116 research outputs found

    A novel role of Drosophila cytochrome P450-4e3 in permethrin insecticide tolerance

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    The exposure of insects to xenobiotics, such as insecticides, triggers a complex defence response necessary for survival. This response includes the induction of genes that encode key Cytochrome P450 monooxygenase detoxification enzymes. Drosophila melanogaster Malpighian (renal) tubules are critical organs in the detoxification and elimination of these foreign compounds, so the tubule response induced by dietary exposure to the insecticide permethrin was examined. We found that expression of the gene encoding Cytochrome P450-4e3 (Cyp4e3) is significantly up-regulated by Drosophila fed on permethrin and that manipulation of Cyp4e3 levels, specifically in the principal cells of the Malpighian tubules, impacts significantly on the survival of permethrin-fed flies. Both dietary exposure to permethrin and Cyp4e3 knockdown cause a significant elevation of oxidative stress-associated markers in the tubules, including H2O2 and lipid peroxidation byproduct, HNE (4-hydroxynonenal). Thus, Cyp4e3 may play an important role in regulating H2O2 levels in the endoplasmic reticulum (ER) where it resides, and its absence triggers a JAK/STAT and NF-ÎşB-mediated stress response, similar to that observed in cells under ER stress. This work increases our understanding of the molecular mechanisms of insecticide detoxification and provides further evidence of the oxidative stress responses induced by permethrin metabolism

    Chloride channels in stellate cells are essential for uniquely high secretion rates in neuropeptide-stimulated Drosophila diuresis

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    Epithelia frequently segregate transport processes to specific cell types, presumably for improved efficiency and control. The molecular players underlying this functional specialization are of particular interest. In Drosophila, the renal (Malpighian) tubule displays the highest per-cell transport rates known and has two main secretory cell types, principal and stellate. Electrogenic cation transport is known to reside in the principal cells, whereas stellate cells control the anion conductance, but by an as-yet-undefined route. Here, we resolve this issue by showing that a plasma membrane chloride channel, encoded by ClC-a, is exclusively expressed in the stellate cell and is required for Drosophila kinin-mediated induction of diuresis and chloride shunt conductance, evidenced by chloride ion movement through the stellate cells, leading to depolarization of the transepithelial potential. By contrast, ClC-a knockdown had no impact on resting secretion levels. Knockdown of a second CLC gene showing highly abundant expression in adult Malpighian tubules, ClC-c, did not impact depolarization of transepithelial potential after kinin stimulation. Therefore, the diuretic action of kinin in Drosophila can be explained by an increase in ClC-a–mediated chloride conductance, over and above a resting fluid transport level that relies on other (ClC-a–independent) mechanisms or routes. This key segregation of cation and anion transport could explain the extraordinary fluid transport rates displayed by some epithelia

    Novel roles for GATAe in growth, maintenance and proliferation of cell populations in the Drosophila renal tubule

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    The GATA family of transcription factors is implicated in numerous developmental and physiological processes in metazoans. In Drosophila melanogaster, five different GATA factor genes (pannier, serpent, grain, GATAd and GATAe) have been reported as essential in the development and identity of multiple tissues, including the midgut, heart and brain. Here, we present a novel role for GATAe in the function and homeostasis of the Drosophila renal (Malpighian) tubule. We demonstrate that reduced levels of GATAe gene expression in tubule principal cells induce uncontrolled cell proliferation, resulting in tumorous growth with associated altered expression of apoptotic and carcinogenic key genes. Furthermore, we uncover the involvement of GATAe in the maintenance of stellate cells and migration of renal and nephritic stem cells into the tubule. Our findings of GATAe as a potential master regulator in the events of growth control and cell survival required for the maintenance of the Drosophila renal tubule could provide new insights into the molecular pathways involved in the formation and maintenance of a functional tissue and kidney disease

    Tracing the evolutionary origins of insect renal function

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    Knowledge on neuropeptide receptor systems is integral to understanding animal physiology. Yet, obtaining general insight into neuropeptide signalling in a clade as biodiverse as the insects is problematic. Here we apply fluorescent analogues of three key insect neuropeptides to map renal tissue architecture across systematically chosen representatives of the major insect Orders, to provide an unprecedented overview of insect renal function and control. In endopterygote insects, such as Drosophila, two distinct transporting cell types receive separate neuropeptide signals, whereas in the ancestral exopterygotes, a single, general cell type mediates all signals. Intriguingly, the largest insect Order Coleoptera (beetles) has evolved a unique approach, in which only a small fraction of cells are targets for neuropeptide action. In addition to demonstrating a universal utility of this technology, our results reveal not only a generality of signalling by the evolutionarily ancient neuropeptide families but also a clear functional separation of the types of cells that mediate the signal

    Designing the club of the future with data: A case study on collaboration of creative industries

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    This paper reflects on the development of a multi-sensory clubbing experience which was deployed during a two-day event within the context of the Amsterdam Dance Event in October 2016 in Amsterdam. We present how the entire experience was developed end-to-end and deployed at the event through the collaboration of several project partners from industries such as art and design, music, food, technology and research. Central to the system are smart textiles, namely wristbands equipped with Bluetooth LE sensors which were used to sense people attending the dance event. We describe the components of the system, the development process, the collaboration between the involved entities and the event itself. To conclude the paper, we highlight insights gained from conducting a real world research deployment across many collaborators and stakeholders with different backgrounds

    Alcan Aluminium Limited v. Franchise Tax Board: State Unitary Apportionment of Foreign Parent Income Taxation Will Have to Go to State Court

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    Viewers using HTTP Adaptive Streaming (HAS) without sufficient bandwidth undergo frequent quality switches that hinder their watching experience. This situation, known as instability, is produced when HAS players are unable to accurately estimate the available bandwidth. Moreover, when several players stream over a bottleneck link, their individual adaptation techniques may result in an unfair share of the channel. These are two detrimental issues in HAS technology, which is otherwise very attractive. To overcome them, a group of solutions are proposed in the literature that can be classified as network-assisted HAS. Solving stability and fairness only in the player is difficult, because a player has a limited view of the network. Using information from network devices can help players in making better adaptation decisions. In this paper we describe our implementation in the form of an HTTP prox

    Drama management system in a controlled virtual environment

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    Trabajo de Fin de Grado en Desarrollo de videojuegos, Facultad de Informática UCM, Departamento de Ingeniería del Software e Inteligencia Artificial, Curso 2020/2021La narrativa es algo que está presente en todas las culturas y épocas. En un contexto en el que los videojuegos se consideran un medio global, existe una creciente necesidad de equilibrar la autoría del diseñador y la libertad del jugador. Los sistemas de gestión narrativa han existido desde hace años, pero pocas veces han podido demostrar sus capacidades en entornos virtuales complejos. En este proyecto se ha diseñado e implementado un drama manager capaz de orientar la trayectoria narrativa de un videojuego, mientras se maximiza la sensación de libertad del jugador. Además, se han implementado dos videojuegos, Emerald Hunt y Tell No Tales, como entornos de pruebas para el sistema. Los experimentos se han llevado a cabo sobre Tell No Tales, evaluando a 40 participantes humanos. Si bien los resultados de esta evaluación no son conclusivos, y ponen de manifiesto la gran labor de diseño que supone utilizar adecuadamente estos gestores, existen indicios de que un trabajo futuro más exhaustivo, en coalición con otros sistemas, puede ser un camino para el desarrollo de videojuegos con una narrativa procedural viable.Narrative is something that is present in all cultures and eras. In a context where videogames are considered a global medium, there is a growing need to balance the designer's authorship and the player's freedom. Drama management systems have been around for years, but have rarely been able to demonstrate their capabilities in complex virtual environments. In this project we have designed and implemented a drama manager capable of guiding the narrative trajectory of a videogame, while maximizing the player's agency. In addition, two video games, Emerald Hunt and Tell No Tales, have been developed as test environments for the system. Experiments have been conducted on Tell No Tales, evaluating 40 human participants. While the results of this evaluation are not conclusive, and highlight the great design work involved in properly utilizing these drama managers, there are indications that more comprehensive future work, in coalition with other systems, may be a path to the development of videogames with viable procedural narrative.Depto. de Ingeniería de Software e Inteligencia Artificial (ISIA)Fac. de InformáticaTRUEunpu

    Specialized stellate cells offer a privileged route for rapid water flux in Drosophila renal tubule

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    Insects are highly successful, in part through an excellent ability to osmoregulate. The renal (Malpighian) tubules can secrete fluid faster on a per-cell basis than any other epithelium, but the route for these remarkable water fluxes has not been established. In Drosophila melanogaster, we show that 4 genes of the major intrinsic protein family are expressed at a very high level in the fly renal tissue: the aquaporins (AQPs) Drip and Prip and the aquaglyceroporins Eglp2 and Eglp4. As predicted from their structure, and by their transport function by expressing these proteins in Xenopus oocytes, Drip, Prip, and Eglp2 show significant and specific water permeability, whereas Eglp2 and Eglp4 show very high permeability to glycerol and urea. Knockdowns of any of these genes result in impaired hormone-induced fluid secretion. The Drosophila tubule has 2 main secretory cell types: active cation-transporting principal cells, wherein the aquaglyceroporins localize to opposite plasma membranes, and small stellate cells, the site of the chloride shunt conductance, with these AQPs localizing to opposite plasma membranes. This suggests a model in which osmotically obliged water flows through the stellate cells. Consistent with this model, fluorescently labeled dextran, an in vivo marker of membrane water permeability, is trapped in the basal infoldings of the stellate cells after kinin diuretic peptide stimulation, confirming that these cells provide the major route for transepithelial water flux. The spatial segregation of these components of epithelial water transport may help to explain the unique success of the higher insects in regulating their internal environments
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