de la migración de la Dorsal de Juan Fernández en el Mioceno (Yañez et al., 2001) y asumiendo que la dorsal afecta una región de 150-200 km desde su centro (Gutscher et al., 2000), el magmatismo del Mioceno Temprano de Altar no estaría relacionado con la dorsal. La llegada de la Dorsal de Juan Fernández occurrió a los ~14 Ma en el segmento de subducción horizontal (Yañez et al., 2001) y a los ~10 Ma en la región de estudio (Maydagán et al., 2001). Kay y Mpodozis (2002) sugieren que durante el Mioceno Temprano en este segmento de los Andes el régimen compresional aumentaba de sur a norte. Las razones La/Yb y Sm/Yb del Complejo Volcánico de Altar respecto a los observados en El Teniente, al sur y en El Indio, al norte, apoyan esta hipótesis. Este trabajo forma parte de un proyecto financiado por el CONICET (PIP N° 1083) y subsidios otorgados por la Society of Economic Geologists (SEG) y por IO Global - Acme labs (IO Stipend). Queremos agradecer a los geólogos de la empresa minera Río Tinto Mining & Exploration, Jorge Bengochea, Santiago Gigola y Guillermo Almandoz, por su autorizarización para iniciar el estudio del prospecto Altar y a los geólogos de la empresa minera Peregrine Metals Ltd., Jeff Toohey y Roger Rey por la ayuda que nos han brindado durante las tareas de campo y muestreo.Fil: Maydagán, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Departamento de Geologia y Petroleo ; Centro Regional Universitario Bariloche ; Universidad Nacional del Comahue;Fil: Franchini, Marta Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Negro. Sede Alto Valle. Instituto de Investigaciones en Paleobiología y Geología; ArgentinaFil: Chiaradia, Massimo. University Of Geneva (ug);Fil: Sato, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; ArgentinaFil: Llambias, Eduardo Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; ArgentinaFil: Pons, María Josefina. Universidad Nacional de Río Negro. Sede Alto Valle. Instituto de Investigaciones en Paleobiología y Geología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaXVIII Congreso Geológico ArgentinoNeuquénArgentinaAsociación Geológica Argentin