Serial analysis of gene expression in the skeletal muscles of zebrafish fed with a methylmercury-contaminated diet
Mercury (Hg) is a widespread environmental contaminant and its organic form, methylmercury (MeHg), has been known as a potent neurotoxic since the Minamata tragedy. In the Amazonian basin, gold mining leads to MeHg biomagnification all along the food web, culminating in piscivorous fish, ultimately responsible for contamination of human beings through fish consumption. In order to assess the biological impact of dietary MeHg on fish at the genome scale, we contaminated zebrafish with MeHg-contaminated food for 25 days (13.5 microg of Hg/g of food). A serial analysis of gene expression (SAGE) was conducted on the skeletal muscle because this tissue does not perform MeHg demethylation, and 19171 SAGE tags were sequenced from the control library versus 22 261 from the MeHg-contaminated library, corresponding to 5280 different transcripts. Among those identified, 60 genes appeared up-regulated and 15 down-regulated by more than 2 times. A net impact of MeHg was noticed on 14 ribosomal protein genes, indicating a perturbation of protein synthesis. Several genes involved in mitochondrial metabolism, the electron transport chain, endoplasmic reticulum (ER) function, detoxification, and general stress responses were differentially regulated, suggesting an onset of oxidative stress and ER stress. Several other genes for which expression varied with MeHg contamination could be clustered in various compartments of the cell's life, such as lipid metabolism, calcium homeostasis, iron metabolism, muscle contraction, and cell cycle regulation. This study reveals the effectiveness of the SAGE approach to acquire a better understanding of the MeHg global effects. Furthermore, this is the first time that the SAGE was used to characterize the effect of a toxicant at the genome scale in an aquatic organism.
(Environmental Science and Technology. vol. 44, n° 0013-936X, pp. 469-475, 01/01/2010)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LMBA, UBS, UBO EPE, CNRS
Seasonal progression of diatom assemblages in surface waters of Ryder Bay, Antarctica
Phytoplankton assemblages from seasonally sea-ice covered Ryder Bay (Adelaide Island, Antarctica) were studied over three austral summers (2004-2007), to link sea-ice variability and environmental conditions with algal speciation. Typical of near-shore Antarctic waters, biomass was dominated by large diatoms, although the prymnesiophyte Phaeocystis antarctica was numerically dominant. Although there was considerable interannual variability between main diatom species, high biomass of certain species or species groups corresponded consistently to certain phases of seasonal progression. We present the first documentation of an extensive bloom of the late-season diatom Proboscia inermis in February 2006, accounting for over 90% of diatom biomass. At this time, water column stratification and nutrient drawdown were high relative to other periods of the study, although carbon export was relatively low. Melt water flux in this region promotes well-stratified surface waters and high chlorophyll levels, but not necessarily concurrent increases in export production relative to seasons with lower freshwater inputs.
(Polar Biology. vol. 33, n° 0722-4060, pp. 13-29, 01/01/2010)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BAS, NERC
What drives the millennial and orbital variations of δ18Oatm?
(Quaternary Science Reviews. vol. 29, n° 0277-3791, pp. 235-246, 01/01/2010)
LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, GLACCIOS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UNIBE, ITU
Experimental toxicity and bioaccumulation of cadmium in freshwater periphytic diatoms in relation with biofilm maturity
A study was undertaken to examine cadmium accumulation in freshwater biofilm, its effects on biofilm development and on diatom community structure in laboratory experimental conditions. A suspension of a biofilm originated from the Riou-Mort River (South West France) was inoculated into three experimental units containing clean glass substrates under laboratory conditions. Settling and already developed biofilms were exposed to a Cd concentration of 100 μgL−1. Metal accumulation (total and intracellular metal content) in biofilms, dry weight and ash-free dry mass, diatom cell density and diatom community composition were analyzed. Both total and intracellular Cd accumulated by the biofilm throughout the experiment increased with duration of metal exposure. Biofilms in the course of maturation were showed higher Cd content and less effective development than settled biofilms. However diatom communities in younger biofilms exposed to Cd increased their tolerance to Cd by a highly significant development of Nitzschia palea. In contrast, Cd exposure had different effect in installed biofilm and taxonomic composition. These results indicate that mature biofilm may limit Cd accumulation into its architecture and protect diatom communities from the effects of metals.
(Science of the Total Environment. vol. 408, n° 0048-9697, pp. 552-562, 28/05/2026)
IRSTEA, UR REBX, CEMAGREF, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Testing the Hypothesis of Fire Use for Ecosystem Management by Neanderthal and Upper Palaeolithic Modern Human Populations
Background: It has been proposed that a greater control and more extensive use of fire was one of the behavioral innovations that emerged in Africa among early Modern Humans, favouring their spread throughout the world and determining their eventual evolutionary success. We would expect, if extensive fire use for ecosystem management were a component of the modern human technical and cognitive package, as suggested for Australia, to find major disturbances in the natural biomass burning variability associated with the colonisation of Europe by Modern Humans. Methodology/Principal Findings: Analyses of microcharcoal preserved in two deep-sea cores located off Iberia and France were used to reconstruct changes in biomass burning between 70 and 10 kyr cal BP. Results indicate that fire regime follows the Dansgaard-Oeschger climatic variability and its impacts on fuel load. No major disturbance in natural fire regime variability is observed at the time of the arrival of Modern Humans in Europe or during the remainder of the Upper Palaeolithic (40-10 kyr cal BP). Conclusions/Significance: Results indicate that either Neanderthals and Modern humans did not influence fire regime or that, if they did, their respective influence was comparable at a regional scale, and not as pronounced as that observed in the biomass burning history of Southeast Asia.
(PLoS ONE. vol. 5, n° 1932-6203, pp. e9157, 28/05/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, PACEA, UB, CNRS, WITS
Viability of differentiated epilithic bacterial communities in the River Garonne (SW France)
Epilithic bacterial community viability was assessed on natural biofilm assemblages from environmentally contrasting locations over a 17-months period to determine if it reflects environmental conditions or conditions within the biofilm assemblage. Vital state was assessed by membrane integrity using LIVE/DEAD® BacLight staining kit. Samples were regularly collected in a large river, up and downstream of a large urban centre. Epilithic biomasses were similar between sites irrespective of the distinct water quality but varied temporarily, peaking up to 48 g AFDM m−2. Bacterial community composition assessed by 16S rDNA based PCR-DGGE significantly differed between sites. Bacterial densities (median of 2.5 × 1011 cell g AFDM−1) were stable whatever the sample origin or biomass. Viable bacterial fractions ranged between 13 and 83% of the total bacterial densities and were correlated with hydrological stability indicators (average of 41.9% during stable water periods, 62.4% during intermediate flow regimes and 50.0% during flow instability) and seasonal parameters. At the river section and epilithic community scales, consistent bacterial densities per unit of biomass could reflect a biofilm assemblage carrying capacity while variable membrane integrity likely integrates changes in the vital state of the community under changing environmental conditions.
(Hydrobiologia. vol. 637, n° 0018-8158, pp. 207-218, 28/05/2026)
CNRS, UR MALY, CEMAGREF, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Abrupt climate changes of the last deglaciation detected in a Western Mediterranean forest record
Abrupt changes in Western Mediterranean climate during the last deglaciation (20 to 6 cal ka BP) are detected in marine core MD95-2043 (Alboran Sea) through the investigation of high-resolution pollen data and pollen-based climate reconstructions by the modern analogue technique (MAT) for annual precipitation (Pann) and mean temperatures of the coldest and warmest months (MTCO and MTWA). Changes in temperate Mediterranean forest development and composition and MAT reconstructions indicate major climatic shifts with parallel temperature and precipitation changes at the onsets of Heinrich stadial 1 (equivalent to the Oldest Dryas), the Bölling-Allerød (BA), and the Younger Dryas (YD). Multi-centennial-scale oscillations in forest development occurred throughout the BA, YD, and early Holocene. Shifts in vegetation composition and (Pann reconstructions indicate that forest declines occurred during dry, and generally cool, episodes centred at 14.0, 13.3, 12.9, 11.8, 10.7, 10.1, 9.2, 8.3 and 7.4 cal ka BP. The forest record also suggests multiple, low-amplitude Preboreal (PB) climate oscillations, and a marked increase in moisture availability for forest development at the end of the PB at 10.6 cal ka BP. Dry atmospheric conditions in the Western Mediterranean occurred in phase with Lateglacial events of high-latitude cooling including GI-1d (Older Dryas), GI-1b (Intra-Allerød Cold Period) and GS-1 (YD), and during Holocene events associated with high-latitude cooling, meltwater pulses and N. Atlantic ice-rafting. A possible climatic mechanism for the recurrence of dry intervals and an opposed regional precipitation pattern with respect to Western-central Europe relates to the dynamics of the westerlies and the prevalence of atmospheric blocking highs. Comparison of radiocarbon and ice-core ages for well-defined climatic transitions in the forest record suggests possible enhancement of marine reservoir ages in the Alboran Sea by 200 years (surface water age 600 years) during the Lateglacial.
(Climate of the Past. vol. 6, n° 1814-9324, pp. 245-264, 28/05/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, EPHE, PSL, LCE, CNRS, UMLP, UBFC
Deciphering of six blocks of Gondwanan origin within Eastern Indonesia (South East Asia)
The French Indonesian research programs, both conducted on land and offshore in the Banda Sea basins area, have led us to formulate a new interpretation of the East Indonesian geological components. In this area we distinguish, within the three main tectonic plates (Eurasian, Indo-Australian and Philippine-Pacific), seven blocks. Six blocks are deciphered as issued from the north-eastern Gondwanan margin and only one (the Halmahera block) issued from the Pacific plate. Among the Gondwanan blocks, two of them, namely Timor (probably originates from "Greater India") and Kolonodale (or the Argo block) came from the north-west Australian margin. The Lucipara, Seram and Banggai-Sula blocks originated from the western extension of the Papua-New Guinea Island while the Irian Jaya block is still linked to the North Australian margin. The last one, the Halmahera block, originated from the Pacific plate, moved westward along the North Papua-New-Guinea margin up to its present position in the northern part of the Banda Sea area. Our interpretation is mainly based on the lithostratigraphic succession, the geological evolution and the Early Mesozoic paleoposition of these blocks with respect to the climatic environment deduced from micropaleontological studies. According to previous studies, the Timor and Kolonodale blocks were detached from Gondwana during the Jurassic whereas the Lucipara, Seram and Banggai-Sula blocks were detached from Papua-New Guinea Island during the Neogene period. All these Gondwanan blocks collided with the Eurasian active margin, in the vicinity of Sulawesi Island: Timor and Kolonodale had joined the Eurasian margin by the end of the Paleogene, while Lucipara, Seram and Banggai-Sula collided with Sulawesi Island between the Middle Miocene to Middle Pliocene. After the collisions the last three blocks together with the Kolonodale block did not move again but suffered the opening of North and South Banda back-arc basins, by the Late Miocene. On the contrary, part of the Timor block moved south together with the southern margin of the south Banda basin and, later on during the middle Pliocene, collided with the northern Australian margin. The detachment of these blocks from the Gondwana margin, and their amalgamation with the Eurasian margin, are discussed and illustrated through palaeogeographic maps.
(Gondwana Research. vol. 18, n° 1342-937X, pp. 420-437, 28/05/2026)
FRE 2761, CNRS, UNIGE, LDO, INSU - CNRS, UBO EPE, CNRS, PEPS, UCBL, INSU - CNRS, CNRS, CEREGE, IRD, INRA, AMU, CdF (institution), INSU - CNRS, CNRS, Unhas, ISTO, INSU - CNRS, UO, UT, CNRS, iSTeP, UPMC, CNRS, LPGN, UN, CNRS
How life history contributes to stress response in the Manila clam Ruditapes philippinarum
Introduction Within the last decade, numerous studies have investigated the role of environmental history on tolerance to stress of many organisms. This study aims to assess if Manila clams Ruditapes philippinarum may react differently to cadmium exposure and trematode parasite infection (Himasthla elongata) depending on their origin and environmental history in Arcachon Bay (France). Materials and methods Clams were exposed to Cd (15 µg L−1) and parasites (25 cercariae per clam), alone or in combination, at 15°C under controlled laboratory conditions for 7 days. Metal accumulation and success of parasite infestation were examined, also physiological parameters such as metallothionein response and hemocyte counts and activities (phagocytosis, oxidative burst, viability, and adhesion). Results and Discussion Sensitivity of Manila clams to both stressors differed from one site to another, suggesting local adaptation of populations. Clams from the more parasitized site presented better resistance to trematodes than the others in terms of first line defense, i.e., avoidance of infection. On the other hand, clams that adapted to chronic Cd contamination showed better detoxification mechanisms, both in a faster transfer of metal from gills to visceral mass and in a higher metallothionein baseline, than clams which had never experienced Cd contamination. Finally, hemocyte concentration and viability differed between clam origin site, highlighting the fact that populations living in different environments may adapt their physiological and biochemical responses to environmental stressors. Conclusion It is therefore important to be cautious when extrapolating results from field studies of one species and one site, if the life history of the organisms is not taken into account.
(Environmental Science and Pollution Research. vol. 17, n° 0944-1344, pp. 987-998, 28/05/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEMAR, IRD, IFREMER, UBO EPE, CNRS
4D CHARACTERIZATION OF METALS BY 3DXRD
The status of 3DXRD microscopy is reviewed, with a special view to applications in metallurgy. Various approaches are compared in terms of perfounance. In addition several recent advances are presented, such as a 3D grain map with an unprecedented spatial resolution of 500 nm, first results from the commissioning of a novel 3D detector set-up and a validation of the box-scan procedure.
(pp. 101-119, 28/05/2026)
DTU, MATEIS, UCBL, INSA Lyon, INSA, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ESRF