Dissolved organic matter fluctuations in an intermittent headwater stream: from storm oscillations to decadal hydrological changes = Fluctuacions de la matèria orgànica dissolta en un riu de capçalera intermitent : de crescudes a canvis hidrològics decennals

[eng] Dissolved organic matter (DOM) is an important source of carbon for aquatic microorganisms and it regulates many biogeochemical processes. Therefore, changes in river DOM concentration and properties could notably affect the functioning of fluvial and coastal ecosystems and alter the global carbon cycle. The DOM in headwater streams is strongly influenced by hydrology, as a consequence of the modification of catchment flow paths with high discharges. During storm events, the catchment hillsides are washed and terrigenous DOM is transported to rivers. In the Mediterranean region, the precipitation regime and evapotranspiration strongly modulate fluvial hydrology, which shows low discharges in summer and even flow disappearance. These dry–wet cycles of conditions affect many ecological and biogeochemical processes. In this thesis, I analyse a long time series of discharge and DOM data from Fuirosos, an intermittent headwater stream in NE Spain. My aim is to examine the relationship between DOM and hydrology at different temporal scales. First, I characterise the hydrological regime of this Mediterranean stream. A decrease in discharge was revealed, although trends in temperature and precipitation were not significant. In contrast, I did not find a clear temporal trend in dry period duration. However, rewetting has been significantly delayed, moving from September to October. The frequency of storm events decreased over the interval 1998–2015, showing a significant positive relationship with solar activity with a 2-year lag. Dissolved organic carbon (DOC) concentration saw a slight decrease during the study period, which was opposed to that observed in boreal systems. This pattern might respond to a reduction of terrigenous DOC input from forest hillsides as a consequence of the decrease in flushing episodes. The DOC temporal dynamics during the rewetting was regulated by dry period duration. Discharge oscillations explained up to 50% of total DOC variability during the wet period. Notably, this weight of discharge increased significantly over the years. DOM quality was also explored, and described in terms of absorbance and fluorescence properties. Most of the DOM properties were strongly related to discharge, revealing the input of allochthonous, degraded, aromatic, humic and large-molecular DOM under high flow conditions. However, these relationships were altered during drying and rewetting periods. The DOM responses at the individual storm event scale were highly heterogeneous. Multiple linear regression and commonality analyses showed that, in addition to the magnitude of storm episodes, antecedent hydrological conditions, namely pre-event basal flow and the magnitude of the previous storm event, played a significant role in regulating the trends and shapes of DOM–discharge hysteresis. Finally, I identified the differences and similarities in the DOM–discharge relationships between the intermittent Mediterranean stream analysed herein and a perennial Alpine stream with higher mean discharge (Oberer Seebach). The DOM in Fuirosos was significantly more concentrated, more terrigenous, more degraded, more aromatic and more humified. The sign of the global DOM–discharge response was the same in both streams. However, discharge was a more robust predictor of DOM variability in Oberer Seebach. In fact, low flow and rewetting periods in Fuirosos introduced considerable dispersion into the relationship. During snowmelt in Oberer Seebach the sensitivity to discharge also decreased or disappeared. The flushing/dilution patterns were essentially associated with the magnitude of storm events in Fuirosos. In contrast, the DOM quality change was more coupled to basal flow conditions in Oberer Seebach, while the storms were behind the DOC oscillations. This study attests to the importance of generating and analysing long-term and high-frequency biogeochemical series, which allow relationships between DOM and hydrology to be explored in intermittent headwater streams that are subjected to extreme hydrological regimes.[cat] La matèria orgànica dissolta (MOD) és una important font de carboni per als microorganismes aquàtics i regula molts processos biogeoquímics. La MOD en els rius de capçalera està modelada principalment per la hidrologia. A la regió mediterrània, el règim de precipitació i evapotranspiració impacta fortament la hidrologia fluvial, que mostra cabals baixos a l’estiu i pot arribar fins i tot a la seva desaparició. En aquesta tesi hem analitzat un sèrie temporal a llarg termini de cabal i MOD a Fuirosos, un riu de capçalera intermitent al NE de la Península Ibèrica. El nostre objectiu era examinar la relació entre la MOD i la hidrologia en diferents escales temporals. Primer, vam caracteritzar el règim hidrològic d’aquest riu mediterrani. Al llarg de l’estudi es va revelar una disminució del cabal, no vam trobar una tendència temporal clara en la durada de la sequera i la freqüència de les crescudes va disminuir en l’interval 1998–2015. La concentració de carboni orgànic dissolt (COD) ha patit una lleugera disminució durant el període d’estudi, cosa que contrasta amb el que s’ha observat en sistemes boreals. La dinàmica temporal del COD durant el període de transició va ser regulada per la durada del període sec. La qualitat de la MOD també va ser explorada, i descrita en termes de propietats d’absorbència i fluorescència. La majoria de les propietats de la MOD van ser clarament relacionades amb el cabal. No obstant, aquestes relacions van ser alterades durant els períodes de fragmentació i de transició. A més de la magnitud dels episodis de crescuda, les condicions hidrològiques prèvies juguen un paper significatiu perquè regulen les tendències i formes de les histèresis MOD–cabal. Per acabar, vaig identificar les diferències i semblances en les relacions MOD–cabal entre el riu mediterrani intermitent analitzat i un riu perenne alpí amb un cabal mitjà superior (Oberer Seebach). Aquest estudi testifica la importància de generar i analitzar sèries biogeoquímiques de llarga durada i alta freqüència, que permeten explorar les relacions entre la MOD i la hidrologia en rius de capçalera intermitents que estan subjectes a règims hidrològics extrems

Gestió forestal de masses d'arboç (Arbutus unedo) en regeneració després de foc al terme municipal d'Esparreguera

Els incendis forestals són una pertorbació amb un paper decisiu en l'estructura i dinàmica dels ecosistemes mediterranis. La majoria de les seves espècies vegetals presenten mecanismes de resposta al foc, com la germinació de llavors i la rebrotada d'individus cremats. Les masses forestals regenerades a partir de rebrots assoleixen densitats massa altes i una baixa producció, i, per tant, és fonamental dur a terme una gestió mitjançant tractaments silvícoles. El principal objectiu d'aquest projecte és quantificar l'efecte de la selecció de rebrots i la selecció de rebrots més la desbrossada sobre el creixement de l'Arbutus unedo. S'han estudiat 12 parcelles en regeneració després dels incendis de 1985, 1986 i 1994 al terme municipal d'Esparreguera. Els resultats mostren que els dos tractaments afavoreixen de la mateixa manera el creixement dels peus d'Arbutus unedo, a causa de la disminució de la competència intraespecífica i interespecífica. La desbrossada (a nivell de parcella, no d'individu), no obstant, provoca un increment probablement perjudicial de l'alçada dels rebrots, per la major disponibilitat de llum. Per tal de proposar un model de gestió forestal, s'ha realitzat una anàlisi multicriterial dels diferents escenaris, on s'han considerat altres criteris, com són el model de combustible, la possibilitat de pastura i el cost econòmic. L'alternativa preferida en els boscos d'Arbutus unedo és la selecció de rebrots i la desbrossada.Los incendios forestales son una perturbación con un papel decisivo en la estructura y dinámica de los ecosistemas mediterráneos. La mayoría de sus especies vegetales presentan mecanismos de respuesta al fuego, como la germinación de semillas y el rebrote de individuos quemados. Las masas forestales regeneradas a partir de rebrotes alcanzan densidades demasiado elevadas y una baja producción, y por lo tanto es fundamental llevar a cabo una gestión mediante tratamientos silvícolas. El principal objectivo de este proyecto es cuantificar el efecto de la selección de rebrotes y la selección de rebrotes más el desbrozado sobre el crecimiento del Arbutus unedo. Se han estudiado 12 parcelas en regeneración después de los incendios de 1985, 1986 y 1994 en el término municipal de Esparreguera. Los resultados muestran que los dos tratamientos favorecen de la misma manera el crecimiento de los pies de Arbutus unedo, a causa de la disminución de la competencia intraespecífica i interespecífica. Sin embargo, el desbroce (a nivel de parcela, no de individuo) provoca un incremento probablemente perjudicial de la altura de los rebrotes, por la mayor disponibilidad de luz. Para proponer un modelo de gestión forestal, se ha realizado un anàlisis multicriterial de los diferentes escenarios, donde se han considerado otros criterios, como son el modelo de combustible, la posibilidad de pasto y el coste económico. La alternativa preferida en los bosques de Arbutus unedo es la selección de rebrotes y el desbrozado.Wildfires are a perturbation with a decisive role in the structure and dynamics of Mediterranean ecosystems. Most Mediterranean plant species have fire response mechanisms like seed germination and resprouting from burned stools. Forests regenerated by resprouts get too high density and low production, and so it is essential to carry out a management through forestry treatments. The main objective of this project is to quantify the effect of selection of resprouts and selection of resprouts plus elimination of shrub layer on Arbutus unedo growth. We have studied 12 plots in regeneration after the 1985, 1986 and 1994 wildfires in Esparreguera. Results showed that both treatments favour equally the growth of Arbutus unedo stems, due to the diminution of intraespecific and interespecific competition. However, elimination of understory at plot level promote a likely damaging increase of new resprouts height because of the greater light availability. In order to propose a forestry management model, we have realized a multi-criteria analysis of different scenarios, incorporating other criteria like combustible model, grazing possibility and economic cost. The most preferred alternative in Arbutus unedo forests is the selection of resprouts and elimination of shrub layer

Quality and reactivity of dissolved organic matter in a Mediterranean river across hydrological and spatial gradients.

Understanding DOM transport and reactivity in rivers is essential to having a complete picture of the global carbon cycle. In this study, we explore the effects of hydrological variability and downstream transport on dissolved organic matter (DOM) dynamics in a Mediterranean river. We sampled the main stem of the river Tordera from the source to the sea, over a range of fifteen hydrological conditions including extreme events (flood and drought). By exploring spatial and temporal gradients of DOM fluorescence properties, river hydrology was found to be a significant predictor of DOM spatial heterogeneity. An additional space-resolved mass balance analysis performed on four contrasting hydrological conditions revealed that this was due to a shift in the biogeochemical function of the river. Flood conditions caused a conservative transport of DOM, generating a homogeneous, humic-like spatial profile of DOM quality. Lower flows induced a non-conservative, reactive transport of DOM, which enhanced the spatial heterogeneity of DOM properties. Moreover, the downstream evolution of DOM chemostatic behaviour revealed that the role of hydrology in regulating DOM properties increased gradually downstream, indicating an organised inter-dependency between the spatial and the temporal dimensions. Overall, our findings reveal that riverine DOM dynamics is in constant change owing to varying hydrological conditions, and emphasize that in order to fully understand the role of rivers in the global carbon cycle, it is necessary to take into account the full range of hydrological variability, from floods to droughts

Mitochondrial physiology

As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery

Gestió forestal de masses d'arboç (Arbutus unedo) en regeneració després de foc al terme municipal d'Esparreguera

Els incendis forestals són una pertorbació amb un paper decisiu en l’estructura i dinàmica dels ecosistemes mediterranis. La majoria de les seves espècies vegetals presenten mecanismes de resposta al foc, com la germinació de llavors i la rebrotada d’individus cremats. Les masses forestals regenerades a partir de rebrots assoleixen densitats massa altes i una baixa producció, i, per tant, és fonamental dur a terme una gestió mitjançant tractaments silvícoles. El principal objectiu d’aquest projecte és quantificar l’efecte de la selecció de rebrots i la selecció de rebrots més la desbrossada sobre el creixement de l’Arbutus unedo. S’han estudiat 12 parcelles en regeneració després dels incendis de 1985, 1986 i 1994 al terme municipal d’Esparreguera. Els resultats mostren que els dos tractaments afavoreixen de la mateixa manera el creixement dels peus d’Arbutus unedo, a causa de la disminució de la competència intraespecífica i interespecífica. La desbrossada (a nivell de parcella, no d’individu), no obstant, provoca un increment probablement perjudicial de l’alçada dels rebrots, per la major disponibilitat de llum. Per tal de proposar un model de gestió forestal, s’ha realitzat una anàlisi multicriterial dels diferents escenaris, on s’han considerat altres criteris, com són el model de combustible, la possibilitat de pastura i el cost econòmic. L’alternativa preferida en els boscos d’Arbutus unedo és la selecció de rebrots i la desbrossada.Los incendios forestales son una perturbación con un papel decisivo en la estructura y dinámica de los ecosistemas mediterráneos. La mayoría de sus especies vegetales presentan mecanismos de respuesta al fuego, como la germinación de semillas y el rebrote de individuos quemados. Las masas forestales regeneradas a partir de rebrotes alcanzan densidades demasiado elevadas y una baja producción, y por lo tanto es fundamental llevar a cabo una gestión mediante tratamientos silvícolas. El principal objectivo de este proyecto es cuantificar el efecto de la selección de rebrotes y la selección de rebrotes más el desbrozado sobre el crecimiento del Arbutus unedo. Se han estudiado 12 parcelas en regeneración después de los incendios de 1985, 1986 y 1994 en el término municipal de Esparreguera. Los resultados muestran que los dos tratamientos favorecen de la misma manera el crecimiento de los pies de Arbutus unedo, a causa de la disminución de la competencia intraespecífica i interespecífica. Sin embargo, el desbroce (a nivel de parcela, no de individuo) provoca un incremento probablemente perjudicial de la altura de los rebrotes, por la mayor disponibilidad de luz. Para proponer un modelo de gestión forestal, se ha realizado un anàlisis multicriterial de los diferentes escenarios, donde se han considerado otros criterios, como son el modelo de combustible, la posibilidad de pasto y el coste económico. La alternativa preferida en los bosques de Arbutus unedo es la selección de rebrotes y el desbrozado.Wildfires are a perturbation with a decisive role in the structure and dynamics of Mediterranean ecosystems. Most Mediterranean plant species have fire response mechanisms like seed germination and resprouting from burned stools. Forests regenerated by resprouts get too high density and low production, and so it is essential to carry out a management through forestry treatments. The main objective of this project is to quantify the effect of selection of resprouts and selection of resprouts plus elimination of shrub layer on Arbutus unedo growth. We have studied 12 plots in regeneration after the 1985, 1986 and 1994 wildfires in Esparreguera. Results showed that both treatments favour equally the growth of Arbutus unedo stems, due to the diminution of intraespecific and interespecific competition. However, elimination of understory at plot level promote a likely damaging increase of new resprouts height because of the greater light availability. In order to propose a forestry management model, we have realized a multi-criteria analysis of different scenarios, incorporating other criteria like combustible model, grazing possibility and economic cost. The most preferred alternative in Arbutus unedo forests is the selection of resprouts and elimination of shrub layer

Variation at FCGR2A and Functionally Related Genes Is Associated with the Response to Anti-TNF Therapy in Rheumatoid Arthritis

OBJECTIVE: Anti-TNF therapies have been highly efficacious in the management of rheumatoid arthritis (RA), but 25-30% of patients do not show a significant clinical response. There is increasing evidence that genetic variation at the Fc receptor FCGR2A is associated with the response to anti-TNF therapy. We aimed to validate this genetic association in a patient cohort from the Spanish population, and also to identify new genes functionally related to FCGR2A that are also associated with anti-TNF response. METHODS: A total of 348 RA patients treated with an anti-TNF therapy were included and genotyped for FCGR2A polymorphism rs1081274. Response to therapy was determined at 12 weeks, and was tested for association globally and independently for each anti-TNF drug (infliximab, etanercept and adalimumab). Using gene expression profiles from macrophages obtained from synovial fluid of RA patients, we searched for genes highly correlated with FCGR2A expression. Tag SNPs were selected from each candidate gene and tested for association with the response to therapy. RESULTS: We found a significant association between FCGR2A and the response to adalimumab (P=0.022). Analyzing the subset of anti-CCP positive RA patients (78%), we also found a significant association between FCGR2A and the response to infliximab (P=0.035). DHX32 and RGS12 were the most consistently correlated genes with FCGR2A expression in RA synovial fluid macrophages (P<0.001). We found a significant association between the genetic variation at DHX32 (rs12356233, corrected P=0.019) and a nominally significant association between RGS12 and the response to adalimumab (rs4690093, uncorrected P=0.040). In the anti-CCP positive group of patients, we also found a nominally significant association between RGS12 and the response to infliximab (rs2857859, uncorrected P=0.042). CONCLUSIONS: In the present study we have validated the FCGR2A association in an independent population, and we have identified new genes associated with the response to anti-TNF therapy in RA

Switching TNF antagonists in patients with chronic arthritis: An observational study of 488 patients over a four-year period

The objective of this work is to analyze the survival of infliximab, etanercept and adalimumab in patients who have switched among tumor necrosis factor (TNF) antagonists for the treatment of chronic arthritis. BIOBADASER is a national registry of patients with different forms of chronic arthritis who are treated with biologics. Using this registry, we have analyzed patient switching of TNF antagonists. The cumulative discontinuation rate was calculated using the actuarial method. The log-rank test was used to compare survival curves, and Cox regression models were used to assess independent factors associated with discontinuing medication. Between February 2000 and September 2004, 4,706 patients were registered in BIOBADASER, of whom 68% had rheumatoid arthritis, 11% ankylosing spondylitis, 10% psoriatic arthritis, and 11% other forms of chronic arthritis. One- and two-year drug survival rates of the TNF antagonist were 0.83 and 0.75, respectively. There were 488 patients treated with more than one TNF antagonist. In this situation, survival of the second TNF antagonist decreased to 0.68 and 0.60 at 1 and 2 years, respectively. Survival was better in patients replacing the first TNF antagonist because of adverse events (hazard ratio (HR) for discontinuation 0.55 (95% confidence interval (CI), 0.34-0.84)), and worse in patients older than 60 years (HR 1.10 (95% CI 0.97-2.49)) or who were treated with infliximab (HR 3.22 (95% CI 2.13-4.87)). In summary, in patients who require continuous therapy and have failed to respond to a TNF antagonist, replacement with a different TNF antagonist may be of use under certain situations. This issue will deserve continuous reassessment with the arrival of new medications. © 2006 Gomez-Reino and Loreto Carmona; licensee BioMed Central Ltd