Effects of macroalgae, with emphasis on Sargassum spp., on coral reef recruitment processes in Martinique (French West Indies)

Many coral reef ecosystems have undergone profound ecological changes over the past decades leading sometimes to a shift from coral to macroalgal-dominated areas. In Martinique (Caribbean region), the proliferation of macroalgae is an important phenomenon. Coral reef resilience, involving reef building species recruitment, might be modified by macroalgal presence. This work aimed at understanding reef recruitment processes in areas dominated either by macroalgae, coral or intermediate, based on scuba diving observations, manipulative experiments and laboratory studies. Particular attention was given to the physical and chemical effects of Sargassum (one of the most represented species: 100-200 g.m-2 (wet weight) in algal beds) on benthic invertebrates’ larvae recruitment. Further experiments focused on the effects of surface molecules and of the waterborne cues produced by Sargassum polyceratium on the development of marine invertebrates’ embryos. This study demonstrated that juvenile coral diversity and density vary between the considered habitat types (i.e: dominated by algae, coral or intermediate with numerous sea urchins). It was low in algal areas (0.9-1.4 recruit.m-2) as compared to coral ones (7-8 recruit.m-2) and intermediate in urchin zones (2-3.2 recruit.m-2). Moreover, species recruiting differed according to their reproductive mode. Brooders recruited more in coral areas, which suggested that they settled in the vicinity of their parent colonies. Settlement and recruitment experiments demonstrated the barrier effect of Sargassum species on settlement but no allelochemical impacts could be identified in situ. However, the laboratory based experiments demonstrated that S. polyceratium surface molecules were active against the early stages of development of Arenicola brasiliensis (annelid), Codakia orbicularis (bivalvia) and Diadema antillarum (sea urchin, a reef key stone species) (LC50 between 25 and 51 μg.mL-1). These results give insight into the coral recruitment capacities in several habitats, which is of major importance for reef managers.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Diagnostic du Covid-19 en milieu ambulatoire [COVID-19 Diagnosis]

The need to curb the circulation of SARS-CoV-2 virus in the community and to diagnose those at risk of developing complications implies that an appropriate test should be chosen according to the epidemiological and clinical context. Rapid antigen tests, either nasopharyngeal or nasal, have the advantage of reflecting contagiousness better than PCR and giving an immediate result, reason why they are used as first-line for community diagnosis and screening. A rapid test allows immediate management of outpatients and does not falsely attribute the current acute episode to a previous SARS-CoV-2 infection. PCR, whether nasopharyngeal or buccosalivary, is useful for epidemiological surveillance, including that of new variants, as well as identification of severe COVID in the post-infectious phase

Prevalence of SARS-CoV-2 in Household Members and Other Close Contacts of COVID-19 Cases: A Serologic Study in Canton of Vaud, Switzerland.

Research on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission within households and other close settings using serological testing is scarce. We invited coronavirus disease 2019 (COVID-19) cases diagnosed between February 27 and April 1, 2020, in Canton of Vaud, Switzerland, to participate, along with household members and other close contacts. Anti-SARS-CoV-2 immunoglobulin G antibodies were measured using a Luminex immunoassay. We estimated factors associated with serological status using generalized estimating equations. Overall, 219 cases, 302 household members, and 69 other close contacts participated between May 4 and June 27, 2020. More than half of household members (57.2%; 95% CI, 49.7%-64.3%) had developed a serologic response to SARS-CoV-2, while 19.0% (95% CI, 10.0%-33.2%) of other close contacts were seropositive. After adjusting for individual and household characteristics, infection risk was higher in household members aged ≥65 years than in younger adults (adjusted odds ratio [aOR], 3.63; 95% CI, 1.05-12.60) and in those not strictly adhering to simple hygiene rules like hand washing (aOR, 1.80; 95% CI, 1.02-3.17). The risk was lower when more than 5 people outside home were met during semiconfinement, compared with none (aOR, 0.35; 95% CI, 0.16-0.74). Individual risk of household members to be seropositive was lower in large households (22% less per each additional person). During semiconfinement, household members of a COVID-19 case were at very high risk of getting infected, 3 times more than close contacts outside home. This highlights the need to provide clear messages on protective measures applicable at home. For elderly couples, who were especially at risk, providing external support for daily basic activities is essential

PKCα and PKCδ Regulate ADAM17-Mediated Ectodomain Shedding of Heparin Binding-EGF through Separate Pathways

Epidermal growth factor receptor (EGFR) signalling is initiated by the release of EGFR-ligands from membrane-anchored precursors, a process termed ectodomain shedding. This proteolytic event, mainly executed by A Disintegrin And Metalloproteases (ADAMs), is regulated by a number of signal transduction pathways, most notably those involving protein kinase C (PKC). However, the molecular mechanisms of PKC-dependent ectodomain shedding of EGFR-ligands, including the involvement of specific PKC isoforms and possible functional redundancy, are poorly understood. To address this issue, we employed a cell-based system of PMA-induced PKC activation coupled with shedding of heparin binding (HB)-EGF. In agreement with previous studies, we demonstrated that PMA triggers a rapid ADAM17-mediated release of HB-EGF. However, PMA-treatment also results in a protease-independent loss of cell surface HB-EGF. We identified PKCα as the key participant in the activation of ADAM17 and suggest that it acts in parallel with a pathway linking PKCδ and ERK activity. While PKCα specifically regulated PMA-induced shedding, PKCδ and ERK influenced both constitutive and inducible shedding by apparently affecting the level of HB-EGF on the cell surface. Together, these findings indicate the existence of multiple modes of regulation controlling EGFR-ligand availability and subsequent EGFR signal transduction

Wheat landraces : action-oriented data for Pays de la Loire organic farmers

Cultivated biodiversity dramatically decreased along XXth century, what is especially true for tender wheat. In France farming systems, this disappearing is today manifested by inadequacy between certified varieties available and organic farmers requirements. To answer this needs, several groups of participatory wheat landraces breeding emerged along last decade. That is how Coordination Agrobiologique (CAB) initiated its breeding program in 2006, reproducing wheat landraces from botanic conservatory. CAB was thus an opportune structure to carry out this thesis, which purpose was to give field-oriented data on wheat landraces to help Pays de la Loire farmers choices of varieties. Notations for these last three years were gathered into 3 categories : weed suppressiveness, damage resistance (especially lodging) and economic profitability. These agronomic data were then completed by bread-making tests and sampling to foster use and diffusion of varieties bred in the program in regional food system. Even if it seems that wheat landraces are more suitable for poor soils than commercial seeds, almost no difference could be certified with more than 95% confidence. Firsts bread-making trials showed that there is not any specific problem to bake landraces when practices are adapted. Sampling results show that genotype (varieties) seem to influence bread taste less than bread-making practices and terroir effect. These results can be seen as new hypothesis that should be verified next years.Le XXème siècle a connu une forte érosion de la biodiversité cultivée, ce qui s'illustre clairement par le cas du blé tendre. Dans les fermes françaises, cette disparition se manifeste aujourd'hui par l'inadéquation entre l'offre de variétés certifiées et la demande des agriculteurs biologiques. Pour pallier à cette demande, des groupes de sélection participatives ont émergé au cours de la dernière décennie. C'est le cas de la Coordination Agrobiologique (CAB) qui a initié depuis une dizaine d'année un programme de sélection participative, en multipliant des variétés de pays sorties de conservatoire. La CAB a ainsi été un lieu propice à cette étude, ayant pour but de procurer des données facilitant le choix par les agriculteurs des variétés à cultiver dans leur ferme des Pays de la Loire. Les notations des 5 dernières années ont été regroupées en trois grandes catégories : compétitivité face aux adventices, résistance aux dégâts des cultures (et plus spécifiquement : la verse), et à la productivité économique. Ces données agronomiques ont été complétées par des tests de panification et de dégustation en vue de faciliter l'utilisation et la diffusion de variétés du programme, faisant des variétés paysannes une clé de reconstitution des filières locales. Même si il semble que les variétés paysannes soient plus adaptées aux terres à faible potentiel, très peu de différence n'a pu être vérifiée statistiquement. Les premières expérimentation ont pu montrer que la panification des variétés de pays n'est pas un problème dans le cas de diagrammes appropriés et que les différences variétales influencent moins le goût du pain que les pratiques boulangères et le terroir. Ces pistes devront être confirmées et affinées au cours des prochaines années, notamment dans le cadre d'un programme CAB restructuré.M-A

Des illusions

Ce mémoire part du constat que les outils informatiques sont devenus indispensables dans la pratique actuelle du métier d’architecte, qu’ils soient utilisés pour la réalisation de plans, de modélisation ou d’images virtuelles. L’image (de synthèse notamment) s’est imposée comme vecteur de communication par sa facilité d’accès et ses codes universels, qui reprennent ceux de la photographie, du dessin, de la peinture. Ayant gagné une place prépondérante dans la chaîne de production graphique, cet instrument ne peut être négligé. Ce mémoire part alors du postulat que l’image numérique induit une défiance, engendrée par le potentiel de tromperie qu’elle incarne. Le but de ce mémoire est alors de valider ou invalider cet axiome, en se demandant en quoi la création d’une image de concours peut provoquer une désillusion et surtout, si cette désillusion est issue d’un possible potentiel déceptif lié à l’image. Pour cela, ce travail de mémoire se base sur l’étude de cas de la nouvelle École des Beaux-Arts de Nantes Saint-Nazaire, dessinée par l’architecte Franklin Azzi