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Vegetation and climate changes at the Early-Late Pliocene Transition around the Mediterranean basin: A case from the Burdur Basin in Southwestern Anatolia
No full textInternational audienceThe Pliocene (5.33-2.58 Ma), particularly the Early-Late Pliocene transition (~3.6 Ma), is a key period for understanding future climate change linked to increases in greenhouse gases. Around the Western Mediterranean Basin, the Early-Late Pliocene transition was marked by the establishment of a Mediterranean 20 climate with summer droughts, cool/wet winters and latitudinal gradients. However, environmental changes in the eastern part of the Mediterranean area during the Early-Late Pliocene transition have rarely been documented.Here, we propose to reconstruct the environmental and climate changes during the Early-Late Pliocene transition from the Lake Burdur sequence, located in Southwestern Türkiye. The aim of this study is to characterize the vegetation, lake dynamics, and water level changes based on pollen and Non-Pollen Palynomorph (NPP) proxies, 25 to quantitatively reconstruct climate changes using a multimethod approach (Modern Analogue Technique, Weighted Averaging Partial Least Squares regression, Random Forest, and Boosted Regression Trees and Climatic Amplitude Method) and morphologically characterize the large pollen grains of Poaceae (Cerealia-type). The results indicate that, during the Early-Late Pliocene transition at Burdur, the vegetation was dominated by steppes with Poaceae, Artemisia, and Amaranthaceae. Subsequently, arboreal taxa decreased and a 30 alternation between steppe grasslands with deciduous Quercus and steppes dominated by Amaranthaceae became evident. Large Poaceae pollen grains (Cerealia-type) are recorded in the Burdur sequence, but their percentages are lower than those at Acıgöl, a nearby record dated to the Pleistocene. The morphological characteristics of these large Poaceae pollen grains from Burdur are similar to those of domesticated cereals from recent periods, preventing a clear distinction between wild and domesticated Poaceae pollen. The lacustrine ecosystem was 35 characterized by semi-aquatic vegetation and freshwater algae, exhibiting alternating oligotrophic and eutrophic conditions. Climate reconstructions of Burdur show similar trends across different methods, with reconstructed values during the Early-Late transition being close to present-day values. Following a climatic optimum in precipitation and temperature, climate reconstructions indicate an alternation between cool, wet conditions and warmer, drier conditions during the Late Pliocene in Southwestern Anatolia. Around the Mediterranean Basin, 40 climate reconstructions during the Early Pliocene show warmer conditions compared to modern values and a northsouth gradient in terms of precipitation, with wetter conditions in the north in comparison to the south
PCR Milieu et Peuplement en Languedoc occidental du Néolithique au Bronze ancien, Quatrième période triennale 2023-2025: Rapport de l'année 2025
No full textLe Projet Collectif de Recherche (PCR) « Milieu et peuplement en Languedoc occidental du Néolithique au Bronze ancien » vise à explorer les dynamiques d’anthropisation, de l’émergence des premières communautés agropastorales au développement des sociétés protohistoriques. Ancré dans le territoire du Languedoc central et occidental, ce projet s’appuie sur les fouilles préventives et programmées, et s’attache à publier des données inédites alimentant cette réflexion de fond. L’abondance des données récentes, couplée à des méthodes analytiques innovantes, offre un regard renouvelé sur les modes d’occupation des territoires. En croisant les résultats des fouilles récentes et des données issues d’anciennes opérations, ce PCR ambitionne de caractériser l’évolution des sociétés préhistoriques, leurs interactions avec leur milieu naturel et les impacts progressifs de l’anthropisation. Ce projet, fédérant une trentaine de chercheurs issus d’institutions variées (Inrap, CNRS, universités, collectivités, secteur privé), s’inscrit dans une démarche interdisciplinaire. Il associe notamment archéologie, anthropologie, géomorphologie, paléogénétique ou encore analyses pétrographiques pour reconstituer les paysages anciens, les différentes traditions techniques et culturelles et les stratégies des réseaux d’approvisionnement et d’exploitation des milieux. Ce rapport est celui de l'année 2025
Paleohydrological reconstructions from lake and wetland sediment archives of southwest Asia, investigating the links between climate changes, land use and water management strategies
No full textInternational audienceMultimillennial reconstructions of hydrological variability in the semi-arid regions ofSouthwest Asia are essential for placing modern water stress and the impacts of climatechange within a natural, long-term context. Beyond natural variability, understanding ancientwater management techniques and their interaction with hydrological networks is alsocrucial for addressing current and future water scarcity. This contribution will lift the numerousmultiproxy studies (especially sedimentology, geochemistry, chironomids, and palynology)carried out on lake and spring-fed wetland sedimentary archives of Iran over thelast 20 years (i.e. Lake Maharlou, Lake Alvan, Gomban wetland, Rouzian wetland, Gahakwetland...) to investigate the links between past hydrological changes, agro-sylvo-pastoralpractices, and water management techniques, particularly at three key moments of the humanhistory: (i) the Neolithic transition, (ii) the Achaemenid and Sasanian imperial transformations,and (iii) the Medieval Climate Anomaly-Little Ice Age transition
Les Goths sur la côte sud de la Crimée du IVe au VIIIe siècle et les fouilles récentes à Gorzouvites.
No full textInternational audienceThe most ancient Germanie findings on the southern coast of Crimea are dated back to the late Roman period (the necropoleis of Ay-Todor and Chatyr-Dag). However, the Goths are attested by written sources only from the sixth century. We know that, at the time of Justinian, these Goths were allied with the Eastern Roman Empire andwere Orthodox Christians. We know, thanks to Procopius of Caesarea, that the empire erected two fortresses on the coast, as strongholds of Byzantine power: this same Gorzuvites and Alouston ( today's Gurzuf and Alushta). Recent salvage excavations carried out by the Institute of Archaeology of the Russian Academy of Sciences in the first of these sites have revealed a medieval settlement ( with a church and a necropolis) of the seventh-thirteenthcenturies. This site has all the typical features of the Byzantine civilization, in its material culture, its funerary customs, and its architecture. This testifies to the 'Byzantinization' and deep Christianization of the Goths in Crimea during the seventh and eighth centuries.Les découvertes germaniques les plus anciennes sur la côte sud de la Crimée remontent à la fin de la période romaine (nécropole d'Ay-Todor et Chatyr-Dag). Cependant, les Goths ne sont attestés par des sources écrites qu'à partir du VIe siècle. Nous savons qu'à l'époque de Justinien, ces Goths étaient alliés à l'Empire romain d'Orient et qu 'ils étaient des chrétiens orthodoxes. Nous savons, grâce à Procope de Césarée, que l'Empire érigea deux forteresses sur la côte, comme bastions du pouvoir byzantin : la même Gorzuvites et Alouston (aujourd'hui Gourzouf et Alouchta). Des fouilles récentes menées par l'Institut d'archéologie de l'Académie des Sciences de Russie dans le premier des deux sites ont révélé une agglomération médiévale (avec une église et une nécropole) des VIIe-XIIIe siècles. Ce site présente tous les traits typiques de la civilisation byzantine, dans sa culture matérielle, ses coutumes funéraires et son architecture. Cela témoigne de la « byzantinisation » et de la profonde christianisation des Goths en Crimée au cours des VIIe et VIIIe s
Châtelperronian cultural diversity at its western limits: Shell beads and pigments from La Roche-à-Pierrot, Saint-Césaire
No full textInternational audienceThe timing and mechanisms underlying the gradual replacement of Neanderthal populations by Homo sapiens groups have elicited heated debate for decades. The Châtelperronian of France and northern Spain has figured prominently in these discussions. While the Neanderthal authorship of this techno-complex is far less certain than previously thought, the Châtelperronian is now generally accepted as being among the first genuine Upper Paleolithic industries in Eurasia rather than a \"transitional\" stone tool technology. Here, we report the first association of shell beads with Châtelperronian artifacts from new excavations at the site of La-Roche-à-Pierrot, Saint-Césaire (France), supported by a multiproxy spatial analysis that incorporates site formation processes. Similar types of personal ornaments are unknown from Middle Paleolithic contexts. Comparable examples have, however, been recovered from contexts penecontemporaneous with the Châtelperronian in south-eastern Europe and around the Mediterranean. This hitherto undocumented combination of an early Upper Paleolithic industry and shell beads provides insights into cultural variability in western Europe and raises the question as to whether the makers of the Châtelperronian were influenced by or formed part of the earliest dispersals of H. sapiens into the region
Consciousness and the Cogito: The Huet/Regis controversy
No full textInternational audienceThis chapter examines the debate between the Cartesian Pierre-Sylvain Régis and the fierce critic of Cartesian philosophy, bishop Pierre-Daniel Huet, on the Cogito. A widely accepted thesis among the Cartesians is that consciousness is distinct from reflection. Consciousness involves only one thing: the thought that presents itself to the mind. But reflection (i.e., thought about thought) is a form of representation, and representation always involves two things. On that basis, Huet argued that the subject who thinks cannot reflect on his own thought without changing what he is thinking about, thereby making the Cogito impossible. The chapter argues that Régis’ attempt to answer this challenge (by arguing that the Cogito is not an instance of reflection but a mere expression of consciousness) ultimately fails. Answering Huet’s challenge seems to require acknowledging the self-referential character of the reflective thought involved in Cogito ; however, this appears to be incompatible with the claim that the reflective thought in question makes consciousness explicit and is, therefore, continuous with it. The chapter elaborates on a position that finds support from Descartes’ works, which qualifies the self-referentiality involved in the Cogito in a way that preserves the necessary continuity between consciousness and reflection
Investigating the bulge morphology of dual AGN host galaxies from the gothic survey
No full textInternational audienceWe present a structural analysis of bulges in dual active galactic nuclei (AGNs) host galaxies. Dual AGNs arise in galaxy mergers where both supermassive black holes are actively accreting. The AGNs are typically embedded in compact bulges, which appear as luminous nuclei in optical images. Galaxy mergers can result in bulge growth, often via star formation. The bulges can be discy (pseudo-bulges), classical bulges, or belong to elliptical galaxies. Using Sloan Digital Sky Survey Data Release 18 gri images and galfit modelling, we performed 2D decomposition for 131 dual AGNs bulges (comprising 61 galaxy pairs and 3 galaxy triplets) identified in the gothic survey. We derived Sérsic indices, luminosities, masses, and scale lengths of the bulges. Most bulges (105/131) are classical, with Sérsic indices lying between and . Among these, 64 per cent are elliptical galaxies, while the remainder are classical bulges in disc galaxies. Only per cent of the sample exhibits pseudo-bulges. Bulge masses span to , with the most massive systems being ellipticals. Galaxy-type matching shows that elliptical–elliptical and elliptical–disc mergers dominate over disc–disc mergers. At least one galaxy in two-thirds of the dual AGN systems is elliptical and only per cent involve two disc galaxies. Although our sample is limited, our results suggest that dual AGNs preferentially occur in evolved, red, quenched systems, which typically form via major mergers. They are predominantly hosted in classical bulges or elliptical galaxies rather than star-forming disc galaxies
Suivi de la plasticité cortico-striatale lors de la transition d’un comportement dirigé vers un but vers des stratégies habituelles
No full textThe aim of this PhD project was to better understand how learning-related plasticity emerges and evolves within the dorsal striatum during the acquisition of new skills. Motivated by this goal, we developed a novel behavioral paradigm to investigate the neural mechanisms underlying procedural learning by longitudinally tracking synaptic plasticity in corticostriatal circuits. Through head-fixed mice performing a self-paced task, combined with chronic in vivo recordings of Channelrhodopsin-2 evoked local field potentials (ChR2-eLFPs), we revealed a distinct spatial and temporal dissociation of plasticity within the dorsal striatum. Specifically, the dorsolateral striatum (DLS) displayed robust and sustained long-term potentiation (LTP) of cortical inputs across training, whereas the dorsomedial striatum (DMS) showed either stable responses or a gradual decline consistent with long-term depression. These opposing dynamics may not be purely epiphenomenal but also functionally significant: applying low-frequency stimulation to disrupt DLS-LTP appeared to impair both synaptic potentiation and behavioral performance, suggesting a possible contribution of DLS plasticity to skill acquisition and consolidation. Interestingly, following more detailed behavioral and correlation analyses, mice showing LTD in the DMS were among the best performers, supporting a framework in which DMS-LTD helps refine goal-directed behavior by suppressing outdated strategies and facilitating behavioral consistency. Whether animals develop automatic or habitual strategies during learning remains an open question, currently under investigation through more detailed behavioral analyses. Classical reward devaluation tests, commonly used to assess habitual control, have proven only partially informative in our task, likely due to high interindividual variability. To better characterize behavioral strategies, ongoing work combines refined behavioral metrics with dopamine fiber photometry aligned to licking behavior, which may offer a complementary approach to identify and cluster distinct learning profiles in mice.Altogether, these findings suggest a model in which procedural learning may involve region-specific and temporally distinct forms of corticostriatal plasticity, with DMS-LTD potentially contributing to the refinement of goal-directed behavior and DLS-LTP supporting the emergence of automaticity. This mechanistic dissociation enhances our understanding of how complex actions are acquired, consolidated, and optimized through dynamic cortical-striatal interactions.L’objectif de ce projet de thèse était de mieux comprendre comment la plasticité liée à l’apprentissage émerge et évolue au sein du striatum dorsal lors de l’acquisition de nouvelles compétences. Motivés par ce but, nous avons développé un nouveau paradigme comportemental afin d’étudier les mécanismes neuronaux sous-jacents à l’apprentissage procédural en suivant longitudinalement la plasticité synaptique dans les circuits corticostriataux. En entraînant des souris dans un dispositif qui les maintient par la tête à réaliser une tâche auto-initiée, et en combinant cela à des enregistrements in vivo chroniques de potentiels locaux évoqués par optogénétique (opto-eLFPs), nous avons mis en lumière une dissociation claire, à la fois spatiale et temporelle, de la plasticité au sein du striatum dorsal. Plus précisément, le striatum dorsolatéral (DLS) présent une potentialisation à long terme (LTP) robuste et soutenue des entrées corticales tout au long de l’entraînement, tandis que le striatum dorsomédial (DMS) montre soit des réponses stables, soit un déclin progressif cohérent avec une dépression à long terme (LTD). Ces dynamiques opposées ne sont probablement pas de simples épiphénomènes mais pourraient avoir une signification fonctionnelle : l’application d’une stimulation basse fréquence (LFS) pour perturber la LTP dans le DLS semble altérer à la fois la potentialisation synaptique et la performance comportementale, suggérant une possible contribution de la plasticité du DLS à l’acquisition et à la consolidation des compétences. Remarquablement, à la suite d’analyses comportementales et de corrélations plus détaillées, les souris montrant une LTD dans le DMS figuraient parmi les plus performantes, ce qui soutient un cadre dans lequel la LTD du DMS contribue à affiner le comportement orienté vers un but. La question de savoir si les animaux adoptent des stratégies automatiques au cours de l’apprentissage reste encore ouverte. Les tests classiques de dévaluation de la récompense, souvent utilisés pour évaluer l’émergence d’automatisme, se sont révélés peu informatifs dans notre paradigme comportemental en raison d’une importante variabilité interindividuelle des souris. Afin de mieux caractériser les stratégies comportementales, les travaux en cours associent les différents paramètres comportementaux à de la photométrie mesurant la dopamine. Cette approche pourrait permettre d’identifier et de regrouper différents profils d’apprentissage chez la souris. Dans l’ensemble, ces résultats appuient un modèle selon lequel l’apprentissage procédural repose sur des formes de plasticité corticostriatale à la fois spécifiques à certaines régions et distinctes dans le temps : la LTD dans le DMS contribuerait à affiner le comportement orienté vers un but, tandis que la LTP dans le DLS favoriserait l’émergence de l’automaticité. Cette dissociation fonctionnelle enrichit notre compréhension des processus par lesquels des actions complexes sont acquises, consolidées et optimisées au travers d’interactions dynamiques entre cortex et striatum
A pre-loaded and assembled human Ago2-miRISC orchestrates Shigella -induced vacuolar rupture through the targeting of RhoGDIα
No full textPosted April 24, 2025 on bioRxiv.International audienceThe enteroinvasive bacterium Shigella flexneri causes bacillary dysentery. It invades intestinal epithelial cells and forms a bacterium-containing vacuole, which it rapidly ruptures to reach the cytosol. Here, we found that human Argonaute 2 (Ago2), the central component of miRNA-induced silencing complex (miRISC), positively regulates early steps of Shigella infection, including vacuolar rupture. This is consistent with the rapid recruitment of Ago2 at Shigella entry foci. The ability of Ago2 to form an assembled miRISC was found required for vacuolar maturation, while its slicer activity is dispensable for this process. Furthermore, we found that the RhoGTPase inhibitor RhoGDIα is targeted by specific miRNAs, pre-loaded in Ago2, which, collectively, accelerate vacuolar rupture. Therefore, a pre-loaded and assembled Ago2-miRISC orchestrates vacuolar maturation by targeting RhoGDIα. These findings may have wider implications in the understanding of how stored Ago2-loaded miRNAs control immediate steps of infection, prior to the differential expression of microbe-responsive miRNAs