HAL Portal ESPCI (Ecole Supérieure de Physique et de Chimie Industrielles)
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The speed of vaccination rollout and the risk of pathogen adaptation
No full textInternational audienceVaccination is expected to reduce disease prevalence and to halt the spread of epidemics. But pathogen adaptation may erode the efficacy of vaccination and challenge our ability to control disease spread. Here we examine the influence of the speed of vaccination rollout on the overall risk of pathogen adaptation to vaccination. We extend the framework of evolutionary epidemiology theory to account for the different steps leading to adaptation to vaccines: (1) introduction of a vaccine-escape variant by mutation from an endemic wild-type pathogen, (2) invasion of this vaccine-escape variant in spite of the risk of early extinction, (3) spread and, eventually, fixation of the vaccine-escape variant in the pathogen population. We show that the risk of pathogen adaptation is maximal for intermediate speed of vaccination rollout. On the one hand, slower rollout decreases pathogen adaptation because selection is too weak to avoid early extinction of the new variant. On the other hand, faster rollout decreases pathogen adaptation because it reduces the influx of adaptive mutations. Hence, vaccinating faster is recommended to decrease both the number of cases and the likelihood of pathogen adaptation. We also show that pathogen adaptation is driven by its basic reproduction ratio, the efficacy of the vaccine and the effects of the vaccine-escape mutations on pathogen life-history traits. Accounting for the interplay between epidemiology, selection and genetic drift, our work clarifies the influence of vaccination policies on different steps of pathogen adaptation and allows us to anticipate the effects of public-health interventions on pathogen evolution
Abnormal Connectivity of the Head Neural Integrator in Cervical Dystonia
No full textInternational audienceAbstract Background Cervical dystonia is characterized by abnormal neck and head movements, possibly related to a dysfunction of the interstitial nucleus of Cajal (INC) and the head neural integrator, a system responsible for the control of head and eye movements. However, neuroanatomical evidence of alterations in the head neural integrator in cervical dystonia is sparse. Objectives We investigated structural and functional integrity of the INC and its connections in cervical dystonia. Methods This cross‐sectional, observational study compared 19 cervical dystonia patients and 21 healthy controls, using anatomical, diffusion‐weighted, and resting‐state functional images. We reconstructed tracts converging on the INC, and involved in the control of head movements. We evaluated group differences in microstructural integrity using fixel‐based analysis, and effective connectivity using dynamic causal modeling. Results Compared with controls, patients showed microstructural abnormalities within the INC and cerebral peduncle. Effective connectivity showed abnormal self‐inhibition in the INC, substantia nigra, and vermis in patients, with decreased excitation from the substantia nigra to the INC, increased inhibition from the deep cerebellar nuclei and primary sensorimotor cortex, and decreased excitation from the INC to the cerebellar vermis. Conclusions A dysfunction of the INC might contribute to altered sensorimotor integration in cervical dystonia, and abnormal feedback from its afferent connections could alter its integrative function, resulting in a disturbed head and neck posture. © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society
Catalytic Oxygen Atom Transfer Through Photochemical and Electrochemical Activation of O<sub>2</sub> or H<sub>2</sub>O
No full textInternational audienceChemical transformations involving oxygen atom transfer (OAT) to organic substrates attract significant interest across industrial, pharmaceutical, and fundamental chemical research, including areas such as bioinorganic chemistry, catalysis, and synthetic methodology. Recent advances in electrochemical and photochemical catalysis have opened up new pathways for enabling OAT processes, particularly through the reductive activation of dioxygen or oxidative activation of water. This minireview explores emerging approaches in the field, including electrocatalytic methods leveraging bioinspired transition metal complexes, photocatalytic platforms integrating catalysts with photosensitizers, photoactive materials, or organic photocatalysts, and hybrid methodologies combining electrochemical and photochemical activation. We outline future directions for innovation, ranging from the design of functional molecular architectures and device engineering to the development of scalable technologies for industrial applications
PSL Chemical Biology Symposia: The Increasing Impact of Chemistry in Life Sciences
No full textInternational audienceThis symposium is the 6th Paris Sciences & Lettres (PSL) Chemical Biology meeting (2015, 2016, 2019, 2023, 2024, 2025) being held at Institut Curie. This initiative originally started in 2013 at Institut de Chimie des Substances Naturelles (ICSN) in Gif‐sur‐Yvette and was mostly focused on organic synthesis. It was then exported at Institut Curie to cover a larger scope, before becoming the official French Chemical Biology meeting. This year, around 200 participants had the opportunity to meet world leaders in chemistry and biology who described their latest innovations and future trends covering topics as diverse as prebiotic chemistry, activity‐based protein profiling, high‐resolution cell imaging, nanotechnologies, bio‐orthogonal chemistry, metal ion signaling, ferroptosis, and biocatalysis
Illumination optimization and low-power trapping of Limnospira indica PCC 8005 using bulk acoustic waves in microgravity
No full textSpace missions require sustainable life support systems capable of producing oxygen and biomass under microgravity. We report the use of acoustic levitation to trap and manipulate the filamentous cyanobacterium Limnospira indica PCC 8005 during parabolic flights. Within a millimeter-scale fluidic chamber, this helical microorganism rapidly assembles into thin layers under a standing ultrasonic wave. Stable trapping in microgravity requires substantially less acoustic power (0.42 mW) than on Earth (1.4 mW), highlighting the potential for energy-efficient bioprocessing in space. Monte Carlo simulations and light attenuation modelling show that layered structuring enhances light penetration, potentially overcoming the “compensation point” limitation in bulk cultures. These findings open new perspectives for photobioreactors using acoustic manipulation to boost photosynthetic efficiency and reduce energy demands for oxygen and biomass production in space
Gelatin Thin Coatings Covalently Cross-Linked and Grafted on Model Plane Substrates and Surgical Implant Fibers
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The Baldwin Effect Reloaded: Intermediate Levels of Phenotypic Plasticity Favor Evolutionary Rescue
No full textInternational audienceAbstract Since the late 1890s and until today, how phenotypic plasticity interacts with genetic adaptation is a debated issue. Proponents of a positive causal role of phenotypic plasticity –James M. Bald-win in the first place– supported the view that, in altered environmental conditions, phenotypic plasticity is a key factor allowing a population to avoid extinction and then genetic evolution to catch up (“Original Baldwin Effect”, thereafter OBE). Opponents, like for instance Ernst Mayr, regularly pointed out that phenotypic plasticity, by masking genetic variation, slows gene-level evolution (“Mayr Effect”, thereafter ME). For decades this opposition remained only verbal and qualitative. To resolve it, we propose here a stochastic model that, following Baldwin’s intuitive take, combines the minimal number of ingredients to account for extinction, selection, mutation and plasticity. We study evolutionary rescue of the population (arrival and invasion of an adaptive genetic mutant) in the altered environment for different values of phenotypic plasticity, here quantified as the probability p that the maladapted genotype develops into the adapted phenotype. Our claim is that OBE can be a genuine evolutionary mechanism, depending on the level of phenotypic plasticity with respect to a threshold value p ⋆ : when p < p ⋆ , increasing p promotes evolutionary rescue by delaying extinction (“Strong” OBE); when p > p ⋆ , plasticity sustains population survival and increasing p has two antagonistic effects: to accelerate adaptation by increasing the supply of adaptive mutants (“Weak” OBE, intermediate values of p ), and to slow down adaptation by decreasing their fitness advantage (ME, high values of p )
Rheological response of soft Solid/Liquid Composites
No full textInternational audienceUnderstanding a material's dissipative response is important for their use in many applications, such as adhesion or fracture resistance. In dispersions, the interplay between matrix and inclusions complicates any description. Fractional rheology is conveniently used to fit the storage and loss moduli of complex materials. In conjugation with superposition methods, they allow to better capture the behavior of materials of complex rheology.We study the rheology of soft solid/liquid composites of liquid poly(ethylene glycol) (PEG) droplets in a soft poly(dimethylsiloxane) (PDMS) matrix. We analyze the influence of the droplets through fractional rheology and a time-concentration superposition in the continuous-phase-dominated region. Viscous dissipation increases proportionally with volume fraction, independently of the frequency, whereas the elastic response is almost unchanged
Tuning the Diameter of Supramolecular Nanocylinders: Balancing Long and Short Polymer Arms for Optimized Self‐Assembly
No full textInternational audienceNanocylinders find applications in biology, catalysis, and material science due to their high aspect ratio and nanometric diameter, granting them a high specific area. They can be formed by supramolecular assembly in solution of polymers decorated by stickers promoting directional assembly. Controlling the dimensions of nanocylinders impacts their applicative properties. Many strategies exist to tune their length, but much fewer to tune their diameter. We address this point here by synthesizing water‐soluble polymers of different lengths end‐functionalized by hydrogen bonding tris(urea) stickers. It is shown through a combination of light/neutron scattering experiments and cryo‐transmission electron microscopy that short polymer arms (DP ≤ 80) produce thin (d = 10 nm) and long (L > 500 nm) nanocylinders, whereas longer polymer arms (DP ≥ 500), required to significantly increase d, inhibit self‐assembly due to the strong entropic penalty caused by their stretching. A compromise to control d is to mix a few long arms, which increase d, with a sufficient amount of short arms, which alleviate the entropic penalty and maintain high L. This approach proposes a straightforward way to tune the specific area of nanocylinders—a key parameter for applications in catalysis, emulsion stabilization, or interactions with biological materials
Unveiling photoinduced electron transfers in photosensitized polyoxometalates for solar energy conversion
No full textInternational audienceArtificial photosynthesis faces the challenge of developing visible-light-driven strategies for converting and storing solar energy in the form of fuels and high-value chemicals. In such an approach, selective fuel production often depends on the accumulation of multiple electrons at a catalytic site. However, this process is constrained by the rapid recombination of photogenerated charges and the inherently slow kinetics of multi-electron catalytic reactions, which hinder efficient charge buildup and utilization. Polyoxometalates (POMs), a tunable class of nanoscale metal oxides, have emerged as promising multi-electron acceptors due to their redox versatility and stability. Their electron storage capabilities make them attractive as both reservoirs and catalysts. In most cases, their UV-limited absorption necessitates pairing of the POM with visible-light-absorbing antennas. Advances in photosensitized POM derivatives—via electrostatic assembly, covalent bonding, or band-gap engineering—are herein detailed. Covalent hybrids, in particular, allow precise control over electron transfer. Still, a detailed understanding of photoinduced electron transfer kinetics remains limited. This perspective article explores the potential applications of POMs in solar fuel generation, emphasizing the need for kinetic insight to design efficient, visible-light-driven photocatalysts and photoelectrochemical devices