HAL Portal ESPCI (Ecole Supérieure de Physique et de Chimie Industrielles)
Not a member yet
13939 research outputs found
Sort by
A Microfluidic Platform for Actin‐Based Membrane Remodeling Reveals the Stabilizing Role of Branched Actin Networks on Lipid Microdomains
No full textInternational audienceCell shape changes, essential for processes such as motility or division, are controlled by the actomyosin cortex that actively remodels biological membranes. Their mechanisms can be deciphered in vitro using biomimetic reconstituted systems, such as giant unilamellar vesicles (GUVs) with controlled lipid composition coupled to reconstituted actin networks. These assays allow mimicking cell shape changes in controlled biochemical and biophysical environments. However, studying the dynamics of these shape changes on statistically significant populations of GUVs with the possibility to sequentially modify the protein composition of the assay is a major experimental challenge. To address these issues, a microfluidic approach is used to immobilize several dozens of isolated GUVs and monitor membrane and actin network evolution. The loading of the chamber with GUVs and actin is first characterized. Then, the actin‐induced remodeling of populations of homogeneous and phase‐separated GUVs is monitored and shows that actin networks prevent the coalescence of lipid microdomains and that, in return, the number of domains affects the actin network structure. This microfluidic‐based experimental strategy, thus, allows for studying actin‐induced membrane deformation in vitro and can be adapted to other studies on membrane remodeling processes
Recent Advances in Synthetic Strategies of Glycans and their Pharmaceutical Applications
No full textInternational audienceThe understanding of glycans, the third life chain, is widely desired. Naturally, the glycoconjugates are found in heterogeneous forms due to the enzyme competition in the same process. As a result, the synthesis of homogeneous glycans has become one of the trending research topics. In this review, orthogonal protection strategies were summarized to overcome the difficulties, such as the numerous hydroxyl groups of oligosaccharides and stereoselectivities during glycosylations. A variety of synthetic glycomics, including glycoproteins, glycolipids, and newly discovered glycoRNAs, were also presented. Their applications were categorized by different diseases, which elucidated the great potential of glycans as drug candidates in the next generation
Synthesis and Biological Evaluation of a New Biphenyl-Based Organogold(III) Complex with In Vitro and In Vivo Anticancer Activity
No full textInternational audienceDespite recent advances in cancer treatment, there is still a need for novel compounds with antineoplastic activity. Among, 11 biphenyl-based organogold(III) N-heterocyclic carbene (BGC) complexes of the general formula [(C^C)Au(NHC-pyr)X], where (C^C) = 4,4'-diterbutylbiphenyl, X = Cl or phenylacetylide, and (NHC-pyr) is a pyridyl-substituted NHC ligand, the complex BGC4 bearing a 4-CF3-pyridyl substituent and a chloride ligand showed promising antineoplastic activity on the triple negative breast cancer cell line. BGC4 was able to induce cell apoptosis but had no effect on the cell cycle. In vivo, BGC4 reduced the tumor growth rate by increasing the necrosis area and decreasing the mitotic activity. Repeated injections of BGC4 did not induce common side effects. The present investigation shows that BGC4 is a promising antineoplastic candidate. Its potential as a future chemotherapy for the treatment of cancer will be strengthened by evaluating its efficacy in combined treatment with current chemotherapy
Convergent iridescence and divergent chemical signals in sympatric sister-species of Amazonian butterflies
No full textInternational audienceClosely-related species are often partitioned into different geographic areas or micro-habitats as a result of competition and reproductive interference. Here, we investigate how the evolution of shared adaptive traits may shape ecological interactions and genetic divergence, and facilitate coexistence in sympatry. In closely-related Morpho butterfly species living in the understory of the neo-tropical rainforest, the blue iridescent coloration of the wings is likely involved in predation evasion as well as in mating recognition and courtship. These contrasted selective pressures acting on this visual trait shared between closely-related species has likely shaped their coexistence. We used spectrophotometry, behavioral experiments, visual modeling and chemical analyses applied to samples from allopatric and sympatric populations of Morpho helenor and Morpho achilles to characterize how the evolution of visual and chemical traits might favor their coexistence in sympatry: we quantified the differences in wing iridescence and tested for variations in the sexual preference for this trait between allopatric vs. sympatric populations. We found a strong similarity in iridescence among species in sympatry, suggesting convergence driven by predation. Although behavioral results suggest that iridescent signals could also be used as visual cues during mate choice, convergent iridescent signals may impair the visual recognition of sympatric Morpho species. In contrast, divergent chemical bouquets among species suggest that the visual similarity of sympatric Morpho species might have favored the divergence of alternative traits involved in species recognition such as chemical cues. This study underlines how ecological interactions and trait evolution can shape species coexistence in sympatry. Significance StatementBy changing the visual aspect of animals in movement, iridescence likely impacts multiple visual interactions within and among species, and might therefore shape ecological interactions and species diversification in sympatry. Here we study the relative importance of predation-driven mimicry and sexual selection on the evolution of iridescence on the wings of sister-species of Morpho butterflies. We finely quantify this conspicuous wing phenotype and used behavioral experiments to test whether the sexual preference for this trait can vary between allopatric and sympatric populations of sister-species. We find that convergent iridescence in sympatric Morpho species, putatively driven by predators and supporting the hypothesis of evasive mimicry, impairs species recognition and could promote the divergence in alternative chemical cues involved in mate discrimination.</div
Characterization of the Orphan Cytochrome P450 CYP135B1 from Mycobacterium tuberculosis : Involvement in Metabolism but Not in the Antibacterial Activity of the Antitubercular Drug SQ109
No full textInternational audienc
De la chrysocolle au cuivre : retracer les savoir-faire des métallurgistes préhispaniques
No full textInternational audienceLes sociétés anciennes de l'Atacama (Chili) ont bénéficié d'abondantes ressources minérales, notamment le cuivre, ce qui a permis le développement autonome d'une métallurgie andine à petite échelle bien avant l'arrivée des Incas. Les zones minières correspondantes sont souvent isolées, situées en haute altitude, avec un climat aride. La colonisation inca de ces régions (XIVe s. ap. J.-C.), va de pair avec une augmentation significative de la production de cuivre. Comment s'est opéré le changement d'échelle de cette production ?En 2015, une cinquantaine de fours de réduction ont été découverts sur les collines entourant le camp de Collahuasi-37, constituant le site de production de cuivre préhispanique le plus important connu pour le nord du Chili. Certains fours ont été fouillés et ont permis de recueillir des marqueurs de ces opérations métallurgiques. Le minerai de cuivre exploité à Collahuasi est composé d'un mélange de chrysocolle, de brochantite et de malachite. Il a été traité dans des fours en forme de banquette, qui étaient ventilés grâce aux vents très puissants soufflant dans la région. Ces fours atteignaient des températures supérieures à 1200°C ; la forme ouverte des foyers indique que les fours opéraient en atmosphère relativement oxydante. Les scories résultantes, riches en silicium, présentent diverses phases minéralogiques, notamment des phases jaunes-vertes-orangées, qui suscitent des interrogations. À la fois riches en cuivre et en silicium, ces scories pourraient être liées à la présence abondante de chrysocolle parmi les minerais utilisés.Cette communication se concentre sur la caractérisation approfondie de la chrysocolle, un silicate de cuivre à la structure atomique controversée car très peu cristallisé. À température ambiante, plusieurs techniques analytiques (PIXE, MEB-EDS et RMN du solide) ont permis de surmonter les défis liés à sa composition chimique variable et à sa structure cristalline désordonnée. La décomposition thermique de la chrysocolle a été étudiée en chauffant plusieurs échantillons à haute température, puis en les caractérisant par microscopie optique, DRX, spectroscopie IR et MEB-EDS. Une étude de DRX in-situ à haute température a également été réalisée sur un échantillon de chrysocolle.Par ailleurs, les résultats obtenus documentent la transformation de la chrysocolle observée dans les scories préhispaniques. Les analyses des scories provenant du site d'Ujina 10, comprenant trois fours datés du Xe au XIVe siècle ap. J.-C. mettent en évidence un traitement pyrométallurgique particulier : la composition chimique de la scorie ne semble pas avoir été optimisée étant donné le très net excédent de silice. Malgré un système chimique très simple, avec seulement deux éléments majoritaires (cuivre et silicium), la composition structurale de la scorie est complexe, ce qui explique que l'extraction du cuivre était si difficile.Malgré le recours à ce procédé peu efficace, il n'y a aucun signe de modification majeure du procédé à la période inca. Pour expliquer le passage à la production à grande échelle, nous posons donc l'hypothèse d'une intensification du mode d'exploitation préexistant, plutôt que d'une recherche d'innovations dans le domaine des techniques métallurgiques
Ripples Induced by Capillary Rise on a Spherical Particle in a Film of Drying Polymer Solution
No full textInternational audienceWe report on the flows associated with the capillary rise occurring when a glass sphere is put into contact with a film of drying polymer solution. A visco-capillary ripple is observed to form at early times and to propagate until it freezes. Its dynamics and final position are in quantitative agreement with those predicted in the frame of the lubrication theory, provided an effective time is introduced, which accounts for the increase in viscosity and decrease in thickness of the drying film. At later times, a secondary ripple forms and we show that its amplitude correlates with the volume of the meniscus. We suggest it results from flows in the drying meniscus, driven by similar effects as in drying droplets and giving way to significant polymer accumulation
Shipping Noise Impact on Blue Mussel
No full textInternational audienceThe global anthropogenic oceanic noise due to shipping is predicted to double every 11.5 years, putting marine organisms at risk. While the impact of noise on marine mammals is well documented, its effect on molluscs, which hold immense economic and ecological importance, remain largely unknown. To investigate the consequences of noise on mollusc metabolism during crucial early life stages, blue mussel larvae were exposed to shipping noise in a laboratory setting until the post-larval stage and their metabolome was analysed. Multivariate analyses of the metabolome showed that shipping noise induces stress-related inflammation with increased energy demand, higher protein turnover, and disrupted nervous system activity. Consequently, noise promoted a delayed metamorphosis in suboptimal habitats with greater metabolic costs, which may impact ecosystem and aquaculture sustainability as competent mussel larvae struggle to select suitable development habitats. Without action to limit underwater noise, such impacts could disrupt population structures and marine biodiversit
Stationary and transient correlations in driven electrolytes
No full textParticle-particle correlation functions in ionic systems control many of their macroscopic properties. In this work, we use stochastic density functional theory to compute these correlations, and then we analyze their long-range behavior. In particular, we study the system's response to a rapid change (quench) in the external electric field. We show that the correlation functions relax diffusively toward the non-equilibrium stationary state and that in a stationary state, they present a universal conical shape. This shape distinguishes this system from systems with short-range interactions, where the correlations have a parabolic shape. We relate this temporal evolution of the correlations to the algebraic relaxation of the total charge current reported previously.</div