Methane sources, sinks and fluxes in a temperate tidal lagoon: The Arcachon Lagoon (SW France)
(Estuarine, Coastal and Shelf Science. vol. 89, n° 0272-7714, pp. 256-266, 24/02/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LMTG, UT3, Comue de Toulouse, CNRS, COM, INSU - CNRS, CNRS, BOME, MNHN, UPMC, CNRS, LEMAR, IRD, IFREMER, UBO EPE, CNRS, CNRS
Prevalence, intensity, and aneuploidy patterns of disseminated neoplasia in cockles (Cerastoderma edule) from Arcachon Bay: Seasonal variation and position in sediment
The present report presents the first evidence of disseminated neoplasia (DN) in cockles Cerastoderma edule from Arcachon Bay (France). Aneuploidy of neoplastic cells allowed the use of flow cytometry (FCM) to diagnose and stage DN. A 1 year survey (2007) of the prevalence and intensity (% of aneuploid circulating cells in neoplastic cockles) was conducted. Prevalences ranged from 2.2% (June) to 13.6% (May), and disease intensity ranged from 18.7% (June) to 95.5% (September). These percentages were not correlated with seawater temperature, but rather showed unexplained oscillations over the year. Prevalence and intensity of DN were higher in cockles found at the surface of sediment compared to those buried normally (11.8% vs. 6.7% and 53.0% vs. 40.6%, respectively, p < 0.05). DN could thus be one mechanism leading to unexplained presence of cockles at the surface of the sediment in Arcachon Bay. Ploidy characteristics of neoplastic cells were also investigated using FCM, revealing an unusual, broad continuum of ploidy distribution from 1.6 to 9.6n. Ploidy values were not in whole numbers in contrast to the rounded values reported in other studies. Ploidy varied according to DN intensity, with the ploidy distribution of neoplastic cells from lightly-diseased cockles being unimodal (3.7n median). In contrast, highly-diseased cockles showed a bimodal ploidy distribution (3.0n and 4.7n medians). This suggests that, in cockles from Arcachon Bay, mechanisms leading to aneuploidy are complex, developing during disease progression.
(Journal of Invertebrate Pathology. vol. 104, n° 0022-2011, pp. 110-118, 24/02/2026)
CEMCA, UBO EPE, INC-CNRS, CNRS, IBSAM, UBO EPE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEMAR, IRD, IFREMER, UBO EPE, CNRS
Rapid climatic variability in the western Mediterranean during the last 25,000 years from the high resolution pollen record ODP 976
(14/12/2009)
LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LCE, CNRS, UFC, UBFC, UHH
Sonochemical Disproportionation of Carbon Monoxide in Water: Evidence for Treanor Effect during Multibubble Cavitation
(Angewandte Chemie International Edition. vol. 48, n° 1433-7851, pp. 9529-9532, 07/12/2009)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSFC, ICSM - UMR 5257, CEA, ENSCM, INC-CNRS, UM, CNRS
Caractérisation de l'activité hydrosédimentaire dans le Système Turbiditique du Var (NO Méditerranée) et de son enregistrement dans l'archive sédimentaire
Le système turbiditique du Var présente la particularité d'être fréquemment parcouru par des écoulements gravitaires. Cela en fait un endroit privilégié pour étudier simultanément les facteurs déclenchant des courants de turbidité, leurs caractéristiques hydrodynamiques, leur contenu particulaire et les dépôts associés. Dans le cadre du projet Européen HERMES (6ème Programme Cadre), nous avons acquis pendant 2 ans dans le canyon du Var et dans la vallée turbiditique (1) des séries temporelles dans la colonne d'eau (30 m et 400 m au dessus du fond) sur la vitesse des courants, la température et le flux particulaire, et (2) des prélèvements répétés par carottage du sédiment de surface. Nos résultats mettent en évidence deux types de transport sédimentaire: (1) des écoulements gravitaires, et (2) des remises en suspension sur le fond par le Courant Nord. L'étude des caractéristiques hydrodynamiques des courants gravitaires permet de préciser nos connaissances sur leur mécanisme de formation. Les courants gravitaires peuvent être initiés par des déstabilisations dans le canyon ou par le plongement en mer de l'eau turbide du fleuve (courant de turbidité hyperpycnal). Ces derniers peuvent être générés lorsque le débit liquide du fleuve franchit un seuil de 306 m3.s-1 à l'embouchure, et à condition que la crue soit étendue à l'ensemble du réseau hydrographique. L'étude combinée des mesures sur les deux années et des faciès sédimentaires dans les dépôts du siècle dernier souligne la prépondérance des courants de turbidité hyperpycnaux, qui représentent 80 % des écoulements gravitaires. De plus, cette étude combinée montre que les écoulements de faible magnitude (résultant de petites instabilités ou de crues annuelles du fleuve) s'arrêtent généralement au débouché de la vallée supérieure et ne déposent du sédiment que sur une terrasse située à 70 m au dessus du fond de la vallée. Les courants gravitaires de grande magnitude (résultant de larges instabilités ou de crues majeures du fleuve) sont fortement érosifs dans la partie du système située avant le pied de pente, et déposent des séquences sédimentaires sur les terrasses, la levée, et localement dans le chenal. Le cadre chrono-stratigraphique établi pour l'étude des séquences sédimentaires permet de mieux contraindre la manière dont ces courants gravitaires sont enregistrés et préservés, à plusieurs échelles de temps.
(07/12/2009)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GM, IFREMER, DRO-EP, IFREMER
A new conceptual model for the deposition process of homogenite: Application to a cretaceous megaturbidite of the western Pyrenees (Basque region, SW France)
The north Pyrenean megaturbidite is a 19–63m exceptional thick bed deposited during the Late Turonian and extending over more than 90km in the Basque region Country (SW France). Its thickness varies from more than 63m to about 19m from east (Mauléon area) to west (Basque coast). It represents a total compacted volume of about 90km3 of carbonates. On the field, rare sedimentary structures are visible in the turbidite bed. They consist of laminar planar lamination and rare cross laminations in the eastern region and antidune-like structures in the western region. Five sites have been sampled with a vertical step of 50cm to 1m. Thin sections have been quantitatively analyzed for counting the terrigeneous fraction, the quartz grain size and the mineral orientation. The deposits fine westward, which suggests a source located in the east of the Mauléon Basin. This is consistent with the quartz grain orientation in the lower part of the megaturbidite. The deposits fine upward from medium sand to clayey-silt. This is consistent with the classical definition of homogenites and suggests that these kinds of deposits are turbidites. These observations also suggest that the term “megaturbidite” is appropriated for these deposits. The sedimentary analysis indicates that the deposit results from a single event. The volume of sediment involved in the process, as well as the quartz grain orientation indicating flow motion in the opposite direction of the initial flow and the antidune-like structure suggest the formation of reflected flows and the formation of standing waves over the complete water column in the Basque flysch sub-basins corresponding to a “Seiche effect”. The origin of the megaturbidite is probably an earthquake-generated collapse on the carbonate platform. This example allows providing a new conceptual model for the process of homogenite deposition. This model explains the deposition of thick, fine-grained, crudely-graded megaturbidites.
(Sedimentary Geology. vol. 222, n° 0037-0738, pp. 263-273, 01/12/2009)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, EGID
Nitrogen isotopic evidence for deglacial changes in nutrient supply in the eastern equatorial Pacific
The Eastern Equatorial Pacific (EEP) is a high nutrient-low chlorophyll region of the ocean. Downcore nitrogen isotope records from the EEP have been previously interpreted as a direct reflection of changes in nutrient consumption. However, the observed changes in sedimentary d 15 N since the last glacial maximum have no coherent relationship with export productivity or an inferred variation in the iron-to-nitrate ratio of the surface waters. Rather, downcore N isotope records in the EEP strongly resemble changes in the extent of water column denitrification as recorded in nearby sedimentary d 15 N records along the western margin of the Americas. This similarity is attributed to the overprinting of the N isotopic composition of nitrate in the EEP through the advection of nitrate westward from the margins in the subsurface. A local nitrogen isotope record of changes in the degree of nutrient consumption is extracted from the bulk sedimentary record by subtracting two different sedimentary d 15 N records of denitrification changes from two new EEP d 15 N records (TR163-22 and ODP Site 1240). The denitrification records used are from 1) the Central American margin (ODP Site 1242) and 2) the South American margin (GeoB7139-2). The degree of consumption in the surface waters declines rapidly from elevated values during the last glacial maximum to a pair of minima around 15 and 11-13 ka, and finally it increases into the Holocene. The derived EEP nitrogen isotope record indicates that the regional peak in export productivity occurred when the supply of nutrients exceeded the apparently high demand. The influx of nutrients during the deglaciation is attributed to the resumption of intense overturning in the Southern Ocean and the release of sequestered CO 2 and nutrient-rich, O 2 poor waters from the deep ocean. This has important implications for understanding the glacial-interglacial scale variation in intermediate water suboxia and water column denitrification.
(Paleoceanography. vol. 24, n° 0883-8305, 01/12/2009)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
A 1.2Ma record of glaciation and fluvial discharge from the West European Atlantic margin
The correlation of continental sedimentary records with the marine isotope stratigraphy is a challenge of central importance in Quaternary stratigraphy, particularly in Western Europe where long records of glaciation on land areas are particularly rare. Here we demonstrate for the first time the interrelationship of events during the last 1.2 Ma in an ocean-sediment core from the Bay of Biscay (NE Atlantic), SW of the Channel. The identification of discharge variations from tributary river systems to the ‘Fleuve Manche’ palaeoriver during glacio-eustatic sea-level lowstands demonstrates the correlation of the marine sediment stratigraphy to the expansion and recession of the European ice-sheets. The amplitude and chronology of European ice-sheet oscillations since the late Early Pleistocene is discussed and our results demonstrate that the first coalescence of the Fennoscandian and British ice-sheets in the North Sea basin ca 450 ka ago caused a profound change in lowstand European drainage alignment. This change caused a rerouting of Fennoscandian and eastern British ice-sheets-derived meltwaters from northwards into the Nordic Seas to southwards into the eastern North Atlantic thereafter. Besides allowing a thorough synchronisation of the European ice-sheet palaeogeography with the well-dated records of palaeoceanographical changes, our results improve the stratigraphy of the English Channel palaeovalleys and will provide important constraints on paleoclimatic scenarios considering the impact that such rerouting and meltwater surges might have on the stability of the oceanic conveyor belt.
(Quaternary Science Reviews. vol. 28, n° 0277-3791, pp. 2974 - 2981, 01/12/2009)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IFREMER, CAM, LSCE, CEA, CNRS
A 1.2Ma record of glaciation and fluvial discharge from the West European Atlantic margin
(Quaternary Science Reviews. vol. 28, n° 0277-3791, pp. 2974-2981, 01/12/2009)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IFREMER, CAM, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA
Cadmium-Induced genotoxicity in zebrafish at environmentally relevant doses
Genotoxic effects of cadmium on zebra fish Danio rerio have been assessed by random amplified polymorphic DNA and real time PCR, followed by a comparison of the melting temperature patterns between each amplification reaction. Fish were exposed to two concentrations of cadmium chloride dissolved in the medium (1.9+/-0.6 microg Cdl(-1), C(1); 9.6+/-2.9 microg Cdl(-1), C(2)) for 21 days. A discriminative RAPD probe, OPB11, was first selected producing differential band patterns between control and metal-exposed genomic DNAs. RAPD-PCR showed an increase in the relative hybridization efficiency of OPB11 on the genomic DNAs coming from fish exposed to both Cd concentrations as compared to the control condition. In addition, the RAPD-PCR melting temperature patterns showed that with the OPB11 probe, the frequency of PCR products whose fusion temperature belongs to the [86-87 degrees C] interval decreased with Cd contamination, whereas an increase of frequency for the [78-80 degrees C] and [85-86 degrees C] intervals was correlated with Cd exposure.
(Ecotoxicology and Environmental Safety. vol. 73, n° 0147-6513, pp. 312-319, 01/11/2009)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS