Effects of uranium uptake on transcriptional responses, histological structures and survival rate of the crayfish Procambarus clarkii
This work aims to investigate the accumulation levels and effects (transcriptional responses, histopathology and survival rate) associated with a wide range of dissolved uranium (U) concentrations (0, 0.03, 0.6, 4 and 8. mg/L of U) on adult male crayfish Procambarus clarkii during 4 (T4) and 10 (T10) days of exposure. The follow-up of the crayfish mortality showed that P. clarkii was highly resistant to U. Increasing waterborne U concentrations led to increasing bioaccumulation in key crayfish organs and increasing histological damages. U distribution in tissues was also evaluated using transmission electron microscopy and showed the presence of a detoxified form of U in the gill's epithelium in the shape of flakes. Expression levels of mitochondrial genes (cox1, atp6 and 12S gene) and genes involved in oxidative stress (sod(Mn) and mt) were examined together with the housekeeping gene 18S. atp6 and mt genes of P. clarkii were cloned and sequenced before analysis. Significant correlations were observed between U bioaccumulation and the down-regulation of both cox1 and sod(Mn) genes. This work provides a first U toxicogenomic and histopathological pattern of P. clarkii, identify U biomarkers and associate gene expression endpoints to accumulation levels. It also provides new insights into the mechanisms involved in U stress. © 2011.
(Ecotoxicology and Environmental Safety. vol. 74, n° 0147-6513, pp. 1800--1807, 01/10/2011)
IRSN/DEI/SECRE/LRE, IRSN/DEI/SECRE, IRSN, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Highly branched isoprenoids as proxies for variable sea ice conditions in the Southern Ocean
Concentrations of a highly branched isoprenoid (HBI) diene determined in over 200 sediment samples from the Arctic co-vary with those of an HBI monoene (IP 25) shown previously to be a sedimentary sea ice proxy for the Arctic. The same diene, but not monoene IP 25 , occurred in nine sea ice samples collected from various locations around Antarctica. The diene has been reported previously in Antarctic sea ice diatoms and the 13 C isotopic compositions of the diene determined in two Antarctic sea ice samples were also consistent with an origin from sea ice diatoms (d 13 C-5.7 to-8.5%). In contrast, HBIs found in two Antarctic phytoplankton samples did not include the diene but comprised a number of tri-to pentaenes. In sediment samples collected near Adélie Land, East Antarctica, both the diene and the tri-to pentaenes often co-occurred. 13 C isotopic compositions of the tri-to pentaenes in three sediment samples ranged from-35 to-42% whereas that of the diene in a sediment sample was-18%. We propose the presence of this isotopically 13 C enriched HBI diene in Antarctic sediments to be a useful proxy indicator for contributions of organic matter derived from sea ice diatoms. A ratio of the concentrations of diene/ trienes might reflect the relative contributions of sea ice to phytoplanktonic inputs of organic matter to Antarctic sediments.
(Antarctic Science. vol. 23, n° 0954-1020, pp. 487-498, 01/10/2011)
LOCEAN, IPSL, ENS-PSL, PSL, UVSQ, UPMC, CEA, INSU - CNRS, X, IP Paris, CNES, CNRS, MNHN, IRD, UPMC, INSU - CNRS, CNRS, BGC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
The 7-13 March 2006 major Saharan outbreak: Multiproxy characterization of mineral dust deposited on the West African margin
Mineral dust deposits were collected at Mbour, Senegal, throughout the spring of 2006 and especially during the well-documented March 7-13 large Saharan dust outbreak. During this 7-day period, significant changes in mass flux, grain-size, clay mineralogy and Sr and Nd isotopic compositions were recorded, indicating distinct provenances for the dust transported and deposited during and outside the event. All these terrigenous proxies, as well as freshwater diatom taxa, also showed significant temporal variations during the outbreak, implying contributions from at least two different provenance regions. Tri-dimensional back-trajectories and satellite imaging enabled us to link those distinct signatures to regions increasingly to the southeast within a large area covering Mauritania, Mali and southern Algeria, identified by the Total Ozone Mapping Spectrometer (TOMS) as the main source of the prominent winter/spring plume over the tropical Atlantic. The multiproxy characterization of the March 7-13 dust fall therefore enables us to typify the terrigenous signature of two different regions supplying dust off West Africa, and provide valuable clues for the interpretation of Northeastern Tropical Atlantic Ocean dust sedimentary records in terms of changes in provenance regions and transport systems. Additionally, because dust deposition data are scarce, flux and grain size data obtained in this study, among other parameters such as clay assemblages, provide important constraints for atmospheric transport models and dust deposition budget estimates in this area.
(Journal of Geophysical Research. vol. 116, n° 0148-0227, pp. D18210, 29/09/2011)
MPIC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, NIOZ, MARUM, LOA, INSU - CNRS, CNRS, LISA (UMR_7583), INSU - CNRS, UPD7, UPEC UP12, CNRS, LTHE, OSUG, UJF, Grenoble INP, INSU - CNRS, IRSTEA, USMB [Université de Savoie] [Université de Chambéry], CNRS, IRD, INSU - CNRS, INPG, CNRS, IMAGO
Cloning, characterization and gene expression of a metallothionein isoform in the edible cockle Cerastoderma edule after cadmium or mercury exposure
Metallothionein (MT) genes encode crucial metal-binding proteins ubiquitously expressed in living organisms and which play important roles in homeostasis of essential metals and detoxification processes. Here, the molecular organization of the first metallothionein gene of the edible cockle Cerastoderma edule and its expression after cadmium (Cd) or mercury (Hg) exposures were determined. The resulting sequence (Cemt1) exhibits unusual features. The full length cDNA encodes a protein of 73 amino acids with nine classical Cys-X((1-3))-Cys motifs, but also one Cys-Cys not generally found in molluscan MT. Moreover, characterization of the molecular organization of the Cemt1 gene revealed two different alleles (A1 and A2) with length differences due to large deletion events in their intronic sequences involving direct Short Interspersed repeated Elements (SINE), while their exonic sequences were identical. To our knowledge, such large excision mechanisms have never before been reported in a bivalve gene sequence. After 10 days of Cd exposure at environmentally relevant doses, quantitative real-time PCR revealed a strong induction of Cemt1 in gills of C. edule. Surprisingly, neither induction of the Cemt1 gene nor of MT protein was shown after Hg exposure, despite the fact that this organism is able to bioaccumulate a high amount of this trace metal which is theoretically one of the most powerful inducers of MT biosynthesis.
(Ecotoxicology and Environmental Safety. vol. 75, n° 0147-6513, pp. 119-126, 28/09/2011)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Estimateurs non paramétriques appliqués à des données valvométriques
Dans cette présentation, diverses méthodes statistiques sont explorées pour analyser des mesures valvométriques c'est-à-dire des enregistrements d'écartement de la coquille de mollusques bivalves comme par exemple, d'huîtres. Nous décrivons dans un premier temps l'allure du signal ainsi que ses caractéristiques principales. Nous essayons ensuite de le séparer en deux parties correspondant respectivement à des valeurs élevées ou basses de l'ouverture de la coquille. Nous utilisons pour cela un estimateur à noyau avec une fenêtre de lissage qui impose la présence de deux modes dans notre estimation. Ensuite, nous nous intéressons à la détection de pics dans ce signal, en présence de bruit. Des méthodes utilisant des décomposition en ondelettes sont, pour cela, décrites. Enfin, des considérations logicielles sont évoquées.
(05/09/2011)
IMB, UB, Bordeaux INP, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CQFD, IMB, UB, Bordeaux INP, CNRS, Inria
Evaluation of coastal perturbations: A new mathematical procedure to detect changes in the reference state of coastal systems
he pressure exerted by human activities on living systems has become so intense that it is inspiring the inception of a global network of monitoring of the biosphere and the use of robust statistical procedures to detect potential changes. Here, we propose a new multivariate non-parametric procedure, based on the Mahalanobis generalised distance and a simplification of the multiple response permutation procedure to identify rapidly changes in any natural systems. The procedure can be virtually coupled on all monitoring programmes and is not influenced by missing data, a common feature found in many ecological databases. In France, physical, chemical and biological variability of coastal waters have been monitored since 1997 by the SOMLIT Network. Applied to this data set, this technique enabled a first quantification of the impacts of human disturbance through changes in the concentration of nutrients. Our results revealed how climate may interact with anthropogenic pressure to alter coastal marine systems and suggest a synergism between nutrient enrichment, human activities and local climatic conditions. Indeed some effects of climate (e.g. insolation duration - increase in duration of daylight) may attenuate the fertility of coastal systems, while some others (e.g. precipitation) amplify the human signals.
(Ecological Indicators. vol. 11, n° 1470-160X, pp. 1290-1300, 01/09/2011)
LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEMAR, IRD, IFREMER, UBO EPE, CNRS
The monsoon imprint during the ‘atypical’ MIS 13 as seen through north and equatorial Indian Ocean records
(Quaternary Research. vol. 76, n° 0033-5894, pp. 285-293, 01/09/2011)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA
Atmospheric Chemistry of 2,3-Pentanedione: Photolysis and Reaction with OH Radicals
(Journal of Physical Chemistry A. vol. 115, n° 1089-5639, pp. 9160-9168, 25/08/2011)
CERI EE - IMT Nord Europe, IMT Nord Europe, IMT, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, PC2A, CNRS
Assessment of sea surface temperature changes in the Gulf of Cadiz during the last 30 ka: implications for glacial changes in the regional hydrography
New dinocyst analyses were conducted on core MD99-2339 retrieved from the central Gulf of Cadiz. Dinocyst and foraminiferal assemblages from this core are combined with existing data off SW Portugal and NW Morocco to investigate past hydrological and primary productivity regimes in the subtropical NE Atlantic Ocean over the last 30 ka. Our results have revealed highest upwelling intensity during Heinrich Stadial 1 (HS 1) and the Younger Dryas and weaker upwelling cells during the Last Glacial Maximum (LGM) and HS 2, off the SW Iberian and NW Moroccan margins. Similar assemblages between the Gulf of Cadiz and the NW Moroccan margin, and distinct species off Portugal, were observed during the cold climatic extremes that punctuated the last 30 ka. This pattern has been linked to the occurrence of a hydrological structure between SW Iberia and Cadiz during the last glacial period, perhaps similar to the modern Azores Front. This front was probably responsible locally for heterotrophic dinocysts found in the Gulf of Cadiz during the last glacial period, even if this sector is not conductive to upwelling phenomena by Ekman transport. Regional reconstructions of paleo-sea-surface temperatures (SSTs) using dinocyst and foraminiferal transfer functions, as well as alkenones, are also discussed and depict coherent scenarios over the last 30 ka. Seasonal reconstructions of LGM SSTs obtained with this multi-proxy panel are discussed jointly with model outputs in order to contribute to ongoing efforts in model-data comparison.
(Biogeosciences. vol. 8, n° 1726-4170, pp. 2295-2316, 23/08/2011)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LDO, INSU - CNRS, UBO EPE, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, CLIM, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA
Stratigraphic, sedimentological and palaeoenvironmental constraints on the rise of the Urgonian platform in the western Swiss Jura" by A. Godet et al. (2010) Sedimentology 57, 1088-1125: Discussion
(Sedimentology. vol. 59, n° 0037-0746, pp. 1121-1125, 08/08/2011)
LDO, INSU - CNRS, UBO EPE, CNRS, UNIGE, UNIMI, CR2P, MNHN, UPMC, CNRS, UniCa, SGN