Portail HAL du Collège de France
Not a member yet
22122 research outputs found
Sort by
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
Atomic Force Microscopy Reveals Differences In Mechanical Properties Linked To Cortical Structure In Mouse And Human Oocytes
No full textInternational audienceCell mechanical properties regulate biological processes such as oocyte development. Cortical tension is regulated via actomyosin cortex remodeling to ensure optimal oocyte quality. However, the evolution of other mechanical parameters and their relationship with cortex structure remain poorly understood in mammalian oocytes. In this work, a methodology combining multiple mechanical parameters measured through Atomic Force Microscopy is proposed to investigate the relationship between oocyte mechanical properties and cortex organization. By studying mouse oocytes at various stages of development, along with engineered ones with specific cortex organization, it is demonstrated that a thin actin cortex corresponds to stiff oocytes while a thick one is associated with softer oocytes. It is further revealed that maternal age, a critical factor for fertility, affects mouse oocytes mechanics, correlating with alterations in their cortex structure. Finally, it is shown that the evolution of mechanical properties differs between human and mouse oocyte development, highlighting species-specific differences in cortex organization
Histoire et philologie de la Chine classique : Le déclin et la chute des Ming dans la littérature de fiction du XVIIe siècle (3). — I. Le récit vernaculaire et la transmission du savoir sur les événements contemporains : histoire littéraire, approches critiques (3). — II. Écritures et réécritures du récit historique d’actualité : étude des sources, lecture de textes (3)
No full textInternational audienceProgramme de l’année 2023-2024 : Le déclin et la chute des Ming dans la littérature de fiction du XVIIe siècle (3). I. Le récit vernaculaire et la transmission du savoir sur les événements contemporains : histoire littéraire, approches critiques (3). — II. Écritures et réécritures du récit historique d’actualité : étude des sources, lecture de textes (3)
The refractory-to-ice ratio in comet 67P: Implications on the composition of the comet-forming region of the protoplanetary disk
No full textInternational audienceComets, asteroids, and other small bodies are thought to be remnants of the original planetesimal population of the Solar System. As such, their physical, chemical, and isotopic properties hold crucial details on how and where they formed and how they evolved. Yet, placing precise constraints on the formation region of these bodies has been challenging. Data from spacecraft missions have a particularly high potential of addressing the question of the origin of the visited bodies. ESA's Rosetta mission to comet 67P/Churyumov-Gerasimenko returned data from the comet for two years on its journey around the Sun. This extensive data set has revolutionized our view on comets and still holds unsolved problems. Here, we aim to determine comet 67P's bulk elemental composition from Rosetta data, including its refractory-to-ice ratio. We use these results to constrain the temperature in the protoplanetary disk where comets formed and, using a disk model, the formation location. We use the Rosetta/ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) measurement of the volatile/ice composition and the Rosetta/COSIMA (COmetary Secondary Ion Mass Analyzer) measurements of the refractory composition of comet 67P. These measurements are combined using a Monte Carlo method. The refractory-to-ice ratio is a free parameter that is constrained a posteriori. Using only the composition, we constrain the refractory-to-ice ratio to 0.5 < chi < 1.7, and derive the bulk elemental abundances for 67P of H, C, N, O, Na, Mg, Al, S, K, Ar, Ca, Cr, Mn, Fe, Kr, and Xe. We find the noble gas xenon in near solar elemental abundance in comet 67P. Krypton is slightly depleted, while argon is heavily depleted. Comet 67P is enriched in all three noble gases by up to 2.5 orders of magnitude compared to CI chondrites. We show this is consistent with a formation region between 25 and 35 au in a protoplanetary disk region with temperatures between 30 and 40 K and with the trapping of dust for a long time in rings of the protoplanetary disk
The Nine Vehicles of the Central Treasure
No full textInternational audiencePresentation and translation of "The Canon Expounding the Sequence of Vehicles," the root text of the Bonpo system of nine vehicles of spiritual practice according to the traditions of the "Central Treasure," originating with the translator and culture hero Berotsana
Actualités de 2024 en santé du sommeil
No full textInternational audienceRecent studies emphasize sleep as a pivotal public health priority on par with diet and exercise. Global data are limited, but the development of standardized measures (e.g., Sleep Health Index) can help assess population-level sleep duration and quality. Digital tools supported by artificial intelligence now enable personalized behavioral recommendations for improved sleep. Nonetheless, social and environmental factors (including racial and socioeconomic disparities) strongly shape sleep experiences, highlighting the necessity of viewing sleep health through both an individual and collective lens. Integrating technology with broader social initiatives and ensuring equitable access remain paramount in advancing sleep health on a global scale.Des études récentes soulignent l’importance du sommeil comme priorité de santé publique, au même titre que l’alimentation et l’exercice physique. Les données mondiales sont limitées, mais la mise en place de mesures standardisées (par exemple l’Indice de santé du sommeil) peut aider à évaluer la durée et la qualité du sommeil à l’échelle de la population. Les outils numériques, soutenus par l’intelligence artificielle, permettent désormais de formuler des recommandations comportementales personnalisées pour améliorer le sommeil. Néanmoins, les déterminants sociaux et environnementaux (y compris les disparités raciales et socio-économiques) influencent fortement l’expérience du sommeil, soulignant la nécessité d’envisager la santé du sommeil à la fois à l’échelle individuelle et collective. L’intégration de la technologie à de plus vastes initiatives sociales et la garantie d’un accès équitable demeurent primordiales pour faire progresser la santé du sommeil à l’échelle mondiale
