Effects of Methylmercury Contained in a Diet Mimicking the Wayana Amerindians Contamination through Fish Consumption: Mercury Accumulation, Metallothionein Induction, Gene Expression Variations, and Role of the Chemokine CCL2.
Methylmercury (MeHg) is a potent neurotoxin, and human beings are mainly exposed to this pollutant through fish consumption. We addressed the question of whether a diet mimicking the fish consumption of Wayanas Amerindians from French Guiana could result in observable adverse effects in mice. Wayanas adult men are subjected to a mean mercurial dose of 7 g Hg/week/kg of body weight. We decided to supplement a vegetarian-based mice diet with 0.1% of lyophilized Hoplias aimara fish, which Wayanas are fond of and equivalent to the same dose as that afflicting the Wayanas Amerindians. Total mercury contents were 1.4 ± 0.2 and 5.4 ± 0.5 ng Hg/g of food pellets for the control and aimara diets, respectively. After 14 months of exposure, the body parts and tissues displaying the highest mercury concentration on a dry weight (dw) basis were hair (733 ng/g) and kidney (511 ng/g), followed by the liver (77 ng/g). Surprisingly, despite the fact that MeHg is a neurotoxic compound, the brain accumulated low levels of mercury (35 ng/g in the cortex). The metallothionein (MT) protein concentration only increased in those tissues (kidney, muscles) in which MeHg demethylation had occurred. This can be taken as a molecular sign of divalent mercurial contamination since only Hg(2+) has been reported yet to induce MT accumulation in contaminated tissues. The suppression of the synthesis of the chemokine CCL2 in the corresponding knockout (KO) mice resulted in important changes in gene expression patterns in the liver and brain. After three months of exposure to an aimara-containing diet, eight of 10 genes selected (Sdhb, Cytb, Cox1, Sod1, Sod2, Mt2, Mdr1a and Bax) were repressed in wild-type mice liver whereas none presented a differential expression in KO Ccl2(-/-) mice. In the wild-type mice brain, six of 12 genes selected (Cytb, Cox1, Sod1, Sod2, Mdr1a and Bax) presented a stimulated expression, whereas all remained at the basal level of expression in KO Ccl2(-/-) mice. In the liver of aimara-fed mice, histological alterations were observed for an accumulated mercury concentration as low as 32 ng/g, dw, and metal deposits were observed within the cytoplasm of hepatic cells.
(International Journal of Molecular Sciences. vol. 13, n° 1661-6596, pp. 7710-38, 28/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UPMC, INSERM, CNRS, IBGC, UB, CNRS
Effect of trematode parasites on cockle Cerastoderma edule growth and condition index: a transplant experiment
We quantified the effect of trematode parasites in cockles through a 303 d transplant experiment. Cockles were sampled in 3 different sites on the southwest coast of France characterized by 3 different trematode communities, i.e. Royan (RO): high Meiogymnophallus minutus abundance near cockle heart, South Arguin (SA): high Himasthla interrupta abundance in the mantle margin, and North Arguin (NA): almost free of trematodes. Sampled cockles were individually tagged and placed in different cages at Banc d’Arguin, Arcachon Bay. At the end of the experiment, RO cockles had lost their trematodes, highlighting the fact that trematode lifespan can be short, while SA cockles maintained their trematode load. When cockles were the second intermediate host, there was no effect of site of origin on cockle condition index and survival. The effect on growth rate was mostly due to initial cockle length. Within each treatment, the only significant effect of trematode infection on growth was found for H. interrupta at SA. The 23% growth deficit observed could be due to the disruption of cockle shell synthesis in the mantle margin. During the transplant experiment, cockles were also infected at an exceptionally high rate by Bucephalus minimus, a trematode which invades most of the tissues and uses the cockle as a first intermediate host. Surprisingly, there was an effect on the growth rate and condition index of cockles at only one of the sites under study. This field experiment succeeded in quantifying the moderately negative effect of trematode parasites on the growth and condition of their host and suggested the existence of interactions with as yet unknown factors.
(Marine Ecology Progress Series. vol. 471, n° 0171-8630, pp. 111-121, 28/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UM5, UCC
Mise au point d’un indice diatomique pour les cours d’eau de la Réunion (IDR) : Construction de la démarche biomathématique, résultats et perspectives
L'étude ayant conduit à la genèse de l'IDR (Indice Diatomique Réunion) s'est appuyée sur l’acquisition de 269 relevés taxinomiques des espèces rencontrées sur place et de données associées de chimie des eaux, obtenues sur un réseau de 56 sites à l'occasion de 5 campagnes de prélèvements de terrain. L'analyse de ces données a permis une caractérisation plus ou moins consolidée des préférences écologiques de 343 espèces, le repérage de communautés diatomiques-types caractéristiques de conditions environnementales particulières et, au final, la mise au point de ce nouvel indice, qui mobilise les profils de qualité écologique de 175 espèces suffisamment occurrentes.
(pp. 22, 28/10/2026)
UR REBX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Les collections scientifiques de l'université Bordeaux 1. Sciences et Technologies
De nombreuses universités scientifiques possèdent des collections. L'université Bordeaux 1 possède neuf grandes collections concernant les domaines de la préhistoire, de l'anthropologie, de la géologie terrestre et marine, de la paléontologie et micropaléontologie, de la biologie, de l'astronomie et d'un fonds ancien et moderne d'ouvrages scientifiques. Certaines collections sont riches de milliers de spécimens : fossiles d'invertébrés, ossements de vertébrés, silex taillés, ossements humains préhistoriques ou historiques, animaux naturalisés, carottes de sédiments, instruments d'astronomie et livres anciens. Ces collections ont été constituées par des privés ou des chercheurs et ont ensuite été léguées à l'université. Il est important d'identifier les collectionneurs et surtout les motivations qui ont guidé leurs choix : recherche, enseignement, passion. Entre histoires personnelles et histoires locales, ce regard sur les collections est aussi une porte ouverte sur l'histoire des Sciences.
(In Situ : Revue des patrimoines. vol. -, pp. on line, 28/10/2026)
L3AB, UB, INSU - CNRS, CNRS, OASU, UB, INSU - CNRS, ULR, CNRS, INRAE, LAB, UB, INSU - CNRS, CNRS, UB, PACEA, UB, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Removal of xenobiotics by adsorption on two mineral adsorbent materials as an alternative to activated carbon: a comparative batch approach
Xenobiotics, such as some pharmaceuticals and pesticides, are poorly treated in wastewater treatment plants (WWTPs). Thus, their occurrence into the aquatic environment is more and more highlighted. Adsorption process on materials, such as in tertiary stage of treatment, could be a solution to decrease the concentrations of xenobiotics in effluents that are discharged into the aquatic environment. We carried out an original experiment involving treated domestic wastewater spiked with a cocktail of 10 xenobiotics known as being poorly eliminated in WWTPs (8 pharmaceuticals and 2 pesticides). Two mineral adsorbent materials (expanded clay and zeolite), representing a possible alternative to activated carbon, were evaluated for the adsorption of the cocktail of xenobiotics. We studied the influence of the concentration level of xenobiotics on adsorption results. We focused on the concentrations near from usual effluent ranges to be representative with conditions faced in tertiary treatment stage. If activated carbon was the most efficient adsorbent material, both alternative adsorbent materials showed good adsorption efficiencies for the 10 xenobiotics (in the range of 50-100% depending on the couple adsorbent material / xenobiotic). Kd partition coefficients were quantified for different xenobiotics concentration ranges. At low concentration (0.1 – 10 µg/L), expanded clay showed higher Kd values than at high concentration (100 – 1000 µg/L) for a majority of xenobiotics (7 among 10). Kd values for zeolite seemed to be independent of xenobiotic concentration levels. Our results point out that mineral microporous adsorbent are credible alternatives to activated carbon for adsorption of xenobiotics usually known to be poorly eliminated in WWTPs. The results suggest a possible use into a tertiary stage of treatment in wastewater treatment plants.
(pp. 6, 28/10/2026)
UR MALY, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UM
Consistency in diatom response to metal-contaminated environments
Diatoms play a key role in the functioning of streams, and their sensitivty to many environmental factors has led to the development of numerous diatom-based indices used in water quality assessment. Although diatom-based monitoring of metal contamination is not currently included in water qual ty monitoring programs, the effects of metals on diatom commun ties have been studied in many polluted watersheds as well as in laboratory experiments, underlying their high potential for metal contamination assessment. Here, we review the response of diatoms to metal pollution from individual level (e.g. size, growth form, and morphological abnormalities) to community structure (replacement of sensitive species by tolerant ones). These potential effects are then tested using a large multi-country database combining diatom and metal information. Metal contamination proved to be a strong driver of the community structure, and enabled for the identification of tolerant species like Cocconeis placentula var. euglypta, Eolimna minima , Fragilaria gracilis, Nitzschia sociabilis, Pinnularia parvulissima, and Surirella angusta. Among the traits tested, diatom cell size and the occurrence of diatom deformities were found to be good indicators of high metal contamination. This work provides a basis for further use of diatoms as indicators of metal pollution.
(pp. 117-146, 28/10/2026)
UR REBX, IRSTEA, IRSTEA, IRSTEA, IRSTEA, ICRA, UdG, UdG, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Deglacial and Holocene vegetation and climatic changes at the southernmost tip of the Central Mediterranean from a direct land-sea correlation
Despite a large number of studies, the long-term and millennial to centennial-scale climatic variability in the Mediterranean region during the last deglaciation and the Holocene is still debated, in particular in the Southern Central Mediterranean. In this 5 paper, we present a new marine pollen sequence (MD04-2797CQ) from the SiculoTunisian Strait documenting the regional vegetation and climatic changes in the Southern Central Mediterranean during the last deglaciation and the Holocene. The MD04-2797CQ marine pollen sequence shows that semi-desert plants dominated the vegetal cover in the Southern Central Mediterranean between 18 and 10 12.3 kyr BP indicating prevailing dry conditions during the deglaciation, even during the Greenland Interstadial (GI)-1. Such arid conditions likely restricted the expansion of the trees and shrubs despite the GI-1 climatic amelioration. Across the transition Greenland Stadial (GS)-1 – Holocene, Asteraceae-Poaceae steppe became dominant till 10.1 kyr. This record underlines with no chronological ambiguity that even 15 though temperatures increased, deficiency in moisture availability persisted into the Early Holocene.Temperate trees and shrubs with heaths as oak forest understorey or heath maquis expanded between 10.1 and 6.6 kyr, while Mediterranean plants only developed from 6.6 kyr onwards. These changes in vegetal cover show that the regional climate in Southern Central Mediterranean was wetter during Sapropel 1 (S1) 20 and became drier during the Mid- to Late Holocene. Wetter conditions during S1 were likely due to increased winter precipitation while summers remained dry. We suggest, in agreement with published modelling experiments, that the increased melting of the Laurentide Ice Sheet between 10 to 6.8 kyr in conjunction with weak winter insolation played a major role in the development of winter precipitation maxima in the Mediter25 ranean region in controlling the strength and position of the North Atlantic storm track. Finally, our data provide evidences of centennial-scale vegetation and climatic changes in the Southern Central Mediterranean. During the wet Early Holocene, alkenones-derived cooling episodes are synchronous to herbaceous composition changes that indicate muted changes in precipitation. In contrast, enhanced aridity episodes, as detected by strong reduction in trees and shrubs, are recorded during the Mid- to Late Holocene. We show that the impact of the Holocene cooling events depend on the baseline climate states insolation and ice sheet volume, shaping the response of the mid-latitude atmospheric circulation.
(pp. 5687–5741, 28/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, LCE, CNRS, UMLP, IDES, UP11, INSU - CNRS, CNRS, LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France]
Occurrence of Polybrominated Diphenyl Ethers, Polychlorinated Biphenyls, and Phthalates in Freshwater Fish From the Orge River (Ile-de France)
Polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), and phthalates were investigated from July 2009 to April 2010 in three fish species from the Orge river, which flows in a densely populated area of Ile-de-France. In two Cyprinidae (roach and chub) and one Percidae (perch), muscle contents in increasing order ranged as follows: 12-18 ng g(-1) dw for PBDEs (I tri-hepta) pound, 120-170 ng g(-1) dw for PCBs (I 7) pound, and 2,250-5,125 ng g(-1) dw for phthalates (I 7) pound. No variation was observed between contaminant contents and lipid levels. No biomagnification was found according to the trophic level for PBDEs and PCBs, whereas for phthalates the highest contents were found in perch. Seasonal variations were observed with the lowest PBDE and PCB contents occurring in July after spawning in roach and perch (p < 0.001). PBDE content followed a decreasing trend-gonad > liver > muscle-whatever the period. For PCBs, gonad and liver contents remained greater than that of muscle (p < 0.05). Our results indicate a preferential accumulation of halogenated compounds in gonad and liver outside the reproduction period. Bioaccumulation factors for PCBs in muscle were significantly correlated to their chlorination degree in perch (p < 0.01) and roach (p < 0.01). In roach, that correlation slope was by decreasing importance order as follows: gonad > liver > muscle. The biota-sediment accumulation factors varied from 0.1 to 29.2, from 1.6 to 4.8, and from 1 to 123.5 for PBDEs, PCBs, and phthalates, respectively. These results contribute to document the use of freshwater fish as bioindicators of river quality.
(Archives of Environmental Contamination and Toxicology. vol. 63, n° 0090-4341, pp. 101-113, 28/10/2026)
SISYPHE, UPMC, EPHE, PSL, PSL, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Short-term and small-scale variability in planktic foraminifera test flux in the Bay of Biscay
Test fluxes of planktic foraminifera in the Bay of Biscay were sampled in spring using drifting sediment traps deployed at 200 m depth. At a temporal and spatial resolution of 3 h and approximately 1 km the foraminifer flux varied with a factor of 5. The consecutive deployments within the same area, at distances of ∼50 km differed significantly in flux and relative species abundances. Flux sequences of the total foraminifer assemblage and individual species were significantly autocorrelated. The significance of autocorrelation analyses was affected by sample size of the flux sequences and limited to flux sequences with large fluxes. Autocorrelation in planktic foraminifer fluxes and standing stocks was restricted to distances <2 km, and were not attributed to the temporal domain.
(Deep Sea Research Part I: Oceanographic Research Papers. vol. 64, n° 0967-0637, pp. 146 - 156, 28/10/2026)
HUJ, LPG-ANGERS, LPG, UA, UN UFR ST, UN, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
High resolution Holocene record in the southeastern Bay of Biscay: use of benthic and planktic foraminifera as paleoenvironmental proxies
The southeastern part of the Bay of Biscay is under the combined influence of the eastern branch of the North Atlantic Current (NAC) and coastal river plumes. The objective of this study is to use foraminiferal distribution from a 3 m high resolution record (SE Bay of Biscay; 550 m water depth) as proxies to evaluate the hydrological pattern of the Bay of Biscay during the Holocene; a period of rapid climatic change.
Faunal distributions coupled to grain size variability suggest a rapid evolution of the sedimentary structuring of the basin. Major changes are recorded in benthic and planktic foraminiferal communities suggesting important fluctuations of primary and exported productivity during the Holocene. These rapid changes could be related to variations of the oceanic hydrology of the basin and/or to the coastal rivers hydrological regimes.
(28/10/2026)
LPG-ANGERS, LPG, UA, UN UFR ST, UN, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS