Search

International audience; Hepatitis C virus (HCV) is a leading cause of liver diseases including the development of hepatocellular carcinoma (HCC). Particularly, core protein has been involved in HCV-related liver pathologies. However, the impact of HCV core on signaling pathways supporting the genesis of HCC remains largely elusive. To decipher the host cell signaling pathways involved in the oncogenic potential of HCV core, a global quantitative phosphoproteomic approach was carried out. This study shed light on novel differentially phosphorylated proteins, in particular several components involved in translation. Among the eukaryotic initiation factors that govern the translational machinery, 4E-BP1 represents a master regulator of protein synthesis that is associated with the development and progression of cancers due to its ability to increase protein expression of oncogenic pathways. Enhanced levels of 4E-BP1 in non-modified and phosphorylated forms were validated in human hepatoma cells and in mouse primary hepatocytes expressing HCV core, in the livers of HCV core transgenic mice as well as in HCV-infected human primary hepatocytes. The contribution of HCV core in carcinogenesis and the status of 4E-BP1 expression and phosphorylation were studied in HCV core/ Myc double transgenic mice. HCV core increased the levels of 4E-BP1 expression and phosphorylation and significantly accelerated the onset of Myc-induced tumorigenesis in these double transgenic mice. These results reveal a novel function of HCV core in liver carcinogenesis potentiation. They position 4E-BP1 as a tumor-specific target of HCV core and support the involvement of the 4E-BP1/eIF4E axis in hepatocarcinogenesis.

International audience; The Mediterranean is a water stressed environment due to its limited water resources and to increasing anthropogenic and climatic pressures that threaten not only the amount of available water but also its quality. Moreover, catchments in this region exhibit high sediment yields that may increase in the future, due to land cover change and higher frequency of intense rainstorms, further deteriorating the quality of surface water. This work presents a review of hydrological studies carried out in the Mediterranean region. It contributes to the ongoing hydrological research initiative on “Hydrology in a changing world” launched by the IAHS in 2014 and aims to characterize the hydrological response of Mediterranean catchments and its implications for sediment transport and the overall quality of surface water in the region. It also aims to compare different methods and modeling approaches used for individual-catchment studies. The study region is divided into three sub-regions: Northwestern Mediterranean (NWM), Eastern (EM) and Southern Mediterranean (SM). Information on catchments responses and modeling approaches at different time scales (annual, dry season and event) were extracted from published studies, and analyzed. In terms of hydrological response characteristics, results indicate regional discrepancies (between NWM, EM and SM sub-regions) in the distribution of hydrological response characteristics at the annual and the event scale. The NWM catchments are the wettest, and the SM catchments are the driest, while the EM catchments are intermediate and exhibit the largest variability. The NWM sub-region shows the most extreme rainfall regime in the Mediterranean, particularly, in an arc that extends from Northeastern Spain to southern Italy. Observations indicate decreasing tendency in water resources due to both anthropogenic and climatic factors, and a more extreme rainfall regime. Moreover, Mediterranean catchments show very heterogeneous responses over time and space, resulting in limitations in hydrological modeling and large uncertainties in predictions. Nevertheless, the models in use are classical ones; very few were developed to address the specificities of the region. These results will be further analyzed to assess the implications of Mediterranean hydrological response characteristics on catchments sediment yields and water quality.

International audience; This work analyzes the hydrological response characteristics at the event scale of catchments in Lebanon (eastern Mediterranean); and discusses the impact of climatic conditions and physiographic characteristics on the catchment response. Furthermore, the Lebanese catchments are compared throughout this work to catchments in other parts of the Mediterranean. The comparison was used not only to learn from similarities and differences but also to compensate the lack of high-resolution data. Hydro-meteorological data relative to 17 rainfall-runoff events (22 drainage basins ranging in area from 28.6 to 1432 km2) are collected and analysed across the country. Similar data are gathered from the literature for 137 events (137 drainage basins ranging in area from 3.8 to 4915 km2) all across the Mediterranean divided into the northwestern (NWM), eastern (EM) and southern Mediterranean (SM). All the chosen events are of at least a 10 years return period. The gathered information consist of the physiographic and climatic characteristics of the affected catchments, the date, duration and rainfall depth of the event, and the catchment response in term of peak flow, runoff depth and ratio. The analysis shows that the majority of the Lebanese catchments are mountainous with high relief ratio and drainage density which favors the rapid concentration of runoff along flow lines. Although under Mediterranean climate these catchments do not exhibit water-limited conditions, in fact annual runoff ratio/aridity index values are higher/lower than recorded in other EM catchments. Estimation of the unit peak flows are in the range of those recorded in other EM catchments however, events runoff ratios (mean = 0.39) are more in the range of the NWM catchments (mean runoff ratios are 0.4 for NWM, 0.35 for SM and only 0.12 in EM),. This could be attributed to the karstic nature of the Lebanese terrains. Finally, antecedent soil moisture conditions appear to have a major impact on the catchment response especially in term of event runoff ratio. This work shed some lights on the hydrological response characteristics of poorly-gauged Lebanese catchments at the event scale. Nevertheless, it does not omit the need for higher resolution data that permits more in-depth investigation of the mechanism that trigger Lebanese catchment response.

International audience; The Mediterranean region is a water stressed environment with increasing climatic and anthropogenic pressures. This work presents a review of 120 hydrological studies carried out in the Mediterranean region. It contributes to the ongoing hydrological research initiative on “Hydrology in a changing world” launched by the IAHS in 2014. It aims to understand the characteristics of hydrological response under Mediterranean conditions, taking into account changes driven by anthropogenic and climatic factors; and to compare modeling and regionalization approaches in use.

National audience; Les cartes de risque et celles de la susceptibilité des versants aux mouvements de terrain ont été établies sur le bassin versant du Nahr Ibrahim (Liban), en utilisant une méthode de corrélation univariée et bivariée. Le site étudié couvre une surface de 312 km2, soit 3% du Liban. Des images satellites IKONOS ont été utilisées pour délimiter les glissements de terrain. Des facteurs morphologiques, géologiques, pédologiques, hydrologiques et anthropiques intervenant dans les mouvements de terrain, ont été extraits à partir d’un Système d’Informations Géographiques (SIG). Des corrélations statistiques univariée et bivariée entre les mouvements de terrain existants et les facteurs de prédisposition ou de susceptibilité ont également été effectuées. La base de données des facteurs déclenchants et de prédisposition des glissements de terrain a permis d’établir des cartes de susceptibilité et de risque de mouvements de terrain pour le site étudié. L’interprétation visuelle des images satellites a permis la délimitation de 229 glissements de terrain couvrant une surface de 7.6 km2. L’étude montre, selon la télédétection bivariée et les corrélations statistiques sous SIG (corrélation du Tau-b de Kendall), que la lithologie est le facteur le plus influent sur l’occurrence des glissements de terrain, en ayant la corrélation la plus élevée avec les autres paramètres (7 fois corrélée à 1% de niveau de signification et 3 fois à 5%). Il est également montré que les corrélations statistiques des glissements de terrain semblent meilleures avec les autres paramètres, mais avec des niveaux de signification plus faibles. La méthode mathématique proposée de prise de décision (VABU), qui considère deux niveaux de poids pour la cartographie de la susceptibilité et du risque des mouvements de terrain, a montré que 19% et 7% du bassin sont identifiés comme des surfaces à très forte susceptibilité et risque.

International audience; Increased landslide activity is commonly listed as an expected impact of anthropo‐genic‐climatic change. This chapter correlates between factors inducing landslides and explores the effect of human induced climate change (rainfall and forest fires) on land stability. Landslide susceptibility/hazard maps were established using an adapted Value Analytical Bi‐Univariate (VABU) method for Naher El Damour watershed located in Lebanon. The site covered an area of 318 km2 compromising 3% of Lebanon. Aerial photography of 1956, IKONOS images of 2005 & 2008 along with filed investigation were conducted to delineate landslides and their corresponding increase during the last five and half decade. Morphological, geological‐soil, hydrological, and anthropogenic parametric factors affecting landslides were extracted under GIS environment. Statistical correlation between existing landslides and related factors using both univariate and bivariate analysis was also conducted. The later along with landslide inventory mapping and GIS databases enabled establishing the susceptibility and hazard maps for the basin. The visual interpretation of aerial photographs and satellite images allowed the delineation of 694 landslides with a 21% increase in landslides number during the last 7 years which is mainly due to anthropogenic‐climate change factors. The study indicates, depending on bivariate remote sensing and GIS statistical correlations, that lithology (preconditioning factor) and forest fire (triggering factor) are the most influencing parameters on Landslide occurrence. The later summed up with rainfall to hold 73% of secondary weighing factor in triggering landslides. The proposed mathematical decision making method (VABU) that considered two‐level weights for mapping landslide susceptibility/hazard showed that 19 % and 14 % of the watershed is identified as very‐high susceptibility and hazard areas respectively. The accuracy of the model was checked and proved to be approximately 74% in both maps.

International audience; This work is a synthesis of hydrological studies across Mediterranean climates. It aims to characterize the hydrological response of Mediterranean catchments at the annual water balance scale and the event scale. This study is an analysis based of 50 studies reported in the literature for 200 catchments across the Mediterranean climate. At the annual water balance scale, physical and climatic catchment descriptors (area, elevation, slope, forest cover, karst, annual precipitation, annual evapotranspiration, aridity index) and catchment response indices (annual runoff, specific discharge, runoff coefficient) were extracted. While at the event scale, in addition to the former catchment descriptors, information relative to the catchment wetness conditions were also taken into account, alongside with the meteorological event characteristics (date, duration, rainfall depth, rainfall intensity) and the corresponding catchment response indices (runoff depth, maximum peak discharge, event runoff coefficient). Relationships between catchment descriptors and/or meteorological events characteristics on the one hand, and catchment hydrological response on the other hand were plotted and discussed at the annual and the event scale respectively.

International audience; Increased landslide activity is commonly listed as an expected impact of anthropogenic-climatic change. This study correlates between factors inducing landslides and explores the effect of human induced climate change (rainfall and forest fires) on land stability. Landslide susceptibilit y/hazard maps were established using an adapted Value Analytical Bi-Univariate (VABU) method for Naher El Damour watershed located in Lebanon.

International audience; Although a global catchment classification scheme is yet to be established, grouping of catchments according to their hydrologic similarities based upon catchment structure and function is an important tool for modeling guidance, generalization, transferability, prediction in un-gauged basins and anthropogenic global change impacts. The purpose of this study is to create a typology of a set of 17 catchments in Lebanon according to their hydrologic similarities using structural (landform, topography, geology, land use, climate, etc.) and functional (magnitude, duration, frequency, rate of change, climate, etc.) hydrological indices. These indices could be derived from widely available hydrologic and landscapes data. Correlations were performed over pairs of indices and only those showing little or no positive correlation were kept for analysis. To further reduce the number of variables, PCA (Principal Component Analysis) was carried out between structural and functional hydrological indices; as variables, and their correspondingbasins respectively. Only variables strongly associated with one or more of the three principal axes were retained. Furthermore, a stepwise linear regression was used to define relationship between multiple structural indices and each individual functional characteristic for each basin. Herein, two classification approaches has been followed. (1) Classification according to functional index: for each index, basins showing similar regression relationships were grouped together, thus resulting in different catchment classifications from one index to another. One can use one or another of these different classifications according to the problematic that have been raised. (2) A global classification approach where catchments representing similar regressions in more than half of their functional indices were gathered in one class. This latter approach permits the regrouping of catchments that have the maximum of similarities in term of their structural and functional characteristics.

Arbuscular mycorrhizas (AM) are widespread symbiotic associations between plant roots and AM fungi. Deep membrane alterations are the foremost morphological changes occurring in the host plant in response to AM symbiosis. Two-dimensional gel electrophoresis (2-DE) is the workhorse method in AM proteomics. Membrane proteins are under-represented in 2-DE because of their hydrophobicity, low abundance, and precipitation at their isoelectric point, thereby few are the identified membrane proteins involved in sustaining the AM symbiosis. Membrane proteomics is still challenging due to 2-DE related shortcomings, however latest trends and advancements in mass spectrometry (MS)-based quantitative proteomics offer enormous potential to monitor membrane protein change in abundance in large scale experiments. In the current work microsomal proteins of Medicago truncatula roots inoculated with Rhizophagus irregularis were, for the first time, scrutinised by state-of-the-art MS-based proteomic approaches iTRAQ-OFFGEL-LC-MS/MS and label-free 1-DE-LC-MS/MS. The applied workflows combine two novel proteomic procedures, label-based and -free, targeting an insight view on the membrane proteome changes in AM symbiosis. A subcellular fractionation method is herein described to access the total membrane-associated proteins with sufficient recovery and purity for their subsequent in-depth analysis. In addition to the biological gain by shedding the light on candidate AM-related membrane proteins, a methodological approach was carried out in the present work in order to elucidate the iTRAQ labelling impact on peptide isoelectric points., La symbiose mycorhizienne à arbuscules (SMA) est le résultat de l'interaction entre les racines de plus de 80% des familles de plantes terrestres et les champignons MA. Divers types de membranes jouent un rôle crucial dans la mise en place et le fonctionnement de la SMA chez l’hôte végétal. Si l’électrophorèse bidimensionnelle (2-DE) reste la méthode la plus couramment utilisée pour des analyses protéomiques quantitatives dans la SMA, elle résout difficilement les protéines membranaires en raison de leur hydrophobicité, leur précipitation au point isoélectrique (pI) et leur faible abondance comparativement aux protéines cytosoliques. Donc peu nombreuses sont les protéines membranaires identifiées comme étant régulées en réponse à la symbiose. Afin d’avoir accès à cette catégorie de protéines et contourner les défauts de la 2-DE, l’application de nouvelles méthodes permet de réaliser des analyses quantitatives avec marquage chimique (comme l’iTRAQ) ou non (label-free). Dans ce contexte, deux méthodes de protéomique quantitative, iTRAQ-OFFGEL-CL-SM/SM et « label-free » 1-DE-CL-SM/SM, sont adoptées dans ce travail visant à identifier et quantifier les variations d’accumulation des protéines microsomales de racines de Medicago truncatula inoculées par Rhizophagus irregularis, préalable indispensable à l’analyse de leur rôle fonctionnel dans la SMA. Un protocole d’extraction donnant accès à des fractions radiculaires enrichies en protéines microsomales nécessaires pour les analyses ultérieures est décrit dans cette étude. En plus de l’analyse quantitative du protéome membranaire en réponse à la SMA, une approche méthodologique a été mise en place afin d’étudier l’impact du marquage iTRAQ sur le pI des peptides.

International audience

International audience; Emergent population and expansions of settlements and life-lines over hazardous areas in the Mediterranean region have largely increased the impact of Mass Movements (MM) both in industrialized and developing countries. This trend is expected to continue in the next decades due to increased urbanization and development, continued deforestation and increased regional precipitation in MM-prone areas due to changing climatic patterns. Consequently, and over the past few years, monitoring ofMMhas acquired great importance from the scientific community as well as the civilian one. This article begins with a discussion of the MM classification, and the different topographic, geologic, hydrologic and environmental impacting factors. The intrinsic (preconditioning) variables determine the susceptibility ofMMand extrinsic factors (triggering) can induce the probability ofMMoccurrence. The evolution of slope instability studies is charted from geodetic or observational techniques, to geotechnical field-based origins to recent higher levels of data acquisition through Remote Sensing (RS) and Geographic Information System (GIS) techniques. Since MM detection and zoning is difficult in remote areas, RS and GIS have enabled regional studies to predominate over site-based ones where they provide multi-temporal images hence facilitate greatly MM monitoring. The unusual extent of the spectrum of MM makes it difficult to define a single methodology to establish MM hazard. Since the probability of occurrence of MM is one of the key components in making rational decisions for management of MM risk, scientists and engineers have developed physical parameters, equations and environmental process models that can be used as assessment tools for management, education, planning and legislative purposes. Assessment of MM is attained through various modeling approaches mainly divided into three main sections: quantitative/Heuristic (1:2.000–1:10.000), semi-quantitative/Statistical (1:25.000–1:50.000) and qualitative/Deterministic (1:100.000 to 1:250.00).The scale of study is usually chosen on the basis of the purpose of assessment, the extent of the study area and data availability. Despite the operational and theoretical limitations due to an extent of data uncertainty where geomorphologic data for instance remains basically subjective and descriptive in addition to unpredictable climatic factors, MM hazard evaluation may constitute a suitable, cost-effective aid to land-use planning. The objective of this paper is to provide a holistic understanding of the nature of different MM, parameters affecting their occurrence and to put forward the wide range of MM detection, modeling and zoning techniques that would eventually serve as prediction and warning systems for communities at risk.

International audience; Hydrological models are an important basis of flash flood forecasting and early warning systems. They provide significant data on hydrological risks. Flash floods, on the other hand, occur periodically in Lebanon; especially in the semi-arid region of the country, due to the thunderstorms that usually hit the area during the summer and autumn periods. The frequency of these events seems to be following an increasing trend in the last few decades, as a result of the global warming phenomenon. The aim of this paper is to develop a flood model for catchments in semiarid regions. The catchment that witnessed the night of September 25, 2011 a flash flood located NE Bekaa valley of Lebanon was chosen as our case study. The model consists of a rainfall-runoff model that converts excess precipitation to direct runoff using the SCS curve number method, and of a hydraulic model that compute the unsteady state flow in the main channel based on the hydrological model (rainfall-runoff model) derived hydrographs, using the kinematic wave method. The rainfall data used as input for the hydrological model was derived from recently implemented rain gauge station in the catchment, while the basin parameters were extracted from the available 10 m Digital Elevation Model, soil and land use maps for the catchment area. The hydrological model was calibrated using a post flood measurements of the maximum water level observed at some control cross sections and by investigating with local eye witnesses since the catchment is missing a stream gauging network. The calibrated hydrological model was simulated for flash floods of different return periods, to estimates the maximum peak discharge possible in the catchment for a 20, 50 70, and 100 years flood. The different obtained recurrence flood models was simulated with proposed dams, detention ponds, and other water retention structures in different location to attenuate the peak discharge at the basin outlet. The designed model represents a tool for flash flood prediction and can be of great aid for flood damages prevention in an area that suffered from flash floods for a long period of time.

Deep changes in the shape and number of organelles, together with profound modifications in various membrane compartments, are induced within arbuscular mycorrhizal (AM) symbiosis. In this context, to investigate the membrane-associated proteins that are regulated in the model interaction Medicago truncatula – Rhizophagus irregularis, label-free 1DE-LC-MS/MS approach has been employed as alternative to two-dimensional gel electrophoresis. The existence of a correlation between protein abundance and peak areas or number of MS/MS spectra has widened the choice of label-free quantitative proteomics. The results highlighted microsomal protein candidates that could be involved in the symbiotic exchanges between plant and fungal cells.

Arbuscular mycorrhizas (AM) are widespread symbiotic associations between plant roots and AM fungi. Deep membrane alterations are the foremost morphological changes occurring in the host plant in response to AM symbiosis. Two-dimensional gel electrophoresis (2-DE) is the workhorse method in AM proteomics. Membrane proteins are under-represented in 2-DE because of their hydrophobicity, low abundance, and precipitation at their isoelectric point, thereby few are the identified membrane proteins involved in sustaining the AM symbiosis. Membrane proteomics is still challenging due to 2-DE related shortcomings, however latest trends and advancements in mass spectrometry (MS)-based quantitative proteomics offer enormous potential to monitor membrane protein change in abundance in large scale experiments. In the current work microsomal proteins of Medicago truncatula roots inoculated with Rhizophagus irregularis were, for the first time, scrutinised by state-of-the-art MS-based proteomic approaches iTRAQ-OFFGEL-LC-MS/MS and label-free 1-DE-LC-MS/MS. The applied workflows combine two novel proteomic procedures, label-based and -free, targeting an insight view on the membrane proteome changes in AM symbiosis. A subcellular fractionation method is herein described to access the total membrane-associated proteins with sufficient recovery and purity for their subsequent in-depth analysis. In addition to the biological gain by shedding the light on candidate AM-related membrane proteins, a methodological approach was carried out in the present work in order to elucidate the iTRAQ labelling impact on peptide isoelectric points, La symbiose mycorhizienne à arbuscules (SMA) est le résultat de l'interaction entre les racines de plus de 80% des familles de plantes terrestres et les champignons MA. Divers types de membranes jouent un rôle crucial dans la mise en place et le fonctionnement de la SMA chez l’hôte végétal. Si l’électrophorèse bidimensionnelle (2-DE) reste la méthode la plus couramment utilisée pour des analyses protéomiques quantitatives dans la SMA, elle résout difficilement les protéines membranaires en raison de leur hydrophobicité, leur précipitation au point isoélectrique (pI) et leur faible abondance comparativement aux protéines cytosoliques. Donc, peu nombreuses sont les protéines membranaires identifiées comme étant régulées en réponse à la symbiose. Afin d’avoir accès à cette catégorie de protéines et contourner les défauts de la 2-DE, l’application de nouvelles méthodes permet de réaliser des analyses quantitatives avec marquage chimique (comme l’iTRAQ) ou non (label-free). Dans ce contexte, deux méthodes de protéomique quantitative, iTRAQ-OFFGEL-CL-SM/SM et « label-free » 1-DE-CL-SM/SM, sont adoptées dans ce travail visant à identifier et quantifier les variations d’accumulation des protéines microsomales de racines de Medicago truncatula inoculées par Rhizophagus irregularis, préalable indispensable à l’analyse de leur rôle fonctionnel dans la SMA. Un protocole d’extraction donnant accès à des fractions radiculaires enrichies en protéines microsomales nécessaires pour les analyses ultérieures est décrit dans cette étude. En plus de l’analyse quantitative du protéome membranaire en réponse à la SMA, une approche méthodologique a été mise en place afin d’étudier l’impact du marquage iTRAQ sur le pI des peptides

Among the various natural hazards, landslides are probably the most damaging to the natural and human environment in the Mediterranean countries. The landslides in Jwaya, a town in southern Lebanon in winter 2010 have been studied., Parmi les différents risques naturels, les glissements de terrain sont probablement ceux qui créent le plus de dommages dans les pays méditerranéens. Le glissement de terrain de l'hiver 2010 à Jwaya au sud du Liban a été étudié.

International audience; Exploratory GIS and remote sensing analysis for developing statistical correlations between environmental parameters and mass movements' occurrence.; Caractérisation spatiale et statistique des paramètres environnementaux et anthropiques conditionnant la stabilité des terrains au Liban.

International audience; Among the various natural hazards, mass movements (MM) are probably the most damaging to the natural and human environment in Mediterranean countries, including Lebanon which represents a good case study. This research deals with how to use Geographic Information Systems (GIS) for establishing the relationships between MM occurrence and different factor terrain parameters over a representative region of Lebanon. Parameters expressed by: 1ancillary data like lithology, proximity to fault zone, soil type, land cover/use, distance to drainage line and rainfall quantity, and 2derived data like slope gradient, slope aspect, soil rugosity, and soil texture from radar satellite imageries were correlated withMMusing GIS-approaches. TheMMwere first detected through visual interpretation of two stereo-pairs of SPOT 4 images (anaglyph) at 10 m resolution. This study indicates, depending on bivariate Remote Sensing and GIS statistical correlations (Kendall Tau-b correlation), that the lithology is the most influencing factor on MM occurrence. It also shows that statistical correlations to mass movements exist best between factors at the following decreasing order of importance: lithologyproximity to fault line, lithologysoil type and lithologydistance to drainage line at 1% level of significance, and soilland cover/use, slope aspect-land cover/use, and soilslope gradient at 5% level of significance. These correlations were verified and checked through field observations and explained using univariate statistical correlations. Therefore, they could be extrapolated to other Mediterranean countries having similar geoenvironmental conditions.

International audience

National audience