Vegetation patch effects on flow resistance at channel scale

International audienceThanks to a specific experimental design in a controlled channel, this paper aimed at quantifying how patches of four different ditches plant species affect integrated flow resistance parameters, the Manning coefficient. These plants, frequently encountered in the farmland ditches and irrigation channels of the south of France, were selected according to a large range of hydrophilic requirements, flexibility and branching complexity related to the plant blockage factor. Eight different spatial patches (regular, random, lateral or central patches) of each plant with crescent or similar plant densities were implanted at the bottom of a controlled channel where the water levels and water velocities were measured for three different discharges in steady and unsteady flow conditions. Resistance parameters (Manning parameters) were then estimated from the total head-loss, or from flow propagation velocity in the channel thanks to inversion of an hydrodynamic model. These experiments allow us to test the significance effect of channel vegetation patches and densities on flow resistance parameters at the reach scale

Antioxidant actions of ovothiol-derived 4-mercaptoimidazoles: glutathione peroxidase activity and protection against peroxynitrite-induced damage

Abstract4-Mercaptoimidazoles derived from the naturally occurring antioxidants, ovothiols, were tested for their glutathione peroxidase-like (GSH Px-like) activity and protection against peroxynitrite-induced damage. All the thiol compounds displayed similar significant GSH Px-like activities, which are however weaker than that of the reference compound, ebselen. The inhibitions of the peroxynitrite-dependent oxidation of Evans blue dye and dihydrorhodamine 123 showed that the thiol compounds substituted on position 5 of the imidazole ring were nearly as effective as ebselen while the C-2 substituted ones were less effective. Both assays corroborate the large superiority of mercaptoimidazoles over glutathione as inhibitors of peroxynitrite-dependent oxidation

Synthesis and biological activity of isogranulatimide analogues

The synthesis of new isogranulatimide analogues, their inhibitory activities toward the Checkpoint 1 kinase (Chk1), and their in vitro cytotoxicities toward four tumor cell lines (one murine L1210 leukemia, and three human cell lines: DU145 prostate carcinoma, A549 non-small cell lung carcinoma, and HT29 colon carcinoma) are described. The affinity for DNA of some representative compounds and their ability to induce DNA cleavage mediated by topoisomerase I have been examined. In some of the newly synthesized compounds, the imidazole heterocycle of isogranulatimide is replaced by a pyrrole and/or the indole unit is replaced by a 7-azaindole. Compounds in which a sugar part is attached to the 7-azaindole moiety have also been prepared. Some of the newly synthesized compounds are more potent Chk1 inhibitors than granulatimide. The selectivity of two potent Chk1 inhibitors 24 and 26 has been evaluated using various kinases. The strongest inhibitory properties are found toward Chk

Automatic reconstruction of urban wastewater and stormwater networks based on uncertain manhole cover locations

International audienceAccurate maps of sewer and stormwater networks in cities are mandatory for an integrated management of water resources. However, in many countries this information is unavailable or inaccurate. A new two-fold mapping method is put forward. The first step consists in using imageprocessing techniques to detect buried network surface elements such as manhole covers on very high resolution aerial imagery. The second step consists in connecting them automatically using a tree-shaped graph constrained by industry rules. The method is tested on Prades-le-Lez, Southern France. The shape and topology of the reconstructed network are compared to the actual ones.The impact of the detected objects’ density is also assessed

Use of 2,6-diaminopurine as a potent suppressor of UGA premature stop codons in cystic fibrosis

Nonsense mutations are responsible for around 10% of cases of genetic diseases, including cystic fibrosis. 2,6-diaminopurine (DAP) has recently been shown to promote efficient readthrough of UGA premature stop codons. In this study, we show that DAP can correct a nonsense mutation in the Cftr gene in vivo in a new CF mouse model, in utero, and through breastfeeding, thanks, notably, to adequate pharmacokinetic properties. DAP turns out to be very stable in plasma and is distributed throughout the body. The ability of DAP to correct various endogenous UGA nonsense mutations in the CFTR gene and to restore its function in mice, in organoids derived from murine or patient cells, and in cells from patients with cystic fibrosis reveals the potential of such readthrough-stimulating molecules in developing a therapeutic approach. The fact that correction by DAP of certain nonsense mutations reaches a clinically relevant level, as judged from previous studies, makes the use of this compound all the more attractive

Le motif de reconnaissance specifique de l'ADN, SPKK et son utilisation pour l'elaboration d'hybrides peptide-intercalant

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : T 84814 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Alpine ocean seafloor spreading and onset of pelagic sedimentation: new radiolarian data from the Chenaillet-Montgenèvre ophiolite (French-Italian Alps)

International audienceRadiolarians of Middle Jurassic age (tentatively middle Bathonian) provide the first direct age determination from oceanic sediments associated with the Chenaillet-Montgenèvre ophiolite (Piemonte zone, French-Italian Alps). This datum obtained from radiolarites of the Lago Nero-Replatte thrust sheet is older than those previously established on ophiolite sedimentary covers from this segment of the western Alps. It also shows that Lago Nero-Replatte basal radiolarites are anterior to the youngest intrusives from the overlying Chenaillet s.s. thrust sheet. This chronological relationship implies either a late seafloor spreading-related magmatic activity in places younger than adjacent initial pelagic sedimentation, or more likely that the Lago Nero-Replatte and the Chenaillet s.s. thrust sheets are distinct and distant pieces of lithosphere that were eventually stacked together: the Lago Nero-Replatte unit was trapped within the accretionary wedge while the Chenaillet s.s., of a younger age and in a more distal position with regards to the European margin, was obducted. Regionally, the Lago Nero-Replatte sediments appear to be coeval to other Bathonian supraophiolitic radiolarites exposed in the western Alps. These results strengthen the Bathonian correlation of widespread seafloor spreading in both western Tethys and the central Atlantic ocean

L'écohydrologie des fossés

National audienceL'écohydrologie est la science qui étudie l'interaction mutuelle entre les cycles hydrologiques et les écosystèmes. Dans les bassins versants méditerranéens, l'eau est souvent un facteur limitant, non seulement en raison de sa rareté mais aussi à cause de sa disponibilité intermittente et imprévisible. Elle est aussi une ressource abiotique pour les organismes vivants (les « biotes ») : les plantes, les animaux et les invertébrés. Observer et comprendre les lois qui régulent l'interdépendance entre l'hydrologie et ces « biotes » permettront ensuite de simuler les changements des régimes de pluie, de changement du paysage mais aussi de quantifier la plus-value apportée par les paysages agricoles aux écosystèmes. Sur la base des préférences écologiques des espèces recensées début août 2012, 10 espèces présentant des aires de distribution très caractéristiques ont été retenues pour être échantillonnées de manière exhaustive sur le bassin versant de Roujan étendu au Bourdic durant 3 jours fin août 2012. Perspectives Grâce à l'analyse de la structuration spatiale des espèces végétales, nous pouvons espérer accéder à des données difficiles à mesurer sur le terrain, telles qu'une estimation des durées de submersion annuelles dans le fossé, son ensoleillement, son humidité et sa granulométrie. Les espèces végétales sont des marqueurs des conditions pédo-climatiques présentes et passées. D'autre part, l'analyse plus détaillée de la distribution spatiale de certaines espèces hydrochores dans les fossés pourra nous renseigner sur le trajet de l'eau, voire sa vitesse d'écoulement. L'écohydrologie apporte ainsi des éléments fondamentaux pour comprendre les interrelations entre les flux biotiques et abiotiques dans les paysages, et ainsi les services écosystémiques qu'ils produisent. Il existe des relations avérées entre l'eau circulant dans les fossés et la flore et la faune. D'une part, la couverture végétale bordant les fossés intercepte la lumière et diminue la température de l'eau qui y circule. Les végétaux présents dans les fossés peuvent également modifier la vitesse de l'eau du fossé, augmenter les risques de débordement ou favoriser l'infiltration. D'autre part, l'eau permet aux graines ou aux pollens de certaines plantes, dites hydrochores, de se propager dans le bassin versant. Enfin les préférences écologiques des espèces nous renseignent sur les caractéristiques pédo-climatiques régnant à l'intérieur des fossés. La considération des préférences écologiques des dix espèces échantillonnées nous permet de cartographier le taux d'humidité du sol sur l'ensemble du réseau. Carte représentant un exemple de trois espèces dont les aires sont clairement distinctes. Cela permet de mettre en évidence les liens entre les caractéristiques physiques du bassin (relief, pente) et les les préférences écologiques des espèces

Using geomorphological variables to predict the spatial distribution of plant species in agricultural drainage networks

To optimize ecosystem services provided by agricultural drainage networks (ditches) in headwater catchments, we need to manage the spatial distribution of plant species living in these networks. Geomorphological variables have been shown to be important predictors of plant distribution in other ecosystems because they control the water regime, the sediment deposition rates and the sun exposure in the ditches. Whether such variables may be used to predict plant distribution in agricultural drainage networks is unknown. We collected presence and absence data for 10 herbaceous plant species in a subset of a network of drainage ditches (35 km long) within a Mediterranean agricultural catchment. We simulated their spatial distribution with GLM and Maxent model using geomorphological variables and distance to natural lands and roads. Models were validated using k-fold cross-validation. We then compared the mean Area Under the Curve (AUC) values obtained for each model and other metrics issued from the confusion matrices between observed and predicted variables. Based on the results of all metrics, the models were efficient at predicting the distribution of seven species out of ten, confirming the relevance of geomorphological variables and distance to natural lands and roads to explain the occurrence of plant species in this Mediterranean catchment. In particular, the importance of the landscape geomorphological variables, ie the importance of the geomorphological features encompassing a broad environment around the ditch, has been highlighted. This suggests that agro-ecological measures for managing ecosystem services provided by ditch plants should focus on the control of the hydrological and sedimentological connectivity at the catchment scale. For example, the density of the ditch network could be modified or the spatial distribution of vegetative filter strips used for sediment trapping could be optimized. In addition, the vegetative filter strips could constitute new seed bank sources for species that are affected by the distance to natural lands and roads

Ecohydrology of agricultural ditches

International audienceLandscape is a complex object that supports both biotic and abiotic processes. Understanding the interrelations between the biotic and abiotic processes of the landscape is of primary importance as these interrelations act as limitation factors for severale ecosystem propertics. We considered as case study the composition in flora of agricultural ditches that drive flows of water, because of the relationships between biotic and abiotic elements, as plants immersed affect rugosity and friction of water running, and water velocity affects plant seed dispersal. During august 2012, we sampled exaustively along a eighty-kilometers ditches network ten plant species. The study of niche preference of these species help us determining variables that drives water movement, such as granulometry, hygrometry, that are generally difficult to assess. Furtbermore, the spatial distribution of some hydrochorus species, i.e. for which seeds are dispersed by water, help us collecting usefull informations on water circulation and speed in ditches. The interest of using distribution of flora for hydrologists is discussed in this work