Los estudios en el laboratorio han permitido identificar cambios del metabolismo de halógenos en suero y líquido cefalorraquídeo (LCR) de pacientes con enfermedad de Parkinson, que indican la ...presencia de «autohalogenación acelerada» del LCR de los pacientes o aumento de haloperoxidasas, en concreto, tiroperoxidasa en sangre y lactoperoxidasa en LCR. Además, se ha detectado un exceso en suero y LCR de algunos derivados halogenados, como proteínas con halogenación avanzada tipo advanced oxidation protein products (AOPP). Estos hechos, «autohalogenación acelerada» e incremento de haloperoxidasas y proteínas AOPP, indican la presencia de estrés halogenativo en la enfermedad de Parkinson. Además, un derivado halogenado, la 3-yodo-L-tirosina, muestra toxicidad parkinsoniana en modelos experimentales, pues se ha observado que induce agregados de α-sinucleína y daño de las neuronas de dopamina en cerebro e intestino en ratones. La hipótesis que se maneja es que en la enfermedad de Parkinson existe un exceso halogenativo, relacionado con una alteración haloenzimática de síntesis o degradación de oxiácidos de halógenos y sus derivados halogenados. Este estrés halogenativo se relacionaría con el daño del sistema nervioso.
Laboratory studies identified changes in the metabolism of halogens in the serum and cerebrospinal fluid (CSF) of patients with Parkinson's disease, which indicates the presence of «accelerated self-halogenation» of CSF and/or an increase in haloperoxidases, specifically serum thyroperoxidase and CSF lactoperoxidase. Furthermore, an excess of some halogenated derivatives, such as advanced oxygenation protein products (AOPP), has been detected in the CSF and serum. «Accelerated self-halogenation» and increased levels of haloperoxidases and AOPP proteins indicate that halogenative stress is present in Parkinson's disease. In addition, 3-iodo-L-tyrosine, a halogenated derivative, shows «parkinsonian» toxicity in experimental models, since it has been observed to induce α-synuclein aggregation and damage to dopaminergic neurons in the mouse brain and intestine. The hypothesis is that patients with Parkinson's disease display halogenative stress related to a haloenzymatic alteration of the synthesis or degradation of oxyacid of halogens and their halogenated derivatives. This halogenative stress would be related to nervous system damage.
Why do forest productivity and biomass decline with elevation? To address this question, research to date generally has focused on correlative approaches describing changes in woody growth and ...biomass with elevation.
We present a novel, mechanistic approach to this question by quantifying the autotrophic carbon budget in 16 forest plots along a 3300m elevation transect in Peru.
Low growth rates at high elevations appear primarily driven by low gross primary productivity (GPP), with little shift in either carbon use efficiency (CUE) or allocation of net primary productivity (NPP) between wood, fine roots and canopy. The lack of trend in CUE implies that the proportion of photosynthate allocated to autotrophic respiration is not sensitive to temperature. Rather than a gradual linear decline in productivity, there is some limited but nonconclusive evidence of a sharp transition in NPP between submontane and montane forests, which may be caused by cloud immersion effects within the cloud forest zone. Leaf-level photosynthetic parameters do not decline with elevation, implying that nutrient limitation does not restrict photosynthesis at high elevations.
Our data demonstrate the potential of whole carbon budget perspectives to provide a deeper understanding of controls on ecosystem functioning and carbon cycling.
La enfermedad de Parkinson es un trastorno neurológico degenerativo que afecta a más de 7 millones de personas en todo el mundo. Se desconoce su etiología, aunque se acepta que existe una ...susceptibilidad genética a agentes ambientales. Estos agentes ambientales incluyen hongos, bacterias y virus. Tres microorganismos están directamente relacionados con un mayor riesgo estadístico de presentar enfermedad de Parkinson: el género de hongos Malassezia, la bacteria Helicobacter pylori y el virus de la hepatitis C. Estos microorganismos, si el huésped es vulnerable por susceptibilidad genética o debilidad inmunológica, pueden acceder al sistema nervioso, infectarlo y causar neuroinflamación crónica con neurodegeneración. Otros microorganismos se relacionan desde una vertiente epidemiológica con la enfermedad, destacando los virus influenza tipo A, de la encefalitis japonesa tipo B, de San Luis y del Nilo Occidental. Estos virus pueden afectar al sistema nervioso causando encefalitis, cuya consecuencia puede ser un parkinsonismo. En este artículo se hace una revisión de los mencionados agentes infecciosos y su papel en la enfermedad de Parkinson.
Parkinson's disease is a neurodegenerative disorder that affects more than 7 million people worldwide. Its aetiology is unknown, although the hypothesis of a genetic susceptibility to environmental agents is accepted. These environmental agents include fungi, bacteria, and viruses. Three microorganisms are directly associated with a significantly increased risk of developing Parkinson's disease: the fungal genus Malassezia, the bacterium Helicobacter pylori, and the hepatitis C virus. If the host is vulnerable due to genetic susceptibility or immune weakness, these microorganisms can access and infect the nervous system, causing chronic neuroinflammation with neurodegeneration. Other microorganisms show an epidemiological association with the disease, including the influenza type A, Japanese encephalitis type B, St Louis, and West Nile viruses. These viruses can affect the nervous system, causing encephalitis, which can result in parkinsonism. This article reviews the role of all these microorganisms in Parkinson's disease.
Parkinson's disease (PD) is a neurodegenerative disorder that affects more than 7 million people worldwide. Its aetiology is unknown, although the hypothesis of a genetic susceptibility to ...environmental agents is accepted. These environmental agents include fungi, bacteria, and viruses. Three microorganisms are directly associated with a significantly increased risk of developing Parkinson's disease: the fungal genus Malassezia, the bacterium Helicobacter pylori, and the hepatitis C virus. If the host is vulnerable due to genetic susceptibility or immune weakness, these microorganisms can access and infect the nervous system, causing chronic neuroinflammation with neurodegeneration. Other microorganisms show an epidemiological association with the disease, including the influenza type A, Japanese encephalitis type B, St Louis, and West Nile viruses. These viruses can affect the nervous system, causing encephalitis, which can result in parkinsonism. This article reviews the role of all these microorganisms in Parkinson's disease.
Laboratory studies identified changes in the metabolism of halogens in the serum and cerebrospinal fluid (CSF) of patients with Parkinson's disease, which indicates the presence of «accelerated ...self-halogenation» of CSF and/or an increase in haloperoxidases, specifically serum thyroperoxidase and CSF lactoperoxidase. Furthermore, an excess of some halogenated derivatives, such as advanced oxygenation protein products (AOPP), has been detected in the CSF and serum. «Accelerated self-halogenation» and increased levels of haloperoxidases and AOPP proteins indicate that halogenative stress is present in Parkinson's disease. In addition, 3-iodo-L-tyrosine, a halogenated derivative, shows «parkinsonian» toxicity in experimental models, since it has been observed to induce α-synuclein aggregation and damage to dopaminergic neurons in the mouse brain and intestine. The hypothesis is that patients with Parkinson's disease display halogenative stress related to a haloenzymatic alteration of the synthesis or degradation of oxyacid of halogens and their halogenated derivatives. This halogenative stress would be related to nervous system damage.
The net primary productivity, carbon (C) stocks and turnover rates (i.e. C dynamics) of tropical forests are an important aspect of the global C cycle. These variables have been investigated in ...lowland tropical forests, but they have rarely been studied in tropical montane forests (TMFs). This study examines spatial patterns of above‐ and belowground C dynamics along a transect ranging from lowland Amazonia to the high Andes in SE Peru. Fine root biomass values increased from 1.50 Mg C ha⁻¹ at 194 m to 4.95 ± 0.62 Mg C ha⁻¹ at 3020 m, reaching a maximum of 6.83 ± 1.13 Mg C ha⁻¹ at the 2020 m elevation site. Aboveground biomass values decreased from 123.50 Mg C ha⁻¹ at 194 m to 47.03 Mg C ha⁻¹ at 3020 m. Mean annual belowground productivity was highest in the most fertile lowland plots (7.40 ± 1.00 Mg C ha⁻¹ yr⁻¹) and ranged between 3.43 ± 0.73 and 1.48 ± 0.40 Mg C ha⁻¹ yr⁻¹ in the premontane and montane plots. Mean annual aboveground productivity was estimated to vary between 9.50 ± 1.08 Mg C ha⁻¹ yr⁻¹ (210 m) and 2.59 ± 0.40 Mg C ha⁻¹ yr⁻¹ (2020 m), with consistently lower values observed in the cloud immersion zone of the montane forest. Fine root C residence time increased from 0.31 years in lowland Amazonia to 3.78 ± 0.81 years at 3020 m and stem C residence time remained constant along the elevational transect, with a mean of 54 ± 4 years. The ratio of fine root biomass to stem biomass increased significantly with increasing elevation, whereas the allocation of net primary productivity above‐ and belowground remained approximately constant at all elevations. Although net primary productivity declined in the TMF, the partitioning of productivity between the ecosystem subcomponents remained the same in lowland, premontane and montane forests.
In 2005 and 2010 the Amazon basin experienced two strong droughts, driven by shifts in the tropical hydrological regime possibly associated with global climate change, as predicted by some global ...models. Tree mortality increased after the 2005 drought, and regional atmospheric inversion modelling showed basin-wide decreases in CO2 uptake in 2010 compared with 2011 (ref. 5). But the response of tropical forest carbon cycling to these droughts is not fully understood and there has been no detailed multi-site investigation in situ. Here we use several years of data from a network of thirteen 1-ha forest plots spread throughout South America, where each component of net primary production (NPP), autotrophic respiration and heterotrophic respiration is measured separately, to develop a better mechanistic understanding of the impact of the 2010 drought on the Amazon forest. We find that total NPP remained constant throughout the drought. However, towards the end of the drought, autotrophic respiration, especially in roots and stems, declined significantly compared with measurements in 2009 made in the absence of drought, with extended decreases in autotrophic respiration in the three driest plots. In the year after the drought, total NPP remained constant but the allocation of carbon shifted towards canopy NPP and away from fine-root NPP. Both leaf-level and plot-level measurements indicate that severe drought suppresses photosynthesis. Scaling these measurements to the entire Amazon basin with rainfall data, we estimate that drought suppressed Amazon-wide photosynthesis in 2010 by 0.38 petagrams of carbon (0.23-0.53 petagrams of carbon). Overall, we find that during this drought, instead of reducing total NPP, trees prioritized growth by reducing autotrophic respiration that was unrelated to growth. This suggests that trees decrease investment in tissue maintenance and defence, in line with eco-evolutionary theories that trees are competitively disadvantaged in the absence of growth. We propose that weakened maintenance and defence investment may, in turn, cause the increase in post-drought tree mortality observed at our plots.
The key role of tropical forest belowground carbon stocks and fluxes is well recognised as one of the main components of the terrestrial ecosystem carbon cycle. This study presents the first detailed ...investigation of spatial and temporal patterns of fine root stocks and fluxes in tropical forests along an elevational gradient, ranging from the Peruvian Andes (3020 m) to lowland Amazonia (194 m), with mean annual temperatures of 11.8°C to 26.4 °C and annual rainfall values of 1900 to 1560 mm yr‐1, respectively. Specifically, we analyse abiotic parameters controlling fine root dynamics, fine root growth characteristics, and seasonality of net primary productivity along the elevation gradient. Root and soil carbon stocks were measured by means of soil cores, and fine root productivity was recorded using rhizotron chambers and ingrowth cores. We find that mean annual fine root below ground net primary productivity in the montane forests (0–30 cm depth) ranged between 4.27±0.56 Mg C ha‐1 yr‐1 (1855 m) and 1.72±0.87 Mg C ha‐1 yr‐1 (3020 m). These values include a correction for finest roots (<0.6 mm diameter), which we suspect are under sampled, resulting in an underestimation of fine roots by up to 31% in current ingrowth core counting methods. We investigate the spatial and seasonal variation of fine root dynamics using soil depth profiles and an analysis of seasonal amplitude along the elevation gradient. We report a stronger seasonality of NPPFineRoot within the cloud immersion zone, most likely synchronised to seasonality of solar radiation. Finally, we provide the first insights into root growth characteristics along a tropical elevation transect: fine root area and fine root length increase significantly in the montane cloud forest. These insights into belowground carbon dynamics of tropical lowland and montane forests have significant implications for our understanding of the global tropical forest carbon cycle.
Key pointsIncrease of NPPFine Root seasonality in cloud forestChange in fine root growth characteristics in montane forestPossible sampling bias of finest roots ( < 6mm) in IC data collection
Parkinson’s disease (PD) is a neurodegenerative disorder that affects more than 7 million people worldwide. Its aetiology is unknown, although the hypothesis of a genetic susceptibility to ...environmental agents is accepted. These environmental agents include fungi, bacteria, and viruses. Three microorganisms are directly associated with a significantly increased risk of developing Parkinson’s disease: the fungal genus Malassezia, the bacterium Helicobacter pylori, and the hepatitis C virus. If the host is vulnerable due to genetic susceptibility or immune weakness, these microorganisms can access and infect the nervous system, causing chronic neuroinflammation with neurodegeneration. Other microorganisms show an epidemiological association with the disease, including the influenza type A, Japanese encephalitis type B, St Louis, and West Nile viruses. These viruses can affect the nervous system, causing encephalitis, which can result in parkinsonism. This article reviews the role of all these microorganisms in Parkinson’s disease.
La enfermedad de Parkinson es un trastorno neurológico degenerativo que afecta a más de siete millones de personas en todo el mundo. Se desconoce su etiología, aunque se acepta que existe una susceptibilidad genética a agentes ambientales. Estos agentes ambientales incluyen hongos, bacterias y virus. Tres microorganismos están directamente relacionados con un mayor riesgo estadístico de padecer enfermedad de Parkinson: el género de hongos Malassezia, la bacteria Helicobacter pylori y el virus de la hepatitis C. Estos microorganismos, si el huésped es vulnerable por susceptibilidad genética o debilidad inmunológica, pueden acceder al sistema nervioso, infectarlo y causar neuroinflamación crónica con neurodegeneración. Otros microorganismos se relacionan desde una vertiente epidemiológica con la enfermedad, destacando los virus influenza tipo A, de la encefalitis japonesa tipo B, de San Luis y del Nilo Occidental. Estos virus pueden afectar al sistema nervioso causando encefalitis, cuya consecuencia puede ser un parkinsonismo. En este artículo se hace una revisión de los mencionados agentes infecciosos en la enfermedad de Parkinson.
Solar power generation using PV (photovoltaic) technology is a key but still evolving technology with the fastest growing renewable-based market worldwide in the last decade. In this sector with ...tremendous potential for energy security and economic development, grid-connected PV systems are becoming today the most important application of solar PV generation. Based on this trend, PV system designers require an accurate and reliable tool in order to predict the dynamic performance of grid-tied PV systems at any operating conditions. This will allow evaluating the impact of PV generation on the electricity grids. This paper presents a detailed characterization of the performance and dynamic behavior of a grid-connected PV energy conversion system. To this aim, a flexible and accurate PV simulation and evaluation tool (called PVSET 1.0) is developed. The PV system is modeled, simulated and validated under the MATLAB/Simulink environment. The accuracy of simulation results has been verified using a 250 Wp PV experimental set-up.
•Development of a flexible and accurate PV simulation and evaluation tool (called PVSET 1.0).•Characterization of the performance and evaluation of the dynamic behavior of grid-tied PV systems at any operating conditions.•Evaluation of the impact of different PV energy conversion systems on electricity grids.•Detailed Modeling and control system design of advanced PV generators for grid-interactive operations.•Validation of developments by digital simulations and experimental results.
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