Trophic history of French sub-alpine lakes over the last ~150 years: phosphorus reconstruction and assessment of taphonomic biases

Like many lakes worldwide, French sub-alpine lakes (lakes Annecy, Bourget and Geneva) have suffered from eutrophication in the mid-20th century. Although restoration measures have been undertaken and resulted in significant reductions in nutrient inputs and concentrations over the last 30 years in all three lakes, the limnological monitoring does not extend back far enough to establish the reference conditions, as defined by the European Water Framework Directive. The over-arching aim of this work was to reconstruct, using a paleolimnological approach, the pre-eutrophication levels and subsequent temporal changes in the lakes trophic status over the last century. The objectives were three-fold: i) to test whether fossil diatoms archived in deep sediment cores adequately reflect past changes in the planktonic diatom communities for these deep sub-alpine lakes based on data from lake Geneva; ii) to investigate changes in the diatom communities over the last 150 years in the three lakes; and iii) to infer the past total phosphorus (TP) concentrations of the lakes from a diatom based transfer function. Annual paleolimnological and limnological diatom countings for lake Geneva were strongly correlated over the last 30 years. Most notable differences essentially resulted from both taphonomic and depositional biases, as evidenced by the underestimation of thin skeleton species such as Asterionella formosa and Diatoma tenuis in the paleolimnological dataset and the presence of many benthic taxa. The fossil diatom records revealed shifts in the communities in the three lakes over time, most of which were changes typically associated with nutrient enrichment. Indeed, in all three lakes, the proportion of Cyclotella spp. was very high before the 1950s, but these species were then replaced by more eutrophic taxa, such as Stephanodiscus spp, by the mid-20th century. From the 1980s, some but not all diatom species typical of re-oligotrophicated conditions (i.e. Cyclotella sp.) re-appeared in all three lakes. Yet, not all changes that occurred in the diatom communities since then may be attributed to decreasing TP. TP concentrations inferred from weighted averaging with classical deshrinking in lake Annecy and lake Geneva and weighted averaging with inverse deshrinking in Lake Bourget were very close to the monitored values. Comparisons of diatom-inferred TP concentrations to other paleo-proxies for trophic status revealed though that the transfer functions were rather insensitive to changes occurring below 10 ?g L-1, which limits the study ability to set accurate TP reference conditions below this threshold. However, current diatom community compositions arestill rather different from the pre-eutrophication ones, suggesting that reference conditions are still not achieved

Evaluation of Regional-Scale River Depth Simulations Using Various Routing Schemes within a Hydrometeorological Modeling Framework for the Preparation of the SWOT Mission

The Surface Water and Ocean Topography (SWOT) mission will provide free water surface elevations, slopes, and river widths for rivers wider than 50 m. Models must be prepared to use this new finescale information by explicitly simulating the link between runoff and the river channel hydraulics. This study assesses one regional hydrometeorological model’s ability to simulate river depths. The Garonne catchment in southwestern France (56 000 km2) has been chosen for the availability of operational gauges in the river network and finescale hydraulic models over two reaches of the river. Several routing schemes, ranging from the simple Muskingum method to time-variable parameter kinematic and diffusive waves schemes, are tested. The results show that the variable flow velocity schemes are advantageous for discharge computations when compared to the original Muskingum routing method. Additionally, comparisons between river depth computations and in situ observations in the downstream Garonne River led to root-mean-square errors of 50–60 cm in the improved Muskingum method and 40–50 cm in the kinematic–diffusive wave method. The results also highlight SWOT’s potential to improve the characterization of hydrological processes for subbasins larger than 10 000 km2, the importance of an accurate digital elevation model, and the need for spatially varying hydraulic parameters

Evaluation of regional-scale water level simulations using various river routing schemes within a hydrometeorological modelling framework for the preparation of the SWOT mission

The ability of a regional hydrometeorological model to simulate water depth is assessed in order to prepare for the SWOT (Surface Water and Ocean Topography) mission that will observe free surface water elevations for rivers having a width larger than 50/100 m. The Garonne river (56 000 km2, in south-western France) has been selected owing to the availability of operational gauges, and the fact that different modeling platforms, the hydrometeorological model SAFRAN-ISBA-MODCOU and several fine scale hydraulic models, have been extensively evaluated over two reaches of the river. Several routing schemes, ranging from the simple Muskingum method to time-variable parameter kinematic and diffusive waves schemes with time varying parameters, are tested using predetermined hydraulic parameters. The results show that the variable flow velocity scheme is advantageous for discharge computations when compared to the original Muskingum routing method. Additionally, comparisons between water level computations and in situ observations led to root mean square errors of 50-60 cm for the improved Muskingum method and 40-50 cm for the kinematic-diffusive wave method, in the downstream Garonne river. The error is larger than the anticipated SWOT resolution, showing the potential of the mission to improve knowledge of the continental water cycle. Discharge computations are also shown to be comparable to those obtained with high-resolution hydraulic models over two reaches. However, due to the high variability of river parameters (e.g. slope and river width), a robust averaging method is needed to compare the hydraulic model outputs and the regional model. Sensitivity tests are finally performed in order to have a better understanding of the mechanisms which control the key hydrological processes. The results give valuable information about the linearity, Gaussianity and symetry of the model, in order to prepare the assimilation of river heights in the model

The XC chemokine receptor 1 is a conserved selective marker of mammalian cells homologous to mouse CD8α+ dendritic cells

Human BDCA3+ dendritic cells (DCs) were suggested to be homologous to mouse CD8α+ DCs. We demonstrate that human BDCA3+ DCs are more efficient than their BDCA1+ counterparts or plasmacytoid DCs (pDCs) in cross-presenting antigen and activating CD8+ T cells, which is similar to mouse CD8α+ DCs as compared with CD11b+ DCs or pDCs, although with more moderate differences between human DC subsets. Yet, no specific marker was known to be shared between homologous DC subsets across species. We found that XC chemokine receptor 1 (XCR1) is specifically expressed and active in mouse CD8α+, human BDCA3+, and sheep CD26+ DCs and is conserved across species. The mRNA encoding the XCR1 ligand chemokine (C motif) ligand 1 (XCL1) is selectively expressed in natural killer (NK) and CD8+ T lymphocytes at steady-state and is enhanced upon activation. Moreover, the Xcl1 mRNA is selectively expressed at high levels in central memory compared with naive CD8+ T lymphocytes. Finally, XCR1−/− mice have decreased early CD8+ T cell responses to Listeria monocytogenes infection, which is associated with higher bacterial loads early in infection. Therefore, XCR1 constitutes the first conserved specific marker for cell subsets homologous to mouse CD8α+ DCs in higher vertebrates and promotes their ability to activate early CD8+ T cell defenses against an intracellular pathogenic bacteria

Cushing's Syndrome and Fetal Features Resurgence in Adrenal Cortex–Specific Prkar1a Knockout Mice

Carney complex (CNC) is an inherited neoplasia syndrome with endocrine overactivity. Its most frequent endocrine manifestation is primary pigmented nodular adrenocortical disease (PPNAD), a bilateral adrenocortical hyperplasia causing pituitary-independent Cushing's syndrome. Inactivating mutations in PRKAR1A, a gene encoding the type 1 α-regulatory subunit (R1α) of the cAMP–dependent protein kinase (PKA) have been found in 80% of CNC patients with Cushing's syndrome. To demonstrate the implication of R1α loss in the initiation and development of PPNAD, we generated mice lacking Prkar1a specifically in the adrenal cortex (AdKO). AdKO mice develop pituitary-independent Cushing's syndrome with increased PKA activity. This leads to autonomous steroidogenic genes expression and deregulated adreno-cortical cells differentiation, increased proliferation and resistance to apoptosis. Unexpectedly, R1α loss results in improper maintenance and centrifugal expansion of cortisol-producing fetal adrenocortical cells with concomitant regression of adult cortex. Our data provide the first in vivo evidence that loss of R1α is sufficient to induce autonomous adrenal hyper-activity and bilateral hyperplasia, both observed in human PPNAD. Furthermore, this model demonstrates that deregulated PKA activity favors the emergence of a new cell population potentially arising from the fetal adrenal, giving new insight into the mechanisms leading to PPNAD

La filiacion y la fecundacion "in vitro"

Las tecnicas de reproduccion asistida no solo representan una solucion para ayudar a superar problemas de esterilidad, sino que su practica conlleva problemas eticos y juridicos. Esta Tesis analiza los problemas que plantea la fecundacion "in vitro", desde el punto de vista de la filiacion, para determinar la paternidad y maternidad cuando se utilizan los gametos de la pareja o de un tercero. Desde este punto de vista, se estudian la situacion juridica del tercero -llamado donante- y de las madres subrogadas, asi como las acciones de filiacion Tambien se examina la problematica que plantea la congelacion de semen y embriones, al poder un hombre engendrar un hijo despues de muerto. Entre las fuentes que se analizan estan los principales informes extranjeros que han estudiado la problematica de estas tecnicas, asi como el Informe especial de..

Energy Resolution Performance of the CMS Electromagnetic Calorimeter

The energy resolution performance of the CMS lead tungstate crystal electromagnetic calorimeter is presented. Measurements were made with an electron beam using a fully equipped supermodule of the calorimeter barrel. Results are given both for electrons incident on the centre of crystals and for electrons distributed uniformly over the calorimeter surface. The electron energy is reconstructed in matrices of 3 times 3 or 5 times 5 crystals centred on the crystal containing the maximum energy. Corrections for variations in the shower containment are applied in the case of uniform incidence. The resolution measured is consistent with the design goals

Evolution de l’abondance de différents traits biologiques de diatomées en rivières le long de gradients de trophie et de saprothie

rapport de Master 2 1page préliminaire de l'auteurMaste

Changement climatique et perturbations locales dans trois grands lacs alpins au cours du dernier siècle : ce qu'enseignent les diatomées et les rotifères

During the XXth century, lacustrine ecosystems have undergone deep changes due to increased human activities on lakes and their watershed. Although significant restoration efforts have been undertaken since the 1980's, their efficiency can be limited. For instance, although phosphorous concentrations of Lake Geneva have been cut by 10 in the last 30 years (for a total cost of four billlions euros), the algal biomass and the primary production remain as high as during the eutrophication maximum, even if water transparency increased. So, the counter-intuitive response of lakes to restoration measures emphasizes that although phosphorous concentration is a major driver of phytoplankton, there is a need to consider the interaction with other environmental drivers, such as climate or top-down controls. Another fence however to the understanding of lake recent response to restoration measures is the lack of long-term monitoring data.The objective of this Ph-D work is to investigate how three human perturbations, i.e. changes in nutrient concentrations, fisheries management practices and climate change, can explain the response of the planktonic communities of three peri-alpine lakes (Lakes Geneva, Annecy and Bourget), using a high-resolution paleolimnological approach conducted on recent time periods. More specifically, the objectives of this PhD are three-fold:(i) To perform the methodological development of the use of rotifer egg banks archived in sediment for paleolimnological reconstructions(ii) To perform methodological development of paleolimnolgical reconstruction of diatom sesaon variability(iii) To delineate ecological responses of diatom and rotifer communities facing anthropogenic perturbations over the last century(iv) To scale the impact of local versus global perturbations over these ecological trajectoriesLa lutte contre l'eutrophisation des grands lacs péri-alpins a permis une réduction des concentrations internes en phosphore, pour des réponses écologiques parfois mitigées. Dans le Léman, les concentrations en P ont été divisées par dix en trente ans pourtant la biomasse algale et la production primaire restent aussi élevées qu'au maximum de l'eutrophisation, malgré une augmentation de la transparence des eaux. Donc, bien que la concentration en phosphore soit une variable de forçage majeure des communautés planctoniques, il apparait nécessaire de considérer le rôle d'autres variables de forçage qui interagissent avec la concentration interne en nutriments pour comprendre les réponses écologiques des lacs aux mesures de reoligotrophisation. Les communautés planctoniques peuvent être impactées par les pratiques de la gestion appliquées d'autres compartiments du réseau trophique tels que les populations piscicoles. A l'effet de ces facteurs locaux s'ajoutent à l'impact du réchauffement climatique, un phénomène planétaire participant au changement global qui se manifeste à partir du début des années 1980, et dont l'impact est de mieux en mieux mis en évidence dans les lacs.Peu de lacs ayant fait ou font l'objet de suivis de routine, l'observation des effets de ces divers forçages anthropiques et la compréhension de leurs interactions se heurtent au faible nombre de base de données disponibles. En outre les données collectées ne permettent pas de remonter assez loin dans le temps pour couvrir entièrement la période au cours de laquelle les perturbations anthropiques se sont accrues. Elles ne permettent pas non plus d'étudier les conditions environnementales précédant cette période. La paléolimnologie à haute résolution (échelle annuelle et saisonnière) appliqué aux périodes récentes (dernier siècle) est une démarche alternative proposée pour palier cette absence de données instrumentales.Ce travail de thèse vise à comprendre comment les modifications des concentrations en nutriments, la gestion piscicole d'une espèce zooplantonophage, le corégone, et le changement climatique contribuent à modifier la structure et la diversité des communautés planctoniques de diatomées et de rotifères des grands lacs péri-alpins français depuis la fin du XIXe siècle.Les communautés planctoniques choisies ont chacune un fort potentiel bio-indicateur et une très grande importance dans la structure et le fonctionnement des écosystèmes lacustres. Les trois perturbations majeures et simultanées survenant lors de la période d'étude se présentent avec des intensités différentes dans les trois lacs. L'évolution temporelle de certains paramètres physico-chimiques au sein de ces lacs est déjà en partie connue grâce à un suivi de limnologie mis en place depuis plusieurs dizaines d'années.Les acquis de la thèse sont de divers natures. (i) développement méthodologique concernant la reconstruction paléolimnologique des communautés de rotifères à partir des banques d'œufs archivées dans les sédiments, (ii) reconstruction des les réponses écologiques des compartiments diatomiques et rotifèriens au cours du dernier siècle, (iii) de comparer ces trajectoires entre lacs afin de discriminer les réponses à des perturbations locales, de celles à des perturbations plus globales et (iv) d'améliorer notre compréhension des interactions entres toutes ces perturbations