Tetherin Restricts Productive HIV-1 Cell-to-Cell Transmission

The IFN-inducible antiviral protein tetherin (or BST-2/CD317/HM1.24) impairs release of mature HIV-1 particles from infected cells. HIV-1 Vpu antagonizes the effect of tetherin. The fate of virions trapped at the cell surface remains poorly understood. Here, we asked whether tetherin impairs HIV cell-to-cell transmission, a major means of viral spread. Tetherin-positive or -negative cells, infected with wild-type or ΔVpu HIV, were used as donor cells and cocultivated with target lymphocytes. We show that tetherin inhibits productive cell-to-cell transmission of ΔVpu to targets and impairs that of WT HIV. Tetherin accumulates with Gag at the contact zone between infected and target cells, but does not prevent the formation of virological synapses. In the presence of tetherin, viruses are then mostly transferred to targets as abnormally large patches. These viral aggregates do not efficiently promote infection after transfer, because they accumulate at the surface of target cells and are impaired in their fusion capacities. Tetherin, by imprinting virions in donor cells, is the first example of a surface restriction factor limiting viral cell-to-cell spread

Numerical modeling of subduction zones with slab breakoff : application to adakite genesis

PosterInternational audienc

Lead accumulation in oyster shells, a potential tool for environmental monitoring

International audiencePb/Ca profiles were measured on ten live collected Ostrea edulis from three sites characterized by different levels of lead content. Intra-shell and inter-shell reproducibility were tested comparing several Pb/Ca profiles measured by LA-ICP-MS within a specimen, and within specimens from the same site. Results indicate that signals recorded are reproducible and mean shell Pb/Ca values are site-dependent. Second order variability is explained either by smoothing effects, biological effects or micro-environmental heterogeneities in lead distribution. Mean Pb contents measured in marine bivalve shells are reviewed here. Ranging from 0 to 50 ppm, they show a strong relationship with the environmental level of local lead contamination, and do not appear species-dependent. Our measurements show a linear relationship between mean shell Pb/Ca and surface sediment Pb concentrations, making marine bivalves and particularly O. edulis a potential accurate bio-monitoring tool able to monitor bioavailable lead along European coasts since Mesolithic, with an annual resolution. © 2017 Elsevier Lt

Influence of crustal thickness on partial melting in subduction zones : numerical modelling basis and first results

International audienc

Segregation vesicles, cylinders and sheets in vapor-differentiated pillow lavas: Examples from Tore-Madeira Rise and Chile Triple Junction

International audienc

Influence of crustal thickness on partial melting in subduction zones : numerical modelling basis and first results

International audienc

Mise en place de basaltes enrichis le long d'un axe d'accrétion actif en domaine arrière-arc (dorsale Sud Pandora-Tripartite, bassin Nord-Fidjien, Sud-Ouest Pacifique)

Sept dragages ont été réalisés le long du système d'accrétion actif Sud Pandora-Tripartite dans le nord du bassin Nord-Fidjien (Sud-Ouest Pacifique) lors de la campagne NOFI du N/O L'Atalante (programme Newstarmer), en 1994. Les laves émises sont des basaltes tholéitiques légèrement à fortement enrichis en éléments incompatibles, ne montrant pas l'appauvrissement en Nb caractéristique d'une contamination des zones de subduction, et dont les rapports La/Yb, Ba/La et La/Nb sont intermédiaires entre ceux des MORB (mid-ocean ridge basalts) enrichis et des OIB (oceanic-island basalts). Ce système d'accrétion évolue ainsi de façon indépendante par rapport aux subductions avoisinantes, au moins du point de vue géochimique et cinématique. L'activité des dorsales du nord du bassin Nord-Fidjien pourrait être sous la dépendance de remontées de manteau profond, plus enrichi que celui généralement présent à l'axe des dorsales médio-océaniques. (Résumé d'auteur