Humans and environments in the most arid place of the world

The Atacama Desert lies between the Pacific coast and the Andes in northern Chile. It is the largest desert in South America and the driest on Earth. Here, annual precipitation is almost zero. The little water that is available depends on the summer rainfall that falls on the Andean mountains. It reaches the desert by runoff and is found within some canyons or by the emergence of groundwater. The presence of life in this extreme environment may seem unimaginable today; however, fossil and archaeological records reveal that plants, animals, and even humans lived in this region during various periods over the last 18,000 years.Fil: de Porras, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Gayo, Eugenia M.. Centro de Ciencia del Clima y la Resiliencia; ChileFil: Uribe, Mauricio. Universidad de Chile; ChileFil: Maldonado, Antonio. Comisión Nacional de Investigación Científica y Tecnológica. Centro de Investigación Regional. Centro de Estudios en Zonas Áridas; Chil

Vegetation changes and human occupation in the Patagonian steppe, Argentina, during the late Holocene

Vegetation changes during the late Holocene are interpreted from four fossil pollen sequences from two caves at the Los Toldos archaeological locality, Santa Cruz province, Argentina. Taphonomic processes are particularly taken into account in order to analyze the effects on the fossil pollen records of biotic factors such as human occupation and animals, and abiotic ones such as volcanic ash fall. Fossil pollen assemblages are interpreted using local modern pollen data. The main vegetation change occurred at ca. 3750 uncal B.P., when a shrub steppe of Asteraceae subf. Asteroideae with Schinus, Ephedra frustillata and a high proportion of grasses was replaced by a shrub steppe of Colliguaja integerrima and Asteraceae subf. Asteroideae. This change is synchronous with an archaeological record change and could be related either to moderate climatic variations or the effects of ash fall on the environment. Plant communities similar to the present-day ones were established in the Los Toldos area from ca. 3750 uncal B.P.Fil: de Porras, Maria Eugenia. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Laboratorio de Paleoecología y Palinología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Mancini, Maria Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Laboratorio de Paleoecología y Palinología; ArgentinaFil: Prieto, Aldo Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Laboratorio de Paleoecología y Palinología; Argentin

Late Quaternary Palynology methodologies and advances on the South American Arid Diagonal

La Diagonal Árida Sudamericana (DAS) es un rasgo biogeográfico y climático que ha experimentado cambios importantes en los ambientes, en las plantas, en los animales e incluso en las poblaciones humanas como consecuencia de la dinámica climática durante el Cuaternario tardío. El objetivo de este trabajo es revisar el desarrollo de las investigaciones en palinología del Cuaternario tardío a lo largo de la DAS, analizar sus desafíos, destacar las metodologías aplicadas para obtener registros polínicos robustos en términos paleoambientales y paleoclimáticos y resaltar los avances logrados. La mayoría de las zonas de la DAS presentan una concentración importante de registros polínicos fósiles, pero resulta difícil todavía en algunas áreas generar marcos paleoclimáticos y paleoambientales desde el Pleistoceno Tardío o bien que comprendan todo el Holoceno a escala regional. Esto es consecuencia de que (1) la mayoría de los ambientes depositacionales son “no convencionales” y, por lo tanto, presentan discontinuidades, preservación diferencial del polen y representatividad diferencial de la vegetación local versus la regional lo que complejiza más el análisis de un registro polínico fósil, y (2) la dispersión polínica en las zonas áridas y semiáridas dominadas por vegetación arbustiva y herbácea (en su mayoría entomófila) ha sido escasamente estudiada. Sin embargo, a partir de casos de estudio en tres áreas de la DAS -el desierto de Atacama y los Andes mediterráneos de Chile y la meseta patagónica en Argentina- se demuestra el potencial que los registros polínicos de estas áreas tienen para reconstruir la dinámica paleoclimática desde el Pleistoceno Tardío de manera robusta y confiable, aplicando las metodologías apropiadas.The South American Arid Diagonal (SAAD) constitutes a major biogeographic and climatic feature which has experimented significant changes in its environments, plants, animals and human societies due to the late Quaternary climatic dynamics. The aim of this paper is to review the development of Quaternary palynology studies on the SAAD, analyze the challenges, highlight the applied methodologies in order to obtain robust pollen records in palaeoenvironmental and palaeoclimatical terms and therefore, stress the achieved advances. Although most of the areas of the SAAD present a vast number of pollen records, it is still difficult to achieve regional paleoenvironmental and paleoclimatic framework for some areas since the Late Pleistocene or even the Holocene. This is based on the fact that (1) most of the depositional environments are not “standard” so they present discontinuities, differential pollen preservation and differential pollen representation of local versus regional vegetation which complicates the pollen analysis, and (2) the pollen dispersion processes in arid and semiarid zones dominated by shrubs and herbs (with many entomophilous species) are scarcely studied. However, taking study cases from three areas of the South American Arid Diagonal –Atacama Desert and Mediterranean Andes of Chile, and Patagonian plateau in Argentina– the potential of the pollen records from these areas to reconstruct the paleoclimatic dynamics since the Late Pleistocene can be demonstrated firmly and convincingly if appropriate methodologies are applied.Fil: de Porras, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina. Comisión Nacional de Investigación Científica y Tecnológica. Centro de Investigación Regional. Centro de Estudios en Zonas Áridas; ChileFil: Maldonado, Antonio. Comisión Nacional de Investigación Científica y Tecnológica. Centro de Investigación Regional. Centro de Estudios en Zonas Áridas; Chile. Universidad de La Serena; Chil

First study of fossil rodent middens as source of paleoparasitological evidences (northwestern Patagonia, Argentina)

The present paper reports the first paleoparasitological results obtained fromcoprolites of fossil rodent middens and demonstrates the potential of rodent middens as a source of paleoparasitological evidences in South America. Ten fossil rodent middens from northwestern Patagonia, Argentina, were studied. Five coprolites of each midden were fully processed, rehydrated, homogenized, subjected to spontaneous sedimentation, and examined through light microscopy. Eight of the 10 examined rodent middens contained parasite eggs. The eggs of parasites were assigned to Heteroxynema (Cavioxyura) viscaciae Sutton & Hugot, 1989 and Helminthoxys sp. (Nematoda: Oxyuridae), Trichuris sp. (Nematoda: Trichuridae) and one unidentified nematode. Fossil rodent middens were assigned to Lagidium viscacia (Caviomorph: Chinchillidae). The excellent preservation of parasite remains in coprolites from fossil rodent middens provided an opportunity to perform paleoparasitological inferences. The results of this papers demonstrates that fossil rodent middens offer an excellent opportunity for the recovery of parasite remains for future paleoparasitological studies in the southwest of South AmericaFil: Beltrame, Maria Ornela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología; ArgentinaFil: de Porras, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de La Serena; ChileFil: Barberena, Ramiro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Llano, Carina Lourdes. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Sardella, Norma Haydee. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología; Argentin

Holocene Environmental Dynamics of the Lago Cochrane/Pueyrredón Valley, Central West Patagonia (47°S)

Deglaciation modeling of the Patagonian Ice Field since the Last Glacial Maximum has been a topic of intensive research in Central West Patagonia (44°–49°S). However, the chronology of deglaciation onset, acceleration, and the subsequent thinning and recession of the different ice lobes as well as the timing and extension of large proglacial systems are still a matter of discussion. The maximum eastward extension the Lago Cochrane/Pueyrredón ice lobe was around ∼20,000–27,000 cal yrs BP; its associated proglacial lake drained toward the Pacific between 12,600 and 8,000 cal yrs BP. This study presents the first two pollen and charcoal records from the Lago Cochrane/Pueyrredón valley, spanning the last 11,650 cal yrs BP. The Laguna Maldonado record spans between 11,650 and 8,500 cal yrs BP, while the Laguna Anónima record the last 8,500 cal yrs BP, thereby overlapping chronologically. The lithological record of Laguna Maldonado shows that organic sedimentation began at the onset of the Holocene (11,650 cal yrs BP), once the site was free of glacio-lacustrine influence. Between 11,650 and 10,500 cal yrs BP, an open Nothofagus forest developed associated with high fire occurrence/frequency, followed by a transitional phase to a closer forest associated with a shift from low to high fire activity up to 9,400 cal yrs BP. Between 9,400 and 8,500 cal yrs BP, the Laguna Maldonado record suggests the development of an open forest or probably scattered patches of forest of variable size in a steppe matrix, probably related to geomorphological and paraglacial dynamics as well as climatic forcings, while the Laguna Anónima record indicates the development of a closed Nothofagus forest and high to low fire occurrence/frequency from 8,200 to 3,800 cal yrs BP. Since 3,800 cal yrs BP, a highly dynamic open forest or forest patches scattered in a grass/shrub–grass steppe matrix occurred around Laguna Anónima associated with high fire occurrence/frequency synchronous with an important increase in the presence of hunter-gatherers during the last 3,000 years. The results from the Lago Cochrane/Pueyrredón valley are integrated and discussed at the regional scale alongside other records from Central West Patagonia.Fil: Maldonado, Antonio. Comisión Nacional de Investigación Científica y Tecnológica. Centro de Investigación Regional. Centro de Estudios en Zonas Áridas; Chile. Universidad de La Serena; Chile. Universidad Católica del Norte; ChileFil: de Porras, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Martel Cea, Alejandra. Comisión Nacional de Investigación Científica y Tecnológica. Centro de Investigación Regional. Centro de Estudios en Zonas Áridas; Chile. Universidad Austral de Chile; ChileFil: Reyes, Omar. Centro de Investigacion En Ecosistemas de la Patagonia (ciep); . Universidad de Magallanes; ChileFil: Nuevo Delaunay, Amalia. Centro de Investigacion En Ecosistemas de la Patagonia (ciep);Fil: Méndez, César. Centro de Investigacion En Ecosistemas de la Patagonia (ciep)

Archeopalynology: a review of pollen analysis in caves, shelters and open contexts occupied by huntergatherer societies of Argentina (32º–52º s)

La palinología de sitios arqueológicos o arqueopalinología ha sido frecuentemente utilizada en la Argentina tanto para reconstruir la vegetación y los ambientes desde el final del Pleistoceno Tardío hasta tiempos recientes, como para inferir ciertas actividades culturales desarrolladas dentro de los sitios arqueológicos. En el presente trabajo se realizó una revisión de los análisis polínicos realizados a partir de depósitos sedimentarios en sitios arqueológicos en cuevas, aleros y en contextos abiertos correspondientes a sociedades de cazadores-recolectores de la Argentina (32º–52º S), independientemente del periodo cronológico o cultural. Se explican las metodologías aplicadas y los resultados obtenidos y se discuten las limitaciones del análisis polínico; las diferentes formas en que los datos de polen son útiles en este tipo de sitios arqueológicos, y los procesos tafonómicos tales como dispersión, depositación y preservación polínica en estos ambientes depositacionales. La potencialidad y aplicación del análisis polínico en arqueología de sitios cazadores-recolectores se ejemplificó con trabajos representativos en la región pampeana y patagónica, donde se han realizado la mayoría de los estudios arqueopalinológicos. Estos estudios, aunque complejos, ofrecen oportunidades únicas para comprender los entornos y las actividades humanas del pasado.Archeopalynology has been frequently used in Argentina to reconstruct vegetation and environments since the end of Late Pleistocene to the present, and to infer different cultural activities developed into the archaeological sites. The present paper presents a review of pollen analysis of sedimentary sequences from archaeological sites located in caves, shelters and open contexts occupied by hunter-gatherer societies of Argentina (32º–52º S), regardless the chronological or cultural period. The methodologies applied and results obtained are explained and the following topics are discussed the limitations of the pollen analysis; the different ways in which pollen data are useful in this type of archaeological sites; and the taphonomic processes such as pollen dispersal, deposition and preservation in these depositational environments. The potentiality and application of pollen analysis in archaeology of hunter-gatherer sites were exemplified by representative works in the Pampa and Patagonia regions, where most of the archeopalynology studies have been carried out. These studies, often complex, offer unique opportunities to understand the environments and human activities of the past.Fil: Prieto, Aldo Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Mancini, Maria Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: de Porras, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Bamonte, Florencia Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Marcos, Maria Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin

Holocene tephrochronology of the lower Río Cisnes valley, southern Chile

Sediment cores from lakes and bogs in the Río Cisnes valley contain tephra from explosive eruptions of volcanoes in the southern part of the Andean Southern Volcanic Zone (SSVZ). These tephra, which thicken and coarsen to the west, are attributed to eruptions from Melimoyu, Mentolat, Hudson, and potentially either Macá, Cay or one of the many minor eruptive centers (MEC) located both along the Liquiñe-Ofqui Fault Zone (LOFZ) and surrounding the major volcanoes. Correlation of the tephra between two new cores in the lower Río Cisnes valley, and amongst other cores previously described from the region, and source volcano identification for the tephra, has been done using lithostratigraphic data (tephra layer thickness and grain size), petrography (tephra glass color, vesicle morphology, and type and abundance of phenocryst phases), and by comparison of bulk tephra trace-element characteristics with previously published whole-rock and bulk tephra chemical analysis. Four tephras in these cores are attributed to eruptions of Mentolat, four to eruptions from Melimoyu, one possibly to Hudson, and six cannot be assigned to a specific source volcano. Some of these tephra correspond to pyroclastic tephra fall deposits previously observed in outcrop, including the MEL2 eruption of Melimoyu and the MEN1 eruption of Mentolat. However, others have not been previously observed and represent the products of newly identified small to medium sized eruptions from volcanoes of the SSVZ. These results provide new information concerning the frequency and magnitude of explosive eruption of SSVZ volcanoes and contribute to the evaluation of volcanic hazards in the region

N-methylation of a bactericidal compound as a resistance mechanism in Mycobacterium tuberculosis

The rising incidence of antimicrobial resistance (AMR) makes it imperative to understand the underlying mechanisms. Mycobacterium tuberculosis (Mtb) is the single leading cause of death from a bacterial pathogen and estimated to be the leading cause of death from AMR. A pyrido-benzimidazole, 14, was reported to have potent bactericidal activity against Mtb. Here, we isolated multiple Mtb clones resistant to 14. Each had mutations in the putative DNA-binding and dimerization domains of rv2887, a gene encoding a transcriptional repressor of the MarR family. The mutations in Rv2887 led to markedly increased expression of rv0560c. We characterized Rv0560c as an S-adenosyl-L-methionine-dependent methyltransferase that N-methylates 14, abolishing its mycobactericidal activity. An Mtb strain lacking rv0560c became resistant to 14 by mutating decaprenylphosphoryl-β-d-ribose 2-oxidase (DprE1), an essential enzyme in arabinogalactan synthesis; 14 proved to be a nanomolar inhibitor of DprE1, and methylation of 14 by Rv0560c abrogated this activity. Thus, 14 joins a growing list of DprE1 inhibitors that are potently mycobactericidal. Bacterial methylation of an antibacterial agent, 14, catalyzed by Rv0560c of Mtb, is a previously unreported mechanism of AMR

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality