No description available.

O transporte de água nas plantas é um processo complexo e que envolve a passagem por membranas celulares. Nelas existem aquaporinas, proteínas integrais de membrana, que facilitam o fluxo passivo de água e pequenos solutos. Um fator importante que influencia o transporte de água nas plantas é a condutância hidráulica radicular (LPr), que pode contribuir com até 50% de toda a resistência ao fluxo de água na planta. Várias metodologias são propostas para estimar a LPr, porém os dados obtidos são altamente variáveis, ainda que para a mesma espécie vegetal. Diante do exposto, pretende-se desenvolver e propor uma nova metodologia, o sistema hidráulico de sucção para estimativa da LPr e avaliar a contribuição das aquaporinas no transporte de água radicular em plântulas de milho. O sistema hidráulico de sucção foi construído no Laboratório de Estudos de Plantas sob Estresse (LEPSE/USP) em parceria com Laboritoire d\'Ecophysiologie des Plants sous Stress Environnementaux de Montpellier, França. Os experimentos foram conduzidos no LEPSE, onde as plântulas cresceram em hidroponia na casa de vegetação. Para avaliação da atividade de aquaporinas foi utilizado o tratamento com peróxido de hidrogênio, que em concentrações milimolares inibe os canais de água. As medidas de condutância foram realizadas sempre na mesma hora do dia, uma vez que a própria LPr e as aquaporinas apresentam ritmo circadiano. Houve redução de 53% da condutância no tratamento com peróxido em relação ao controle e correlação significativa entre a LPr e o pH, de modo que o aumento do pH provocou queda de LPr, provavelmente causada por alterações na abundância e/ou atividade de aquaporinas nas raízes de milho. Esses resultados permitem afirmar que o método de sucção foi eficaz na estimativa da condutância hidráulica, podendo ser adotado como técnica alternativa na estimativa da LPr em plantas. / The water transport in plants is a complex process which involves passage through cell membranes. In them there are aquaporins, integral membrane proteins, that facilitate passive flux of water and small solutes. An important factor influencing the water transport in plants is root hydraulic conductance (LPr), which can contribute up to 50% of the water flow resistance in the plant. Various methods are proposed for estimating LPr, but the data are highly variable, even for the same plant species. Therefore, we intend to develop and propose a new methodology, the hydraulic suction system to estimate LPr and evaluate the contribution of aquaporins in root water transport in maize seedlings. The hydraulic suction system was built at the Laboratório de Estudos de Plantas sob Estresse (LEPSE / USP) in partnership with Laboritoire d\'Ecophysiologie Plants des sous Stress Environnementaux Montpellier, France. The experiments were conducted in LEPSE where the seedlings grew in the hydroponics greenhouse. To evaluate the activity of aquaporins was used treatment with hydrogen peroxide, which in millimolar concentrations inhibits water channels. The conductance measurements were performed at the same time of day, since the LPr itself and aquaporins presents the circadian rhythm. There was a 53% reduction in conductance peroxide treatment compared to control and significant correlation between LPr and pH, so that the pH increase caused a drop LPr probably caused by alterations in the abundance and/or activity of aquaporins in maize roots. These results indicate that the suction method was efficient in estimated hydraulic conductance, may be adopted as an alternative technique to estimate the LPr in plants.

The global population is predicted to increase to around 11 billion by 2100. By 2050, the average age in the most populous age group will be over sixty. The ageing population (over sixty-five) is projected to exceed the number of children by 2047. These demographics imply that as the ageing population section increases, there will be a greater need for long-term care services. In order to adequately prepare against this trend, medical experts and evidence-driven policymakers are realising that personalised healthcare can help alleviate the burden related to the planning and commissioning of services allied to long-term care. Central to this picture is conditions that affect the brain - the most important organ of the human body. Dementia, stroke, and other conditions have a tremendous impact on loss of life, quality of life and healthcare cost. The challenge regarding brain disease is exacerbated further due to the difficulty regarding accessibility of this organ, but also due to the immense complexity regarding its morphology and functionality. In this context, advanced biophysical modelling is considered a promising option for studying brain pathophysiology and becomes a priority investment regarding routes for brain research. Simulations offer the promise of improved, clinically relevant, predictive information, acceleration for the pipeline of drug discovery/design and better planning of long-term care for patients. Within this paradigm, a particular model of water transport in the cerebral environment is essential. Numerous brain disorders arise from water imbalance in the cerebral environment, such as hydrocephalus (HCP), oedema and Chiari malformations to name a few. In this research, a novel multiscale model of fluid regulation and tissue displacement in the cerebral environment is developed, arising from the use of Multiple-network Poroelastic Theory (MPET). Characteristics of a four-network poroelastic model (4MPET) are first explored. Then, this model is extended to a fully dynamic (transient) six-network model (6MPET) via the addition of two new compartments, namely the glial cells compartment and the glymphatic system compartment. The introduction of these two compartments in the MPET paradigm reflects recent seminal findings in cerebral physiology, namely the extent and importance regarding transport/clearance of the perivascular spaces of the brain vasculature. We develop and present a numerical implementation of the 6MPET model, and we utilise this framework to analyse acute HCP and cerebral oedema in a variety of settings, in order to show the enhanced capability of the proposed 6MPET model compared to the classical 4MPET. Investigations of acute hydrocephalus through the fully dynamic 6MPET reveal compensatory trans-ependymal pressure behaviour in the glymphatic compartment. It was also shown that aquaporin-4 (AQP4) deficient expression exaggerates ventriculomegaly, and this too is demonstrated in acute hydrocephalus. Additionally, using the 6MPET model, one is able to witness three mitigating factors for cytotoxic oedema. Specifically, these are: reducing water mobility in the glial cells compartment, increasing the compliance of the glial cells compartment and finally AQP4-deficient expression.

O transporte de água nas plantas é um processo complexo e que envolve a passagem por membranas celulares. Nelas existem aquaporinas, proteínas integrais de membrana, que facilitam o fluxo passivo de água e pequenos solutos. Um fator importante que influencia o transporte de água nas plantas é a condutância hidráulica radicular (LPr), que pode contribuir com até 50% de toda a resistência ao fluxo de água na planta. Várias metodologias são propostas para estimar a LPr, porém os dados obtidos são altamente variáveis, ainda que para a mesma espécie vegetal. Diante do exposto, pretende-se desenvolver e propor uma nova metodologia, o sistema hidráulico de sucção para estimativa da LPr e avaliar a contribuição das aquaporinas no transporte de água radicular em plântulas de milho. O sistema hidráulico de sucção foi construído no Laboratório de Estudos de Plantas sob Estresse (LEPSE/USP) em parceria com Laboritoire d\'Ecophysiologie des Plants sous Stress Environnementaux de Montpellier, França. Os experimentos foram conduzidos no LEPSE, onde as plântulas cresceram em hidroponia na casa de vegetação. Para avaliação da atividade de aquaporinas foi utilizado o tratamento com peróxido de hidrogênio, que em concentrações milimolares inibe os canais de água. As medidas de condutância foram realizadas sempre na mesma hora do dia, uma vez que a própria LPr e as aquaporinas apresentam ritmo circadiano. Houve redução de 53% da condutância no tratamento com peróxido em relação ao controle e correlação significativa entre a LPr e o pH, de modo que o aumento do pH provocou queda de LPr, provavelmente causada por alterações na abundância e/ou atividade de aquaporinas nas raízes de milho. Esses resultados permitem afirmar que o método de sucção foi eficaz na estimativa da condutância hidráulica, podendo ser adotado como técnica alternativa na estimativa da LPr em plantas. / The water transport in plants is a complex process which involves passage through cell membranes. In them there are aquaporins, integral membrane proteins, that facilitate passive flux of water and small solutes. An important factor influencing the water transport in plants is root hydraulic conductance (LPr), which can contribute up to 50% of the water flow resistance in the plant. Various methods are proposed for estimating LPr, but the data are highly variable, even for the same plant species. Therefore, we intend to develop and propose a new methodology, the hydraulic suction system to estimate LPr and evaluate the contribution of aquaporins in root water transport in maize seedlings. The hydraulic suction system was built at the Laboratório de Estudos de Plantas sob Estresse (LEPSE / USP) in partnership with Laboritoire d\'Ecophysiologie Plants des sous Stress Environnementaux Montpellier, France. The experiments were conducted in LEPSE where the seedlings grew in the hydroponics greenhouse. To evaluate the activity of aquaporins was used treatment with hydrogen peroxide, which in millimolar concentrations inhibits water channels. The conductance measurements were performed at the same time of day, since the LPr itself and aquaporins presents the circadian rhythm. There was a 53% reduction in conductance peroxide treatment compared to control and significant correlation between LPr and pH, so that the pH increase caused a drop LPr probably caused by alterations in the abundance and/or activity of aquaporins in maize roots. These results indicate that the suction method was efficient in estimated hydraulic conductance, may be adopted as an alternative technique to estimate the LPr in plants.

No description available.

Bei der lichtinduzierten Oxidation von Wasser im Photosystem II (PSII) werden zwei wassermoleküle im katalytischen Zyklus des Metallclusters (Mn4CaO5) benötigt, und vier Protonen aus dem Cluster in den Lumen abgegeben. Daher ist es für das Verständnis des Mechanismus´ der Wasseroxidation von entscheidender Bedeutung, die Veränderung der Protonierungszustände am cluster während der Katalyse zu untersuchen. Hierbei sollten sowohl die Wasserkanäle für die Zuführung der Substratwassermoleküle als auch die Transportwege für die Freisetzung der Protonen untersucht werden. Deshalb wurde in meiner ersten Veröffentlichung ein neues Protokoll entwickelt, um einzelne große Kristalle von dPSII mit einer Länge von ~3 mm in der Längsachse zu züchten. Diese Kristalle mit einer Auflösung von ca. 8 Å gemessen. Um eine höhere Auflösung zu erzielen, ist die Verbesserung der Kristallqualität essenziell. Daher wurde in meiner zweiten Veröffentlichung die Struktur des Detergens-Protein-Komplexes von dPSII mit βDM, durch Anwendung von SANS in Kombination mit SAXS untersucht. Die Ergebnisse zeigten, dass βDM eine monomolekulare Schicht um dPSII bildet. Darüber hinaus konnten freie Mizellen von βDM in der Lösung nachgewiesen werden. Damit ist eine weitere Optimierung der βDM-Konzentration in der Proteinlösung erforderlich, um die Bildung von freien Mizellen zu minimieren. In meiner dritten Veröffentlichung wurde die strukturelle Dynamik in den Wasserkanälen, während des S2-S3 Übergangs mit Hilfe der XFEL untersucht. Ein Datensatz mit einer hohen Auflösung von 1,89 Å wurde durch die Zusammenführung von Daten gewonnen, die während des S2-S3 Übergangs gesammelt wurden. In Anbetracht der Analyse der zusammengeführten Daten und der einzelnen Zeitpunkte, die während des S2-S3 Übergangs gesammelt wurden, ist es wahrscheinlich, dass ein Substratwasser durch den O1-Kanal geliefert wird. Im Gegensatz dazu wird ein Proton aus dem Cluster durch den Cl1 Transportweg in Richtung Lumen freigesetzt. / The light-induced oxidation of water in Photosystem II (PSII) requires incorporating two water molecules in the catalytic cycle of the active metal cluster (Mn4CaO5). Furthermore, four protons are released towards the bulk from the cluster. Therefore, tracking the change of protonation states at the active catalytic site and the surrounding protein side chains during catalysis and elucidating the pathways of water substrate insertion and proton release are crucial to understanding the water oxidation mechanism. Therefore, in the first study of my work, a new protocol was developed to grow single large dPSIIcc crystals with a length of ~3 mm in the long axis. These crystals, soaked in D2O containing buffer, diffracted to about 8 Å resolution. Improving the crystal quality is crucial for achieving a better resolution. Consequently, in the second study of my work, the structure of the detergent-protein complex of βDM-dPSIIcc has been investigated by applying SANS in combination with SAXS. The results showed that βDM is forming a monomolecular layer around the dimeric PSII core complex (dPSIIcc). Moreover, the SAXS data detected a peak assigned to the free micelles of βDM. These results raise the necessity to optimize the βDM concentration in the protein solution to avoid the possible excess of free micelles. In the third study of my work, the structural dynamics in the water channels connecting the cluster to the lumen during the S2  S3 transition were investigated using serial femtosecond XFEL. A high-resolution data set was obtained at a resolution of 1.89 Å by combining data collected at RT. Considering the analysis of the combined data and the individual time points collected during the S2  S3 transition, it is likely that the substrate water insertion into the open coordination site of the Mn1 ion is delivered through the O1 channel. In contrast, a proton from the cluster is released towards the bulk through the Cl1 A channel.