Universidad de Magallanes
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Carotid Body-Mediated Chemoreflex Function in Aging and the Role of Receptor-Interacting Protein Kinase
No full textVentilatory impairment during aging has been linked to carotid body (CB) dysfunction. Anatomical/morphological studies evidenced CB degeneration and reductions in the number of CB chemoreceptor cells during aging. The mechanism(s) related to CB degeneration in aging remains elusive. Programmed cell death encompasses both apoptosis and necroptosis. Interestingly, necroptosis can be driven by molecular pathways related to low-grade inflammation, one hallmark of the aging process. Accordingly, we hypothesized that necrotic cell death dependent on receptori-nteracting protein kinase-3 (RIPK3) may contribute, at least in part, to impair CB function during aging. Adult (3 months) and aged (24 months) wild type (WT) and RIPK3(-/-) mice were used to study chemoreflex function. Aging results in significant reductions in both the hypoxic (HVR) and hypercapnic ventilatory responses (HCVR). Adult RIPK3(-/-) mice showed normal HVR and HCVR compared to adult WT mice. Remarkable, aged RIPK3(-/)- mice displayed no reductions in HVR nor in HCVR. Indeed, chemoreflex responses obtained in aged RIPK3(-/-) KO mice were undistinguishable from the ones obtained in adult WT mice. Lastly, we found high prevalence of breathing disorders during aging and this was absent in aged RIPK3(-/-) mice. Together our results support a role for RIPK3-mediated necroptosis in CB dysfunction during aging
Beyond 'desirable' values: Expanding relational values research to reflect the diversity of human-nature relationships
No full textIn recent years, environmental values have become increasingly important for understanding human-environment relationships and transitions towards sustainability. Pluralistic valuation seeks to account for values associated with the diversity of human-nature relationships. Relational values (RV) have been proposed as a concept that can aid in plural valuation. RV concern the relationships that people have with their environments. Most RV studies focus on 'desirable' or 'beneficial' RV that contribute to pro-environmental actions and sustainable outcomes. We argue that RV could be expanded to understand values that may be less environmentally beneficial. We focus our analysis on RV that exist in 'simplified' landscapes. Drawing on our research on cattle-based livelihoods in Latin America, we highlight potential approaches to the study of RV in such simplified landscapes. We then build on the examples to examine themes and principles of RV with the aim of stimulating discussion about how the concept might be refined and expanded to study a broader range of human-environment relationships. Overall, our aim is to contribute to plural valuation and offer preliminary suggestions for how RV might expand to capture the complexity of values, from those that are desirable to those which contribute to environmental degradation. Expanding the scope of RV research and the depth of the RV concept can help to understand the challenges to sustainability and contribute to the shared goals of sustainability that motivate values research. Read the free Plain Language Summary for this article on the Journal blog
EL APOGEO DE LA PESCA DEMERSAL EN EL SITIO OFFING 2 (LOCUS 1) (ESTRECHO DE MAGALLANES): UN IMPORTANTE CAMPAMENTO DE PESCA A MEDIADOS DEL HOLOCENO TARDÍO
No full textWing reduction and body size variation along a steep elevation gradient: a case study with Magellanic sub-Antarctic mayflies and stoneflies
No full textIntroduction: Ecogeographical patterns in body size have been described across a wide range of vertebrate species. However, insects have shown inconsistent patterns in studies to date. Aquatic insects, particularly those from remote regions, have barely been explored. Methods: The Magellanic sub-Antarctic ecoregion offers an ideal natural laboratory with near pristine environments, limiting the potential influence of confounding variables. In this study, we evaluated the influence of elevation on body and wing size and aspect ratio patterns for 10 species of mayfly (Ephemeroptera) and stonefly (Plecoptera) along a steep coastal elevation gradient (similar to 0-600 m a.s.l.). Results: We detected significant relationships between altitude and morphological features for the studied species. Additionally, we found that in females, morphological changes were slightly more pronounced than in males, probably due to their role as dispersers. While body size showed an increase along the elevation gradient, there was a notable decrease in some species' wing length over a relatively short geographic distance. Discussion: Our data suggest that morphological plasticity might be promoted in response to the harsh environmental conditions that typify the steep coastal Magellanic sub-Antarctic mountain ranges
Signature of the stratosphere-troposphere coupling on recent record-breaking Antarctic sea-ice anomalies
No full textIn February 2023, the sea-ice extent around Antarctica dropped to 1.79 x 10 6 km 2 , setting a satellite-era record low for the second straight year. Recent records stress the need for further research into the factors behind record-breaking Antarctic sea-ice anomalies. By influencing the circumpolar westerly winds, the stratospheric polar vortex has played a major role in the Antarctic surface climate in recent decades. However, the footprint of the polar vortex variability in the year-to-year changes in the Antarctic sea-ice cover remains obscured. Here, we use satellite retrievals and reanalysis data to study the response of the sea-ice extent around Antarctica to changes in the polar vortex strength. We focus on the last 2 decades that saw sharp changes in the stratospheric zonal flow, the tropospheric westerly winds and the sea-ice cover (the latter climbed to record highs in 2013 and 2014 before dropping to record lows in 2017, 2022 and 2023). Our results suggest that this unprecedented interannual variability is noticeably influenced by the polar vortex dynamics. The signature of the stratosphere-troposphere coupling is apparent in recent records (highs and lows) in the sea-ice extent around Antarctica
Validity and Reliability of Short-Term Heart Rate Variability Parameters in Older People in Response to Physical Exercise
No full textBackground: Currently, and to the best of our knowledge, there is no standardized protocol to measure the effect of low- to moderate-intensity physical exercise on autonomic modulation focused in older people. Aim: Validate a test–retest short-term exercise protocol for measuring the autonomic response through HRV in older people. Methods: A test–retest study design was used. The participants were selected through intentional non-probabilistic sampling. A total of 105 older people (male: 21.9%; female: 78.1%) were recruited from a local community. The assessment protocol evaluated HRV before and immediately after the 2-min step test. It was performed twice on the same day, considering a time of three chronological hours between the two measurements. Results: The posterior distribution of estimated responses in the Bayesian framework suggests moderate to strong evidence favoring a null effect between measurements. In addition, there was moderate to robust agreement between heart rate variability (HRV) indices and assessments, except for low frequency and very low frequency, which showed weak agreement. Conclusions: Our results provide moderate to strong evidence for using HRV to measure cardiac autonomic response to moderate exercise, suggesting that it is sufficiently reliable to show similar results to those shown in this test–retest protocol
Photoprotective responses of three intertidal Antarctic macroalgae to short-term temperature stress
No full textThe Antarctic Peninsula is experiencing one of the highest warming rates globally. In polar regions, macroalgae thrive under extreme environmental conditions, which could worsen because of future climate change scenarios, including increased ultraviolet exposure, extremely low light availability, and fluctuating temperatures, particularly in the intertidal zones. To investigate the potential role of photoprotective and antioxidant mechanisms in response to future increases in sea surface temperatures caused by climate change, we conducted laboratory experiments using three intertidal macroalgae model species: Adenocystis utricularis (Ochrophyta, Phaeophyceae), Pyropia endiviifolia (Rhodophyta, Bangiophyceae), and Monostroma hariotii (Chlorophyta, Ulvophyceae). These algae were collected in Punta Artigas (King George Island, Antarctica) and acclimated at 2 degrees C for 48 h. They were then assessed in laboratory experiments for up to 5 days under two treatments: (1) control conditions at 2 degrees C and (2) elevated tem.perature conditions at 8 degrees C, representing the most negative increment in SSTs estimated by the end of the 21st century. Carbon, nitrogen, pigments (chlorophylls and carotenoids), mycosporine-like amino acids (MAAs), and phenolic compounds were quantified after 3 and 5 days of exposure. For M. hariotii, elevated temperatures led to an increase in the C/N ratio, total antioxidant capacity, and levels of nitrogen, total carotenoids, chlorophyll-a, pigments (chlorophyll-b and violaxanthin), and phenolic compounds. For A. utricularis, elevated temperatures led to elevated C/N ratio and levels of chlorophyll-a and carotenoids (fucoxanthin and beta-carotene). For P. endiviifolia, elevated temperatures resulted in elevated levels of carotenoids (lutein and beta-carotene), phenolic compounds, and MAAs (porphyra-334, shinorine, and palythine). Thus, our study suggests that increasing water temperatures due to global warming can enhance the photoprotective abilities of three Antarctic intertidal macroalgae (M. hariotii, A. utricularis, and P. endiviifolia), with each species showing specific responses
Hybrid renewable energy systems sizing for the colombian context by multiple attribute decision making evaluation
No full textDue to the environment's adverse effects caused by electricity generation based on fossil resources, renewable energies have been promoted, where wind and solar energy stand out for the recent reduction in installation, operation, and maintenance costs. Wind and solar are stochastic natural resources; however, their complementarity is exploited by Hybrid Renewable Energy Systems, impacting energy availability for a particular demand. This study presents the sizing of hybrid renewable systems considering the resources existing in La Guajira, Colombia, applying an Analytic Hierarchy Process to evaluate the Loss Power Supply Probability, the Total Annual Cost and the Levelized Cost of Energy, and the Net Present Value of all possible configurations. Furthermore, the results were compared with a previous study that optimized the configurations through Genetic Algorithms and Particle Swarm Optimization. Three demand profiles were analyzed: (1) a reference case that includes a characteristic normalized non-interconnected single-family house composed of three users with an electrical consumption of 3.6 kWh/day, (2) the previous reference case plus the energy consumption for a water purifying system of 200 L/user/day, aiming a load of 4.3 kWh/day, and (3) a load profile for 150 users non-interconnected community with a demand of 156.2 kWh/day. Based on the results, it is observed that a 100% solar photovoltaic system presented the lower economic indicators values without affecting the availability of electricity generation for the cases with a minimum energy load (i.e., cases (1) and (2)). However, with the energy demand increasing, hybridization with wind turbines is essential to meet the load during operation
Changes and continuities in subsistence and interaction between marine hunter-gatherer and agro-pottery societies during the late Holocene in the Northern Archipelago, Patagonia, Chile
No full textDistinctive cultural systems converged during the Late Holocene in the northern Patagonian Archipelago (similar to 41 degrees 30'-47 degrees S), connecting groups with ceramic-bearing cultural traditions and economies based on food production (horticultural) with groups of marine hunter-gatherer-fishers established since the Middle Holocene. This article evaluates changes and continuities in the subsistence and dietary patterns of the groups that occupied this archipelago throughout its occupation sequence, based on the results of delta C-13 and delta N-15 value analysis of 27 individual human remains (similar to 4400-150 cal yr BP) from the Chiloe Archipelago (similar to 41 degrees 30'-43 degrees S). These data are integrated with information previously obtained from 36 individuals (similar to 2000-300 cal yr BP) from the Chonos Archipelago (similar to 43 degrees-47 degrees S), as well as complementary samples of algae and archaeofauna. From the estimated diet of 63 individuals, we suggest a low intensity of interaction between these cultural trajectories over time in the northern Patagonian Archipelago, and continuity of hunting, fishing, and marine gathering systems. After European contact, significant changes in the subsistence of these human groups would be reflected, particularly in the Chiloe Archipelago
Revised classification of the Cyanidiophyceae based on plastid genome data with descriptions of the Cavernulicolales ord. nov. and Galdieriales ord. nov. (Rhodophyta)
No full textThe Cyanidiophyceae, an extremophilic red algal class, is distributed worldwide in extreme environments. Species grow either in acidic hot environments or in dim light conditions (e.g., "cave Cyanidium"). The taxonomy and classification systems are currently based on morphological, eco-physiological, and molecular phylogenetic characters; however, previous phylogenetic results showed hidden diversity of the Cyanidiophyceae and suggested a revision of the classification system. To clarify phylogenetic relationships within this red algal class, we employ a phylogenomic approach based on 15 plastomes (10 new) and 15 mitogenomes (seven new). Our phylogenies show consistent relationships among four lineages (Galdieria, "cave Cyanidium", Cyanidium, and Cyanidioschyzon lineages). Each lineage is distinguished by organellar genome characteristics. The "cave Cyanidium" lineage is a distinct clade that diverged after the Galdieria clade but within a larger monophyletic clade that included the Cyanidium and Cyanidioschyzon lineages. Because the "cave Cyanidium" lineage is a mesophilic lineage that differs substantially from the other three thermoacidophilic lineages, we describe it as a new order (Cavernulicolales). Based on this evidence, we reclassified the Cyanidiophyceae into four orders: Cyanidiales, Cyanidioschyzonales, Cavernulicolales ord. nov., and Galdieriales ord. nov. The genetic distance among these four orders is comparable to, or greater than, the distances found between other red algal orders and subclasses. Three new genera (Cavernulicola, Gronococcus, Sciadococcus), five new species (Galdieria javensis, Galdieria phlegrea, Galdieria yellowstonensis, Gronococcus sybilensis, Sciadococcus taiwanensis), and a new nomenclatural combination (Cavernulicola chilensis) are proposed