HAL Portal ESPCI (Ecole Supérieure de Physique et de Chimie Industrielles)
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Coupled quartz crystal microbalance – Surface enhanced Raman scattering strategy for the design and testing of aptasensors for small analytes
No full textInternational audienceBoth quartz crystal microbalance with dissipation (QCM-D) and Surface Enhanced Raman Scattering (SERS) stand at the forefront of label-free transducing techniques to trace and monitor biomolecular association events occurring at solid-liquid interfaces. Although these techniques provide highly complementary information on thin films' structure and molecular composition, they have never been simultaneously coupled in a single sensor element. We report herein the design of nanostructured gold-coated quartz crystal sensors acting as bimodal transducer elements to subsequentially or even in parallel and in situ monitor biomolecular recognition events by QCM-D and SERS. As a proof-of-concept, this bimodal sensor was applied to investigate the interaction between a chemisorbed DNA aptamer and a small molecule target, the antibiotic streptomycin. Combined QCM-D and SERS measurements provided evidence of successful engineering of the aptamer sensing layer as well as thermodynamic and structural information on the subsequent binding of streptomycin. QCM-D data enabled the measurement of a dissociation constant KD of 23±4 nM for the binding of streptomycin to the aptamer with a number of binding sites roughly equal to one. SERS data confirmed the conformational change of the aptamer upon interaction with streptomycin and indicated the nucleotides possibly involved in its recognition
Drift, diffusion and divergence
No full textInternational audienceTurbulent Taylor-Couette flow displays traces of axisymmetric Taylor vortices even at high Reynolds numbers. With this motivation, Feldmann & Avila (2025) J. Fluid Mech, 1008, R1, carry out long-time numerical simulations of axisymmetric high-Reynolds-number Taylor-Couette flow. They find that the Taylor vortices, using the only degree of freedom that remains available to them, carry out Brownian motion in the axial direction, with a diffusion constant that diverges as the number of rolls is reduced below a critical value
An experimental review of the reaction paths followed by alkali-activated slag pastes
No full textInternational audienceNMR, XRD, mechanical strength measurements, bound water quantification and isothermal calorimetry were combined to contrast the degree of reaction and the paths followed by slag under the influence of three activators: NaOH, Na2CO3, and Na2Si1.7O4.4. NaOHactivation led to the concomitant formation of a very ordered C-A-S-H gel and of hydrotalcite, giving rise to early mechanical strength. For Na2Si1.7O4.4, a N-A-S-H gel formed first due to the high quantities of silicon in solution. This led to quick setting but no mechanical strength. Later, an amorphous C-A-S-H gel provided mechanical strength, while an aluminate phase precipitated. Finally, Na2CO3-activation also led to the formation of N-A-S-H, formation favored by the initial consumption of calcium to form calcite. This did not bring any real structuration and mechanical strength. Only after a few days of hydration did the mechanical strength improve with the precipitation of amorphous C-A-S-H, an ill-defined hydrated aluminate phase, and of gaylussite
Transient Supramolecular Polymers by pH‐Gated Conformational Control of a Self‐Assembling Cyclodextrin
No full textInternational audienceLinking a cyclodextrin (CD) host to a hydrophobic guest can result in two distinct conformations: an introverted form (in), in which the guest is self‐included within the CD cavity, and an extraverted form (out), which enables intermolecular interactions and thus the formation of a supramolecular polymer. In this study, we demonstrate that a subtle variation of the linker enables interconversion between these two conformations, the in conformer being thermodynamically the most stable in water. At basic pH (>8) the out conformer is instantly converted into the in. In contrast, at acidic pH (<2), the out monomer can be kinetically trapped and can self‐assemble into a supramolecular polymer. DFT calculations reveal that the interconversion mechanism is governed by a key hydrogen bond that locks the conformational states. Furthermore, we show that pH provides fine kinetic control over the interconversion rate and, consequently, the polymerization process. The system can then be reset toward the out conformation by using DMSO. This system stands in contrast to known transient supramolecular polymerization processes, which rely on metastable (non‐assembled) monomers. Here, it is the kinetic trapping of the assembling monomer that allows control over the lifetime of the transient supramolecular polymer via a pH‐responsive mechanism
Hsc70-4: An unanticipated mediator of dsRNA internalization in Drosophila
No full textInternational audienceThe small interfering RNA pathway is the primary antiviral defense mechanism in invertebrates and plants. This systemic mechanism relies on the recognition, transport, and internalization of double-stranded RNA (dsRNA). Our aim was to identify cell surface proteins that bind extracellular dsRNA and mediate its internalization in Drosophila cells. We used coimmunoprecipitation coupled with proteomics analysis and found that silencing heat shock cognate protein 70-4 (Hsc70-4), a constitutively expressed heat shock protein, impairs dsRNA internalization. Unexpectedly, despite lacking a predicted transmembrane domain, Hsc70-4 localizes to the cell membrane via lipid interactions. Antibody blocking experiments revealed an extracellular domain on Hsc70-4 that is essential for dsRNA internalization. Intriguingly, this dsRNA-specific binding capacity of Hsc70-4 functions independently of its chaperone activity. These findings not only highlight Hsc70-4 as a previously uncharacterized and essential component in the dsRNA internalization process but also offer promising insights for advancing RNA interference–based technologies to combat pests and vector-borne diseases
Nuclear Calcium Signaling in D1 Receptor–Expressing Neurons of the Nucleus Accumbens Regulates Molecular, Cellular, and Behavioral Adaptations to Cocaine
No full textInternational audienceBackground: The persistence of cocaine-evoked adaptations relies on gene regulations within the reward circuit, especially in the ventral striatum (i.e., nucleus accumbens [NAc]). Notably, activation of the ERK (extracellular signal-regulated kinase) pathway in the striatum is known to trigger a transcriptional program shaping long-term responses to cocaine. Nuclear calcium signaling has also been shown to control multiple forms of transcription-dependent neuroadaptations, but the dynamics and roles of striatal nuclear calcium signaling in preclinical models of addiction remain unknown.Methods: A genetically encoded cell type-specific nuclear calcium probe has been developed to monitor calcium dynamics in the nuclei of striatal neurons, including in freely moving mice. A cell type-specific inhibitor of nuclear calcium signaling combined with 3-dimensional imaging of neuronal morphology, immunostaining, and behavior was used to disentangle the roles of nuclear calcium in NAc medium spiny neurons (MSNs) expressing the dopamine D1 receptor (D1R) or D2 receptor (D2R) on cocaine-evoked responses.Results: The D1R-mediated potentiation of calcium influx through glutamate NMDA receptors, which shapes cocaine effects, also drives nuclear calcium transients. Fiber photometry revealed that cocaine-treated mice showed a sustained nuclear calcium increase in NAc D1R-MSNs. Disrupting nuclear calcium in D1R-MSNs, but not D2R-MSNs, blocked cocaine-evoked morphological changes of MSNs and gene expression and blunted cocaine's rewarding effects.Conclusions: Our study unravels the dynamics and roles of cocaine-induced nuclear calcium signaling increases in D1R-MSNs on molecular, cellular, and behavioral adaptations to cocaine and represents a significant breakthrough because it could contribute to the development of innovative strategies with therapeutic potential to alleviate addiction symptoms
Physiological effects of nasal high flow therapy during exercise in patients with chronic obstructive pulmonary disease: A crossover randomised controlled trial
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Ebsolve - Solving the matrix transport equation for the transmission eigenvalue distribution in a disordered waveguide
No full textEbsolve is a Fortran 2008 program to solve the matrix transport equation of radiant field theory (D. Gaspard and A. Goetschy, arXiv:2411.10360 [math-ph], arXiv:2411.10355 [math-ph]) in a rectilinear waveguide geometry. The solution of this equation provides the distribution function of transmission eigenvalues through a disordered waveguide
Unveiling conserved HIV-1 open reading frames encoding T cell antigens using ribosome profiling
No full textInternational audienceThe development of ribosomal profiling (Riboseq) revealed the immense coding capacity of human and viral genomes. Here, we used Riboseq to delineate the translatome of HIV-1 in infected CD4+ T cells. In addition to canonical viral protein coding sequences (CDSs), we identify 98 alternative open reading frames (ARFs), corresponding to small Open Reading Frames (sORFs) that are distributed across the HIV genome including the UTR regions. Using a database of HIV genomes, we observe that most ARF amino-acid sequences are likely conserved among clade B and C of HIV-1, with 8 ARF-encoded amino-acid sequences being more conserved than the overlapping CDSs. Using T cell-based assays and mass spectrometry-based immunopeptidomics, we demonstrate that ARFs encode viral polypeptides. In the blood of people living with HIV, ARF-derived peptides elicit potent poly-functional T cell responses mediated by both CD4+ and CD8+ T cells. Our discovery expands the list of conserved viral polypeptides that are targets for vaccination strategies and might reveal the existence of viral microproteins or pseudogenes