Évolution des paysages et occupation humaine en mer d’Iroise (Finistère, Bretagne) du Néolithique à l’Âge du Bronze

Depuis près de dix ans, des recherches archéologiques sont menées dans l’archipel de Molène par une équipe pluridisciplinaire. Ce secteur s’avère particulièrement riche en vestiges du Néolithique et de l’Âge du Bronze. Une concentration exceptionnelle de monuments mégalithiques y a été mise en évidence. Plusieurs habitats sont attestés par la présence d’un bâtiment (Beg ar Loued, Molène) ou de dépotoirs domestiques riches en faune et en mobilier. Ces données nous renseignent sur la chronologie des occupations du secteur et nous permettent, pour la première fois en Bretagne, d’esquisser le mode de vie des hommes de la Préhistoire récente. Afin de pousser plus loin la réflexion, il nous a paru nécessaire de mieux comprendre l’évolution de l’environnement en contexte insulaire, par de nouvelles recherches sur les variations du niveau marin corrélées à l’étude du paysage végétal, de la géomorphologie et de la faune.Les résultats issus des reconstitutions paléogéographiques montrent que l’archipel était déjà constitué au Néolithique moyen II, déconnecté du continent par le chenal du Four dont la traversée nécessitait l’utilisation d’embarcations. Très bien conservés, les monuments mégalithiques de l’archipel sont donc le fait de populations insulaires ayant fréquentées l’archipel sur une longue période, débutant dès le milieu du ve et jalonnant les ive, iiive et iie millénaires avant J.-C. La répartition des sépultures mégalithiques reflète des stratégies d’implantations qui répondent à des choix culturels et à des contraintes naturelles, sur un territoire soumis à un morcellement progressif du fait des dynamiques érosives qui accompagnent la remontée du niveau marin. Durant tout le Néolithique et l’Âge du Bronze, l’isolement géographique n’a cessé de s’accroître, sans donner lieu pour autant à des particularismes culturels marqués, les innovations techniques et artistiques de cette époque ayant pénétré au sein des sociétés insulaires. Néanmoins, l’éloignement croissant des îles a encouragé la recherche de moyens de subsistance basés sur l’exploitation intense des ressources littorales, à travers la collecte de coquillages et de crustacés, la pratique de la pêche et de la chasse côtière. Tournées vers la mer, ces populations n’ont pas négligé les ressources qu’offraient les zones terrestres, comme en témoigne la précocité des pratiques agropastorales dans l’archipel.During almost ten years, an archaeological survey has been carried out in Molène Archipelago by a multidisciplinary team. The area appears to be particularly rich in Neolithic and Bronze Age remains and an exceptional concentration of megaliths has been brought to light. Several settlments are confirmed by dry-stone structures like in Beg ar Loued or by shell middens harbouring large quantities of bones and artefacts. These data give precious indications on the occupation chronology of the area. Moreover they allow for the first time in Brittany to reconstruct the everyday life during the late Prehistory. A prerequisite to this reconstruction was a better understanding of the environment evolution during this period, which locally implies a better knowledge of sea level fluctuations and its effects on landscapes as well as on vegetal and faunal resources.Results obtained via the paleogeographic reconstructions show that the archipelago during the Middle Neolithic II was already disconnected from the mainland by the Four channel which required boats to be crossed. Very well preserved, the megalithic monuments have therefore been erected and used by islanders being present on the archipelago for a long period time, starting from the middle of the Vth millenium BC, and spreading through the IV, III and IInd millenia. The distribution of the megalithic tombs reveals landscape occupation strategies which answer both cultural choices and natural constraints in a territory that undergoes a progressive fragmentation due to the dynamic of erosion linked to the rise of the sea level. Throughout the entire Neolithic and Bronze Age, geographic isolation has continued to increase, but in the meantime it did not imply specific cultural aspects, technical and artistic innovations having reached these island societies. Nevertheless, the increasing remoteness of the islands has fostered the search for livelihoods based on the intense exploitation of coastal ressources, through the gathering of seashells and shellfishes, fishing and coastal hunting. Although facing the sea, these people did not neglect what the land areas could offer as evidenced by the earl agro-pastoral practices in the archipelago

Cachette et rejets des silex taillés

International audienceTrois petites concentrations de silex taillés ont été mises au jour dans l'emprise des fouilles. La première est un petit dépôt de supports bruts en silex qui a été situé à l'extérieur du bâtiment au pied d'un muret. Le dépôt se compose de dix-huit artefacts dont douze éclats et six nucléus qui devaient se trouver dans un contenant souple. Cinq remontages concernant quinze pièces ont été réalisés. Les dimensions des galets de silex débités, supé-rieures à la moyenne de ceux découverts sur le site et leur bonne qualité nous orientent vers une réserve de matière première brute transformable en outils. L'emplacement de la trouvaille, contre un muret et partiellement masqué par un surplomb, va dans le sens d'une cache. Plus importante numériquement, la seconde a été mise au jour dans la structure 3 et doit correspondre aux déchets d'une session de taille rejetés sur place. Une interprétation similaire peut être proposée pour la troisième, située au sud de la structure 4, qui est essentiellement composée d'esquilles. Abstract Three small concentrations of knapped flints have been studied in the course of excavations. The first is a small deposit of raw material flints that were unearthed outside the building at the foot of a wall. The deposit consists of eighteen artefacts including twelve flakes and six cores that were in a flexible container. Five refittings concerning fifteen pieces were carried out. The dimensions of the knapped flint pebbles, above the average of those found at the site and the good quality of the flint point us to a supply of raw material convertible in tools. The location of the find, against a wall and partially hidden by an overhang support the idea of a hiding-place. More important numerically, the second was found in the structure 3 and may match the waste of a knapping session here. A similar interpretation can be proposed for the third concentration, located at the south of structure 4, which is for the main part composed of knapping micro-debris

Study and conservation of the Guiana Dolphin (Sotalia guianensis) (Van Bénéden, 1864) in French Guiana

The Guiana dolphin (Sotalia guianensis) occurs in warm and shallow waters of the Atlantic Ocean and the Caribbean Sea, from southern Brazil to Honduras, including estuarine and freshwater habitats such as Maracaibo Lake (Venezuela), and the Orinoco River. In 2018, the Guiana dolphin was reclassified from Data Deficient to Near Threatened on the global IUCN Red List. Nevertheless, the conservation status identified by national and regional Red Lists is even more alarming. In French Guiana, for example, the species is classified as Endangered based on strong pressures such as bycatch. In this region, the Guiana dolphin inhabits river mouths and coastal waters where most anthropogenic activities occur. Better knowledge of the biology and ecology is needed in French Guiana to help inform effective conservation actions. Here, we present ongoing studies to map the distribution of Guiana dolphins along the French Guiana coast and estimate abundance in a hotspot area. Aerial survey campaigns were conducted during the dry season in 2013, 2014, 2015, and 2019. Eight flights were conducted and 146 dolphins belonging to 39 groups were observed. Boat-based line-transect surveys were also conducted in the coastal waters of Cayenne in 2017 and 2018. Twenty-one survey trips were conducted covering 999.06 km. Three hundred and eighty-two dolphins belonging to 63 groups were observed. The total abundance in the Cayenne area was estimated at 128 dolphins (% CV = 30.92; CI (95%) = 70-235) with a density of 0.80 ind./km² (% CV = 30.92; CI (95%) = 0.44-1.47). Additionally, a descriptive analysis was performed on stranding data collected in French Guiana between 2014 and 2020 to identify the major cause of death and seasonality in the stranding events. In total, 43 dolphins were found, especially on the beaches of Rémire-Montjoly, Cayenne, and Kourou: bycatch was the major identifiable cause of death. We recommend a local conservation strategy and actions to be undertaken in the short- and medium-term to address different issues: knowledge, threats, conservation, and cooperation

Stranding of pygmy sperm whale, Kogia breviceps (de Blainville, 1838), in eastern French Guiana

This short communication presents the first stranding record for pygmy sperm whale in French Guiana

hca: An Arabidopsis mutant exhibiting unusual cambial activity and altered vascular patterning

International audienc

From the core to beyong the margin : Les faces cachées de la zone péritumorale

National audienc

Evolution des paysages et occupation humaine en mer d'Iroise (Finistère, Bretagne) du Néolithique à l'Âge du Bronze

International audienceDuring almost ten years, an archaeological survey has been carried out in Molène Archipelago by a multidisciplinary team. The area appears to be particularly rich in Neolithic and Bronze Age remains and an exceptional concentration of megaliths has been brought to light. Several settlments are confirmed by dry-stone structures like in Beg ar Loued or by shell middens harbouring large quantities of bones and artefacts. These data give precious indications on the occupation chronology of the area. Moreover they allow for the first time in Brittany to reconstruct the everyday life during the late Prehistory. A prerequisite to this reconstruction was a better understanding of the environment evolution during this period, which locally implies a better knowledge of sea level fluctuations and its effects on landscapes as well as on vegetal and faunal resources.Results obtained via the paleogeographic reconstructions show that the archipelago during the Middle Neolithic II was already disconnected from the mainland by the Four channel which required boats to be crossed. Very well preserved, the megalithic monuments have therefore been erected and used by islanders being present on the archipelago for a long period time, starting from the middle of the Vth millenium BC, and spreading through the IV, III and IInd millenia. The distribution of the megalithic tombs reveals landscape occupation strategies which answer both cultural choices and natural constraints in a territory that undergoes a progressive fragmentation due to the dynamic of erosion linked to the rise of the sea level.Throughout the entire Neolithic and Bronze Age, geographic isolation has continued to increase, but in the meantime it did not imply specific cultural aspects, technical and artistic innovations having reached these island societies. Nevertheless, the increasing remoteness of the islands has fostered the search for livelihoods based on the intense exploitation of coastal ressources, through the gathering of seashells and shellfishes, fishing and coastal hunting. Although facing the sea, these people did not neglect what the land areas could offer as evidenced by the earl agro-pastoral practices in the archipelago.Depuis près de dix ans, des recherches archéologiques sont menées dans l'archipel de Molène par une équipe pluridisciplinaire. Ce secteur s'avère particulièrement riche en vestiges du Néolithique et de l'Âge du Bronze. Une concentration exceptionnelle de monuments mégalithiques y a été mise en évidence. Plusieurs habitats sont attestés par la présence d'un bâtiment (Beg ar Loued, Molène) ou de dépotoirs domestiques riches en faune et en mobilier. Ces données nous renseignent sur la chronologie des occupations du secteur et nous permettent, pour la première fois en Bretagne, d'esquisser le mode de vie des hommes de la Préhistoire récente. Afin de pousser plus loin la réflexion, il nous a paru nécessaire de mieux comprendre l'évolution de l'environnement en contexte insulaire, par de nouvelles recherches sur les variations du niveau marin corrélées à l'étude du paysage végétal, de la géomorphologie et de la faune. Les résultats issus des reconstitutions paléogéographiques montrent que l'archipel était déjà constitué au Néolithique moyen II, déconnecté du continent par le chenal du Four dont la traversée nécessitait l'utilisation d'embarcations. Très bien conservés, les monuments mégalithiques de l'archipel sont donc le fait de populations insulaires ayant fréquenté l'archipel sur une longue période, débutant dès le milieu du Ve et jalonnant les IVe, IIIe et IIe millénaires avant J.-C. La répartition des sépultures mégalithiques reflète des stratégies d'implantations qui répondent à des choix culturels et à des contraintes naturelles, sur un territoire soumis à un morcellement progressif du fait des dynamiques érosives qui accompagnent la remontée du niveau marin. Durant tout le Néolithique et l'Age du Bronze, l'isolement géographique n'a cessé de s'accroître, sans donner lieu pour au autant à des particularismes culturels marqués, les innovations techniques et artistiques de cette époque ayant pénétré au sein des sociétés insulaires. Néanmoins, l'éloignement croissant des îles a encouragé la recherche de moyens de subsistance basés sur l'exploitation intense des ressources littorales, à travers la collecte de coquillages et de crustacés, la pratique de la pêche et de la chasse côtière. Tournées vers la mer, ces populations n'ont pas négligé les ressources qu'offraient les zones terrestres, comme en témoigne la précocité des pratiques agropastorales dans l'archipel

Local intracerebral inhibition of IRE1 by MKC8866 sensitizes glioblastoma to irradiation/chemotherapy in vivo

International audienceGlioblastoma multiforme (GBM) is the most severe primary brain cancer. Despite an aggressive treatment comprising surgical resection and radio/chemotherapy, patient's survival post diagnosis remains short. A limitation for success in finding novel improved therapeutic options for such dismal disease partly lies in the lack of a relevant animal model that accurately recapitulates patient disease and standard of care. In the present study, we have developed an immunocompetent GBM model that includes tumor surgery and a radio/chemotherapy regimen resembling the Stupp protocol and we have used this model to test the impact of the pharmacological inhibition of the endoplasmic reticulum (ER) stress sensor IRE1, on treatment efficacy

Dual ire1 rnase functions dictate glioblastoma development

Proteostasis imbalance is emerging as a major hallmark of cancer, driving tumor aggressiveness. Evidence suggests that the endoplasmic reticulum (ER), a major site for protein folding and quality control, plays a critical role in cancer development. This concept is valid in glioblastoma multiform (GBM), the most lethal primary brain cancer with no effective treatment. We previously demonstrated that the ER stress sensor IRE1 alpha (referred to as IRE1) contributes to GBM progression, through XBP1 mRNA splicing and regulated IRE1-dependent decay (RIDD) of RNA. Here, we first demonstrated IRE1 signaling significance to human GBM and defined specific IRE1-dependent gene expression signatures that were confronted to human GBM transcriptomes. This approach allowed us to demonstrate the antagonistic roles of XBP1 mRNA splicing and RIDD on tumor outcomes, mainly through selective remodeling of the tumor stroma. This study provides the first demonstration of a dual role of IRE1 downstream signaling in cancer and opens a new therapeutic window to abrogate tumor progression

CD90 Expression Controls Migration and Predicts Dasatinib Response in Glioblastoma

International audiencePurpose: CD90 (Thy-1) is a glycophosphatidylinositol-anchored glycoprotein considered as a surrogate marker for a variety of stem cells, including glioblastoma (GBM) stem cells (GSC). However, the molecular and cellular functions of CD90 remain unclear.Experimental Design: The function of CD90 in GBM was addressed using cellular models from immortalized and primary GBMlines, in vivo orthotopic mouse models, and GBM specimens' transcriptome associated with MRI features from GBM patients. CD90 expression was silenced in U251 and GBM primary cells and complemented in CD90-negative U87 cells.Results: We showed that CD90 is not only expressed on GSCs but also on more differentiated GBM cancer cells. In GBM patients, CD90 expression was associated with an adhesion/migration gene signature and with invasive tumor features. Modulation of CD90 expression in GBM cells dramatically affected their adhesion and migration properties. Moreover, orthotopic xenografts revealed that CD90 expression induced invasive phenotypes in vivo. Indeed, CD90 expression led to enhanced SRC and FAK signaling in our GBM cellular models and GBM patients' specimens. Pharmacologic inhibition of these signaling nodes blunted adhesion and migration in CD90-positive cells. Remarkably, dasatinib blunted CD90-dependent GBM cell invasion in vivo and killed CD90(high) primary GSC lines.Conclusions: Our data demonstrate that CD90 is an actor of GBM invasiveness through SRC-dependent mechanisms and could be used as a predictive factor for dasatinib response in CD90high GBM patients. (C) 2017 AACR