Design of a bistable switch to control cellular uptake

International audienceBistable switches are widely used in synthetic biology to trigger cellular functions in response to environmental signals. All bistable switches developed so far, however, control the expression of target genes without access to other layers of the cellular machinery. Here, we propose a bistable switch to control the rate at which cells take up a metabolite from the environment. An uptake switch provides a new interface to command metabolic activity from the extracellular space and has great potential as a building block in more complex circuits that coordinate pathway activity across cell cultures, allocate metabolic tasks among different strains or require cell-to-cell communication with metabolic signals. Inspired by uptake systems found in nature, we propose to couple metabolite import and utilization with a genetic circuit under feedback regulation. Using mathematical models and analysis, we determined the circuit architectures that produce bistability and obtained their design space for bistability in terms of experimentally tuneable parameters. We found an activation–repression architecture to be the most robust switch because it displays bistability for the largest range of design parameters and requires little fine-tuning of the promoters' response curves. Our analytic results are based on on–off approximations of promoter activity and are in excellent qualitative agreement with simulations of more realistic models. With further analysis and simulation, we established conditions to maximize the parameter design space and to produce bimodal phenotypes via hysteresis and cell-to-cell variability. Our results highlight how mathematical analysis can drive the discovery of new circuits for synthetic biology, as the proposed circuit has all the hallmarks of a toggle switch and stands as a promising design to control metabolic phenotypes across cell cultures

Caledonian and late Caledonian Europe: a working hypothesis involving two contrasted compressional/extensional scenarios

The tectonomagmatic and metamorphic structuration of the European Caledonian realm suggests that two mutually perpendicular compressional/extensional scenarios developed during the Ordovician-Devonian time-span. As a result of the mid Ordovician Grampian compressional scheme (Caledonian s.s.), a major extensional province developed further east from the Caledonian foldbelt in continental Europe. This scenario ended by early/mid Devonian, with the complete locking of North America, Baltica and Gondwana into a Pangaea supercontinent, thus triggering a contrasted tectonic environment which might be termedLa estructuración tectonomagmática y metamórfica del dominio caledónico europeo sugiere que dos escenarios, compresional y extensional, mutuamente perpendiculares, se desarrollaron durante el Ordovícico-Devónico. Como resultado del esquema compresional del Ordovícico medio (Grampian, caledónico s.s.), en el O de Europa continental se desarrolló una provincia extensional localizada al E de la faja de plegamiento caledónica. Esta situación finalizó hacia el Devónico inferior/medio, cuando la convergencia de América del Norte, Báltica y Gondwana dió origen al supercontinente Pangea. Esta colisión generó un ambiente tectónico caracterizado por: 1. plegamiento y plutonismo en Europa continental occidental, y 2. extensión y volcanismo en la parte N de la faja de plegamiento caledónica (Escocia, SO de Noruega y E de Groenlandia). Este evento puede ser tentativamente denominado «Tardicaledónico». En términos globales, la evolución del dominio caledónico puede ser explicada en términos de «tectónica de inversión» (s.l.), esto es, períodos de adelgazamiento cortical (extensionales) seguidos por períodos de engrosamiento cortical (compresionales) y vicevers

El diseño de un contrato ambiental para las explotaciones ganaderas de extensivo. Estudio aplicado a la Reserva de la Biosfera de las sierras de Béjar y Francia

publishedTomo I . Sección: Sistemas Ganaderos-Economía y Gestión. Sesión: Sostenibilidad. Ponencia nº 3

Giant Magnetoresistance In Cluster-assembled Nanostructures: A Quantitative Approach

In a recent publication [1] we have discussed qualitatively the applicability of commonly used assumptions and models in the description of giant magnetoresistance in granular media by comparing to well-defined cluster-assembled nanostructures of cobalt clusters embedded in copper thin films. In this article we present a quantitative analysis and discuss the relevant parameters appearing in the model. © Published under licence by IOP Publishing Ltd.5211 Region Languedoc-Roussillon,Universite de Perpignan Via DomitiaOyarzún, S., Domingues Tavares De Sa, A., Tuaillon-Combes, J., Tamion, A., Hillion, A., Boisron, O., Mosset, A., Hillenkamp, M., (2013) J. Nanopart. Res., 15 (9), p. 1968. , 10.1007/s11051-013-1968-8 1388-0764Perez, A., Dupuis, V., Tuaillon-Combes, J., Bardotti, L., Prevel, B., Bernstein, E., Melinon, P., Jamet, M., Functionalized cluster-assembled magnetic nanostructures for applications to high integration-density devices (2005) Advanced Engineering Materials, 7 (6), pp. 475-485. , DOI 10.1002/adem.200400220Tamion, A., Hillenkamp, M., Tournus, F., Bonet, E., Dupuis, V., (2009) Appl Phys. Lett., 95 (6), p. 062503. , 10.1063/1.3200950 0003-6951Allia, P., Knobel, M., Tiberto, P., Vinai, F., (1995) Phys. Rev., 52 (21), pp. 15398-15411. , 10.1103/PhysRevB.52.15398 0163-1829 BBatlle, X., Labarta, A., (2002) J. Phys. D: Appl. Phys., 35 (6), pp. 15-R42. , 0022-3727 201Zhang, S., Levy, P.M., (1993) J. Appl. Phys., 73 (10), p. 5315. , 10.1063/1.353766 0021-8979Rubin, S., Holdenried, M., Micklitz, H., (1998) Eur. Phys. J., 5 (1), pp. 23-28. , 10.1007/s100510050414 1434-6028 BTamion, A., Hillenkamp, M., Tournus, F., Bonet, E., Dupuis, V., (2012) Appl. Phys. Lett., 100 (13), p. 136102. , 10.1063/1.3696891 0003-6951Henriquez, R., Cancino, S., Espinosa, A., Flores, M., Hoffmann, T., Kremer, G., Lisoni, J.G., Munoz, R.C., (2010) Phys. Rev., 82 (11), p. 113409. , 10.1103/PhysRevB.82.113409 1098-0121 BHenriquez, R., Moraga, L., Kremer, G., Flores, M., Espinosa, A., Munoz, R.C., (2013) Appl. Phys. Lett., 102 (5), p. 051608. , 10.1063/1.4791600 0003-695

Riboswitch identification using Ligase-Assisted Selection for the Enrichment of Responsive Ribozymes (LigASERR)

In vitro selection of ligand-responsive ribozymes can identify rare, functional sequences from large libraries. While powerful, key caveats of this approach include lengthy and demanding experimental workflows; unpredictable experimental outcomes and unknown functionality of enriched sequences in vivo. To address the first of these limitations we developed Ligase-Assisted Selection for the Enrichment of Responsive Ribozymes (LigASERR). LigASERR is scalable, amenable to automation and requires less time to implement compared to alternative methods. To improve the predictability of experiments, we modelled the underlying selection process, predicting experimental outcomes based on sequence and population parameters. We applied this new methodology and model to the enrichment of a known, in vitro-selected sequence from a bespoke library. Prior to implementing selection, conditions were optimised and target sequence dynamics accurately predicted for the majority of the experiment. In addition to enriching the target sequence, we identified two new, theophylline-activated ribozymes. Notably, all three sequences yielded riboswitches functional in Escherichia coli, suggesting LigASERR and similar in vitro selection methods can be utilised for generating functional riboswitches in this organism

La actividad metalogénica durante el Tardihercínico en el centro de España: una visión desde cinco localidades tipo

The most outstanding metallogenic period in central Spain took place during the so-cal/ed lateHercynian episode. This episode was characterized by widespread extensional conditions resulting from the collapse of an overthickened and overheated Hercynian orogen. A combination of magmatic activity and favorable structures induced hydrothermal activity leading to Sn-W, Pb-Zn, Ag-base metals, base metals-Ba-(F) and Sb-(Au) deposition. Five ore deposits/districts: El Trasquilón (Sn), Linares-La CarolinaTorrecillas (Pb-Zn-Ba-[Ag]), Sierra de Guadarrama (Ba-(F)-[base metals]), El Juncalón (Sb-[Au]), and Hiendelaencina (Ag-base metals) allow characterization of the main geologic features of this metallogenic episode.Depto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEpu

Encapsulation of gold nanostructures and oil-in-water nanocarriers in microgels with biomedical potential

Indexación: Scopus.Funding: This research was funded by FONDECYT 1161450, 1150744, 11130494 and 1170929, FONDEQUIP EQM160157, EQM170111, CONICYT-FONDAP 15130011, and CONICYT PhD Scholarship 21141137.Here we report the incorporation of gold nanostructures (nanospheres or nanorods, functionalized with carboxylate-end PEG) and curcumin oil-in-water (O/W) nanoemulsions (CurNem) into alginate microgels using the dripping technique. While gold nanostructures are promising nanomaterials for photothermal therapy applications, CurNem possess important pharmacological activities as reported here. In this sense, we evaluated the effect of CurNem on cell viability of both cancerous and non-cancerous cell lines (AGS and HEK293T, respectively), demonstrating preferential toxicity in cancer cells and safety for the non-cancerous cells. After incorporating gold nanostructures and CurNem together into the microgels, microstructures with diameters of 220 and 540 µm were obtained. When stimulating microgels with a laser, the plasmon effect promoted a significant rise in the temperature of the medium; the temperature increase was higher for those containing gold nanorods (11–12 ◦ C) than nanospheres (1–2 ◦ C). Interestingly, the incorporation of both nanosystems in the microgels maintains the photothermal properties of the gold nanostructures unmodified and retains with high efficiency the curcumin nanocarriers. We conclude that these results will be of interest to design hydrogel formulations with therapeutic applications. © 2018 by the authors.https://www.mdpi.com/1420-3049/23/5/120

Variations of the Vocal Fold Epithelium in a Menopause Induced Model

During menopause, changes occur in the laryngeal structures that have implications for the voice. The purpose of this study was to determine the effect of induced menopause on the morphological parameters of the vocal fold mucosa in rats. Ten adult female Sprague-Dawley rats were used as samples and divided into two groups: 5 were surgically oophorectomized (OVX), and 5 underwent a surgical procedure similar to oophorectomy but without removal of the ovaries (SHAM). After 30 days surgery, the characteristics of the epithelium that forms the vocal fold mucosa in terms of cellular arrangement and organization of the epithelium were observed. Through the Morphometrics XS software, the epithelial height and the number and density of cellular layers were determined. Our results indicate that there were alterations in the number of cell layers that constitute the epithelium, as well as features, such as cellular cohesion and increased extracellular matrix. The number of cell layers was significantly higher (p<0.01) in the SHAM group with 6.66 (SD 1.07), whereas in the OVX was 3.2 (SD 0.83). The average thickness of the epithelium was 534.71 mm (SD 119.89), whereas in the SHAM group was 486.84 mm (SD 82.95); these differences were not statistically significant (p = 0.112). Changes in the characteristics of the epithelium covering the vocal folds can be related to clinical abnormalities, such as reduced voice quality and degeneration of the vocal folds in postmenopausal women

Analysing the PMIP4-CMIP6 collection: a workflow and tool (pmip_p2fvar_analyzer v1)

Experiment outputs are now available from the Coupled Model Intercomparison Project's sixth phase (CMIP6) and the past climate experiments defined in the Palaeoclimate Modelling Intercomparison Project's fourth phase (PMIP4). All of this output is freely available from the Earth System Grid Federation (ESGF). Yet there is overhead in analysing this resource that may prove complicated or prohibitive. Here we document the steps taken by ourselves to produce ensemble analyses covering past and future simulations. We outline the strategy used to curate, adjust the monthly calendar aggregation and process the information downloaded from the ESGF. The results of these steps were used to perform analysis for several of the initial publications arising from PMIP4. We provide post-processed fields for each simulation, such as climatologies and common measures of variability. Example scripts used to visualise and analyse these fields are provided for several important case studies