Universidad Austral de Chile

One of the most important factors regulating the distribution and abundance of seaweeds is desiccation, mainly triggered by tidal changes and climatic variation. Porphyra and Pyropia species have evolved multiple strategies to tolerate desiccation stress; however, how these tolerance strategies differ in these species in-habiting different latitudes is still unknown. In this context, we analyzed in situ the physiological responses of these species (collected from 18°S to 41°S along the Chilean coast) to desiccation stress using biochemical and molecular analyses. The hyper-arid terrestrial climate of northern Chile with high evaporation and lack of constant rain determines a very steep increase in desiccation stress in the upper intertidal during low tide for these species. Accordingly, the results showed that in comparison to the southernmost populations, the Porphyra/Pyropia species from the north zone of Chile (18°–30°S), exhibited higher contents of lipoperoxide and carbonyls (1.6–1.9 fold) together with higher enzymatic activities, including ascorbate peroxidase, catalase, peroxiredoxin and thioredoxin (2–3 fold). In addition, a substantial expression of cat, prx and trx transcripts during desiccation was demonstrated, mainly in the northernmost populations. These results provide evidence of (i) significant activation of antioxidant enzymes and transcripts (principally cat and prx); (ii) participation of phenolic antioxidant compounds as a highly plastic physiological strategy to cope with desiccation; (iii) the activation of the tolerance responses was affected by species latitudinal distribution. Thus, for the first time, this study integrated the biochemical and genetic responses of diverse Porphy-ra/Pyropia species to better understand their physiological dynamics of tolerance over a wide latitudinal range.

This paper presents a study on Spanish doubling patterns that follows the line of analysis advanced by Muñoz Pérez and Verdecchia (2022). It introduces a doubling pattern that has not been previously discussed in the literature, clausal doubling, and compares it with predicate doubling. It argues that both patterns have essentially the same structure but are distinguished by the nature of the constituents that are dislocated in each case. This factor triggers a number of formal and interpretative differences that are captured by a unified analysis.

Different Andean societies underwent processes of expansion and collapse during propitious or adverse climate conditions, resource boost or depletion along with population variations. Previous studies have emphasized that demographic collapses of polities in the Central Andes Area were triggered by warfare and the negative impacts of fluctuating climate (droughts) on crop productivity. Nevertheless, the interactions between climatic variability, demography and warfare have been less thoroughly evaluated. We develop population dynamic models to test feedback relationships between population growth, climate change and warfare in the Central Andes, where considerable regional hydroclimate variations have occurred over a millennium. Through population models, we found out that the rise and demise of social polities in the northern coast of the Central Andes appear to be a consequence of climate change. In contrast, for the highlands of Peru and the Titicaca basin, population models suggest that warfare intensity has a negative effect on population growth rates.

Objective Uncover the experiences of caregivers of elderly people living in long-term care institutions, during confinement in the context of the Covid-19 pandemic. Method Qualitative, descriptive research, through an intrinsic case study. Intentional sample by criteria and convenience of six caregivers, Los Ríos Region, Chile; a semi-structured interview was carried out in 2021. Analysis applying the constant comparative method and progressive focusing approach. Validity was ensured by compliance with the criteria of rigor and researcher triangulation. Results 489 units of meaning gave rise to four thematic groups: Meaning of having lived the experience, facilitating factors, hindering factors and recommendations. Two domains emerged: Contribution of caregivers to strengthening their role during the pandemic and Contribution to strengthening management. Conclusions: it allows recognizing and validating the emotional bond, commitment and vocation of care providers, key aspects to be reinforced through counseling and training to guarantee the quality of care. KEYWORDS: Long-term care institution for the elderly; Caregivers; Pandemic; Psychological stress.

Objective Uncover the experiences of caregivers of elderly people living in long-term care institutions, during confinement in the context of the Covid-19 pandemic. Method Qualitative, descriptive research, through an intrinsic case study. Intentional sample by criteria and convenience of six caregivers, Los Ríos Region, Chile; a semi-structured interview was carried out in 2021. Analysis applying the constant comparative method and progressive focusing approach. Validity was ensured by compliance with the criteria of rigor and researcher triangulation. Results 489 units of meaning gave rise to four thematic groups: Meaning of having lived the experience, facilitating factors, hindering factors and recommendations. Two domains emerged: Contribution of caregivers to strengthening their role during the pandemic and Contribution to strengthening management. Conclusions: it allows recognizing and validating the emotional bond, commitment and vocation of care providers, key aspects to be reinforced through counseling and training to guarantee the quality of care. KEYWORDS: Long-term care institution for the elderly; Caregivers; Pandemic; Psychological stress.

Tracking and preventing continued extinctions requires robust spatially explicit metrics quantifying the impacts of human activities on habitat extent. Existing metrics either fail to consider species identity or focus solely on recent habitat losses. The persistence score approach represented an important development by combining species ecologies and land-cover data whilst considering the cumulative and non-linear impact of past habitat loss on species’ probability of persistence. However, it is computationally demanding, limiting its global use and application. Here we couple the persistence score approach with high-performance computing to generate global maps of what we term the LIFE (Land-cover change Impacts on Future Extinctions) metric for 29153 species of terrestrial vertebrates at 1 arc-minute resolution (3.4km2 at the equator). These maps quantify, for the first time, the marginal changes in the expected number of extinctions caused by (1) converting remaining natural vegetation to agriculture, and (2) restoring farmland to natural habitat. We demonstrate statistically that this approach integrates information on species richness, endemism, and past habitat loss. Our resulting maps can reliably be used at scales from 0.5-1000km2, and offer unprecedented opportunities to estimate the impact on extinctions of diverse actions, from dietary choices right through to global protected area development.

Natural history museums are vital repositories of specimens, samples and data that inform about the natural world; this Formal Comment revisits a Perspective that advocated for the adoption of compassionate collection practices, querying whether it will ever be possible to completely do away with whole animal specimen collection.

Ordinary (customary) light gauge steel framing is a convenient construction technology; however, given the studs low axial capacity, it has been considered mainly for low-rise buildings in low seismicity regions. This paper investigates the boundaries of application of this type of steel framing (in moderate and high seismicity areas) by designing the structures of three representative 5, 7 and 10-storey buildings in order to examine their feasibility. The necessity of using built-up columns consisting of two or more sections is investigated. The axial capacity of studs is estimated by code-type analyses. The critical buckling stress is determined with well-known closed-form expressions; as they do not contemplate the flexibility of the screwed connections (in built-up sections), the obtained results are complemented with those of the finite strip method and generalized beam theory formulations.

The Chilean Patagonian fjords are globally renowned as one of the few remaining pristine environments on Earth; however, their ecosystems are under significant threat from climatic and anthropogenic pressures. Of particular concern is the lack of research into the impact of plastic pollution on the waters and biodiversity of these fjords. In this study, the marine environment of a secluded and sparsely populated fjord system in southern Patagonia was sampled to assess microplastics in seawater, beaches, bottom sediment, and zooplankton. Microplastics were found to be widespread across the water surface of the fjord, but with low abundances of 0.01 ± 0.01 particles m−3 (mean ± SD). The presence of microplastics in sedimentary environments (e.g., beaches and bottom sediments, 15.6 ± 15.3 and 9.8 ± 24 particles kg of dry sediment−1, respectively) provided additional evidence of plastic debris accumulation within the fjord system. Furthermore, microplastics were already bioavailable to key zooplankton species of the Patagonian food web (0.01 ± 0.02 particles individual−1), suggesting bioaccumulation. A comprehensive examination of potential microplastic inputs originating from coastal runoff, coupled with distribution of water masses, suggested minimal local contribution of microplastics to the fjord, strongly indicating that plastic litter is likely entering the area through oceanic currents. The composition and type of microplastics, primarily consisting of polyester fibers (approx. 60 %), provided further support for the proposed distant origin and transportation into the fjord by oceanographic drivers. These results raise significant concern as reveal that despite a lack of nearby population, industrial or agricultural activity, remote Patagonian fjords are still impacted by plastic pollution originating from distant sources. Prioritizing monitoring efforts is crucial for effectively assessing the future trends and ecological impact of plastic pollution in these once so-called pristine ecosystems.

Simple Summary Our results indicate activation of the kynurenine pathway and serotonin activity when stimulated with tryptophan and cortisol supplementation. An amount of 95% of tryptophan is degraded by the kynurenine pathway, indicating the relevance of knowing how this pathway is activated and if stress levels associated with fish culture trigger its activation. Additionally, it is essential to know the consequence of increasing KYNA levels in different species in the short and long term, and even during the fish ontogeny. Abstract Aquaculture fish are kept for long periods in sea cages or tanks. Consequently, accumulated stress causes the fish to present serious problems with critical economic losses. Fish food has been supplemented to reduce this stress, using many components as amino acids such as tryptophan. This study aims to determine the transcriptional effect of tryptophan and cortisol on primary cell cultures of salmon head and posterior kidney. Our results indicate activation of the kynurenine pathway and serotonin activity when stimulated with tryptophan and cortisol. An amount of 95% of tryptophan is degraded by the kynurenine pathway, indicating the relevance of knowing how this pathway is activated and if stress levels associated with fish culture trigger its activation. Additionally, it is essential to know the consequence of increasing kynurenic acid “KYNA” levels in the short and long term, and even during the fish ontogeny.

Since 2019, there has been a long‐duration low water event that has no previous records in the floodplain of the Paraná River. This event highlights the lack of backgrounds and a lack of information on the socio‐economic and ecohydrological impacts, as well as the difficulty of implementing relevant management measures to address this hydrological condition. This scenario has triggered several environmental and socio‐economic conflicts associated with fishing activity. However, a conventional fisheries management approach with merely hydrological criteria is still carried out. This decoupling between the hydrological reality and the intensity of the fishing activity poses a threat to fish resources. The objective of this study was to discuss the application of ecohydrological criteria to advance the understanding of fish assemblage responses to the dynamics of hydrological processes in order to apply it to the management of the Paraná River fisheries, particularly in scenarios of extraordinary low water levels. We conclude that available knowledge does not include a comprehension of the effects of prolonged low water level on commercial fish assemblage recruitment and structure during prolonged low water levels, and there is not enough knowledge to establish criteria to define the sustainable management of fishery resources.

The overall trajectory for the human–environment interaction has been punctuated by demographic boom-and-bust cycles, phases of growth/overshooting as well as of expansion/contraction in productivity. Although this pattern has been explained in terms of an interplay between population growth, social upscaling, ecosystem engineering and climate variability, the evoked demographic–resource-complexity mechanisms have not been empirically tested. By integrating proxy data for population sizes, palaeoclimate and internal societal factors into empirical modelling approaches from the population dynamic theory, we evaluated how endogenous (population sizes, warfare and social upscaling) and exogenous (climate) variables module the dynamic in past agrarian societies. We focused on the inland Atacama Desert, where populations developed agriculture activities by engineering arid and semi-arid landscapes during the last 2000 years. Our modelling approach indicates that these populations experienced a boom-and-bust dynamic over the last millennia, which was coupled to structure feedback between population sizes, hydroclimate, social upscaling, warfare and ecosystem engineering. Thus, the human–environment loop appears closely linked with cooperation, competition, limiting resources and the ability of problem-solving. This article is part of the theme issue ‘Evolution and sustainability: gathering the strands for an Anthropocene synthesis’.

Abrupt and rapid changes in human societies are among the most exciting population phenomena. Human populations tend to show rapid expansions from low to high population density along with increased social complexity in just a few generations. Such demographic transitions appear as a remarkable feature of Homo sapiens population dynamics, most likely fuelled by the ability to accumulate cultural/technological innovations that actively modify their environment. We are especially interested in establishing if the demographic transitions of pre-historic populations show the same dynamic signature of the Industrial Revolution transition (a positive relationship between population growth rates and size). Our results show that population growth patterns across different pre-historic societies were similar to those observed during the Industrial Revolution in developed western societies. These features, which appear to have been operating during most of our recent demographic history from hunter–gatherers to modern industrial societies, imply that the dynamics of cooperation underlay sudden population transitions in human societies. This article is part of the theme issue ‘Evolution and sustainability: gathering the strands for an Anthropocene synthesis’.

Aging is a major risk factor for neurodegenerative diseases, and coronavirus disease 2019 (COVID-19) is linked to severe neurological manifestations. Senescent cells contribute to brain aging, but the impact of virus-induced senescence on neuropathologies is unknown. Here we show that senescent cells accumulate in aged human brain organoids and that senolytics reduce age-related inflammation and rejuvenate transcriptomic aging clocks. In postmortem brains of patients with severe COVID-19 we observed increased senescent cell accumulation compared with age-matched controls. Exposure of human brain organoids to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induced cellular senescence, and transcriptomic analysis revealed a unique SARS-CoV-2 inflammatory signature. Senolytic treatment of infected brain organoids blocked viral replication and prevented senescence in distinct neuronal populations. In human-ACE2-overexpressing mice, senolytics improved COVID-19 clinical outcomes, promoted dopaminergic neuron survival and alleviated viral and proinflammatory gene expression. Collectively our results demonstrate an important role for cellular senescence in driving brain aging and SARS-CoV-2-induced neuropathology, and a therapeutic benefit of senolytic treatments.

West Antarctica plays a pivotal role in sea level rise in projected scenarios with global socioenvironmental and economic consequences. Therefore, describing its recent and past climate history and changes is essential for identifying the main climate controls and past responses. To better understand the climatic sensitivity of this region, we analyzed sedimentary records from newly surveyed proglacial lacustrine profiles dated from the middle Holocene to the present on the North Antarctic Peninsula. We combined atmosphere-glacier-land databases that evidenced a close coupling among these compartments during intense melting events. Our analyses furthermore suggest that a short Neoglacial phase from ∼2,000 kyr BP until the onset of the 20th century was possibly influenced by a combined long-term decline in total solar irradiance, Andean volcanism and ENSO.

West Antarctica plays a pivotal role in sea level rise in projected scenarios with global socioenvironmental and economic consequences. Therefore, describing its recent and past climate history and changes is essential for identifying the main climate controls and past responses. To better understand the climatic sensitivity of this region, we analyzed sedimentary records from newly surveyed proglacial lacustrine profiles dated from the middle Holocene to the present on the North Antarctic Peninsula. We combined atmosphere-glacier-land databases that evidenced a close coupling among these compartments during intense melting events. Our analyses furthermore suggest that a short Neoglacial phase from ~2,000 kyr BP until the onset of the 20 th century was possibly influenced by a combined long-term decline in total solar irradiance, Andean volcanism and ENSO.

This study aimed to determine the acute effects of high-intensity forward-backward and low-intensity side-to-side plyometric jumps performed following the warm-up on sprint (5, 10, and 15 m) and change-of-direction (COD) (T-half test and repeated T-half tests) performance in youth volleyball players. After a familiarization week, 30 male volleyball players (age = 12.04 ± 1.03 years) performed three randomized conditions (no-plyometrics, high-intensity plyometrics, and low-intensity plyometrics) in three sessions. In a within-subject design, three sets of six repetitions of forward-backward 30-cm hurdle jumps (high-intensity) and side-to-side 20-cm hurdle jumps (low-intensity) were completed. Sprint and COD were tested after each of the conditions with a 2-min rest. A significant effect of the plyometric condition was observed on sprint ( p < .001, range: .56–.70) and COD ( p < .01, ), but not on repeated COD. More specifically, the high-intensity plyometric condition exhibited significantly better results compared with the low-intensity plyometric (Cohen’s d range: 0.73–1.21) and control conditions (Cohen’s d range: 0.91–2.21). Due to the importance of speed and COD in volleyball, these results suggest that young volleyball players may benefit from high-intensity forward-backward plyometric protocols following the warm-up to improve subsequent performance.

Background Obstructive sleep apnea (OSA) is characterized by recurrent episodes of chronic intermittent hypoxia (CIH), which has been linked to the development of sympathoexcitation and hypertension. Furthermore, it has been shown that CIH induced inflammation and neuronal hyperactivation in the nucleus of the solitary tract (NTS), a key brainstem region involved in sympathetic and cardiovascular regulation. Since several studies have proposed that NTS astrocytes may mediate neuroinflammation, we aimed to determine the potential contribution of NTS-astrocytes on the pathogenesis of CIH-induced hypertension. Results Twenty-one days of CIH induced autonomic imbalance and hypertension in rats. Notably, acute chemogenetic inhibition (CNO) of medullary NTS astrocytes using Designer Receptors Exclusively Activated by Designers Drugs (DREADD) restored normal cardiac variability (LF/HF: 1.1 ± 0.2 vs. 2.4 ± 0.2 vs. 1.4 ± 0.3, Sham vs. CIH vs. CIH + CNO, respectively) and markedly reduced arterial blood pressure in rats exposed to CIH (MABP: 82.7 ± 1.2 vs. 104.8 ± 4.4 vs. 89.6 ± 0.9 mmHg, Sham vs. CIH vs. CIH + CNO, respectively). In addition, the potentiated sympathoexcitation elicit by acute hypoxic chemoreflex activation in rats exposed to CIH was also completely abolished by chemogenetic inhibition of NTS astrocytes using DREADDs. Conclusion Our results support a role for NTS astrocytes in the maintenance of heightened sympathetic drive and hypertension during chronic exposure to intermittent hypoxia mimicking OSA.