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1.
Sci Total Environ ; 722: 137875, 2020 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-32199381

RESUMO

In September 2014, the Kashmir valley (north-west India) experienced a massive flood causing significant economic losses and fatalities. This disaster underlined the high vulnerability of the local population and raised questions regarding the resilience of Kashmiris to future floods. Although the magnitude of the 2014 flood has been considered unprecedented within the context of existing measurements, we argue that the short flow series may lead to spurious misinterpretation of the probability of such extreme events. Here we use a millennium-long record of past floods in Kashmir based on historical and tree-ring records to assess the probability of 2014-like flood events in the region. Our flood chronology (635 CE-nowadays) provides key insights into the recurrence of flood disasters and propels understanding of flood variability in this region over the last millennium, showing enhanced activity during the Little Ice Age. We find that high-impact floods have frequently disrupted the Kashmir valley in the past. Thus, the inclusion of historical records reveals large flood hazard levels in the region. The newly gained information also underlines the critical need to take immediate action in the region, so as to reduce the exposure of local populations and to increase their resilience, despite existing constraints in watershed management related to the Indus Water Treaty.

2.
Nat Ecol Evol ; 4(1): 40-45, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31844189

RESUMO

According to the competitive exclusion principle, species with low competitive abilities should be excluded by more efficient competitors; yet, they generally remain as rare species. Here, we describe the positive and negative spatial association networks of 326 disparate assemblages, showing a general organization pattern that simultaneously supports the primacy of competition and the persistence of rare species. Abundant species monopolize negative associations in about 90% of the assemblages. On the other hand, rare species are mostly involved in positive associations, forming small network modules. Simulations suggest that positive interactions among rare species and microhabitat preferences are the most probable mechanisms underpinning this pattern and rare species persistence. The consistent results across taxa and geography suggest a general explanation for the maintenance of biodiversity in competitive environments.


Assuntos
Biodiversidade , Ecologia , Geografia
3.
Environ Int ; 135: 105357, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31864024

RESUMO

The Bernese Alps are a region that is very prone for the initiation of thunderstorms. In fact, the flow and convergence of air and water vapor from the Swiss Plateau to the Swiss Alps is frequently favouring the formation of isolated rainfall events, which then may cause loss and damage in settlements. Due to the complex topography of the Bernese Alps, the forecasting and nowcasting of heavy convective precipitation remain challenging. A critical need therefore exists for the development of new forecasting tools so as to improve the predictability of convective precipitation events, also with the aim to alert first responders and to subsequently reduce damage. This study aims at developing an empirical index for the forecasting of heavy precipitation events in the Bernese Alps by using two reanalysis datasets, ECMWF's ERA-Interim and NASA's MERRA-2; in addition, the ICON-EU model is employed here to test and verify the index for the 2018 summer period. Our approach is based on the calculation of several convective indices as well as on the assessment of their relative forecast skills using a dichotomous scheme. The Heavy Precipitation Index (HPI) is then defined by combining the best performing combination of convective indices. HPI is aimed at forecasting heavy precipitation events over the Bernese Alps. We show that the combination of several indices, including DCI or KI, have a better capability to forecast heavy precipitation in the Bernese Alps than has the commonly used CAPE. Therefore, HPI should be seen as a pre-alert index when it comes to assist first responders in situations of crisis and in the process of decision making.

4.
Am J Bot ; 106(12): 1536-1544, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31758552

RESUMO

PREMISE: Fire scars on trees are created by excessive heat from a fire that kills the vascular cambium. Although, fires are one of the most important forest disturbances in Patagonia, the effects of fire on tree physiology and wood anatomy are still unknown. In this study, we hypothesized that abnormal functioning of the cambium after a fire will induce anatomical changes in the wood. We also assumed that these anatomical changes would affect xylem safety transport. METHODS: We quantified wood anatomical traits in Nothofagus pumilio, the dominant subalpine tree species of Patagonia, using two approaches: time and distance. In the first, anatomical changes in tree rings were compared before, during, and after fire occurrence. In the second, the spatial extent of these changes was evaluated with respect to the wound by measuring anatomical traits in sampling bands in two directions (0° and 45°) with respect to the onset of healing. RESULTS: Reductions in lumen diameter and vessel number were the most conspicuous changes associated with fire damage and observed in the fire ring and subsequent post-fire rings. In addition, the fire ring had more rays than in control rings. In terms of distance, anatomical changes were only restricted to short distances from the wound. CONCLUSIONS: Post-fire changes in wood anatomical traits were confined close to the wound margins. These changes might be associated with a defense strategy related to the compartmentalization of the wound and safety of water transport.

5.
Cell Rep ; 29(2): 283-300.e8, 2019 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-31597092

RESUMO

The regulation of hepatic gene expression has been extensively studied at the transcriptional level; however, the control of metabolism through posttranscriptional gene regulation by RNA-binding proteins in physiological and disease states is less understood. Here, we report a major role for the hormone-sensitive RNA-binding protein (RBP) APOBEC1 complementation factor (A1CF) in the generation of hepatocyte-specific and alternatively spliced transcripts. Among these transcripts are isoforms for the dominant and high-affinity fructose-metabolizing ketohexokinase C and glycerol kinase, two key metabolic enzymes that are linked to hepatic gluconeogenesis and found to be markedly reduced upon hepatic ablation of A1cf. Consequently, mice lacking A1CF exhibit improved glucose tolerance and are protected from fructose-induced hyperglycemia, hepatic steatosis, and development of obesity. Our results identify a previously unreported function of A1CF as a regulator of alternative splicing of a subset of genes influencing hepatic glucose production through fructose and glycerol metabolism.

6.
Sci Rep ; 9(1): 14560, 2019 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-31601991

RESUMO

Landslides are frequently triggered by extreme meteorological events which has led to concern and debate about their activity in a future greenhouse climate. It is also hypothesized that dry spells preceding triggering rainfall may increase slope predisposition to sliding, especially in the case of clay-rich soils. Here we combined dendrogeomorphic time series of landslides and climatic records to test the possible role of dry spells and extreme downpours on process activity in the Outer Western Carpathians (Central Europe). To this end, we tested time series of past frequencies and return periods of landslide reactivations at the regional scale with a Generalized Linear Mixed (GLM) model to explore linkages between landslide occurrences and triggering climate variables. Results show that landslide reactivations are concentrated during years in which spring and summer precipitation sums were significantly higher than usual, and that triggering mechanisms vary between different types of landslides (i.e. complex, shallow or flow-like). The GLM model also points to the susceptibility of landslide bodies to the combined occurrence of long, dry spells followed by large precipitation. Such situations are likely to increase in frequency in the future as climate models predict an enhancement of heatwaves and dry spells in future summers, that would be interrupted by less frequent, yet more intense storms, especially also in mountain regions.

7.
Cell Rep ; 28(11): 2892-2904.e7, 2019 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-31509750

RESUMO

Cyclin-dependent kinases (CDKs) contribute to vital cellular processes including cell cycle regulation. Loss of CDKs is associated with impaired insulin secretion and ß cell survival; however, the function of CDK8 in ß cells remains elusive. Here, we report that genetic ablation of Cdk8 improves glucose tolerance by increasing insulin secretion. We identify OSBPL3 as a CDK8-dependent phosphoprotein, which acts as a negative regulator of insulin secretion in response to glucose. We also show that embryonic gene silencing of neuropeptide Y in ß cells is compromised in Cdk8-null mice, leading to continued expression into adulthood. Cdk8 ablation in ß cells aggravates apoptosis and induces de novo expression of neuropeptides upon oxidative stress. Moreover, pancreatic islets exposed to stress display augmented apoptosis in the presence of these same neuropeptides. Our results reveal critical roles for CDK8 in ß cell function and survival during metabolic stress that are in part mediated through de novo expression of neuropeptides.

8.
Environ Int ; 127: 291-304, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30951945

RESUMO

Extreme precipitation events with high local precipitation intensities, heavy snowfall or extensive freezing rain can have devastating impacts on society and economy. Not only is the quantitative forecast of such events sometimes difficult and associated with large uncertainties, also are the potential consequences highly complex and challenging to predict. It is thus a demanding task to anticipate or nowcast the impacts of extreme precipitation, even more so in situations where human lives or critical infrastructure might be at risk. In recent years, the term "cascading effects" has been increasingly used to describe events in which an initial trigger leads to a sequence of consequences with significant magnitude. We here analyze three examples for different precipitation types where the initial triggering event generated a cascade of events and impacts, namely a convective precipitation event in the Swiss Prealps, a freezing rain in Slovenia, and a heavy snowfall episode in Catalonia. With the aim to improve process understanding of complex precipitation-triggered events, we assess the prediction of the selected events and analyze the cascading effects that caused diverse impacts. To this end, we use a framework of cascading effects which should ultimately allow the development of a better design risk assessment and management strategies. Our findings confirm that damage of extreme precipitation events is clearly related to the knowledge of potential cascading effects. Major challenges of predicting cascading effects are the high complexity, the interdependencies and the increasing uncertainty along the cascade. We propose a framework for cascading effects including two approaches: (i) one to analyze cascading effects during past extreme precipitation events, which then serves as a basis for a (ii) more generalized approach to increase the preparedness level of operational services before and during future extreme precipitation events and to anticipate potential cascading effects of extreme precipitation. Both approaches are based on pathway schemes that can be used in addition to numerical models or hazard maps to analyze and predict potential cascading effects, but also as training tools.


Assuntos
Chuva , Europa (Continente) , Humanos
9.
J Vis Exp ; (143)2019 01 07.
Artigo em Inglês | MEDLINE | ID: mdl-30663651

RESUMO

Sheet erosion is among the crucial drivers of soil degradation. Erosion is controlled by environmental factors and human activities, which often lead to severe environmental impacts. The understanding of sheet erosion is, consequently, a worldwide issue with implications for both environment and economies. However, the knowledge on how erosion evolves in space and time is still limited, as well as its effects on the environment. Below, we explain a new dendrogeomorphological protocol for deriving eroded soil thickness (Ex) by acquiring accurate microtopographic data using both terrestrial laser scanning (TLS) and microtopographic profile gauges. Additionally, standard dendrogeomorphic procedures, dependent on anatomical variations in root rings, are utilized to establish the timing of exposure. Both TLS and microtopographic profile gauges are used to obtain ground surface profiles, from which Ex is estimated after the threshold distance (TD) is determined, i.e., the distance between the root and the sediment knickpoint, which allows defining the lowering of the ground surface caused by sheet erosion. For each profile, we measured the height between the topside of the root and a virtual plane tangential to the ground surface. In this way, we intended to avoid small-scale impacts of soil deformation, which may be due to pressures exerted by the root system, or by the arrangement of exposed roots. This may provoke small amounts of soil sedimentation or erosion depending on how they physically affect the surface runoff. We demonstrate that an adequate microtopographic characterization of exposed roots and their associated ground surface is very valuable to obtain accurate erosion rates. This finding could be utilized to develop the best management practices designed to eventually halt or perhaps, at least, lessen soil erosion, so that more sustainable management policies can be put into practice.


Assuntos
Meio Ambiente , Laboratórios
10.
Ann N Y Acad Sci ; 1436(1): 206-216, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-29968302

RESUMO

In this study, we analyze the linkage between atmosphere and ocean modes and winter flood variability over the 20th century based on long-term flow-discharge series, historical archives, and tree-ring records of past floods in the North Atlantic Basin (NAB). The most extreme winter floods occurred in 1936 and had strong impacts on either side of the Atlantic. We hypothesize that the joint effects of sea surface temperatures (SSTs) over the Atlantic and Pacific Oceans and the Arctic Oscillation (AO), which is closely related to the North Atlantic Oscillation, play a significant role when describing flood variability in North America and Europe since 1900. Statistical modeling supports the assumption that the response of flood anomalies over the NAB to AO phases is subsidiary of SST phases. Besides, we shed light on the extraordinarily winter flood of 1936 that was characterized by very high SSTs over both the Atlantic and Pacific (>98th percentile) and very low, negative values of AO (<1st percentile). This outstanding winter flood episode was most likely characterized by stratospheric polar vortex anomalies, which can usually be linked to an increased probability of storms in western and southwestern Europe and increased snowfall events in eastern North America. By assessing the flood anomalies over the NAB as a coupled AO and SST function, one could further the understanding of such large-scale events and presumably improve anticipation of future extreme flood occurrences.


Assuntos
Inundações/história , Modelos Teóricos , Estações do Ano , Oceano Atlântico , Europa (Continente) , História do Século XX , História do Século XXI , América do Norte
11.
Nat Commun ; 9(1): 4671, 2018 11 07.
Artigo em Inglês | MEDLINE | ID: mdl-30405106

RESUMO

The epithelial-to-mesenchymal transition (EMT) is an important mechanism for cancer progression and metastasis. Numerous in vitro and tumor-profiling studies point to the miR-200-Zeb1 axis as crucial in regulating this process, yet in vivo studies involving its regulation within a physiological context are lacking. Here, we show that miR-200 ablation in the Rip-Tag2 insulinoma mouse model induces beta-cell dedifferentiation, initiates an EMT expression program, and promotes tumor invasion. Strikingly, disrupting the miR-200 sites of the endogenous Zeb1 locus causes a similar phenotype. Reexpressing members of the miR-200 superfamily in vitro reveals that the miR-200c family and not the co-expressed and closely related miR-141 family is responsible for regulation of Zeb1 and EMT. Our results thus show that disrupting the in vivo regulation of Zeb1 by miR-200c is sufficient to drive EMT, thus highlighting the importance of this axis in tumor progression and invasion and its potential as a therapeutic target.


Assuntos
Diferenciação Celular , MicroRNAs/metabolismo , Neoplasias/genética , Neoplasias/patologia , Transdução de Sinais , Homeobox 1 de Ligação a E-box em Dedo de Zinco/metabolismo , Animais , Sequência de Bases , Diferenciação Celular/genética , Proliferação de Células/genética , Progressão da Doença , Transição Epitelial-Mesenquimal/genética , Regulação Neoplásica da Expressão Gênica , Redes Reguladoras de Genes , Camundongos Endogâmicos C57BL , MicroRNAs/genética , Mutação/genética , Invasividade Neoplásica , Homeobox 1 de Ligação a E-box em Dedo de Zinco/genética
12.
Ecol Evol ; 8(16): 8598-8606, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30250726

RESUMO

Increasing CO 2 concentration ([CO 2]) is likely to affect future species distributions, in interaction with other climate change drivers. However, current modeling approaches still seldom consider interactions between climatic factors and the importance of these interactions therefore remains mostly unexplored. Here, we combined dendrochronological and modeling approaches to study the interactive effects of increasing [CO 2] and temperature on the distribution of one of the main European liana species, Hedera helix. We combined a classical continent-wide species distribution modeling approach with a case study using H. helix and Quercus cerris tree rings, where we explored the long-term influence of a variety of climate drivers, including increasing [CO 2], and their interactions, on secondary growth. Finally, we explored how our findings could influence the model predictions. Climate-only model predictions showed a small decrease in habitat suitability for H. helix in Europe; however, this was accompanied by a strong shift in the distribution toward the north and east. Our growth ring data suggested that H. helix can benefit from high [CO 2] under warm conditions, more than its tree hosts, which showed a weaker response to [CO 2] coupled with higher cavitation risk under high temperature. Increasing [CO 2] might therefore offset the negative effects of high temperatures on H. helix, and we illustrate how this might translate into maintenance of H. helix in warmer areas. Our results highlight the need to consider carbon fertilization and interactions between climate variables in ecological modeling. Combining dendrochronological analyses with spatial distribution modeling may provide opportunities to refine predictions of how climate change will affect species distributions.

13.
Sci Total Environ ; 642: 619-628, 2018 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-29909329

RESUMO

Climate change can impair ecosystem functions and services in extensive dry forests worldwide. However, attribution of climate change impacts on tree growth and forest productivity is challenging due to multiple inter-annual patterns of climatic variability associated with atmospheric and oceanic circulations. Moreover, growth responses to rising atmospheric CO2, namely carbon fertilization, as well as size ontogenetic changes can obscure the climate change signature as well. Here we apply Structural Equation Models (SEM) to investigate the relative role of climate change on tree growth in an extreme Mediterranean environment (i.e., extreme in terms of the combination of sandy-unconsolidated soils and climatic aridity). Specifically, we analyzed potential direct and indirect pathways by which different sources of climatic variability (i.e. warming and precipitation trends, the North Atlantic Oscillation, [NAO]; the Mediterranean Oscillation, [MOI]; the Atlantic Mediterranean Oscillation, [AMO]) affect aridity through their control on local climate (in terms of mean annual temperature and total annual precipitation), and subsequently tree productivity, in terms of basal area increments (BAI). Our results support the predominant role of Diameter at Breast Height (DHB) as the main growth driver. In terms of climate, NAO and AMO are the most important drivers of tree growth through their control of aridity (via effects of precipitation and temperature, respectively). Furthermore and contrary to current expectations, our findings also support a net positive role of climate warming on growth over the last 50 years and suggest that impacts of climate warming should be evaluated considering multi-annual and multi-decadal periods of local climate defined by atmospheric and oceanic circulation in the North Atlantic.


Assuntos
Mudança Climática , Florestas , Árvores/crescimento & desenvolvimento , Ecossistema , Região do Mediterrâneo , Temperatura Ambiente
14.
Elife ; 72018 06 18.
Artigo em Inglês | MEDLINE | ID: mdl-29911972

RESUMO

In yeast, the glucose-induced degradation-deficient (GID) E3 ligase selectively degrades superfluous gluconeogenic enzymes. Here, we identified all subunits of the mammalian GID/CTLH complex and provide a comprehensive map of its hierarchical organization and step-wise assembly. Biochemical reconstitution demonstrates that the mammalian complex possesses inherent E3 ubiquitin ligase activity, using Ube2H as its cognate E2. Deletions of multiple GID subunits compromise cell proliferation, and this defect is accompanied by deregulation of critical cell cycle markers such as the retinoblastoma (Rb) tumor suppressor, phospho-Histone H3 and Cyclin A. We identify the negative regulator of pro-proliferative genes Hbp1 as a bonafide GID/CTLH proteolytic substrate. Indeed, Hbp1 accumulates in cells lacking GID/CTLH activity, and Hbp1 physically interacts and is ubiquitinated in vitro by reconstituted GID/CTLH complexes. Our biochemical and cellular analysis thus demonstrates that the GID/CTLH complex prevents cell cycle exit in G1, at least in part by degrading Hbp1.


Assuntos
Proliferação de Células , Proteínas de Grupo de Alta Mobilidade/metabolismo , Proteínas Repressoras/metabolismo , Fatores de Transcrição/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Animais , Linhagem Celular , Células Cultivadas , Fase G1 , Regulação da Expressão Gênica , Células HEK293 , Células HeLa , Proteínas de Grupo de Alta Mobilidade/genética , Humanos , Camundongos Endogâmicos C57BL , Proteínas Repressoras/genética , Fatores de Transcrição/genética , Enzimas de Conjugação de Ubiquitina/genética , Enzimas de Conjugação de Ubiquitina/metabolismo , Ubiquitina-Proteína Ligases/genética
15.
Tree Physiol ; 38(8): 1237-1245, 2018 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-29788327

RESUMO

Reconstructions of defoliation by larch bud moth (LBM, Zeiraphera diniana Gn.) based on European larch (Larix decidua Mill.) tree rings have unraveled outbreak patterns over exceptional temporal and spatial scales. In this study, we conducted tree-ring analyses on 105 increment cores of European larch from the Valais Alps, Switzerland. The well-documented history of LBM outbreaks in Valais provided a solid baseline for evaluating the LBM defoliation signal in multiple tree-ring parameters. First, we used tree-ring width measurements along with regional records of LBM outbreaks to reconstruct the occurrence of these events at two sites within the Swiss Alps. Second, we measured earlywood width, latewood width and blue intensity, and compared these parameters with tree-ring width to assess the capacity of each proxy to detect LBM defoliation. A total of six LBM outbreaks were reconstructed for the two sites between AD 1850 and 2000. Growth suppression induced by LBM was, on average, highest in latewood width (59%), followed by total ring width (54%), earlywood width (51%) and blue intensity (26%). We show that latewood width and blue intensity can improve the temporal accuracy of LBM outbreak reconstructions, as both proxies systematically detected LBM defoliation in the first year it occurred, as well as the differentiation between defoliation and non-defoliation years. This study introduces blue intensity as a promising new proxy of insect defoliation and encourages its use in conjunction with latewood width.


Assuntos
Cadeia Alimentar , Larix/crescimento & desenvolvimento , Mariposas/fisiologia , Madeira/crescimento & desenvolvimento , Animais , Comportamento Alimentar , Larix/química , Larva/crescimento & desenvolvimento , Larva/fisiologia , Mariposas/crescimento & desenvolvimento , Suíça , Árvores/química , Árvores/crescimento & desenvolvimento , Madeira/química
16.
Sci Total Environ ; 635: 294-307, 2018 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-29674258

RESUMO

Instream large wood (LW) is widely perceived as a source of hazard that should be avoided. This is also the case of Spain, where wood has been systematically removed from rivers for decades. Consequently, people are accustomed to rivers with minimal or no LW at all. However, the presence and transport of wood is natural and has positive ecological effects. Previous studies reported that the general negative perception towards LW in rivers is related to the lack of background knowledge about stream ecology or fluvial dynamics. However, we hypothesize here that recent flooding experience has an influence on the perception of LW as well. To test this hypothesis, we surveyed groups of individuals living in different areas of Spain that have been affected more or less frequently by floods. In addition, we surveyed a group of scientists to test whether their perception towards LW differs from that of the general public. We observe that flooding experience is not the main controlling factor of how LW is perceived. Instead, we observe that respondents, independently of the time passed since the last flood, perceived watercourses with LW as less aesthetically, more dangerous, and with a larger need to improve channels than in watercourses without LW. Regional differences were detected, potentially related to differences in environmental attitudes. We confirm the existence of a gap in perception between scientific communities and the general public regarding natural river systems with wood; thereby highlighting the need to transfer knowledge, training, and education to bridge this gap. The generalized negative perception towards LW could have important consequences on the implementation of river management measures, such as LW augmentation for restoration purposes. This study underlines that wood removal should be more balanced in post-flood works and that public information is needed to implement a balanced LW management policy.

17.
Clim Change ; 147(3): 369-381, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-31258223

RESUMO

The Eldgjá lava flood is considered Iceland's largest volcanic eruption of the Common Era. While it is well established that it occurred after the Settlement of Iceland (circa 874 CE), the date of this great event has remained uncertain. This has hampered investigation of the eruption's impacts, if any, on climate and society. Here, we use high-temporal resolution glaciochemical records from Greenland to show that the eruption began in spring 939 CE and continued, at least episodically, until at least autumn 940 CE. Contemporary chronicles identify the spread of a remarkable haze in 939 CE, and tree ring-based reconstructions reveal pronounced northern hemisphere summer cooling in 940 CE, consistent with the eruption's high yield of sulphur to the atmosphere. Consecutive severe winters and privations may also be associated with climatic effects of the volcanic aerosol veil. Iceland's formal conversion to Christianity dates to 999/1000 CE, within two generations or so of the Eldgjá eruption. The end of the pagan pantheon is foretold in Iceland's renowned medieval poem, VÇ«luspá ('the prophecy of the seeress'). Several lines of the poem describe dramatic eruptive activity and attendant meteorological effects in an allusion to the fiery terminus of the pagan gods. We suggest that they draw on first-hand experiences of the Eldgjá eruption and that this retrospection of harrowing volcanic events in the poem was intentional, with the purpose of stimulating Iceland's Christianisation over the latter half of the tenth century.

18.
Nat Commun ; 8(1): 2222, 2017 12 20.
Artigo em Inglês | MEDLINE | ID: mdl-29263398

RESUMO

The North Atlantic Oscillation (NAO) depicts annual and decadal oscillatory modes of variability responsible for dry spells over the European continent. The NAO therefore holds a great potential to evaluate the role, as carbon sinks, of water-limited forests under climate change. However, uncertainties related to inconsistent responses of long-term forest productivity to NAO have so far hampered firm conclusions on its impacts. We hypothesize that, in part, such inconsistencies might have their origin in periodical sea surface temperature anomalies in the Atlantic Ocean (i.e., Atlantic Multidecadal Oscillation, AMO). Here we show strong empirical evidence in support of this hypothesis using 120 years of periodical inventory data from Iberian pine forests. Our results point to AMO+ NAO+ and AMO-NAO- phases as being critical for forest productivity, likely due to decreased winter water balance and abnormally low winter temperatures, respectively. Our findings could be essential for the evaluation of ecosystem functioning vulnerabilities associated with increased climatic anomalies under unprecedented warming conditions in the Mediterranean.

19.
Nat Commun ; 8(1): 480, 2017 09 07.
Artigo em Inglês | MEDLINE | ID: mdl-28883393

RESUMO

Nonalcoholic fatty liver disease is one of the most prevalent metabolic disorders and it tightly associates with obesity, type 2 diabetes, and cardiovascular disease. Reduced mitochondrial lipid oxidation contributes to hepatic fatty acid accumulation. Here, we show that the Fas cell surface death receptor (Fas/CD95/Apo-1) regulates hepatic mitochondrial metabolism. Hepatic Fas overexpression in chow-fed mice compromises fatty acid oxidation, mitochondrial respiration, and the abundance of mitochondrial respiratory complexes promoting hepatic lipid accumulation and insulin resistance. In line, hepatocyte-specific ablation of Fas improves mitochondrial function and ameliorates high-fat-diet-induced hepatic steatosis, glucose tolerance, and insulin resistance. Mechanistically, Fas impairs fatty acid oxidation via the BH3 interacting-domain death agonist (BID). Mice with genetic or pharmacological inhibition of BID are protected from Fas-mediated impairment of mitochondrial oxidation and hepatic steatosis. We suggest Fas as a potential novel therapeutic target to treat obesity-associated fatty liver and insulin resistance.Hepatic steatosis is a common disease closely associated with metabolic syndrome and insulin resistance. Here Item et al. show that Fas, a member of the TNF receptor superfamily, contributes to mitochondrial dysfunction, steatosis development, and insulin resistance under high fat diet.


Assuntos
Metabolismo dos Lipídeos/fisiologia , Fígado/metabolismo , Mitocôndrias Hepáticas/metabolismo , Receptor fas/metabolismo , Animais , Dieta Hiperlipídica , Proteína Ligante Fas/genética , Proteína Ligante Fas/metabolismo , Ácidos Graxos/metabolismo , Resistência à Insulina , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Obesos , Camundongos Transgênicos , Hepatopatia Gordurosa não Alcoólica/etiologia , Hepatopatia Gordurosa não Alcoólica/genética , Triglicerídeos/metabolismo , Receptor fas/genética
20.
Mol Metab ; 6(9): 1010-1023, 2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-28951825

RESUMO

BACKGROUND: MicroRNAs have emerged as important regulatory non-coding RNAs that tune cellular responses to physiological perturbations and disease conditions. An increasing body of literature underlines the important roles of miRNA function in pancreatic ß-cells in response to metabolic, genetic and inflammatory stress. Lessons from genetic loss- and gain-of-function studies have implicated several highly expressed and evolutionary conserved miRNAs in stress signal modulation, resolution and buffering, thereby forming stabilizing miRNA networks that preserve ß-cell differentiation, function, proliferation and cell survival. SCOPE OF REVIEW: This review will summarize our current knowledge of how biologically relevant miRNAs regulate stress responses in pancreatic ß-cells, discuss the challenges and opportunities associated with using secreted miRNAs as biomarkers and forecast how mechanistic knowledge of miRNA function can be exploited in developing miRNA-based therapeutics. MAJOR CONCLUSIONS: miRNAs play important roles in the function, differentiation, proliferation, and survival of pancreatic ß-cells. Many miRNA families that are regulated by metabolic, genetic, and inflammatory stressors have been found to coordinate the adaptive responses of ß-cells in vivo in conditions such as obesity and diabetes.


Assuntos
Diabetes Mellitus/genética , Células Secretoras de Insulina/metabolismo , MicroRNAs/fisiologia , Animais , Biomarcadores/metabolismo , Diferenciação Celular/genética , Proliferação de Células/genética , Humanos , Secreção de Insulina/genética , Células Secretoras de Insulina/fisiologia , MicroRNAs/genética , Obesidade/metabolismo , Estresse Fisiológico/genética
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