114 research outputs found

    Ciliary adenylyl cyclases control the Hedgehog pathway

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    Protein kinase A (PKA) accumulates at the base of the cilium where it negatively regulates the Hedgehog (Hh) pathway. Although PKA activity is essentially controlled by the cAMP produced by adenylyl cyclases, the influence of these enzymes on the Hh pathway remains unclear. Here, we show that adenylyl cyclase 5 and adenylyl cyclase 6 (AC5 and AC6, also known as ADCY5 and ADCY6, respectively) are the two isoforms most strongly expressed in cerebellar granular neuron precursors (CGNPs). We found that overexpression of AC5 and AC6 represses, whereas their knockdown activates, the Hh pathway in CGNPs and in the embryonic neural tube. Indeed, AC5 and AC6 concentrate in the primary cilium, and mutation of a previously undescribed cilium-targeting motif in AC5 suppresses its ciliary location, as well as its capacity to inhibit Hh signalling. Stimulatory and inhibitory Gα proteins, which are engaged by the G-protein-coupled receptors (GPCRs), control AC5 and AC6 activity and regulate the Hh pathway in CGNPs and in the neural tube. Therefore, we propose that the activity of different ciliary GPCRs converges on AC5 and AC6 to control PKA activity and, hence, the Hh pathwayThis work was supported by Spanish and Catalan ministries of Science [grant numbers BFU2008-02424/BFI, BFU2011-24099 and SGR200821A333 to S.P.]Peer Reviewe

    Vitronectin regulates Sonic hedgehog activity during cerebellum development through CREB phosphorylation

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    12 páginas, 7 figuras.During development of the cerebellum, Sonic hedgehog (SHH) is expressed in migrating and settled Purkinje neurons and is directly responsible for proliferation of granule cell precursors in the external germinal layer. We have previously demonstrated that SHH interacts with vitronectin in the differentiation of spinal motor neurons. Here, we analysed whether similar interactions between SHH and extracellular matrix glycoproteins regulate subsequent steps of granule cell development. Laminins and their integrin receptor subunit alpha6 accumulate in the outer most external germinal layer where proliferation of granule cell precursors is maximal. Consistent with this expression pattern, laminin significantly increases SHH-induced proliferation in primary cultures of cerebellar granule cells. Vitronectin and its integrin receptor subunits alpha(v) are expressed in the inner part of the external germinal layer where granule cell precursors exit the cell cycle and commence differentiation. In cultures, vitronectin is able to overcome SHH-induced proliferation, thus allowing granule cell differentiation. Our studies indicate that the pathway in granule cell precursors responsible for the conversion of a proliferative SHH-mediated response to a differentiation signal depends on CREB. Vitronectin stimulates phosphorylation of cyclic-AMP responsive element-binding protein (CREB), and over-expression of CREB is sufficient to induce granule cell differentiation in the presence of SHH. Taken together, these data suggest that granule neuron differentiation is regulated by the vitronectin-induced phosphorylation of CREB, a critical event that terminates SHH-mediated proliferation and permits the differentiation program to proceed in these cells.This research was supported by grant PM97-0018 to Dr Ignacio Torres Alemán and by grants PM97-0019 and BIO4-CT98-0399 to Dr Paola Bovolenta, in whose laboratories this research was carried out.Peer reviewe

    Entrevista con Álvaro Pons

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    Álvaro Pons Moreno (Barcelona, 1966) es el académico y crítico especializado en historietas más importante del mundo de habla hispana. Ha leído y estudiado cómics producidos dentro de todas las tradiciones o «escuelas» conocidas del género. Físico por decisión y lector de tebeos por vocación, tal y como él mismo se define, hace unos años lanzó una cuidada selección de sus trabajos publicados por espacio de tres lustros en «La Cárcel de Papel», un blog de referencia en castellano para toda persona que se precie amante o lectora de historietas. Luis Alberto de Cuenca Prado, en el prólogo de la recopilación, lo califica como «el guardián de los cómics»

    La edición de textos de quejas: propuestas preliminares en torno a un corpus histórico discursivo

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    Las últimas investigaciones en lenguas romances han incorporado varios conceptos en sus análisis, como el de actos de habla, de la pragmática, o el de "tradiciones discursivas", surgido en la lingüística de las variedades alemana. Igualmente, se ha recurrido a nuevas metodologías como la lingüística de corpus para ampliar las bases de datos utilizadas en sus estudios. En este trabajo planteamos los fundamentos teóricos para la creación de un corpus diacrónico del discurso en español, cuyo principal objetivo es combinar los nuevos avances para ofrecer al investigador un conjunto de textos de distinto origen y cronología que presentan, sin embargo, una característica común: expresan una queja. Además, trataremos la queja en relación entre las tradiciones discursivas y los actos de habla y aportaremos ejemplos para mostrar los resultados lingüísticos que pueden ser extraídos del análisis de este tipo de corpus.Recent historical research on Romance languages has been updated using concepts such as speech acts from the field of Pragmatics, or discourse tradition rooted in the variationist ideas of German linguists. Equally, new methodologies like corpus linguistics are used to expand the database on which our analysis is based. This study presents the theoretical foundations for the creation of a diachronic discourse corpus in Spanish which aims to combine these new developments offering researchers a set of texts of varied origin and diachrony, whose common factor is that they are used to express complaints. The relationship between discourse tradition and acts of speech is discussed and samples are presented to show the linguistic results that can be provided by this type of corpus

    A novel low-pass filter based on dielectric impedance inverters to enhance the multipactor breakdown threshold

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    This work presents a novel low-pass filter based on using dielectric materials, in the critical areas of the structure, to prevent high-power space condition adverse effects, like multipactor breakdown. It is shown that the use of dielectric pieces in the inverters of the filter leads to increased gaps between metallic parts in the irises. In addition, by completely filling up the air space in critical gaps, the multipactor breakdown thresholds can be increased. Moreover, they also lead to a volume reduction, increasing compactness of the structure. To demonstrate the proposed concept, a prototype has been manufactured with an aluminum housing and a Teflon dielectric material, and tested for multipactor effect at ESA-VSC Laboratory. Tests confirmed that the manufactured filter has good electrical performance with cut-off frequency 13.6 GHz, insertion losses 0.32 dB, return losses better than 15 dB, and additionally does not show multipactor breakdown up to the maximum power tested in the experimental facility (5.5 kW).This research work has been financially supported by the Spanish Ministerio de Ciencia e Innovación in the frame of the project “Green an Efficient Technologies for Advanced Telecommunication Systems (GRETAS)” with Ref. TPID2019-103982RB-C42

    Wideband bandpass filters using a novel thick metallization technology

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    A new class of wideband bandpass filters based on using thick metallic bars as microwave resonators is presented in this work. These bars provide a series of advantages over fully planar printed technologies, including higher coupling levels between resonators, higher unloaded quality factors QU , and larger bandwidths implemented with compact structures. In comparison to dielectric and waveguide resonators filters, higher bandwidths together with lower weight and footprint reduction are achieved with the proposed thick bars technology. Moreover, thick bar resonators can easily be coupled to an additional resonance excited in a box used for shielding, allowing to realize transversal topologies able to implement transmission zeros at desired frequencies. To illustrate the capabilities of this technology, three microwave filters with different topologies have been designed. One of the designed filters has been manufactured and tested using copper bars inside an aluminum housing partially filled with Teflon. Measured data demonstrates a fractional bandwidth of FBW = 32%, spurious free range SFR > 50%, unloaded quality factor of QU = 1180, insertion losses over 0.16 dB and return losses over 20 dB, without requiring any post-tuning operation on the prototype. This result confirms the exciting performance of the proposed technology for wideband applications.This work was supported in part by the National Science Foundation with CAREER under Grant ECCS-1749177, in part by the Spanish Government, Ministerio de Educación, Cultura y Deporte under Grant FPU15/02883, and in part by the Ministerio de Economía y Competitividad through the Coordinated Project under Grant TEC2016-75934-C4-R and Grant PRX18/00092

    Transfection of Capsaspora owczarzaki, a close unicellular relative of animals

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    How animals emerged from their unicellular ancestor remains a major evolutionary question. New genome data from the closest unicellular relatives of animals have provided important insights into the evolution of animal multicellularity. We know that the unicellular ancestor of animals had an unexpectedly complex genetic repertoire, including many genes that are key to animal development and multicellularity. Thus, assessing the function of these genes among unicellular relatives of animals is key to understanding how they were co-opted at the onset of the Metazoa. However, such analyses have been hampered by the lack of genetic tools. Progress has been made in choanoflagellates and teretosporeans, two of the three lineages closely related to animals, whereas no tools are yet available for functional analysis in the third lineage: the filastereans. Importantly, filastereans have a striking repertoire of genes involved in transcriptional regulation and other developmental processes. Here, we describe a reliable transfection method for the filasterean Capsaspora owczarzaki. We also provide a set of constructs for visualising subcellular structures in live cells. These tools convert Capsaspora into a unique experimentally tractable organism to use to investigate the origin and evolution of animal multicellularity.Fil: Parra Acero, Helena. Consejo Superior de Investigaciones Científicas. Museo Nacional de Ciencias Naturales. Departamento de Biodiversidad y Biología Evolutiva; EspañaFil: Ros Rocher, Núria. Consejo Superior de Investigaciones Científicas. Museo Nacional de Ciencias Naturales. Departamento de Biodiversidad y Biología Evolutiva; EspañaFil: Perez Posada, Alberto. Consejo Superior de Investigaciones Científicas. Museo Nacional de Ciencias Naturales. Departamento de Biodiversidad y Biología Evolutiva; EspañaFil: Kożyczkowska, Aleksandra. Consejo Superior de Investigaciones Científicas. Museo Nacional de Ciencias Naturales. Departamento de Biodiversidad y Biología Evolutiva; EspañaFil: Sánchez Pons, Núria. Consejo Superior de Investigaciones Científicas. Museo Nacional de Ciencias Naturales. Departamento de Biodiversidad y Biología Evolutiva; EspañaFil: Nakata, Azusa. Prefectural University of Hiroshima; JapónFil: Suga, Hiroshi. Prefectural University of Hiroshima; JapónFil: Najle, Sebastián Rodrigo. Consejo Superior de Investigaciones Científicas. Museo Nacional de Ciencias Naturales. Departamento de Biodiversidad y Biología Evolutiva; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Ruiz Trillo, Iñaki. Consejo Superior de Investigaciones Científicas. Museo Nacional de Ciencias Naturales. Departamento de Biodiversidad y Biología Evolutiva; España. Institució Catalana de Recerca i Estudis Avancats; España. Universidad de Barcelona; Españ

    Vertical Configuration of a Side Scan Sonar for the Monitoring of Posidonia oceanica Meadows

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    [EN] Posidonia oceanica meadows are ecosystem engineers that play several roles in marine environment maintenance. In this sense, monitoring of the spatial distribution and health status of their meadows is key to make decisions about protecting them against their degradation. With the aim of checking the ability of a simple low-cost acoustic method to acquire information about the state of P. oceanica meadows as ecosystem indicators, ground-truthing and acoustic data were acquired over several of these meadows on the Levantine coast of Spain. A 200 kHz side scan sonar in a vertical configuration was used to automatically estimate shoot density, canopy height and cover of the meadows. The wide athwartship angle of the transducer together with its low cost and user friendliness entail the main advantages of this system and configuration: both improved beam path and detection invariance against boat rolling. The results show that canopy height can be measured acoustically. Furthermore, the accumulated intensity of the echoes from P. oceanica in the first 30 centimeters above the bottom is indirectly related to shoot density and cover, showing a relation that should be studied deeply.Funding for open access charge: Universitat Politècnica de ValènciaLlorens-Escrich, S.; Tamarit, E.; Hernandis, S.; Sánchez-Carnero, N.; Rodilla, M.; Pérez Arjona, I.; Moszynski, M.... (2021). Vertical Configuration of a Side Scan Sonar for the Monitoring of Posidonia oceanica Meadows. Journal of Marine Science and Engineering. 9(12):1-15. https://doi.org/10.3390/jmse912133211591
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