Molecular Characterization of Voltage-Gated Sodium Channels and Their Relations with Paralytic Shellfish Toxin Bioaccumulation in the Pacific Oyster Crassostrea gigas
Paralytic shellfish toxins (PST) bind to voltage-gated sodium channels (Nav) and block conduction of action potential in excitable cells. This study aimed to (i) characterize Nav sequences in Crassostrea gigas and (ii) investigate a putative relation between Nav and PST-bioaccumulation in oysters. The phylogenetic analysis highlighted two types of Nav in C. gigas: a Nav1 (CgNav1) and a Nav2 (CgNav2) with sequence properties of sodium-selective and sodium/calcium-selective channels, respectively. Three alternative splice transcripts of CgNav1 named A, B and C, were characterized. The expression of CgNav1, analyzed by in situ hybridization, is specific to nervous cells and to structures corresponding to neuromuscular junctions. Real-time PCR analyses showed a strong expression of CgNav1A in the striated muscle while CgNav1B is mainly expressed in visceral ganglia. CgNav1C expression is ubiquitous. The PST binding site (domain II) of CgNav1 variants possess an amino acid Q that could potentially confer a partial saxitoxin (STX)-resistance to the channel. The CgNav1 genotype or alternative splicing would not be the key point determining PST bioaccumulation level in oysters.
(Marine drugs. vol. 15, n° 1660-3397, pp. 21, 27/04/2026)
LEMAR, IRD, IFREMER, UBO EPE, CNRS, UFPB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IFREMER
Hydrological and ecological controls on dissolved carbon concentrations in groundwater and carbon export to surface waters in a temperate pine forest watershed
Export of soil carbon to superficial water through the drainage of groundwater is a significant but poorly documented component of the continental carbon budget. We monitored the concentrations of dissolved organic and inorganic carbon (DOC and DIC) in groundwaters and first order streams of a small temperate, forested and sandy watershed where hydrology occurs exclusively through drainage (no surface runoff). The studied watershed was also implemented for continuous measurements of groundwater table, precipitation, evapotranspiration, river discharge, and net ecosystem exchanges of sensible and latent heat fluxes as well as CO2. On a monthly basis, we found a good consistency between precipitation and the sum of evapotranspiration, drainage and groundwater storage. DOC and DIC temporary storage in groundwater and export to streams varied drastically during the hydrological cycle, the residence times of these two carbon forms varying from one month to several years. DOC concentrations in groundwater and streams were maximal at high water table and high stream discharge, when the water table reached the superficial organic rich layer of the soil. A large fraction of this winter DOC maximum was temporarily stored and further mineralized to DIC in the groundwater and only about 15 % was exported to streams during winter periods. In contrast, DIC, which was present in majority in the form of dissolved CO2 in groundwater and streams, was apparently diluted at high water table: DIC concentrations were maximum at low water table and low discharge in late summer and maximum pCO2 in groundwater corresponded to the late summer period of heterotrophic conditions (i.e., Reco>GPP). Groundwater DIC peaked in late summer and was followed by a rapid loss of excess CO2 from stream surface to the atmosphere. Overall, mean carbon export was 7.5 g C m-2 yr-1 (50 % as DOC and 50 % as DIC) and represented only 1.5 % of the NEE. About 65 % of the DIC exported from groundwaters returned to the atmosphere in the form of CO2 in first order streams.
(Biogeosciences Discussions, n° 1810-6277, pp. 1-34, 27/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMR ISPA, INRA, Bordeaux Sciences Agro, UFF
Energy transfer in the Congo deep-sea fan: from terrestrially-derived organic matter to chemosynthetic food webs
Large amounts of recent terrestrial organic matter (OM) from the African continent are delivered to the abyssal plain by turbidity currents and accumulate in the Congo deep-sea fan. In the recent lobe complex, large clusters of vesicomyid bivalves are found all along the active channel in areas of reduced sediment. These soft-sediment communities resemble those fuelled by chemoautotrophy in cold-seep settings. The aim of this study was to elucidate feeding strategies in these macrofaunal assemblages as part of a greater effort to understand the link between the inputs of terrestrially-derived OM and the chemosynthetic habitats. The biochemical composition of the sedimentary OM was first analysed in order to evaluate how nutritious the available particulate OM is for the benthic macrofauna. The terrestrial OM is already degraded when it reaches the final depositional area. However, high biopolymeric carbon contents (proteins, carbohydrates and lipids) are found in the channel of the recent lobe complex. In addition, about one to two thirds of the nitrogen can be assigned to peptide-like material. Even if this soil-derived OM is poorly digestible, turbiditic deposits contain such high amounts of organic carbon that there is enough biopolymeric carbon and proteacinous nitrogen to support dense benthic communities that contrast with the usual depauperate abyssal plains.
(Deep Sea Research Part II: Topical Studies in Oceanography. vol. 142, n° 0967-0645, pp. 197-218, 27/04/2026)
LECOB, OOB, UPMC, CNRS, UPMC, CNRS, LEP, EEP, IFREMER, iSTeP, UPMC, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Precipitation changes in the Mediterranean basin during the Holocene from terrestrial and marine pollen records: a model-data comparison
Climate evolution of the Mediterranean region during the Holocene exhibits strong spatial and temporal variability, which is notoriously difficult for models to reproduce. We propose here a new proxy-based climate synthesis synthesis and its comparison -at a regional (similar to 100 km) level - with a regional climate model to examine (i) opposing northern and southern precipitation regimes and (ii) an east-to-west precipitation dipole during the Holocene across the Mediterranean basin. Using precipitation estimates in-ferred from marine and terrestrial pollen archives, we focus on the early to mid-Holocene (8000 to 6000 cal yr BP) and the late Holocene (4000 to 2000 cal yr BP), to test these hypotheses on a Mediterranean-wide scale. Special attention was given to the reconstruction of season-specific climate in-formation, notably summer and winter precipitation. The reconstructed climatic trends corroborate the north-south partition of precipitation regimes during the Holocene. During the early Holocene, relatively wet conditions occurred in the south-central and eastern Mediterranean regions, while drier conditions prevailed from 45 degrees N northwards. These patterns then reverse during the late Holocene. With regard to the existence of a west-east precipitation dipole during the Holocene, our results show that the strength of this dipole is strongly linked to the reconstructed seasonal parameter; early-Holocene summers show a clear east-west division, with summer precipitation having been highest in Greece and the eastern Mediterranean and lowest over Italy and the western Mediterranean. Summer precipitation in the east re-mained above modern values, even during the late-Holocene interval. In contrast, winter precipitation signals are less spatially coherent during the early Holocene but low precipita-tion is evidenced during the late Holocene. A general drying trend occurred from the early to late Holocene, particularly in the central and eastern Mediterranean. For the same time intervals, pollen-inferred precipita-tion estimates were compared with model outputs, based on a regional-scale downscaling (HadRM3) of a set of global climate-model simulations (HadAM3). The high-resolution detail achieved through the downscaling is intended to enable a better comparison between site-based paleo-reconstructions and gridded model data in the complex terrain of the Mediterranean; the model outputs and pollen-inferred precipitation estimates show some overall correspondence, though modeled changes are small and at the absolute margins of statistical significance. There are suggestions that the eastern Mediterranean experienced wetter summer conditions than present during the early and late Holocene; the drying trend in winter from the early to the late Holocene also appears to be simulated. The use of this high-resolution regional climate model highlights how the inherently patchy nature of climate signals and paleo-records in the Mediterranean basin may lead to local signals that are much stronger than the large-scale pattern would suggest. Nevertheless, the east-to-west division in summer precipitation seems more marked in the pollen reconstruction than in the model outputs. The footprint of the anomalies (like today, or dry winters and wet summers) has some similarities to modern analogue atmospheric circulation patterns associated with a strong westerly circulation in winter (positive Arctic Oscillation-North Atlantic Oscillation (AO-NAO)) and a weak westerly circulation in summer associated with anticy-clonic blocking; however, there also remain important differences between the paleo-simulations and these analogues. The regional climate model, consistent with other global models, does not suggest an extension of the African summer monsoon into the Mediterranean. Therefore, the extent to which summer monsoonal precipitation may have existed in the southern and eastern Mediterranean during the mid-Holocene remains an outstanding question.
(Climate of the Past. vol. 13, n° 1814-9324, pp. 249-265, 27/04/2026)
LCE, CNRS, UFC, UBFC, UMR ISEM, Cirad, EPHE, PSL, UM, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, UOR, SFU.ca, IMBE, AU, AMU, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UHH, UNIROMA
Recovering water wave elevation from pressure measurements
The reconstruction of water wave elevation from bottom pressure measurements is an important issue for coastal applications, but corresponds to a difficult mathematical problem. In this paper we present the derivation of a method which allows the elevation reconstruction of water waves in intermediate and shallow waters. From comparisons with numerical Euler solutions and wave-tank experiments we show that our nonlinear method provides much better results of the surface elevation reconstruction compared to the linear transfer function approach commonly used in coastal applications. More specifically, our method accurately reproduces the peaked and skewed shape of nonlinear wave fields. Therefore, it is particularly relevant for applications on extreme waves and wave-induced sediment transport.
(Journal of Fluid Mechanics. vol. 833, n° 0022-1120, pp. 399-429, 27/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IMB, UB, Bordeaux INP, CNRS
Étude de la contamination atmosphérique par les pesticides à l'aide d'échantillonneurs passifs de type PUF (Polyurethane Foam) : application à l'étude de vergers de pommiers
La France, dont plus de la moitié du territoire est dédiée à l'agriculture, se situe au premier rang européen et au cinquième rang mondial des utilisateurs de pesticides agricoles. L'importance de ce secteur et de l'usage de substances chimiques pour accroître la productivité au cours des dernières décennies suscitent des interrogations tant du point de vue environnemental que de celui de la santé publique. Un rapport récent de l'ANSES montre la nécessité de mettre en oeuvre de nouveaux outils et une surveillance nationale des pesticides dans l'air ambiant. En effet, la connaissance des niveaux de contamination en pesticides dans l'atmosphère demeure toujours partielle et hétérogène. De plus, une stratégie spatio-temporelle d'échantillonnage est nécessaire pour l'étude des impacts des pesticides sur l'Environnement et sur la Santé Humaine. Le projet CANEPA (Cancers et Expositions aux pesticides Agricoles ; IdEx U Bordeaux) vise à caractériser la contamination externe des agriculteurs et la contamination environnementale par les pesticides en arboriculture. La technique de l'échantillonnage passif s'est largement développée ces 20 dernières années. Elle permet le suivi de polluants dans l'environnement et peut-être appliquée à l'eau, l'air ou encore le sol. Les échantillonneurs passifs présentent l'avantage d'intégrer la contamination du milieu pendant une période d'exposition donnée et d'abaisser les limites de détection grâce à l'accumulation des substances. Ces outils de surveillance ne nécessitent pas d'énergie et permettent un déploiement spatio-temporel plus pertinent. Au cours de ce projet, un suivi annuel par échantillonnage passif à l'aide de mousses en polyuréthane (PUF) a été mis en place début 2017 au sein d'une exploitation de pommiers pour un suivi des concentrations en pesticides dans l'air intérieur et extérieur afin de mieux comprendre l'exposition des travailleurs agricoles. L'analyse des différents échantillons du projet permettra de déterminer les débits de prélèvements des pesticides détectés dans l'air ambiant. De plus, les basses limites de quantification obtenues au cours des développements analytiques permettent un suivi très large de ces composés.
(pp. 2, 27/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, INSERM U1219 - UB - ISPED, BPH, UB, INSERM, UR ETBX, IRSTEA
Calibration of benthic foraminifera elemental ratios from the Northeastern Atlantic
(27/04/2026)
GEOPS, UP11, CNRS, LPG-ANGERS, LPG, UA, UN UFR ST, UN, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
High Value-Added Biomolecules from Beach Waste of Marine Origin-Screening for Potential Candidates among Seagrass of the Cymodoceaceae Family
Background: Detrital leaves from seagrass of the Cymodoceaceae family were assayed for biologically active molecules that have commercial as well as societal benefits. Objective: We focused on L-chiro-inositol, a very rare natural occurring cyclitol, and chicoric acid, a polyphenolic compound, in which both applications were found in the nutraceutical segment. Method: Six species of seagrass belonging to the genera Syringodium, Cymodocea and Halodule were collected from their native habitat. The L-chiro-inositol content of the crude aqueous extracts prepared from different batches of Cymodocea nodosa flotsam was measured by quantitative 1H-NMR spectroscopy. High concentrations were found with values ranging from 22.2 to 35.0 mg.g-1 plant dw. The presence of L-chiro-inositol in the tropical species C. rotundata, C. serrulata, Syringodium isoetifolium, and Halodule pinifolia was also characterized by qualitative NMR. The chicoric acid content of crude aqueous methanolic extracts prepared from C. rotundata, C. serrulata, S. isoetifolium, and Halodule pinifolia was determined by quantitative HPLC-DAD. The values found ranged from 0.39 to 6.15 mg.g-1 dry weight. Chicoric acid was unambiguously identified as the major phenolic in S. isoetifolium, and Halodule pinifolia, while it was found in mixture with flavonol derivatives in C. rotundata and C. serrulata. Flavonol derivatives are also of interest for their bioactivity. Result: Considering the demonstrated therapeutic applications of L-chiro-inositol and chicoric acid, their high value on the nutraceutical market, and their rare occurrence in the plant kingdom, their presence in Syringodium, Cymodocea and Halodule detrital leaves makes this abundant biomass of interest for dietary and pharmaceutical applications. Conclusion: These results show that there is a real potential for harvesting beachcast Cymodoceacea.
(The Open Bioactive Compounds. vol. 5, n° 1874-8473, pp. 83-94, 27/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Organic carbon accumulation in modern sediments of the Angola basin influenced by the Congo deep sea fan
Geochemical data (total organic carbon-TOC content, δ13Corg, C:N, Rock-Eval analyses) were obtained on 150 core tops from the Angola basin, with a special focus on the Congo deep sea fan. Combined with the previously published data, the resulting dataset (322 stations) shows a good spatial and bathymetric representativeness. TOC content and δ13Corg maps of the Angola basin were generated using this enhanced dataset. The main difference in our map with previously published ones is the high terrestrial organic matter content observed downslope along the active turbidite channel of the Congo deep sea fan till the distal lobe complex near 5000 m of water-depth. Interpretation of downslope trends in TOC content and organic matter composition indicates that lateral particle transport by turbidity currents is the primary mechanism controlling supply and burial of organic matter in the bathypelagic depths.
(Deep Sea Research Part II: Topical Studies in Oceanography. vol. 142, n° 0967-0645, pp. 64-74, 27/04/2026)
EMBS, iSTeP, UPMC, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GM, IFREMER, LDO, INSU - CNRS, UBO EPE, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, OCEANIS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA
Quality survey of natural mineral water and spring water sold in France: Monitoring of hormones, pharmaceuticals, pesticides, perfluoroalkyl substances, phthalates, and alkylphenols at the ultra-trace level
(Science of the Total Environment. vol. 603-604, n° 0048-9697, pp. 651--662, 27/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LPTC, UB, CNRS, ISM, UB, INC-CNRS, CNRS