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Sous la coordination de Sébastien Pauly.; Lire le rapport sur : https://fr.calameo.com/read/0015242709af194689df6.

Lecture du rapport sur Calaméo : https://fr.calameo.com/read/0015242709af194689df6.

Among the most recognizable and enigmatic artefacts found in pre-Columbian archaeological contexts of the Ceramic Age in the Greater and Lesser Antilles is the three-pointer, a triangular shaped object made of various mineral and organic materials. Despite a few ethno-historic mentions and abundant academic speculations, little is known about the social and spiritual dimensions these once animate objects had in the Amerindian Antillean communities. Furthermore, very little can be empirically verified. The wide array of known specimens shows many variations, including the presence/absence of usually poorly preserved traces of black residue, often described as plant tars, resins or gums, or as inorganic bitumen. Well preserved residues of this type have been observed on a three-pointer specimen recently discovered in a Late Ceramic Age context (Troumassoid series, 10th–11th century AD) of the Tourlourous site on the island of Marie-Galante (Guadeloupe, French Lesser Antilles). They have been physico-chemically characterized as bitumen, and they preserve evidence of a specific tying system. These data raise considerations on two points: the necessity to better document these sometimes tenuous clues of tying and adhesion systems implying bitumen (and other glues), and the need to consider that three-pointers (and other artefacts), while actively used in the mediation between social and spiritual dimensions, also have a practical side which should be addressed in technological terms in order to better understand all their dimensions.

Lecture du rapport sur Calaméo : https://fr.calameo.com/read/0015242709af194689df6.

Introduction Dans l’essor de l’archeologie des periodes historiques des iles de la Caraibe (Kelly 2004), la recherche francaise a integre beaucoup plus tard que les recherches anglo-saxonnes ou hispaniques la problematique de l’esclavage et des conditions de vie des esclaves dans les Antilles francaises (Delpuech 2001). Depuis vingt ans, grâce a la mise en place de services regionaux de l’archeologie dans les directions des affaires culturelles, qui a entraine la multiplication d’operations d...

Decreased expression of neuronal genes such as brain-derived neurotrophic factor (BDNF) is associated with several neurological disorders. One molecular mechanism associated with Huntington disease (HD) is a discrete increase in the nuclear activity of the transcriptional repressor REST/NRSF binding to repressor element-1 (RE1) sequences. High-throughput screening of a library of 6,984 compounds with luciferase-assay measuring REST activity in neural derivatives of human embryonic stem cells led to identify two benzoimidazole-5-carboxamide derivatives that inhibited REST silencing in a RE1-dependent manner. The most potent compound, X5050, targeted REST degradation, but neither REST expression, RNA splicing nor binding to RE1 sequence. Differential transcriptomic analysis revealed the upregulation of neuronal genes targeted by REST in wild-type neural cells treated with X5050. This activity was confirmed in neural cells produced from human induced pluripotent stem cells derived from a HD patient. Acute intraventricular delivery of X5050 increased the expressions of BDNF and several other REST-regulated genes in the prefrontal cortex of mice with quinolinate-induced striatal lesions. This study demonstrates that the use of pluripotent stem cell derivatives can represent a crucial step toward the identification of pharmacological compounds with therapeutic potential in neurological affections involving decreased expression of neuronal genes associated to increased REST activity, such as Huntington disease.

Today, Diploglossine lizards (Anguidae) are common on the Greater Antillean Islands (West Indies), where they are represented by many endemic species. However these lizards are very rare on the Lesser Antillean Islands, where they are only represented by a single species, the Montserrat galliwasp (Diploglossus montisserrati). Here, we show that diploglossine lizards were present in the past on other Lesser Antillean islands, by reporting the discovery of Anguidae fossil remains in two Amerindian archaeological deposits and in a modern deposit. These remains are compared to skeletons of extant diploglossine lizards, including D. montisserrati, using X-ray microtomography of the type specimen of this critically endangered lizard. We also conducted a histological study of the osteoderms in order to estimate the putative age of the specimen. Our results show that the fossil specimens correspond to a member of the Diploglossus genus presenting strong similarities, but also minor morphological differences with D. montisserrati, although we postulate that these differences are not sufficient to warrant the description of a new species. These specimens, identified as Diploglossus sp., provide a new comparison point for the study of fossil diploglossine lizards and reflect the historical 17th century mentions of anguid lizards, which had not been observed since.

Pit cave 6 on Pointe Gros Rempart (Baie-Mahault, La Désirade, French West Indies) is a stratified fossil-bearing site. While the archaeological material and faunal remains from the oldest assemblage demonstrate it to have formed during the Amerindian period, the second assemblage dates to the first one-hundred years of the island's colonial period (mid-18th to mid-19th centuries). Faunal analysis revealed the presence of 4 now locally extinct or extinct species, three of which have never before been documented on La Désirade (Ameivasp.,Leiocephaluscf.cuneusandAlsophissp.). Changing faunal spectrums (invertebrates and vertebrates) due to environmental destabilisation combined with aspects of the island's colonial economy demonstrate habitat degradation and over-grazing to be the principal causes of extinctions and or extirpations.

Sodium valproate (VPA) has been reported to increase the accumulation of the pathologic isoform of prion protein (PrPsc) in scrapie-infected murine neuroblastoma cells. In this study, the effect of VPA on PrPsc accumulation was investigated in murine N2a neuroblastoma cells chronically infected with scrapie strain 22L (N2a-22L). No accumulation of PrPsc was detected after short-term (3 days) or long-term (21 days) treatment of N2a-22L cells with 4.8, 12, 18 or 24 microM VPA. Higher VPA concentrations (240 and 600 microM) also failed to augment PrPsc expression. In conclusion, in our experimental conditions, no deleterious effect was induced by VPA on prions replication.

We have investigated the effects of a series of flavonoids on cell proliferation and cell cycle distribution in human melanoma cells OCM-1. Among the compounds that potently inhibited OCM-1 cell proliferation, we show that the presence of a hydroxyl group at the 3'-position of the ring B in quercetin and luteolin, correlated to a G1 cell cycle arrest while its absence in kaempferol and apigenin correlated to a G2 block. Genistein with a hydroxyl at 5-position of the ring A arrested cells in G2 while daidzein which lacks it, induced an accumulation of cells in G1. We demonstrate that flavonoids, which induced a cell cycle block in G1, inhibited the activity of CDK2 by 40-60%. By contrast, those which caused an accumulation of cells in G2/M were without effect. On the other hand, while quercetin, daidzein and luteolin did not alter the activity of CDK1, kaempferol, apigenin and genistein inhibited this kinase by 50-70%. We demonstrate that the up-regulation of the CDK inhibitors p27(KIP1) and p21(CIP1) is likely responsible for the inhibition of CDK2 while inhibition of CDK1 was rather due to the phosphorylation of the kinase on Tyr15 residue.

Genistein, a natural isoflavone found in soybeans, exerts a number of biological actions suggesting that it may have a role in cancer prevention. We have previously shown that it potently inhibits OCM-1 melanoma cell proliferation by inducing a G(2) cell cycle arrest. Here we show that genistein exerts this effect by impairing the Cdc25C-dependent Tyr-15 dephosphorylation of Cdk1, as the overexpression of this phosphatase allows the cells to escape G(2) arrest and enter an abnormal chromatin condensation stage. Caffeine totally overrides the genistein-induced G(2) arrest, whereas the block caused by etoposide is not bypassed and that caused by adriamycin is only partially abolished. We also report that genistein activates the checkpoint kinase Chk2 as efficiently as the two genotoxic agents and that caffeine may counteract the activation of Chk2 by genistein but not by etoposide. In contrast, caffeine abolishes the accumulation of p53 caused by all the compounds. Wortmannin does not suppress the Chk2 activation in any situation, suggesting that the ataxia telangiectasia-mutated kinase is not involved in this regulation. Finally, unlike etoposide and adriamycin, genistein induces only a weak response in terms of DNA damage in OCM-1 cells. Taken together, these results suggest that the G(2) checkpoints activated by genistein and the two genotoxic agents involve different pathways.

Transforming growth factor beta (TGFbeta) is a potent inhibitor of epithelial cell proliferation, delaying or arresting cell cycle progression in mid-late G1. In long-term life span cells this growth inhibitory action has been attributed to regulatory events on both the levels and activities of G1 cyclin-dependent kinases (CDKs). CDK inhibitors have been shown to play important role in the TGFbeta-induced inhibition of G1 CDKs. In this work, we have investigated the effect of TGFbeta1 on both cell proliferation and G1 CDK activities in primary cultures of human retinal pigment epithelial (RPE) cells. We show that TGFbeta1 exerts a partial inhibitory effect on RPE cell proliferation by causing a significant increase of the RPE cell number in G1. TGFbeta1 induces an up-regulation of the CDK inhibitor p15(INK4B)with its subsequent association to CDK4, and a decline in CDK4 protein level. In parallel, we have observed a decline of p27(KIP1)associated to CDK4 and a significant increase of the inhibitor associated to CDK2. Finally, we show that TGFbeta1 reduces both CDK4 and CDK2 enzymatic activities. The fact that TGFbeta exerts only partial inhibitions on G1 CDKs and cell cycle progression in RPE cells suggests a propensity of these cells to escape from the anti-proliferative action of the cytokine, a phenomenon which could be reinforced during the development of proliferative vitreoretinopathy.

In the present study, we investigated the involvement of phosphatidylinositol 3-kinase (PI 3-kinase) activity in the progression of vascular smooth muscle cells (VSMCs) throughout the G1 phase of cell cycle. Addition of two selective inhibitors of PI 3-kinase, LY 294002 or wortmannin, to quiescent VSMCs prevented serum-induced DNA synthesis in a dose-dependent manner with IC50 of 8.7 +/- 2.0 microM and 53.9 +/- 8.5 nM, respectively. Time course studies revealed that the two PI 3-kinase inhibitors blocked VSMC proliferation in mid-late G1 phase, about 6 h before the G1/S transition. This G1 growth arrest was due, at least in part, to the reduction of the CDK2 associated kinase activity resulting mainly from the upregulation of the inhibitory protein p27KIP1.

Des dépôts alluviaux datant du Tardiglaciaire et du début de l’Holocène ont été découverts dans la plaine du Caudeau, petit affluent de la Dordogne, à La Brunetière sur la commune de Pombonne (Dordogne) à l’occasion de travaux d’archéologie préventive. Leur analyse permet de renouveler nos connaissances sur l’évolution des cours d’eau en Aquitaine pendant cette période charnière. Ils montrent en particulier que les principales phases de métamorphose alluviale décrites dans le nord de l’Europe se sont également produites dans cette région de manière à peu près synchrone, pour autant que l’on puisse en juger d’après les dates disponibles. Deux phases majeures d’incision aux dépens de la nappe alluviale à galets pléniglaciaire sont identifiables. La première intervient pendant une phase très précoce du Bølling, soit avant 12 700 ± 45 BP, dans un environnement steppique. L’abandon rapide du chenal, associé à du soutirage karstique, permet ensuite l’installation d’un petit lac colmaté par des argiles avec quelques intercalations tourbeuses riches en macrorestes végétaux (bouleau nain, saule). L’image de la végétation donnée aussi bien par les pollens que par la faune de mollusques et d’insectes est celle d’une steppe encore très ouverte à armoise et genévriers, alors que les paléotempératures estivales indiquées par les insectes sont déjà proches de celles connues actuellement dans la région. Des paléotempératures hivernales sensiblement plus froides que les actuelles (-20 à 5 °C) renvoient cependant l’image d’un climat à caractère plus continental. Les dépôts lacustres sont ensuite recouverts par une couche de sables d’inondation attribués au Dryas moyen et/ou récent. L’assèchement du chenal et le développement d’un sol hydromorphe pourrait correspondre respectivement soit à l’Allerød, soit au tout début de l’Holocène. La seconde phase d’incision est attribuée au Préboréal et tronque la séquence tardiglaciaire; elle est associée à un style alluvial à chenaux anastomosés. L’abandon de la majorité des chenaux pendant le Boréal marque la réduction du lit à un chenal unique sinueux, comparable à celui qui caractérise le Caudeau actuel. Une industrie lithique de type Magdalénien supérieur a également été découverte sur la berge du chenal tardiglaciaire. L’industrie recueillie est exclusivement taillée dans le silex local maestrichtien. Elle comprend environ 200 éclats et 800 petits restes de taille, pour seulement 15 lames de plein débitage et 6 outils (sans aucun microlithe). L’utilisation exclusive d’un percuteur minéral tendre, la morphologie du nucléus laminaire, la rectitude des petites lames, les 2 lames appointées sont autant de caractères qui évoquent le stade ultime du Magdalénien supérieur, tel qu’il est connu plus en amont le long de la Dordogne sur les sites de la Gare de Couze et du Moulin du Roc. Late-glacial to Holocene alluvial deposits have been discovered along a small tributary of the Dordogne river at “La Brunetière” near Bergerac (Dordogne, southwestern France) and yield novel information on the evolution of rivers at the end of the Weichselian. The deposits show that the main alluvial changes described in Northern Europe occurred simultaneously at “La Brunetière”. Two major phases of channel incision in the basal Pleniglacial gravel body have been identified. The first channels developed at the very onset of the Bølling, i.e. before 12,700 ± 45 BP, in a steppic landscape. Rapid channel abandonment allowed development of a small lake, filled in with alternating peat and clay layers rich in vegetal debris. Pollen data as well as molluscs and insects point to an open Artemisia steppe with juniper trees, together with a local component of riparian shrubs (willow and dwarf birch). Palaeotemperatures reconstructed from coleopteran assemblages indicate larger-than-today yearly thermal amplitude with cold winters and warm summers. The lacustrine clays and peats are buried by sandy overbank deposits that are attributed to the Older and/or the Upper Dryas. Channel drying and subsequent hydromorphic soil development relate respectively to the Allerød or the early Holocene. The second phase of incision corresponds to the Preboreal and is typified by stable anastomosed channel formation. Most of these were abandoned during the Boreal and filled by organicclay. An Upper Magdalenian lithic industry has been discovered in a paleosol on the bank of the Late-glacial channel. It includes ca. 200 flakes and 800 small debris of local Maestrichtian flint, and only 15 full-debitage blades and 6 tools. Exclusive use of soft hammer, laminar core morphology, straightness of the small blades, and the 2 pointed blades indicate an ultimate stage of the Upper Magdalenian.

Identifiant de l'operation archeologique : 23249 Date de l'operation : 2006 (EX) Dans le cadre de la construction du futur lycee Nord Grande-Terre un diagnostic a ete realise au lieu-dit « Beauport », commune de Port-Louis. D’une superficie de 64 175 m2, l’emprise du diagnostic se situe dans une plaine bordee de petits promontoires dont le substrat est constitue de calcaire. A proximite immediate de celle-ci se trouvent les vestiges d’une ancienne sucrerie installee des le XVIIIe s. et transf...

Identifiant de l'operation archeologique : 23245 Date de l'operation : 2006 (EX) Un diagnostic a ete realise sur un terrain de 1 ha, en prealable a la construction d'un lotissement. Il s'agit d'un plateau dominant le cours de la Grande Riviere a Goyave. Aucun vestige ni anomalie n'a ete rencontre dans les 94 tranchees de sondages. Seule une ancienne voie ferree subsiste, en limite ouest de la parcelle. Il s'agit d'un temoin de l'industrie sucriere de ce secteur de la Guadeloupe ou le chemin d...

Some forms of transmissible spongiform encephalopathies result from oral infection. We have thus analyzed the early mechanisms that could account for an uptake of infectious prion particles by enterocytes, the major cell population of the intestinal epithelium. Human Caco-2/TC7 enterocytes cultured on microporous filters were incubated with different prion strains and contaminated brain homogenates in the apical compartment. Internalization of infectious particles was analyzed by Western blotting and immunofluorescence. We observed internalization by enterocytes of prion particles from bovine spongiform encephalopathy brain homogenates but not from mouse-adapted scrapie-strain brain homogenates or purified bovine spongiform encephalopathy scrapie-associated fibrils. Bovine prion particles were internalized via endocytosis within minutes of infection and were associated with subapical vesicular structures related to early endosomes. The endocytosis of the infectious bovine PrP(Sc) was reduced by preincubating the cells with an anti-LRP/LR blocking antibody, identifying the 37 kDa/67 kDa laminin receptor (LRP/LR), which is apically expressed in Caco-2/TC7 cells, as the receptor for the infectious prion protein. Altogether, our results underscore a potential role of enterocytes in the absorption of bovine prions during oral infection through specific LRP/LR-dependent endocytosis.

We have investigated the effect of genistein on cell cycle distribution of the human choroidal melanoma cell line OCM-1. We report that this isoflavonoid arrested cells in G2. This effect was correlated with the induction of the CDK inhibitor p21CIP1. However, while CDK1 activity was markedly reduced following genistein treatment, CDK2 activity was not affected. This was in agreement with the absence of G1 arrest that we observed but caused some doubt about the functionality of p21CIP1. Attempts to demonstrate mutation or post-translational modification of p21CIP1 from OCM-1 cells were unsuccessful. In fact, the level of p21CIP1 induced by genistein was shown to be insufficient to cause CDK2 inhibition. The role of p21CIP1 in the inhibition of CDK1 was questionable, as we demonstrated that genistein impaired Tyr15 dephosphorylation of CDK1 and because CDK1-cyclin B1 complexes from treated cells could be reactivated upon exposure to CDC25 phosphatase. Finally, we report that p21CIP1 was not absolutely required for the genistein-induced G2 arrest, as the isoflavone caused at least partial G2 arrest in p21-deficient Rat-1 fibroblasts as well as in p21-/- mouse embryo fibroblasts.