Feeding mice with diets containing mercury-contaminated fish flesh from French Guiana: a model for the mercurial intoxication of the Wayana Amerindians.
Background: In 2005, 84% of Wayana Amerindians living in the upper marshes of the Maroni River in French Guiana presented a hair mercury concentration exceeding the limit set up by the World Health Organization (10 μg/g). To determine whether this mercurial contamination was harmful, mice have been fed diets prepared by incorporation of mercury-polluted fish from French Guiana. Methods: Four diets containing 0, 0.1, 1, and 7.5% fish flesh, representing 0, 5, 62, and 520 ng methylmercury per g, respectively, were given to four groups of mice for a month. The lowest fish regimen led to a mercurial contamination pressure of 1 ng mercury per day per g of body weight, which is precisely that affecting the Wayana Amerindians. Results The expression of several genes was modified with mercury intoxication in liver, kidneys, and hippocampus, even at the lowest tested fish regimen. A net genetic response could be observed for mercury concentrations accumulated within tissues as weak as 0.15 ppm in the liver, 1.4 ppm in the kidneys, and 0.4 ppm in the hippocampus. This last value is in the range of the mercury concentrations found in the brains of chronically exposed patients in the Minamata region or in brains from heavy fish consumers. Mitochondrial respiratory rates showed a 35–40% decrease in respiration for the three contaminated mice groups. In the muscles of mice fed the lightest fish-containing diet, cytochrome c oxidase activity was decreased to 45% of that of the control muscles. When mice behavior was assessed in a cross maze, those fed the lowest and mid-level fish-containing diets developed higher anxiety state behaviors compared to mice fed with control diet. Conclusion We conclude that a vegetarian diet containing as little as 0.1% of mercury-contaminated fish is able to trigger in mice, after only one month of exposure, disorders presenting all the hallmarks of mercurial contamination.
(Environmental Health. vol. 7, n° 1476-069X, pp. 53, 01/01/2008)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, U1211 INSERM/MRGM, UB, INSERM, IBGC, UB, CNRS, CNIC, UB, CNRS
Discovery of a giant deep-sea valley in the Indian Ocean, off eastern Africa: the Tanzania channel
During the Fanindien 2006 cruise of R/V ‘Beautemps-Beaupré’, high resolution multibeam bathymetry, sub-bottom profiling and sediment coring was carried out along the East African margin, offshore Tanzania and Mozambique (Indian Ocean). The newly acquired data reveal the presence of a giant deep-sea valley (the Tanzania channel) that is more than 10 km wide at 4000 m water depth, along the continental rise. The valley remains 70 m deep and 7 km wide at 800 km from the Tanzania coast. Morphological comparison with worldwide submarine channels show that the Tanzania channel is one of the largest known submarine valleys. This discovery brings new light on development of submarine valleys that drain sediments originated from the East African Rift System (EARS) highlands (i.e. the Tanzania channel and its neighbor Zambezi channel located 1000 km southward). Both of the systems have a morphology markedly different to the classical sinuous, V-shaped channels located at similar latitudes (e.g. the Zaire or Amazon channels). Their submarine drainage system consists of a downslope converging tributary canyons joining a central trunk channel in the continental rise. The presence of such giant deep-sea drainage systems is probably linked to a strong structural control on the sediment pathway, associated to a massive sediment transfer towards the Indian Ocean in relation with the tectonic activity of the East African Rift System (i.e. the uplift periods trough mid-Miocene and Plio-Pleistocene times) and its interplay with the East African equatorial climate changes.
(Marine Geology. vol. 255, n° 0025-3227, pp. 179-185, 01/01/2008)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, SHOM, GM, IFREMER, IFP
Courants induits et dissipation de l'énergie des vagues sur les plages macrotidales de la mer d'Iroise
Several field experiments of both morphological and hydrodynamical measurements occured during springs 2004 and 2005 on four beaches of the Iroise Sea (Finistère). Within these four datasets (sea surface elevation, cross-shore and longshore flow velocities), dissipation of wave energy is investigated through time (accounting with tidal cycle) and space (across the intertidal zone). These results are compared to empirical parametrizations of relative wave height Γs (Raubenheimer et al., 1996 ; Sénéchal et al., 2001), parameter greatly used in hydrodynamic models. Then, the local breaking criteria Γs,b is used to characterize wave-related processes (wave asymetry, breaking-induced undertow) involved in sediment transport in the intertidal zone
(European Journal of Environmental and Civil Engineering. vol. 12, n° 1964-8189, pp. 105-116, 01/01/2008)
LETG - Brest, LETG, UNICAEN, NU, UA, EPHE, PSL, UBO EPE, UR2, CNRS, IGARUN, UN, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Modulation de la toxicité des métaux vis-à-vis du développement des biofilms de cours d'eau (bassin versant de Decazeville, France)
Des études de terrain sur des biofilms matures nous ont permis de souligner une modulation de la toxicité des métaux lourds (cadmium, zinc) en fonction de la disponibilité nutritive. Ainsi, le long d'un gradient de contamination organique et métallique (bassin versant de Decazeville, France), le biofilm se développe plus abondamment (en épaisseur, en densité) dans des conditions nutritives élevées, et de façon comparable en conditions de contamination organique importante et de contaminations combinées nutriments / métaux. L'épaisseur du biofilm exerce un effet protecteur des métaux par : (i) l'existence de gradients de diffusion limitant leur pénétration vers les couches internes du biofilm, (ii) une mortalité élevée des cellules superficielles de la matrice, agissant comme une barrière supplémentaire, (iii) la production par les organismes de polypeptides complexant le métal sous forme moins biodisponible.
(Cryptogamie Algologie. vol. 29, n° 0181-1568, pp. 201-216, 28/05/2026)
UR REBX, CEMAGREF, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Analysis of the Flavobacterium psychrophilum outer-membrane subproteome and identification of new antigenic targets for vaccine by immunomics
Flavobacterium psychrophilum is an important infectious Gram-negative bacterium causing cold-water disease (CWD) and rainbow trout fry syndrome. Outer-membrane proteins (OMPs) are key molecules with regard to the interface between the cell and its environment. Therefore, we sought to define the outer-membrane (OM) subproteome of F. psychrophilum in order to gain insight into the biology and pathogenesis of this bacterium and to identify the dominant antigens targeted by the rainbow trout (Oncorhynchus mykiss) immune system during infection. First, OMs were prepared from a cell-envelope suspension by differential Sarkosyl (sodium lauryl sarcosinate) solubility. We then isolated the OMPs and identified 36 proteins from 34 spots resolved by two-dimensional electrophoresis and LC-MS/MS. An immunoproteomic approach using antibodies from CWD-convalescent rainbow trout was then used to identify 25 immunoreactive F. psychrophilum antigens that may be relevant in pathogenesis and diagnosis. These included the previously characterized surface-exposed OMPs OmpA, OmpH/P18 and FspA, as well as newly described antigenic proteins. This study provides a number of novel candidate proteins for developing vaccine(s) against flavobacteriosis infection in aquaculture.
(Microbiology. vol. 154, n° 1350-0872, pp. 1793-1801, 28/05/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, VIM (UR 0892), INRA, PGFB
TRAITEMENT DES DONNEES TOPOGRAPHIQUES ET BATHYMETRIQUES ACQUISES SUR LE LITTORAL AQUITAIN : OPTIMISATION DES MESURES EFFECTUEES EN QUAD ET AU THEODOLITE
Dans cette communication, nous présenterons les méthodes originales développées pour le traitement des données topographiques et bathymétriques acquises sur le littoral aquitain, afin d'aboutir à une cohérence centimétrique sur les jeux de données d'origine très différentes. Ce programme de traitement est soutenu par l'ANR VULSACO et par le projet ECORS (SHOM/EPOC)
(28/05/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, OASU, UB, INSU - CNRS, ULR, CNRS, INRAE, L3AB, UB, INSU - CNRS, CNRS, LAB, UB, INSU - CNRS, CNRS
Seasonal record of foraminiferal export fluxes in the Bay of Biscay
(28/05/2026)
LPGN, UN, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Diatoms preserved in surface sediments of the northeastern Kerguelen Plateau
An ''island mass effect'' was observed from the sedimentary distribution of diatoms on the northeastern Kerguelen Plateau. Five new samples placed in context to species distributions previously reported from the Permanently Open Ocean Zone (POOZ) revealed a plateau community dominated by three species/taxa: Fragilariopsis kerguelensis, Thalassionema nitzschioides f. nitzschioides and Chaetoceros Hyalochaete resting spores. Intermediate abundances of Thalassiosira antarctica were unique to the plateau sediment signature as were increased abundances of Eucampia antarctica v. antarctica. The off-plateau sediment sample contained typical POOZ sediment distributions dominated by F. kerguelensis, Thalassiosira lentiginosa and Thalassiothrix antarctica. The role of deposition from the surface waters to the sediments was investigated by comparison to the diatom thanatocoenose observed in surface waters. These results suggest that the use of sediment abundances of C. Hyalochaete resting spores and F. kerguelensis to determine past productivity events (such as wind-sourced iron enrichment of the Southern Ocean at the Last Glacial Maximum) is not straightforward. The elevated abundance of T. nitzschioides f. nitzschioides on the plateau did not indicate an iron-deplete regime but the converse. For the evaluation of paleo-productivity hypotheses for the open Southern Ocean, we suggest caution in the use of Subantarctic and Kerguelen Plateau sediment signatures, and emphasize that there is a need to also study Antarctic coastal and especially sea-ice melt-water stimulated blooms. r
(Deep Sea Research Part II: Topical Studies in Oceanography. vol. 55, n° 0967-0645, pp. 677-692, 28/05/2026)
LOB, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, LMGEM, CNRS
Fixed point strategies for elastostatic frictional contact problems
Several fixed point strategies and Uzawa algorithms (for classical and augmented Lagrangian formulations) are presented to solve the unilateral contact problem with Coulomb friction. These methods are analyzed, without introducing any regularization, and a theoretical comparison is performed. Thanks to a formalism coming from convex analysis, some new fixed point strategies are presented and compared to known methods. The analysis is first performed on continuous Tresca problem and then on the finite dimensional Coulomb problem derived from an arbitrary finite element method.
(Mathematical Methods in the Applied Sciences. vol. 31, n° 0170-4214, pp. 415-441, 28/05/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ICJ, ECL, UCBL, INSA Lyon, INSA, UJM, CNRS
SPM fluxes estimates from discrete monitoring : comparison of calculation methods and uncertainties
The SPM (suspended particulate matter) fluxes temporal variabilities are even more complex than water flows and are therefore very difficult to estimate. In France, SPM are surveyed within the national water quality survey system (RNB) and are monitored with a bimonthly or monthly frequency, as other water quality indicators. The flux calculation methods and their related uncertainties on the basis of an experimental data set of continuous – i.e. daily monitoring for contrasted river basins ranging from 100 to 100 000 km2 (in France and in USA, 60 stations totalling 600 station-year of daily SPM and flows). The uncertainties, biases, and errors, result from the analysis of the distribution of errors made on simulated surveys at various frequencies (3, 5, ... 30 days) in comparison to the same value. The duration curves of SPM fluxes and the key indicator M2 %, i.e. the percentage of SPM carried in 2 % of time on a multiannual period (4 to 20 y), are then determined. The M2 % indicator is used to build-up a nomograph linking biases (median or errors) and imprecision (difference between upper and lower deciles of errors) to monitoring frequencies (3, 4, ... 30 days). This nomograph can be used to : i) optimize surveys frequencies, given a flux error target, or to ii) associate error bars. The nomograph is so far established for the mean discharge-weighted concentration method, one of the most common method with the rating curve method.
(La Houille Blanche - Revue internationale de l'eau. vol. 4, n° 0018-6368, pp. 64 à 71, 28/05/2026)
SISYPHE, UPMC, EPHE, PSL, PSL, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CEFREM, UPVD, INSU - CNRS, CNRS, LTHE, OSUG, UJF, Grenoble INP, INSU - CNRS, IRSTEA, USMB [Université de Savoie] [Université de Chambéry], CNRS, IRD, INSU - CNRS, INPG, CNRS, EDF [E.D.F.], AEE