Universidad de Magallanes
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Ionic and stable isotopic content in two Antarctic firn cores under different environment settings
No full textAbstract This article compares isotopic, ionic and climatic data from two firn cores from the West Antarctic Ice Sheet (WAIS). The IC-02 (88°01'21.3"S , 82°04'21.7"W) and the IC-05 (82°30'30.8"S , 79°28'02.7"W) closer to the coast. The IC-02 had 488 samples analyzed covering 14.58 meters depth while the IC-05 had 602 samples analyzed covering 19.73 meters depth. The time interval for both ice cores is 25 years ranging from 1978 to 2003. Sodium, sulfate and chloride were analyzed via ion chromatography using three DionexTM ionic chromatographers at the laboratories of Centro Polar e Climático (CPC) and at the Climate Change Institute. Stable isotope data was determined using cavity ring-down spectroscopy in a Picarro® spectrometer at the CPC. Annual accumulation was greater at IC-05 with an average of 0.35 m.eq.w.a-1 compared to 0.25 m.eq.w.a-1 at the IC-02. Stable isotope data was approximately 1.3 times more negative at the IC-02 which also presented higher d values. Na+ and Cl- were in higher concentrations at the IC-05 however Cl/Na was greater in the IC-02. The Cl excess was found to be derived from fractionation of sea salt aerosols and not related to volcanism. This work presents new insights regarding the chemical differences between ice cores
Commonalities and differences in carotid body dysfunction in hypertension and heart failure
No full textCarotid body pathophysiology is associated with many cardiovascular-respiratory-metabolic diseases. This pathophysiology reflects both hyper-sensitivity and hyper-tonicity. From both animal models and human patients, evidence indicates that amelioration of this pathophysiological signalling improves disease states such as a lowering of blood pressure in hypertension, a reduction of breathing disturbances with improved cardiac function in heart failure (HF) and a re-balancing of autonomic activity with lowered sympathetic discharge. Given this, we have reviewed the mechanisms of carotid body hyper-sensitivity and hyper-tonicity across disease models asking whether there is uniqueness related to specific disease states. Our analysis indicates some commonalities and some potential differences, although not all mechanisms have been fully explored across all disease models. One potential commonality is that of hypoperfusion of the carotid body across hypertension and HF, where the excessive sympathetic drive may reduce blood flow in both models and, in addition, lowered cardiac output in HF may potentiate the hypoperfusion state of the carotid body. Other mechanisms are explored that focus on neurotransmitter and signalling pathways intrinsic to the carotid body (e.g. ATP, carbon monoxide) as well as extrinsic molecules carried in the blood (e.g. leptin); there are also transcription factors found in the carotid body endothelium that modulate its activity (Kruppel-like factor 2). The evidence to date fully supports that a better understanding of the mechanisms of carotid body pathophysiology is a fruitful strategy for informing potential new treatment strategies for many cardiovascular, respiratory and metabolic diseases, and this is highly relevant clinically.image Abstract figure legend The carotid body has been linked with the development of hypertension and heart failure in animals and humans. This review explores mechanisms of carotid body sensitisation across disease models. We ask whether these mechanisms are common or unique to distinct cardiovascular diseases; such knowledge could inform clinical treatment strategies. We propose that carotid body sensitivity increases progressively from health to hypertension and is maximal in heart failure and that there are both shared and distinct sensitisation mechanisms. This sensitisation is followed by an increase in systemic sympathetic outflow. It remains unknown whether the sensitised carotid body drives sympathetic overactivity or vice versa.imag
A new parasitic copepod species of Tautochondria (Siphonostomatoida: Hyponeoidae), found in the narrowmouthed catshark Schroederichthys bivius from the Strait of Magellan
No full textHyponeoidae is a copepod family that is rare around the world, with only three species described until now. Recently, a hyponeoid copepod was found in the narrowmouthed catshark, Schroederichthys bivius, from Chile, which has not been formally described. The objective of this study is to describe morphologically a new species of Hyponeoidae, from samples of the Strait of Magellan, Southern Chile. Also, a genetic analysis, based on the COI gene, was used to determine the relatedness of the new hyponeoid species to other copepods from Siphon-ostomatoida, which were available in the GenBank platform. The new species belongs to the genus Tautochondria and is here described as T. magellanica n. sp. This species differs from T. dolichoura mainly in the presence of long process at each side of the buccal cone, the absence of lobes on the head and short processes on the genital complex. According to the genetic sequences, T. magellanica n. sp. was not closely related to any other species. Therefore, this result confirms that Hyponeoidae is a separate family. However, the relatedness to other genera in Siphonostomatoida is still unknown
La política de inclusión de tecnologías digitales en el sistema escolar chileno. Una revisión sistemática
No full textResumen: Este artículo es el resultado de una investigación que analizó las políticas de inclusión de tecnologías digitales en el sistema escolar chileno durante las últimas décadas, a partir del estudio de las evidencias científicas disponibles, definiendo y estableciendo sus aportes, limitaciones, oportunidades y principales desafíos. Mediante una revisión sistemática de literatura y de la elección de los textos a partir de los criterios sugeridos por el protocolo Prisma, se analizó el contenido de un 23 artículos a través de una clasificación categorizada. Los resultados obtenidos nos permiten conocer la trayectoria y a la vez establecer cuáles han sido los principales hitos de las políticas de inclusión de tecnologías digitales en el sistema escolar chileno. Junto con esto, se han podido identificar los principales lineamientos promovidos desde inicios de la década de los noventa hasta hoy. Según las evidencias analizadas, Chile tiene tareas pendientes en materia de cobertura, desarrollo digital, integración pedagógica y la necesidad de una visión estratégica y mancomunada de cara al futuro
A second update on mapping the human genetic architecture of COVID-19
No full textInvestigating the role of host genetic factors in COVID-19 severity and susceptibility can inform our understanding of the underlying biological mechanisms that influence adverse outcomes and drug development 1,2 .Here we present a second updated genome-wide association study (GWAS) on COVID-19 severity and infection susceptibility to SARS-CoV-2 from the COVID-19 Host Genetic Initiative (data release 7).We performed a meta-analysis of up to 219,692 cases and over 3 million controls, identifying 51 distinct genome-wide significant loci-adding 28 loci from the previous data release 2 .The increased number of candidate genes at the identified loci helped to map three major biological pathways involved in susceptibility and severity: viral entry, airway defense in mucus, and type I interferon
The maple bug Boisea trivittata (Say, 1825) in Chile: Harmless, harmful; or a problem on the rise?
No full textDurante la presente temporada (2022-2023), se ha experimentado en la zona central de Chile un aumento explosivo en las poblaciones de Boisea trivittata (Say, 1825), chinche de origen norteamericano de reciente introducción al país (Faúndez et al. 2020a, 2021). A raíz de esto, ha surgido una serie de información errónea, emitida tanto en medios de comunicación abiertos, e incluso en medios oficiales como instructivos municipales. Dentro de la principal información entregada suele indicarse que esta especie es inofensiva y no causa daño alguno a los seres humanos. Sin embargo, como hemos mencionado anteriormente (Faúndez 2020) el uso de estos términos para clasificar a las especies suele ser tendencioso y no siempre del todo correcto
Role of Peripheral Chemoreceptors on Enhanced Central Chemoreflex Drive in Nonischemic Heart Failure
No full textHeart failure (HF) is a prevalent disease in elderly population. Potentiation of the ventilatory chemoreflex drive plays a pivotal role in disease progression, at least in part, through their contribution to the generation/maintenance of breathing disorders. Peripheral and central chemoreflexes are mainly regulated by carotid body (CB) and the retrotrapezoid nuclei (RTN), respectively. Recent evidence showed an enhanced central chemoreflex drive in rats with nonischemic HF along with breathing disorders. Importantly, increase activity from RTN chemoreceptors contribute to the potentiation of central chemoreflex response to hypercapnia. The precise mechanism driving RTN potentiation in HF is still elusive. Since interdependency of RTN and CB chemoreceptors has been described, we hypothesized that CB afferent activity is required to increase RTN chemosensitivity in the setting of HF. Accordingly, we studied central/peripheral chemoreflex drive and breathing disorders in HF rats with and without functional CBs (CB denervation). We found that CB afferent activity was required to increase central chemoreflex drive in HF. Indeed, CB denervation restored normal central chemoreflex drive and reduced the incidence of apneas by twofold. Our results support the notion that CB afferent activity plays an important role in central chemoreflex potentiation in rats with HF
Iron and silicic acid addition effects on early spring macronutrient drawdown and biogenic silica production of Patagonia estuarine waters
No full textThe Patagonia archipelago interior sea (PAIS) of southern Chile is one of the largest fjord systems on earth. These coastal waters include remote and virtually pristine areas where extreme rainfall/runoff and glacial meltwaters intensify the land-ocean interaction impinging on the biological, physical, and chemical characteristics of oceanic subantarctic Surface Water (SAASW) that flood the archipelago basins. The SAASW mix with silicon-and iron-replete continental water and diatom growth would occur concomitantly with a rapid drawdown of SAASW macronutrients. Consequently, phytoplankton metabolism (e.g. macronutrient utilization for primary productivity) in estuaries of southern Patagonian has been previously assumed independent of iron availability (i.e. iron-replete conditions). Experimental results shown here suggest that the nitrate and phosphate drawdown in low salinity (29) water can be enhanced by a 5 nM dissolved iron enrichment (by 13% and 28%, respectively) during the developing phase of a diatom bloom. The simultaneous enrichment in iron (5 nM) and silicic acid (5 mu M) in these estuarine waters resulted in a similar macronutrient uptake enhancement, a 119% increment of the production of biogenic silica and a 2-fold rise in the abundance of Pseudo-nitzschia spp (a diatom capable to produce the neurotoxin domoic acid). We suggest that natural freshwater pulses of allochthonous bioavailable forms of iron and silicon to inner waters of the Patagonia archipelago during the onset of the productive season play a potentially significant role modulating macronutrient dynamics (input vs utilization) and influencing coastal phytoplankton assemblages
Survival rates in the world's southernmost forest bird community
No full textThe Magellanic sub-Antarctic Forest is home to the world's southernmost avian community and is the only Southern Hemisphere analogue to Northern Hemisphere temperate forests at this latitude. This region is considered among the few remaining pristine areas of the world, and shifts in environmental conditions are predominantly driven by climate variability. Thus, understanding climate-driven demographic processes is critical for addressing conservation issues in this system under future climate change scenarios. Here, we describe annual survival patterns and their association with climate variables using a 20-year mark-recapture data set of five forest bird species in the Cape Horn Biosphere Reserve. We develop a multispecies hierarchical survival model to jointly explore age-dependent survival probabilities at the community and species levels in a group of five forest passerines. At the community level, we assess the association of migratory behavior and body size with survival, and at the species level, we investigate the influence of local and regional climatic variables on temporal variations of survival. We found a positive effect of precipitation and a negative effect of El Nino Southern Oscillation on juvenile survival in the white-crested Elaenia and a consistent but uncertain negative effect of temperature on survival in juveniles and 80% of adults. We found only a weak association of climate variables with survival across species in the community and no temporal trends in survival for any of the species in either age class, highlighting apparent stability in these high austral latitude forests. Finally, our findings provide an important resource of survival probabilities, a necessary input for assessing potential impacts of global climate change in this unique region of the world
New ecophysiological perspectives on the kelp Macrocystis pyrifera: generating a basis for sustainability in the sub-Antarctic region
No full textThese extensive kelps forest are among the most productive and diverse habitats on the planet, playing an important ecological role in marine ecosystems. These habitats have been affected by anthropogenic factors worldwide and directly by environmental variations resulting from climate change. The Magellan ecoregion has the southernmost kelp forests in the world, dominated by the species Macrocystis pyrifera. This species presents high ecophysiological plasticity being able to inhabit heterogeneous environments, characteristic of the fjord and channel systems of the region, and has high ecological, sociocultural, and economic importance for local coastal communities. To understand the ecophysiological acclimation strategies of M. pyrifera, samples from different blades were collected at different depths at four locations in the Magellan Ecoregion: Possession Bay, Skyring Sound, Otway Sound, and Puerto del Hambre seasonally. Abiotic measurements (salinity, temperature, and PAR light) were carried out for each location sampled. Measurements of photosynthetic parameters, F v/F m, rETRmax, Ek and a; pigment analysis of Chl a, Chl c, and fucoxanthin; and fecundity analysis of the sporophylls of each population studied were carried out on the M. pyrifera sporophytes. Significant differences were observed between seasons, locality, and depth of blades. Each population generally showed different photoacclimation processes, depending on the local conditions such as salinity values and probably tidal cycles. This is reflected in the photosynthetic, pigment, and fecundity values obtained during this study. The higher F v/F m values in all populations during the winter and autumn seasons and the differences in Chl c and fucoxanthin concentration during the winter period in Otway Sound and Puerto del Hambre population suggest the marked seasonal acclimation of M. pyrifera. In addition, the coastal environmental heterogeneity observed in the Magellan ecoregion related to salinity gradients (Skyring Sound) or wide tidal amplitudes (Possession Bay) influences the acclimation strategy of each population of M. pyrifera. Therefore, the characteristics of each population should be considered in order to promote its sustainability in times of social and climate change