Gourob

Dans le cadre de cette troisième campagne, le travail sur le terrain (pl. 1) a été réparti entre : Des travaux archéologiques dans les zones à l’est, dites du « fort » et de la « jetée », dans le palais, dans la zone des fours, dans les tombes au nord et à l’est du « fort » ainsi qu’à l’est de la zone des fours. Ils ont été complétés par une étude anthropologique sur les ossements provenant des sépultures. Travaux géoarchéologiques pour localiser l’ancien chenal du Nil à l’est du site. Travau..

The GRAVITY+ Project: Towards All-sky, Faint-Science, High-Contrast Near-Infrared Interferometry at the VLTI

The GRAVITY instrument has been revolutionary for near-infrared interferometry by pushing sensitivity and precision to previously unknown limits. With the upgrade of GRAVITY and the Very Large Telescope Interferometer (VLTI) in GRAVITY+, these limits will be pushed even further, with vastly improved sky coverage, as well as faint-science and high-contrast capabilities. This upgrade includes the implementation of wide-field off-axis fringe-tracking, new adaptive optics systems on all Unit Telescopes, and laser guide stars in an upgraded facility. GRAVITY+ will open up the sky to the measurement of black hole masses across cosmic time in hundreds of active galactic nuclei, use the faint stars in the Galactic centre to probe General Relativity, and enable the characterisation of dozens of young exoplanets to study their formation, bearing the promise of another scientific revolution to come at the VLTI.Comment: Published in the ESO Messenge

Étude de la protéine tyrosine kinase Syk, un nouveau suppresseur de tumeur dans la transformation des mélanocytes en mélanome

Une étape cruciale de la transformation maligne est la perte de voie suppresseur de tumeur qui contrôle la sénescence cellulaire. la protéine tyrosine kinase cytoplasmique syk (spleen tyrosine kinase) a été récemment décrite comme un suppresseur de tumeur des mélanomes, un cancer issu de la transformation maligne des mélanocytes, cellules produisant les pigments mélaniques. Le mécanisme par lequel syk diminue la croissance des mélanomes reste à déterminer. Tout d abord, nous avons observe que l expression de syk est perdue dans la plupart des lignées de mélanome. L inactivation de syk est épigénétique due a une hyperméthylation d îlots cpg de son promoteur. le traitement avec l agent déméthylant 5-aza-2-desoxycytidine restaure son expression. nous avons constate que la réintroduction de syk dans les cellules de mélanome réduit de façon spectaculaire leur croissance en deux et trois dimensions, leur capacité migratoire et invasive. la réexpression de syk favorise la senescence des cellules de mélanomes caracterisée par une diminution de la prolifération, une morphologie large et aplatie, une activité bêta galactosidase associe a la senescence et des foci d hétérochromatine. De plus, syk induit une hypophosphorylation de rb et active la voie suppresseur de tumeur p53, regule positivement l expression de p21 dépendamment de p53. Nous avons également identifie les protéines nck1 et nck2 comme de nouveaux partenaires de syk. Nos résultats démontrent que syk est un nouveau candidat suppresseur de la croissance des mélanomes et suggèrent que l inactivation de syk dans ces tumeurs participe a la levéee de la sénescence qui conduit a la progression maligne des cellules.NICE-BU Sciences (060882101) / SudocSudocFranceF

Doppler Ultrasound Driven Biomechanical Model of the Brain for Intraoperative Brain-Shift Compensation: A Proof of Concept in Clinical Conditions

International audienceAccurate localization of the target is essential to reduce morbidity during brain tumor removal interventions. Yet, image-guided neurosurgery faces an important issue for large skull openings where brain soft-tissues can exhibit large deformations in the course of surgery. As a consequence of this "brain-shift" the pre-operatively acquired images no longer correspond to reality and subsequent neuronavigation is therefore strongly compromised. In this article we present a neuronavigator which addresses this issue and offers passive help to the surgeon by displaying the position of the guided tools with respect to the corrected location of the anatomical features. This low-cost system relies on localized 2D Doppler ultrasound imaging of the brain which makes it possible to track the vascular tree deformation throughout the intervention. An elastic registration procedure is used to match the shifted tree with its pre-operative structure identified within Magnetic Resonance Angiography images. A patient speci c Finite Element biomechanical model of the brain further extends the resulting sparse deformation field to the overall organ volume. Finally, the estimated global deformation is applied to all pre-operatively available volumetric images or data, such as tumor contours, and the corrected planning is displayed to the surgeon. The system, tested on a patient presenting a large meningioma, was able to compensate within seconds for the intraoperatively observed brain-shift, reducing the mean error on tumor margin localization from 3.5 mm (max=7.6 mm, RMS=3.7 mm) to 0.9 mm (max=1.7 mm, RMS=1.0 mm)

Spleen tyrosine kinase functions as a tumor suppressor in melanoma cells by inducing senescence-like growth arrest.: Syk activates p53 signaling pathway

International audienceLoss of tumor-suppressive pathways that control cellular senescence is a crucial step in malignant transformation. Spleen tyrosine kinase (Syk) is a cytoplasmic tyrosine kinase that has been recently implicated in tumor suppression of melanoma, a deadly skin cancer derived from pigment-producing melanocytes. However, the mechanism by which Syk suppresses melanoma growth remains unclear. Here, we report that reexpression of Syk in melanoma cells induces a p53-dependent expression of the cyclin-dependent kinase (cdk) inhibitor p21 and a senescence program. We first observed that Syk expression is lost in a subset of melanoma cell lines, primarily by DNA methylation-mediated gene silencing and restored after treatment with the demethylating agent 5-aza-2-deoxycytidine. We analyzed the significance of epigenetic inactivation of Syk and found that reintroduction of Syk in melanoma cells dramatically reduces clonogenic survival and three-dimensional tumor spheroid growth and invasion. Remarkably, melanoma cells reexpressing Syk display hallmarks of senescent cells, including reduction of proliferative activity and DNA synthesis, large and flattened morphology, senescence-associated beta-galactosidase activity, and heterochromatic foci. This phenotype is accompanied by hypophosphorylated retinoblastoma protein (Rb) and accumulation of p21, which depends on functional p53. Our results highlight a new role for Syk tyrosine kinase in regulating cellular senescence and identify Syk-mediated senescence as a novel tumor suppressor pathway the inactivation of which may contribute to melanoma tumorigenicity

Revisiting global diversity and biogeography of freshwater diatoms: New insights from molecular data

International audienceAbstract The distribution of microorganisms has long been assumed to be cosmopolitan and primarily controlled by the environment, but recent studies suggest that microbes may also exhibit strong biogeographical patterns driven by dispersal limitation. Past attempts to study the global biogeography of freshwater diatoms have always encountered the great difficulty of collecting taxonomically harmonized large‐scale data. However, developments in molecular techniques and DNA metabarcoding provide a unique opportunity to overcome these limitations and to disclose diatom biodiversity at an unprecedented scale and resolution. Here, we assembled DNA metabarcoding data of freshwater benthic diatom communities sampled in seven geographic regions across the world to investigate how diatom diversity varies along latitude and to assess the proportion of genetic variants of these microorganisms which are exclusive or shared across regions. We observed significant differences in assemblages among climate zones and found that genetic richness is not affected by latitude, but by an island effect. The genetic resolution directly impacts the proportion of variants shared across regions; however, the majority of taxa remained specific to a single geographic region. Freshwater diatoms disperse over long distances and across oceans but at rates that allow the appearance of local genetic variants and the regionalization of assemblages. Future work should focus on putting these diversity dynamics into a temporal context, an approach that should be possible by bringing together new sequencing techniques and phylogeography