147 research outputs found

    Protein kinase SnRK2. 4 is a key regulator of aquaporins and root hydraulics in Arabidopsis

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    Soil water uptake by roots is a key component of plant water homeostasis contributing to plant growth and survival under ever-changing environmental conditions. The water transport capacity of roots (root hydraulic conductivity; Lpr ) is mostly contributed by finely regulated Plasma membrane Intrinsic Protein (PIP) aquaporins. In this study, we used natural variation of Arabidopsis for the identification of quantitative trait loci (QTLs) contributing to Lpr . Using recombinant lines from a biparental cross (Cvi-0 x Col-0), we show that the gene encoding class 2 Sucrose-Non-Fermenting Protein kinase 2.4 (SnRK2.4) in Col-0 contributes to >30% of Lpr by enhancing aquaporin-dependent water transport. At variance with the inactive and possibly unstable Cvi-0 SnRK2.4 form, the Col-0 form interacts with and phosphorylates the prototypal PIP2;1 aquaporin at Ser121 and stimulates its water transport activity upon coexpression in Xenopus oocytes and yeast cells. Activation of PIP2;1 by Col-0 SnRK2.4 in yeast also requires its protein kinase activity and can be counteracted by clade A Protein Phosphatases 2C. SnRK2.4 shows all hallmarks to be part of core abscisic acid (ABA) signaling modules. Yet, long-term (>3 h) inhibition of Lpr by ABA possibly involves a SnRK2.4-independent inhibition of PIP2;1. SnRK2.4 also promotes stomatal aperture and ABA-induced inhibition of primary root growth. The study identifies a key component of Lpr and sheds new light on the functional overlap and specificity of SnRK2.4 with respect to other ABA-dependent or independent SnRK2s

    Characterisation and functional analysis of fission yeast tropomyosin mutants and development of quantum dot-antibody conjugates for cellular imaging

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    Tropomyosin (Tm) is an evolutionarily conserved dimeric a-helical coiled coil protein, which interacts end-to-end to form polymers capable of associating with and stabilising actin-filaments and thereby regulate myosin function. The fission yeast, Schizosaccharomyces pombe, possesses a single Tm, Cdc8, an essential protein which can be acetylated on its amino terminus to increase its affinity for actin and enhance its ability to regulate myosin function. During this study extensive analyses on the physical properties of acetylated and unacetylated Cdc8 protein, together with a series of novel amino terminal Cdc8 mutants were undertaken in an attempt to explore the effects of amino terminal modification on the Cdc8 protein. In addition, a series of experiments were undertaken to develop fluorescent quantum dot (QD)-antibody (IgG) conjugates for visualising Cdc8 localisation in S. pombe cells. Modifications to the amino terminus altered the stability of the Cdc8 protein, its ability to form end-to-end interactions and its affinity for actin. Changes in actin affinity were reflected in the ability of the Cdc8 proteins to regulate myosin S1 ATPase activity. Despite changes to their biochemical properties, Cdc8 proteins expressed in a temperature sensitive S. pombe strain were capable of complementing function at the restrictive temperature. However, when expressed in a Naacetyltransferase deficient S. pombe strain, the mutant Cdc8 proteins were unable to rescue the growth defects associated with this strain. The QD-IgG conjugates produced during this study produced superior images when compared to organic fluorophores and were significantly more resistant to photobleaching. This work has provided insights into the importance of acetylation and the structure of the amino terminus for the function of fission yeast Tm and has highlighted the importance of reaction stoichiometry, the difficulties arising from non-specific binding and quenching of fluorescence intensity when coupling QDs to IgG complexes

    Digital innovations in online articles in the field of Chemistry: Implications for the teaching of genre and new academic and digital literacies

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    Este trabajo pretende identificar las innovaciones digitales presentes en tres revistas de Química, considerar sus propósitos retóricos y examinar por qué aparecen en la comunicación académica en línea. El corpus se utilizó con fines pedagógicos en la Universidad de Creta para identificar las habilidades y los retos que los estudiantes de Química necesitaban o afrontaban, respectivamente, al componer, analizar, deconstruir y comparar géneros similares. Se analizaron las percepciones de profesores, jóvenes investigadores y estudiantes para descifrar sus prioridades y necesidades. A partir del análisis de cuatro conjuntos de datos, entre ellos un corpus de artículo de investigación, cuestionarios, entrevistas e informes de reflexión en voz alta, se extrajeron implicaciones para la enseñanza de los géneros y las nuevas alfabetizaciones académicas y digitales, de modo que los profesores de ESP y EAP puedan tomar decisiones informadas sobre el diseño de los cursos, la pedagogía de los géneros y cómo pueden fomentar las alfabetizaciones académicas digitales utilizando publicaciones académicas. Los resultados sugieren que las innovaciones digitales en las revistas de Química, dependiendo de cómo las abordemos, entendamos, remediemos (reutilicemos) y utilicemos (como productores o usuarios de contenidos), pueden afectar a la forma en que nos relacionamos con otros miembros de la comunidad (miembros de la comunidad de discurso o comunidad de práctica), la forma en que percibimos la comunicación académica, cómo "hacemos" comunicación académica y cómo negociamos nuestras formas de ser y hacer dentro de un ecosistema de género establecido pero en constante cambio.<br /

    The Retina in Health and Disease

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    Vision is the most important sense in higher mammals. The retina is the first step in visual processing and the window to the brain. It is not surprising that problems arising in the retina lead to moderate to severe visual impairments. We offer here a collection of reviews as well as original papers dealing with various aspects of retinal function as well as dysfunction. New approaches in retinal research are described, such as the expression and localization of the endocannabinoid system in the normal retina and the role of cannabinoid receptors that could offer new avenues of research in the development of potential treatments for retinal diseases. Moreover, new insights are offered in advancing knowledge towards the prevention and cure of visual pathologies, mainly AMD, RP, and diabetic retinopathy

    En busca de nuevas proteínas interactoras del receptor CB1 cannabinoide

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    Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Químicas, leída el 01-04-2022Extracts from the plant Cannabis sativa have been used for millennia for medicinal, religious or recreative purposes, among others. The plant’s main psychoactive component, Δ9-tetrahydrocannabinol (THC), exerts its actions through the activation of the CB1 receptor (CB1R), a G-protein coupled receptor very abundant in the central nervous system (CNS). The therapeutic potential of THC, and other plant molecules, has been extensively studied in the last years, which has led to the regulation of medicinal and recreational cannabis in numerous countries, as well as the generation of drugs based on cannabinoids to treat various pathologies, such as spasticity associated to multiple sclerosis, childhood refractory epilepsy, neuropathic pain, or as antiemetic and appetite modulator in AIDS and chemotherapy-treated cancer patients. However, one of the major setbacks that withdraw the use of these compounds is the onset of side-effects. Nowadays, the molecular mechanisms underlying CB1R that give rise to beneficial and deleterious effects have not been elucidated in detail. CB1R-induced signal transduction is highly pleiotropic and relies on both the cell type and physiopathological state of the tissue or organism where CB1R molecules are located, as well as the chemical nature of the activating ligand...Extractos de la planta Cannabis sativa se han utilizado durante milenios con fines medicinales, religiosos o recreativos, entre otros. El principal componente psicoactivo de la planta, el Δ9-tetrahidrocannabinol (THC), ejerce sus acciones mayoritariamente por la activación del receptor cannabinoide 1 (CB1R), un receptor acoplado a proteínas G (GPCR)muy abundante en el sistema nervioso central (SNC). En los últimos años, se ha estudiado intensamente el potencial terapéutico del THC y otros compuestos de la planta, lo que ha llevado a la regulación del uso del cannabis para fines medicinales, y también recreativos, en numerosos países, así como la aparición de fármacos basados en compuestos cannabinoides para tratar diversas patologías, como la espasticidad asociada a esclerosis múltiple, epilepsias refractarias infantiles, dolor neuropático, o como antiemético y modulador del apetito en pacientes de SIDA o de cáncer tratados con quimioterapia. Sin embargo, uno de los principales impedimentos al uso de estos compuestos es la aparición de efectos secundarios no deseados. Hoy en día, todavía no se conocen en detalle los mecanismos moleculares que subyacen a la activación de CB1R, a partir de los cuales emergen estos efectos beneficiosos y perjudiciales. La señalización de este GPCR es enormemente pleiotrópica, y depende tanto del tipo celular y del estado fisiopatológico del tejido u organismo dónde se encuentra el receptor, como de la naturaleza química del ligando activante.Fac. de Ciencias QuímicasTRUEunpu

    A computational framework for multidimensional parameter space screening of reaction-diffusion models in biology

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    Reaction-diffusion models have been widely successful in explaining a large variety of patterning phenomena in biology ranging from embryonic development to cancer growth and angiogenesis. Firstly proposed by Alan Turing in 1952 and applied to a simple two-component system, reaction-diffusion models describe spontaneous spatial pattern formation, driven purely by interactions of the system components and their diffusion in space. Today, access to unprecedented amounts of quantitative biological data allows us to build and test biochemically accurate reaction-diffusion models of intracellular processes. However, any increase in model complexity increases the number of unknown parameters and thus the computational cost of model analysis. To efficiently characterize the behavior and robustness of models with many unknown parameters is, therefore, a key challenge in systems biology. Here, we propose a novel computational framework for efficient high-dimensional parameter space characterization of reaction-diffusion models. The method leverages the LpL_p-Adaptation algorithm, an adaptive-proposal statistical method for approximate high-dimensional design centering and robustness estimation. Our approach is based on an oracle function, which describes for each point in parameter space whether the corresponding model fulfills given specifications. We propose specific oracles to estimate four parameter-space characteristics: bistability, instability, capability of spontaneous pattern formation, and capability of pattern maintenance. We benchmark the method and demonstrate that it allows exploring the ability of a model to undergo pattern-forming instabilities and to quantify model robustness for model selection in polynomial time with dimensionality. We present an application of the framework to reconstituted membrane domains bearing the small GTPase Rab5 and propose molecular mechanisms that potentially drive pattern formation

    Drug development progress in duchenne muscular dystrophy

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    Duchenne muscular dystrophy (DMD) is a severe, progressive, and incurable X-linked disorder caused by mutations in the dystrophin gene. Patients with DMD have an absence of functional dystrophin protein, which results in chronic damage of muscle fibers during contraction, thus leading to deterioration of muscle quality and loss of muscle mass over time. Although there is currently no cure for DMD, improvements in treatment care and management could delay disease progression and improve quality of life, thereby prolonging life expectancy for these patients. Furthermore, active research efforts are ongoing to develop therapeutic strategies that target dystrophin deficiency, such as gene replacement therapies, exon skipping, and readthrough therapy, as well as strategies that target secondary pathology of DMD, such as novel anti-inflammatory compounds, myostatin inhibitors, and cardioprotective compounds. Furthermore, longitudinal modeling approaches have been used to characterize the progression of MRI and functional endpoints for predictive purposes to inform Go/No Go decisions in drug development. This review showcases approved drugs or drug candidates along their development paths and also provides information on primary endpoints and enrollment size of Ph2/3 and Ph3 trials in the DMD space

    Coronary Angiography

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    In the intervening 10 years tremendous advances in the field of cardiac computed tomography have occurred. We now can legitimately claim that computed tomography angiography (CTA) of the coronary arteries is available. In the evaluation of patients with suspected coronary artery disease (CAD), many guidelines today consider CTA an alternative to stress testing. The use of CTA in primary prevention patients is more controversial in considering diagnostic test interpretation in populations with a low prevalence to disease. However the nuclear technique most frequently used by cardiologists is myocardial perfusion imaging (MPI). The combination of a nuclear camera with CTA allows for the attainment of coronary anatomic, cardiac function and MPI from one piece of equipment. PET/SPECT cameras can now assess perfusion, function, and metabolism. Assessing cardiac viability is now fairly routine with these enhancements to cardiac imaging. This issue is full of important information that every cardiologist needs to now
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