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Le dispositif « SELI » est mis en place depuis 2016 pour acquérir des données sur les effets biologiques intégrateurs de la contamination chimique chez des organismes marins (poissons et bivalves) et ainsi renseigner le critère 2 du descripteur 8 de la DCSMM (Le niveau de concentration des contaminants ne provoque pas d’effets dus à la pollution). Le présent rapport concerne le volet SELIseine. Des poissons plats (194 soles, flets et limandes) ont été prélevés en septembre 2018 sur le N/O Antéa, et des moules ont été prélevées en février 2019 sur 6 stations dans le cadre du suivi ROCCH MV suivant le protocole de la convention OSPAR (2012). Les biomarqueurs suivis chez ces organismes couvrent plusieurs types d’effets toxiques (reprotoxicité, génotoxicité, neurotoxicité) et incluent des mesures de la santé générale de l'organisme (pathologies, indices somatiques (e.g. RGS, RHS), stabilité de la membrane lysosomale). Les contaminants listés dans les Arrêtés du 17 décembre 2012 relatif à la définition du bon état écologique des eaux marines et du 28 avril 2015 relatif aux critères et méthodes pour l'élaboration et la mise en œuvre du programme de surveillance du plan d'action pour le milieu marin sont suivis. Ils concernent des éléments traces métalliques et des contaminants organiques hydrophobes (historiques et émergents) susceptibles de s’accumuler dans les organismes et/ou de s’amplifier dans les réseaux trophiques. L’ensemble de ces analyses permet de répondre aux questions : 1) Quelles sont les réponses biologiques observées chez les organismes marins (poissons plats, bivalves) ? 2) Quel est le niveau d’imprégnation des organismes marins (poissons plats, bivalves) à la contamination chimique ? et 3) Les réponses biologiques observées peuvent-elles être associées à l’exposition à un stress chimique dans des zones de pressions anthropiques variées ? De plus, les analyses de biomarqueurs et contaminants chez les soles, flets et limandes prélevés lors de la même campa

Telomeres protect the coding sequence of chromosome ends and Telomere Length (TL) has been proposed as a biomarker of cellular aging, cumulative stress exposure and life-span in humans. With the aim to propose new biomarkers, a q-PCR protocol was adapted for the measurement of TL in the European flounder Platichthys flesus. The protocol was then applied in 2-year-old flounders from the Seine Estuary. The absolute TL in the flounder is 54 ± 13 kbp per genome (mean ± standard error). Considering relative or absolute TL, no correlation was observed with DNA damage and any of the measured contaminant concentrations (trace elements, metabolites of polycyclic aromatic hydrocarbons, polychlorobiphenyls, organochlorinated pesticides, polybrominated diphenyl ethers, perfluoroalkyl substances). Because sampling was limited, further investigations are required to state a possible impact of chemical pollution on flatfish telomeres. This is motivated by correlations observed with organochlorinated compounds when decreasing statistical significance (p ≤ 0.10).

This study aimed to assess the ecotoxicological effects of the interaction of fullerene (C60) and benzo[a]pyrene (B[a]P) on the marine mussel, Mytilus galloprovincialis. The uptake of nC60, B[a]P and mixtures of nC60 and B[a]P into tissues was confirmed by Gas Chromatography–Mass Spectrometry (GC–MS), Liquid Chromatography–High Resolution Mass Spectrometry (LC–HRMS) and Inductively Coupled Plasma Mass Spectrometer (ICP–MS). Biomarkers of DNA damage as well as proteomics analysis were applied to unravel the interactive effect of B[a]P and C60. Antagonistic responses were observed at the genotoxic and proteomic level. Differentially expressed proteins (DEPs) were only identified in the B[a]P single exposure and the B[a]P mixture exposure groups containing 1 mg/L of C60, the majority of which were downregulated (~52%). No DEPs were identified at any of the concentrations of nC60 (p < 0.05, 1% FDR). Using DEPs identified at a threshold of (p < 0.05; B[a]P and B[a]P mixture with nC60), gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis indicated that these proteins were enriched with a broad spectrum of biological processes and pathways, including those broadly associated with protein processing, cellular processes and environmental information processing. Among those significantly enriched pathways, the ribosome was consistently the top enriched term irrespective of treatment or concentration and plays an important role as the site of biological protein synthesis and translation. Our results demonstrate the complex multi-modal response to environmental stressors in M. galloprovincialis.

The impact of a microplastic (MP) mixture composed of polyethylene (PE) and polypropylene (PP) plastic particles, prepared from commercially available products, was evaluated in blue mussels Mytilus spp. exposed to three environmentally relevant concentrations: 0.008 μg L−1 (low), 10 μg L−1 (medium), and 100 μg L−1 (high). Organisms were exposed for 10 days followed by 10 days of depuration in clean seawater under controlled laboratory conditions. The evaluation of MP effects on mussel clearance rate, tissue structure, antioxidant defenses, immune and digestive parameters, and DNA integrity were investigated while the identification of plastic particles in mussel tissues (gills, digestive gland, and remaining tissues), and biodeposits (feces and pseudofaeces) was performed using infrared microscopy (μFT-IR). Results showed the presence of MPs only in the digestive gland of mussels exposed to the highest tested concentration of MPs with a mean of 0.75 particle/mussel (after the 10 days of exposure). In biodeposits, PE and PP particles were detected following exposure to all tested concentrations confirming the ingestion of MPs by the organisms. A differential response of antioxidant enzyme activities between digestive gland and gills was observed. Significant increases in superoxide dismutase (SOD) and catalase (CAT) activities were measured in the digestive gland of mussels exposed to the low (0.008 μg L−1) and medium (10 μg L−1) concentrations of MPs and in the gills from mussels exposed to the highest concentration (100 μg L−1) of MPs that could be indicative of a change in the redox balance. Moreover, an increase in acid phosphatase activity was measured in hemolymph of mussels exposed to 0.008 and 10 μg L−1 concentrations. No significant difference was observed in the clearance rate, and histopathological parameters between control and exposed mussels. This study brings new insights on the potential sublethal impacts of MPs at environmentally relevant concentrat

8-oxodeoxyguanosine (8-oxodG), a major oxidised base modification, has been investigated to study its impact on DNA replication in hyperthermophilic Archaea. Here we show that 8-oxodG is formed in the genome of growing cells, with elevated levels following exposure to oxidative stress. Functional characterisation of cell-free extracts and the DNA polymerisation enzymes, PolB, PolD, and the p41/p46 complex, alone or in the presence of accessory factors (PCNA and RPA) indicates that translesion synthesis occurs under replicative conditions. One of the major polymerisation effects was stalling, but each of the individual proteins could insert and extend past 8-oxodG with differing efficiencies. The introduction of RPA and PCNA influenced PolB and PolD in similar ways, yet provided a cumulative enhancement to the polymerisation performance of p41/p46. Overall, 8-oxodG translesion synthesis was seen to be potentially mutagenic leading to errors that are reminiscent of dA:8-oxodG base pairing.

Environmental epigenetic is an emerging field that studies the cause-effect relationship between environmental factors and heritable trait via an alteration in epigenetic marks. This field has received much attentions since the impact of environmental factors on different epigenetic marks have been shown to be associated with a broad range of phenotypic disorders in natural ecosystems. Chemical pollutants have been shown to affect immediate epigenetic information carriers of several aquatic species but the heritability of the chromatin marks and the consequences for long term adaptation remain open questions. In this work, we investigated the impact of the diuron herbicide on the DNA methylation pattern of spat from exposed Crassotrea gigas genitors. This oyster is one of the most important mollusk species produced worldwide and a key coastal economic resource in France. The whole genome bisulfite sequencing (WGBS, BS-Seq) was applied to obtain a methylome at single nucleotide resolution on DNA extracted from spat issued from diuron exposed genitors comparatively to control spat. We showed that the parental diuron exposure has an impact on the DNA methylation pattern of its progeny. Most of the differentially methylated regions occurred within coding sequences and we showed that this change in methylation level correlates with RNA level only in a very small group of genes. Although the DNA methylation profile is variable between individuals, we showed conserved DNA methylation patterns in response to parental diuron exposure. This relevant result opens perspectives for the setting of new markers based on epimutations as early indicators of marine pollutions.

Polycyclic aromatic hydrocarbons (PAH) are environmental contaminants that pose significant risk to health of fish. The International Workshop on Integrated Assessment of Contaminant Impacts on the North Sea (ICON) provided the framework to investigate biomarker responses as well as contaminant concentrations side by side in marine ecosystems. Concentrations of the main PAH metabolites 1-hydroxypyrene, 1-hydroxyphenanthren and 3-hydroxybenzo(a)pyrene were determined in bile by HPLC with fluorescence detection. Fish species under investigation were dab (Limanda limanda), flounder (Platichthys flesus) and haddock (Melanogrammus aeglefinus). A contamination gradient was demonstrated from the low contaminated waters of Iceland and off-shore regions of the North Sea towards higher concentrations in coastal areas. Concentrations of PAH metabolites differed primarily according to sampling region and secondarily to species.

The Pacific oyster Crassostrea gigas is the main oyster species produced in the world, and a key coastal economic resource in France. High mortalities affect Pacific oysters since 2008 in France and Europe. Their origins have been attributed to a combination of biotic and abiotic factors, underlining the importance of environment quality. The impact of water pollution has been pointed out and one of the pollutants, the genotoxic herbicide diuron, occurs at high concentrations all along the French coasts. Previous work has revealed that a parental exposure to diuron had a strong impact on hatching rates and offspring development even if spats were not exposed to diuron themselves. In this study, we explored for the first time the transcriptional changes occurring in oyster spats (non exposed) originating from genitors exposed to an environmentally relevant concentration of diuron during gametogenesis using the RNAseq methodology. We identified a transcriptomic remodeling revealing an effect of the herbicide. Different molecular pathways involved in energy production, translation and cell proliferation are particularly disturbed. This analysis revealed modulated candidate genes putatively involved in response to oxidative stress and mitochondrial damage in offspring of genitors exposed to diuron. Complementary measures of the activity of enzymes involved in these latter processes corroborate the results obtained at the transcriptomic level. In addition, our results suggested an increase in energy production and mitotic activity in 5-month-spats from diuron-exposed genitors. These results could correspond to a "catch-up growth" phenomenon allowing the spats from diuron-exposed genitors, which displayed a growth delay at 3 months, to gain a normal size when they reach the age of 6 months. These results indicate that exposure to a concentration of diuron that is frequently encountered in the field during the oyster’s gametogenesis stage can impact the next generation and

Genitors of the Pacific oyster Crassostrea gigas were submitted during gametogenesis to a short pulse exposure to the herbicide diuron at a realistic environmental concentration. Histological analysis showed no effect of diuron on gametogenesis course, sex ratio and reproductive effort. A non-significant increase in testosterone and progesterone levels was observed in genitors exposed to the herbicide. At cell level, diuron exposure was shown to modulate the phagocytic activity of circulating hemocytes. The results of a transcriptional analysis showed that diuron affected the expression of genes belonging to functions known to play a major role during oyster gametogenesis such as gene transcription regulation, DNA replication and repair, DNA methylation and cytokinesis. Taking into account the results we previously obtained on the same genitors, this study showed a negative effect of diuron on oyster reproduction by inducing both structural and functional modifications of the DNA.