Evolution of coastal zone vulnerability to marine inundation in a global change context. Application to Languedoc Roussillon (France)

The coastal system is likely to suffer increasing costal risk in a global change context. Its management implies to consider those risks in a holistic approach of the different vulnerability components of the coastal zone, by improving knowledge of hazard and exposure as well as analyzing and quantifying present day and future territory vulnerability. The ANR/VMC2007/MISEEVA project (2008-2011) has applied this approach on Languedoc Roussillon region in France. MISEEVA approach relies on several scenarios for 2030 and 2100, in terms of meteorology (driver of coastal hazard), sea level rise, and also considering further trends in demography and economy, and possible adaption strategies Hazard has been modeled (SWAN, MARS and SURFWB), on the base of the presentday situation, sea level rise hypotheses, and existing or modeled data, of extreme meteorological driving f. It allowed to assess the possible surges ranges and map coastal zone exposure to: - a permanent inundation (considering sea level rise in 2030 and 2100, - a recurrent inundation (considering sea level rise and extreme tidal range) - an exceptional inundation (adding extreme storm surge to sea level rise and tidal range). In 2030, exposure will be comparable to present day exposure. In 2100, extreme condition will affect a larger zone. Present days social and economic components of the coastal zone have been analyzed in terms of vulnerability and potential damaging. Adaptation capacity was approached by public inquiries and interviews of stakeholders and policy makers, based on existing planning documents The knowledge of the present day system is then compared to the possible management strategies that could be chosen in the future, so to imagine what would be the evolution of vulnerability to marine inundation, in regards to these possible strategies

Identification moléculaire des agents de la virulence chez les Hyménoptères Braconides parasitoïdes de drosophiles

Pour assurer le succès parasitaire, les endoparasitoïdes ont développé des facteurs divers et variés pouvant manipuler la physiologie de l'hôte. En effet, de nombreux parasitoïdes altèrent le développement ou la physiologie de leurs hôtes en leur injectant des substances de type venin ou fluides ovariens. Les hyménoptères parasitoïdes du genre Asobara constituent un groupe très intéressant de par leurs stratégies de parasitisme différentes vis-à-vis de leurs hôtes drosophiles. Le travail de thèse reporté ici avait pour objet d'étudier les facteurs mis en place et utilisés dans ces stratégies de parasitisme. Nous nous sommes intéressés à deux espèces du genre Asobara. Nous avons entrepris chez les deux parasitoïdes Asobara tabida et Asobara japonica, une étude de l'ultrastructure des glandes à venin, organites où sont produits les facteurs régulant l immunité et la physiologie de l hôte, ainsi qu'une étude des transcrits qui y sont produits. La composition protéique du venin d'A. tabida est relativement faible en comparaison à A. japonica qui possède un venin riche en protéines avec des effets très néfastes sur la physiologie des larves de drosophile. Celle-ci nous a permis de montrer que ces deux espèces, bien qu'appartenant à un même genre, ne présentent pas du tout les mêmes profils protéiques et par conséquent, des transcrits différents. Asobara tabida, se distingue des autres de par sa stratégie de virulence qualifiée de "passive " ou encore d'immunoévasion. Chez cette espèce, on n'observe pas d'altération directe de la physiologie de l'hôte. Pourtant, cette espèce réussit à parasiter les larves de Drosophila melanogaster grâce à ses œufs qui ont la particularité de posséder des propriétés d'adhésivité et de se mêler aux tissus hôtes après infestation. Les mécanismes d'adhésivité sont donc les seuls éléments qui ont révélé avoir un rôle dans le parasitisme à ce jour chez Asobara tabida. Il faut noter qu'une légère paralysie de l'hôte a été également observée chez cette espèce mais celle-ci reste transitoire et devrait apporter une faible contribution dans le succès parasitaire. Nous nous sommes interrogés sur la présence de venin chez Asobara tabida et sur sa composition. Nous avons montré que le venin de cette espèce possède de nombreuses protéines, dont une dont nous avons cloné le gène. Cette protéine, l'aspartylglucosaminidase (AtAGA), représente un composant majoritaire du venin, c'est une enzyme que l'on retrouve chez d'autres organismes où elle est généralement lysosomale. Les résultats, qui découlent des analyses réalisées sur l'AtAGA, nous ont permis de caractériser cette enzyme. Cependant la fonction de l'AtAGA reste inconnue mais plusieurs hypothèses quant à son rôle dans la relation hôte parasitoïde ne sont pas exclues. Par ailleurs des analyses de purification de protéines venimeuses et de séquençage ont été initiées chez le parasitoïde A. japonica. Ces différentes approches montrent qu'il existe une diversité de stratégies et d'agents de la virulence au niveau interspécifique. Les parasitoïdes, soumis aux défenses immunitaires de l'hôte, ont adapté leur capacité de virulence aux variations de résistance de l'hôte. La diversité de stratégie et d'agents existante est le fruit de l'évolution du parasitoïde, mais également de l'évolution de son hôte dont il est dépendant.In order to assure the parasitic success, endophagous parasitoids have developed varied and diverse factors that can manipulate the physiology of the host. Indeed, many parasitoids alter development or physiology of their hosts by injecting them with substances like venom or ovarian fluid. The parasitic wasps of the genus Asobara is a very interesting group because of their different parasitism strategies toward their host fruit flies. The aim of this thesis was to investigate factors used in these strategies of parasitism. We are interested in two species of the genus Asobara. We have realized in both parasitoids, Asobara tabida and Asobara japonica, an ultrastructural study of venom glands, which are organelles produced factors that regulate immunity and physiology of the host, and a study of transcripts from these organelles. The composition of the venom protein A. tabida is relatively small compared to A. japonica, which has a rich venom protein with significant detrimental effects on the physiology of Drosophila larvae. This allowed us to show that these two species, although belonging to the same genus, show different profiles of proteins and therefore different transcripts. Asobara tabida is distinguished from others by its virulence strategy termed "passive" or to immunoevasion. In this case, there is no direct alteration of the physiology of the host. However, this species is able to parasitize larvae of Drosophila melanogaster with eggs that have properties of adhesion and which are embedded with the host tissue after oviposition. At this time, only the adhesive properties of the eggs have demonstrated a role in the virulence of this parasitoid. It should be noted that a slight paralysis of the host was also observed in this species but it is transitional and should make a small contribution in the successful parasite. We are interested in Asobara tabida's venom and its composition. We have shown that the venom of this species has many proteins, one of which we cloned a gene. This protein, named aspartylglucosaminidase (AtAGA), are a major component of the venom and is an enzyme found in other organisms, where it is generally lysosomal. The results arising from tests performed on the AtAGA we have to characterize this enzyme. However the function of the AtAGA remains unknown but several hypotheses about its role in parasitoid-host relationship is not excluded. Moreover, analyses of venomous protein purification and sequencing have been initiated in the parasitoid A. japonica. These different approaches show that there is a diversity of strategies and agents of virulence at an interspecific level. Parasitoids, which are subject to the defences of the host, have adapted their virulence capacity to variations in host resistance. Diversity of strategies and agents is the result of the evolution of parasitoid, but also the evolution of its host where it is dependent.AMIENS-BU Sciences (800212103) / SudocSudocFranceF

Molecular and biochemical analysis of an aspartylglucosaminidase from the venom of the parasitoid wasp Asobara tabida (Hymenoptera: Braconidae)

International audienceThe most abundant venom protein of the parasitoid wasp Asobara tabida was identified to be an aspartylglucosaminidase (hereafter named AtAGA). The aim of the present work is the identification of: 1) its cDNA and deduced amino acid sequences, 2) its subunits organization and 3) its activity. The cDNA of AtAGA coded for a proab precursor molecule preceded by a signal peptide of 19 amino acids. The gene products were detected specifically in the wasp venom gland (in which it could be found) under two forms: an (active) heterotetramer composed of two a and two b subunits of 30 and 18 kDa respectively and a homodimer of 44 kDa precursor. The activity of AtAGA enzyme showed a limited tolerance toward variations of pH and temperatures. Since the enzyme failed to exhibit any glycopeptide N-glycosidase activity toward entire glycoproteins, its activity seemed to be restricted to the deglycosylation of free glycosylasparagines like human AGA, indicating AtAGA did not evolve a broader function in the course of evolution. The study of this enzyme may allow a better understanding of the functional evolution of venom enzymes in hymenopteran parasitoids

Coastal flooding of urban areas by overtopping: dynamic modelling application to the Johanna storm (2008) in Gâvres (France)

International audienceRecent dramatic events have allowed significant progress to be achieved in coastal flood modelling over recent years. Classical approaches generally estimate wave overtopping by means of empirical formulas or 1-D simulations , and the flood is simulated on a DTM (digital terrain model), using soil roughness to characterize land use. The limits of these methods are typically linked to the accuracy of overtopping estimation (spatial and temporal distribution) and to the reliability of the results in urban areas, which are places where the assets are the most crucial. This paper intends to propose and apply a methodology to simulate simultaneously wave overtopping and the resulting flood in an urban area at a very high resolution. This type of 2-D simulation presents the advantage of allowing both the chronology of the storm and the particular effect of urban areas on the flows to be integrated. This methodology is based on a downscaling approach, from regional to local scales, using hydrodynamic simulations to characterize the sea level and the wave spectra. A time series is then generated including the evolutions of these two parameters, and imposed upon a time-dependent phase-resolving model to simulate the overtopping over the dike. The flood is dynamically simulated directly by this model: if the model uses adapted schemes (well balanced, shock capturing), the calculation can be led on a DEM (digital elevation model) that includes buildings and walls, thereby achieving a realistic representation of the urban areas. This methodology has been applied to an actual event, the Johanna storm (10 March 2008) in Gâvres (South Brittany, in western France). The use of the SURF-WB model, a very stable time-dependent phase-resolving model using non-linear shallow water equations and well-balanced shock-capturing schemes, allowed simulating both the dynamics of the over-topping and the flooding in the urban area, taking into account buildings and streets thanks to a very high resolution (1 m). The results obtained proved to be very coherent with the available reports in terms of overtopping sectors, flooded area, water depths and chronology. This method makes it possible to estimate very precisely not only the overtopping flows, but also the main characteristics of flooding in a complex topography like an urban area, and indeed the hazard at a very high resolution (water depths and vertically integrated current speeds). The comparison with a similar flooding simulation using a more classical approach (a digital terrain model with no buildings, and a representation of the urban area by an increased soil roughness) has allowed the advantages of an explicit representation of the buildings and the streets to be identified: if, in the studied case, the impact of the urbanization representation on water levels does indeed remain negligible, the flood dynamics and the current speeds can be considerably underestimated when no explicit representation of the buildings is provided, especially along the main streets. Moreover, on the seaside, recourse to a time-dependent phase-resolving model using non-stationary conditions allows a better representation of the flows caused by overtopping. Finally, this type of simulation is shown to be of value for hazard studies, thanks to the high level of accuracy of the results in urban areas where assets are concentrated. This Published by Copernicus Publications on behalf of the European Geosciences Union. 2498 S. Le Roy et al.: Coastal flooding of urban areas by overtopping methodology, although it is currently still quite difficult to implement and costly in terms of calculation time, can expect to be increasingly resorted to in years to come, thanks to the recent developments in wave models and to the increasing availability of LiDAR data

Simulating overtopping and coastal flooding in urban areas: Perspectives to quantify sea level rise effects

International audienceSimulating overtopping and coastal flooding in urban areas: Perspectives to quantify sea level rise effects Recent progresses in numerical modelling and data acquisition have allowed significant improvements in coastal flooding simulations, with a maturity of numerical tools that now allows very precise results in urban areas. Essentially used for hazard studies, their reliability now offers the perspective to estimate the impact of sea level rise on coastal flooding hazards. Thepresented methodis based on simultaneous simulation of wave overtopping and resulting flood in urban areas. This type of two-dimensional simulationscan afford reproducingboth the chronology and the effect of urban areas on flood dynamics. The method consists in elaborating,from larger simulations, a time-series of instantaneous water levels, including waves. This time-series is imposed upon a time-dependent phase-resolving model to simulate dynamically wave overtopping and the resulting flood, using a Digital Elevation Model that includes buildings. This method has been applied to the Johanna storm (2008) in Gâvres (France). SURF-WB, a NLSW model, allowed simulating both overtopping dynamics and flooding, taking into account buildings thanks to a 1m-resolution. Obtained results proved to be very consistent with available reports (overtopping sectors, flooded area, water heights and chronology). This method allows reproducingvery realistically overtopping andflooding dynamics in an urban area (water heights and velocities), with an increased accuracy and very realistic results compared to more classical approaches. This type of simulations can be used to estimate the potential evolutions of coastal flooding processes in a context of sea level rise due to climate change, supposing nevertheless a non-modified morphology. Preliminary simulations realized on the site of Gâvres showed how sea level rise could increase overtopping for a storm like Johanna. For example, a rise of 20 cm of the sea water level may lead to a slightly larger flooded area, but with water heightsincreasing of about 28 cm, due to the modifications in overtopping flows and chronology

Modélisation de la submersion marine lors de la tempête Johanna (2008) à Gâvres (Morbihan) : phénomène de franchissement en zone urbaine

National audienceLa méthodologie présentée dans le présent article vise à simuler de manière la plus réaliste possible les franchissements par paquets de mer et la submersion qui en résulte en milieu urbain. Elle s'appuie sur des simulations régionales à locales de niveaux d'eau et de vagues pour établir des conditions de forçage pour un modèle à résolution de phase ("vague-à-vague") utilisant des schémas numériques adaptés. Ce modèle est alors utilisé sur un Modèle Numérique d'Elévation (MNE), intégrant les bâtiments, de manière à simuler simultanément le franchissement et la propagation de l'inondation. Cette méthodologie a été appliquée avec le modèle SURF-WB à la submersion survenue à Gâvres (Morbihan) lors de la tempête Johanna (10 mars 2008). Les résultats obtenus s'avèrent tout à fait cohérents avec les observations disponibles (zones de franchissement, étendue de l'inondation, hauteurs d'eau et chronologie). Cette méthode permet d'améliorer la qualité des résultats en milieu urbain par rapport aux approches plus classiques, notamment vis-à-vis de la vitesse des courants à terre. Le développement rapide et récent de ce type de modèle devrait permettre la généralisation de ce type d'approche dans les années à venir. Ce travail a été réalisé dans le cadre du projet JOHANNA (partenariat BRGM-UBO, cofinancé par la Fondation MAIF)

Blepharocheilodontic syndrome is a CDH1 pathway-related disorder due to mutations in CDH1 and CTNND1

PURPOSE: Blepharocheilodontic (BCD) syndrome is a rare autosomal dominant condition characterized by eyelid malformations, cleft lip/palate, and ectodermal dysplasia. The molecular basis of BCD syndrome remains unknown. METHODS: We recruited 11 patients from 8 families and performed exome sequencing for 5 families with de novo BCD syndrome cases and targeted Sanger sequencing in the 3 remaining families. RESULTS: We identified five CDH1 heterozygous missense mutations and three CTNND1 heterozygous truncating mutations leading to loss-of-function or haploinsufficiency. Establishment of detailed genotype-phenotype correlations was not possible because of the size of the cohort; however, the phenotype seems to appear more severe in case of CDH1 mutations. Functional analysis of CDH1 mutations confirmed their deleterious impact and suggested accelerated E-cadherin degradation. CONCLUSION: Mutations in CDH1 encoding the E-cadherin were previously reported in hereditary diffuse gastric cancer as well as in nonsyndromic cleft lip/palate. Mutations in CTNND1 have never been reported before. The encoded protein, p120ctn, prevents E-cadherin endocytosis and stabilizes its localization at the cell surface. Conditional deletion of Cdh1 and Ctnnd1 in various animal models induces features reminiscent of BCD syndrome and underlines critical role of the E-cadherin-p120ctn interaction in eyelid, craniofacial, and tooth development. Our data assert BCD syndrome as a CDH1 pathway-related disorder due to mutations in CDH1 and CTNND1 and widen the phenotypic spectrum of E-cadherin anomalies.Genet Med advance online publication 09 March 2017

Vulnerability of sandy coasts to climate variability

The main objective of the VULSACO (VULnerability of SAndy COasts to climate change and anthropic pressure) project was to investigate present day and potential future vulnerability of sandy coasts at the 2030 horizon, i.e. on a time scale related to climate variability. The method, based on a multidisciplinary approach bringing together geologists, geographers, physicists, social psychologists, engineers and stakeholders, was structured around 4 axes: field data analysis; numerical modelling; analysis of governance and stakeholder perceptions; and development of vulnerability indexes. This approach was designed to investigate vulnerability at a local scale and was applied to 4 contrasting beaches located in France: Sète Lido (Mediterranean Sea), Truc Vert and La Tresson beaches (Atlantic Ocean), and Dewulf (English Channel). The results focus on decadal and multi-annual beach trends at the Truc Vert beach site. There is almost no trend in beach volume at Truc Vert beach, although there is a variation in this parameter on a cycle of 2 to 3 yr, with variations related to wave energy and probably to indexes of climate variability. Numerical modelling identified the sensitivity of beach responses to changes in wave height and direction, especially in terms of subtidal morphology and the potential development of shoreline instability. Together with the observed offshore wave angle at the Biscay Buoy, these model results suggest that a potential change in wave angle due to climate variability could significantly modify the bars’ morphology. The combination of data analysis and numerical modelling contributed to the development of vulnerability indexes designed for sandy coasts, which take into account climate-dependant variables such as waves. This allowed the differentiation of the sites in terms of vulnerability to erosion: Sète Lido and Truc Vert beach were the most and least vulnerable sites, respectively. These indexes help in identifying the dominant components of beach vulnerability, and provide potential for the study of how anthropogenic factors affect vulnerability. The study of stakeholder perceptions and decision-making with regard to climate-related risk also highlighted potential anthropogenic effects on beach vulnerability, and identified possible site-specific outcomes.Postprint (published version

Kinetics of glucosylated and non-glucosylated aryltetralin lignans in Linum hairy root cultures

International audienceDue to their pronounced cytotoxic activity, a number of aryltetralin lignans (ATLs), such as podophyllotoxin (PTOX), are used as antitumor compounds. The production of such molecules from entire plants or plant cell-tissue-organ cultures is thus of interest to the pharmaceutical industry. Hairy root cultures constitute a good tool not only for phytochemical production but also for investigating plant secondary metabolism. This work reports on the growth and ATL biosynthesis in two hairy root cultures of Linum album Kotschy ex Boiss. and Linum flavum. The kinetics of accumulation of the intermediates of MPTOX biosynthesis and of their glucosylated forms are described over a 21-day period of growth. An accumulation of non-glucosylated forms of the ATLs during the exponential phase of the cultures is followed by an accumulation of the glucosylated forms during the stationary phase. Our results show a strong coordination of the biosynthetic paths derived from deoxypodophyllotoxin via deoxypodophyllotoxin 6-hydroxylase and deoxypodophyllotoxin 7-hydroxylase, and a coordinated glucosylation of podophyllotoxin, methoxypodophyllotoxin, and 5'-demethoxymethoxypodophyllotoxin. Furthermore, our results suggest an important role of β-peltatin-6-glucoside formation in the control of ATL accumulation in Linum hairy root cultures