Low growth resilience to drought is related to future mortality risk in trees

Severe droughts have the potential to reduce forest productivity and trigger tree mortality. Most trees face several drought events during their life and therefore resilience to dry conditions may be crucial to long-term survival. We assessed how growth resilience to severe droughts, including its components resistance and recovery, is related to the ability to survive future droughts by using a tree-ring database of surviving and now-dead trees from 118 sites (22 species, >3,500 trees). We found that, across the variety of regions and species sampled, trees that died during water shortages were less resilient to previous non-lethal droughts, relative to coexisting surviving trees of the same species. In angiosperms, drought-related mortality risk is associated with lower resistance (low capacity to reduce impact of the initial drought), while it is related to reduced recovery (low capacity to attain pre-drought growth rates) in gymnosperms. The different resilience strategies in these two taxonomic groups open new avenues to improve our understanding and prediction of drought-induced mortality.Fil: DeSoto, Lucía. Consejo Superior de Investigaciones Científicas; España. Universidad de Coimbra; PortugalFil: Cailleret, Maxime. Eidgenössische Technische Hochschule Züric; Suiza. Université Aix-marseille; Francia. Swiss Federal Institute for Forest, Snow and Landscape Research; SuizaFil: Sterck, Frank. University of Agriculture Wageningen; Países BajosFil: Jansen, Steven. Universitat Ulm; AlemaniaFil: Kramer, Koen. University of Agriculture Wageningen; Países Bajos. Land Life Company; Países BajosFil: Robert, Elisabeth M. R.. Creaf; España. Vrije Unviversiteit Brussel; Bélgica. Royal Museum for Central Africa; BélgicaFil: Aakala, Tuomas. University of Helsinki; FinlandiaFil: Amoroso, Mariano Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural. - Universidad Nacional de Rio Negro. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural; ArgentinaFil: Bigler, Christof. Eidgenössische Technische Hochschule Züric; SuizaFil: Camarero, J. Julio. Consejo Superior de Investigaciones Científicas; EspañaFil: Čufar, Katarina. University 0f Ljubljana; EsloveniaFil: Gea Izquierdo, Guillermo. Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria; EspañaFil: Gillner, Sten. Technische Universität Dresden; AlemaniaFil: Haavik, Laurel J.. Servicio Forestal de los Estados Unidos; Estados UnidosFil: Hereş, Ana Maria. Basque Centre For Climate Change; España. Transilvania University of Brasov; RumaniaFil: Kane, Jeffrey M.. Humboldt State University; Estados UnidosFil: Kharuk, Vyacheslav I.. Siberian Federal University; Rusia. Siberian Division of the Russian Academy of Sciences; RusiaFil: Kitzberger, Thomas. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Klein, Tamir. Weizmann Institute of Science; IsraelFil: Levanič, Tom. Slovenian Forestry Institute; EsloveniaFil: Linares, Juan C.. Universidad Pablo de Olavide; EspañaFil: Mäkinen, Harri. Natural Resources Institute Finland; FinlandiaFil: Oberhuber, Walter. Universidad de Innsbruck; AustriaFil: Papadopoulos, Andreas. Geoponiko Panepistimion Athinon; GreciaFil: Rohner, Brigitte. Eidgenössische Technische Hochschule Zürich; Suiza. Swiss Federal Institute for Forest, Snow and Landscape Research; SuizaFil: Sangüesa Barreda, Gabriel. Universidad de Valladolid; EspañaFil: Stojanovic, Dejan B.. University of Novi Sad; SerbiaFil: Suarez, Maria Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche; ArgentinaFil: Villalba, Ricardo. 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: Martínez Vilalta, Jordi. Universitat Autònoma de Barcelona; España. Creaf; Españ

Altered mitochondrial function and oxidative stress in leukocytes of anorexia nervosa patients.

CONTEXT: Anorexia nervosa is a common illness among adolescents and is characterised by oxidative stress. OBJECTIVE: The effects of anorexia on mitochondrial function and redox state in leukocytes from anorexic subjects were evaluated. DESIGN AND SETTING: A multi-centre, cross-sectional case-control study was performed. PATIENTS: Our study population consisted of 20 anorexic patients and 20 age-matched controls, all of which were Caucasian women. MAIN OUTCOME MEASURES: Anthropometric and metabolic parameters were evaluated in the study population. To assess whether anorexia nervosa affects mitochondrial function and redox state in leukocytes of anorexic patients, we measured mitochondrial oxygen consumption, membrane potential, reactive oxygen species production, glutathione levels, mitochondrial mass, and complex I and III activity in polymorphonuclear cells. RESULTS: Mitochondrial function was impaired in the leukocytes of the anorexic patients. This was evident in a decrease in mitochondrial O2 consumption (P<0.05), mitochondrial membrane potential (P<0.01) and GSH levels (P<0.05), and an increase in ROS production (P<0.05) with respect to control subjects. Furthermore, a reduction of mitochondrial mass was detected in leukocytes of the anorexic patients (P<0.05), while the activity of mitochondrial complex I (P<0.001), but not that of complex III, was found to be inhibited in the same population. CONCLUSIONS: Oxidative stress is produced in the leukocytes of anorexic patients and is closely related to mitochondrial dysfunction. Our results lead us to propose that the oxidative stress that occurs in anorexia takes place at mitochondrial complex I. Future research concerning mitochondrial dysfunction and oxidative stress should aim to determine the physiological mechanism involved in this effect and the physiological impact of anorexia

Endocrine parameters in anorexia nervosa (AN) patients and healthy control subjects.

<p>Data are expressed as mean ± SD, except for triglycerides, which are represented as medians and IQ range. Values of serum triglyceride concentrations were normalized using a log transformation. Comparison between anorexic patients and controls using an unpaired Student’s t-test. n = 20.</p><p>Endocrine parameters in anorexia nervosa (AN) patients and healthy control subjects.</p

Effect of anorexia on O₂ consumption (A) rate, measured as nmol O₂/min/million cells, on membrane potential (B), measured by TMRM fluorescence, and on mitochondrial mass (C), measured by NAO fluorescence. n = 20 per group.

<p>*P<0.05 and **P<0.01 <i>vs.</i> control.</p

Effect of anorexia on mitochondrial complex I activity (A), measured as the NADH oxidation rate at 340 nm, and on complex III activity (B), measured as the cytochrome C reduction rate at 550 nm.

<p>Specific inhibitors for complexes I and III, rotenone and antimycin A, respectively, were employed to ensure the specificity of the assay. n = 8 per group. ***P<0.001 <i>vs.</i> control.</p

Effect of anorexia on ROS production (A), measured by DCFH fluorescence, and on GSH content (B), measured by CMFDA fluorescence.

<p>n = 20 per group. *P<0.05 <i>vs.</i> controls.</p

A synthesis of radial growth patterns preceding tree mortality

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A synthesis of radial growth patterns preceding tree mortality

Altres ajuts: this study generated from the COST Action STReESS (FP1106) financially supported by the EU Framework Programme for Research and Innovation HORIZON 2020. And the EU Project FEDER 0087 TRANSHABITAT and LIFE12 ENV/FI/000409Tree mortality is a key factor influencing forest functions and dynamics, but our understanding of the mechanisms leading to mortality and the associated changes in tree growth rates are still limited. We compiled a new pan-continental tree-ring width database from sites where both dead and living trees were sampled (2970 dead and 4224 living trees from 190 sites, including 36 species), and compared early and recent growth rates between trees that died and those that survived a given mortality event. We observed a decrease in radial growth before death in ca. 84% of the mortality events. The extent and duration of these reductions were highly variable (1-100 years in 96% of events) due to the complex interactions among study species and the source(s) of mortality. Strong and long-lasting declines were found for gymnosperms, shade- and drought-tolerant species, and trees that died from competition. Angiosperms and trees that died due to biotic attacks (especially bark-beetles) typically showed relatively small and short-term growth reductions. Our analysis did not highlight any universal trade-off between early growth and tree longevity within a species, although this result may also reflect high variability in sampling design among sites. The intersite and interspecific variability in growth patterns before mortality provides valuable information on the nature of the mortality process, which is consistent with our understanding of the physiological mechanisms leading to mortality. Abrupt changes in growth immediately before death can be associated with generalized hydraulic failure and/or bark-beetle attack, while long-term decrease in growth may be associated with a gradual decline in hydraulic performance coupled with depletion in carbon reserves. Our results imply that growth-based mortality algorithms may be a powerful tool for predicting gymnosperm mortality induced by chronic stress, but not necessarily so for angiosperms and in case of intense drought or bark-beetle outbreaks