Aurore Zalouk-Vergnoux

A marine mesocosm study on the environmental fate of silver nanoparticles and toxicity effects on two endobenthic species: The ragworm Hediste diversicolor and the bivalve mollusc Scrobicularia plana

Silver nanoparticles are widely used in a range of products and processes for their antibacterial properties, electrical and thermal conductivity. The fate and effects of Ag nanoparticles were examined in two endobenthic species (Scrobicularia plana, Hediste diversicolor), under environmentally realistic conditions in outdoor mesocosms exposed to Ag at 10 μg L(-1) in nanoparticulate (Ag NPs) or soluble salt (AgNO3) forms for 21 days. Labile Ag was determined in water and sediment by using diffusive gradient in thin films. Ag levels were equivalent in contaminated Ag NPs mesocosms to those contaminated with the soluble form. Bioaccumulation of Ag was observed for both species exposed to either Ag in the nanoparticulate or ionic forms. Concerning biomarker responses, both soluble and nanoparticulate Ag forms, induced defenses against oxidative stress, detoxification, apoptosis, genotoxicity and immunomodulation. Nevertheless, DNA damages measured by the comet assay in the digestive gland of S. plana, and Phenoloxidase and lysozyme activities in S. plana and H. diversicolor, respectively, were higher in the presence of Ag NPs compared to soluble Ag suggesting a specific nano effect.

Is there any consistency between the microplastics found in the field and those used in laboratory experiments

The ubiquitous presence and persistency of microplastics (MPs) in aquatic environments are of particular concern since they represent an increasing threat to marine organisms and ecosystems. Great differences of concentrations and/or quantities in field samples have been observed depending on geographical location around the world. The main types reported have been polyethylene, polypropylene, and polystyrene. The presence of MPs in marine wildlife has been shown in many studies focusing on ingestion and accumulation in different tissues, whereas studies of the biological effects of MPs in the field are scarce. If the nature and abundance/concentrations of MPs have not been systematically determined in field samples, this is due to the fact that the identification of MPs from environmental samples requires mastery and execution of several steps and techniques. For this reason and due to differences in sampling techniques and sample preparation, it remains difficult to compare the published studies. Most laboratory experiments have been performed with MP concentrations of a higher order of magnitude than those found in the field. Consequently, the ingestion and associated effects observed in exposed organisms have corresponded to great contaminant stress, which does not mimic the natural environment. Medium contaminations are produced with only one type of polymer of a precise sizes and homogenous shape whereas the MPs present in the field are known to be a mix of many types, sizes and shapes of plastic. Moreover, MPs originating in marine environments can be colonized by organisms and constitute the sorption support for many organic compounds present in environment that are not easily reproducible in laboratory. Determination of the mechanical and chemical effects of MPs on organisms is still a challenging area of research. Among the potential chemical effects it is necessary to differentiate those related to polymer properties from those due to the sorption/desorption of organic compounds.

Fate and effects of metal-based nanoparticles in two marine invertebrates, the bivalve mollusc Scrobicularia plana and the annelid polychaete Hediste diversicolor

The objective of this paper is to synthesize results from seven published research papers employing different experimental approaches to evaluate the fate of metal-based nanoparticles (Ag NPs, Au NPs, CuO NPs, CdS NPs, ZnO NPs) in the marine environment and their effects on two marine endobenthic species, the bivalve Scrobicularia plana and the ragworm Hediste diversicolor. The experiments were carried out under laboratory (microcosms) conditions or under environmentally realistic conditions in outdoor mesocosms. Based on results from these seven papers, we addressed the following research questions: (1) How did the environment into which nanoparticles were released affect their physicochemical properties?, (2) How did the route of exposure (seawater, food, sediment) influence bioaccumulation and effects?, (3) Which biomarkers were the most responsive? and (4) Which tools were the most efficient to evaluate the fate and effects of NPs in the marine environment? The obtained results showed that metal‐based NPs in general were highly agglomerated/aggregated in seawater. DGT tools could be used to estimate the bioavailability of metals released from NPs under soluble form in the aquatic environment. Both metal forms (nanoparticulate, soluble) were generally bioaccumulated in both species. Among biochemical tools, GST and CAT were the most sensitive revealing the enhancement of anti-oxidant defenses in both species exposed to sub-lethal concentrations of metal-based NPs. Apoptosis and genotoxicity were frequently observed.

Dioxin-like, non-dioxin like PCB and PCDD/F contamination in European eel (Anguilla anguilla) from the Loire estuarine continuum: spatial and biological variabilities

To characterize the eel contamination by dioxin-like (dl) and non dioxin-like (ndl) polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), sixty-two eels from the Loire estuary (France) were analyzed. PCB contamination significantly increased from glass eel stage (3.71 ± 1.85 and 15.2 ± 4.2 ng g(-1) dw) to other life stages (for yellow eels: 62.8 ± 34.4 and 382 ± 182 ng g(-1) dw; for silver eels: 93.7 ± 56.3 and 463 ± 245 ng g(-1) dw respectively for dl and ndl-PCBs). An inter-site variability based on PCB levels and profiles was observed among the three studied sites. For glass eels, the profile was mainly characterized by less chlorinated PCBs contrary to the other eels, displaying a different bioaccumulation pathway. Overall, the contamination level in the eels from this estuary was shown to be low for PCDD/Fs and intermediate for dl and ndl-PCBs, compared to other international/national areas. However, more than 60% of the studied silver eels displayed higher values for PCDD/F and dl-PCB WHO2005 TEQ than the EU permissible level of 10 pg g(-1) ww. This statement suggests a potential exposure to PCBs through eel consumption, especially with silver eels, and also points out apparent contamination that could eventually affect the reproductive success of the species.

Occurrence of POPs and other persistent organic contaminants in the European eel (Anguilla anguilla) from the Loire estuary, France

The chemical contamination of the Loire estuary by three classes of persistent organic pollutants (POPs): the polychlorinated biphenyls (PCBs), the polybrominated diphenyl ethers (PBDEs) and the perfluorinated and polyfluorinated alkyl substances (PFAS), and three families of organic contaminants, the alkylphenols (APs), the polycyclic aromatic hydrocarbon metabolites (OH-PAHs) and the bisphenol A (BPA) were investigated in the muscles and bile of European eel (Anguilla anguilla). Yellow eels (n=30) were caught in three different points along the estuary to highlight variations between sites and sources of contaminations. Silver eels (n=15) were also studied to compare contaminant impregnation between different life stages of the species. Average concentrations in the muscles of the eel ranged between: 857 and 4358 ng/gLW for the PCBs, 26 and 46 ng/gLW for the PBDEs, 130 and 1293 ng/gLW for the PFAS; and in bile: 31 and 286 μg/g protein for the APs, 9 and 26 μg/g protein for the OH-PAHs and ND-1213 μg/g protein for the BPA. Among PCBs, PCB 153 (40% contribution to the sum of PCBs) was predominant in all eel muscles. PBDE 47 (60%) was the most predominant PBDE congeners, while perfluorooctanesulfonic acid (85%) was the most widely detected PFAS. For APs, 4p-nonylphenol (91%) was the most abundant and for the OH-PAHs, it was 1OH-Pyrene (63%). All the eels exceeded the environmental quality standards (EQS) for biota for the PBDEs and about 75% were higher than the EQS specific to PFOS. Finally, 20% of the analyzed eels presented TEQ concentrations above the maximum limits for lipid-rich species. These results supplied new data on the occurrence, levels, and patterns of 53 organic chemicals in the eels from the Loire estuary and they highlighted the need of further investigations focused notably on the potential effects of these chemicals on this species and their analysis in the water and sediments of the estuary.

Unprecedented 17-Residue Peptaibiotics Produced by Marine-Derived Trichoderma atroviride

In the course of investigations on marine‐derived toxigenic fungi, five strains of Trichoderma atroviride were studied for their production of peptaibiotics. While these five strains were found to produce classical 19‐residue peptaibols, three of them exhibited unusual peptidic sodium‐adduct [M + 2 Na]2+ ion peaks at m/z between 824 and 854. The sequencing of these peptides led to two series of unprecedented 17‐residue peptaibiotics based on the model Ac‐XXX‐Ala‐Ala‐XXX‐XXX‐Gln‐Aib‐Aib‐Aib‐Ala/Ser‐Lxx‐Aib‐Pro‐XXX‐Aib‐Lxx‐[C129]. The C‐terminus of these new peptides was common to all of them, and its elemental formula C5H9N2O2 was established by HR‐MS. It could correspond to the cyclized form of Nδ‐hydroxyornithine which has already been observed at the C‐terminus of various peptidic siderophores. The comparison of the sequences of 17‐ and 19‐residue peptides showed similarities for positions 1–16. This observation seems to indicate a common biosynthesis pathway. Both new 17‐residue peptaibiotics and 19‐residue peptaibols exhibited weak in vitro cytotoxicities against KB cells.

Cadmium sulfide quantum dots induce oxidative stress and behavioral impairments in the marine clam Scrobicularia plana

Cadmium sulfide (CdS) quantum dots have a number of current applications in electronics and solar cells and significant future potential in medicine. The aim of the present study was to examine the toxic effects of CdS quantum dots on the marine clam Scrobicularia plana exposed for 14 d to these nanomaterials (10 µg Cd L(-1) ) in natural seawater and to compare them with soluble Cd. Measurement of labile Cd released from CdS quantum dots showed that 52% of CdS quantum dots remained in the nanoparticulate form. Clams accumulated the same levels of Cd regardless of the form in which it was delivered (soluble Cd vs CdS quantum dots). However, significant changes in biochemical responses were observed in clams exposed to CdS quantum dots compared with soluble Cd. Increased activities of catalase and glutathione-S-transferase were significantly higher in clams exposed in seawater to Cd as the nanoparticulate versus the soluble form, suggesting a specific nano effect. The behavior of S. plana in sediment showed impairments of foot movements only in the case of exposure to CdS quantum dots. The results show that oxidative stress and behavior biomarkers are sensitive predictors of CdS quantum dots toxicity in S. plana. Such responses, appearing well before changes might occur at the population level, demonstrate the usefulness of this model species and type of biomarker in the assessment of nanoparticle contamination in estuarine ecosystems.

The influence of salinity on the fate and behavior of silver standardized nanomaterial and toxicity effects in the estuarine bivalve Scrobicularia plana

Because of their antibacterial properties, silver (Ag) engineered nanomaterials are included in many products. The present study used a standardized Ag nanomaterial (NM-300K, 20 nm) supplied with a stabilizing agent. The aim was to investigate the behavior of Ag nanomaterial in an estuarine-like medium at 2 salinities (15 psu and 30 psu). Uptake as well as sublethal effects of Ag nanomaterial (10 μg Ag/L), its stabilizing agent, and AgNO3 (10 μg Ag/L) were assessed in the clam Scrobicularia plana, after 7 d of exposure. The release of soluble Ag from Ag nanomaterial in the experimental media was quantified by using diffusive gradient in thin films and ultrafiltration. A multibiomarker approach was employed to reveal responses of clams at subindividual and individual levels. The bioaccumulation of Ag was significantly greater at 15 psu versus 30 psu, which could be explained by differences in Ag speciation. In conclusion, the present study showed different impacts of Ag nanomaterial that were not always explained by the release of Ag ions in clams at both salinities; such impacts were particularly characterized by induction of oxidative stress, cell damage, and impairment of energetic levels. Burrowing of clams was affected by the stabilizing agent depending on the salinity tested, with stronger effects at 15 psu. Finally, the present study highlighted salinity-dependent changes in the physiology of estuarine bivalves. Environ Toxicol Chem 2016;35:2550-2561.

Factors influencing the microplastic contamination of bivalves from the French Atlantic coast: Location, season and/or mode of life?

Monitoring the presence of microplastics (MP) in marine organisms is currently of high importance. This paper presents the qualitative and quantitative MP contamination of two bivalves from the French Atlantic coasts: the blue mussel (Mytilus edulis) and the Pacific oyster (Crassostrea gigas). Three factors potentially influencing the contamination were investigated by collecting at different sampling sites and different seasons, organisms both wild and cultivated. Inter- and intra-species comparisons were also achieved. MP quantity in organisms was evaluated at 0.61±0.56 and 2.1±1.7MP per individual respectively for mussels and oysters. Eight different polymers were identified. Most of the MPs were fragments; about a half of MPs were grey colored and a half with a size ranging from 50 to 100μm for both studied species. Some inter-specific differences were found but no evidence for sampling site, season or mode of life effect was highlighted.

Neurodevelopmental and behavioral effects of nonylphenol exposure during gestational and breastfeeding period on F1 rats

Nonylphenols (NP) are endocrine-disruptors known to be widely present in our environment. This study evaluated the effects of 4-n-NP on neurobehavioral development and memory capacity after perinatal exposure on the offspring rats. Dams were gavaged with 4-n-NP (0, 50 and 200mg/kg/day) from gestational day 5 to postnatal day (PND) 21. Dams exposed to the higher dose lost weight during gestation and had a longer gestational duration. Juvenile female pups of the 200mg 4-n-NP/kg/day group were lighter. Their thyroid somatic index (TSI) was also affected. For male pups, a decrease of TSI at weaning for the 200mg 4-n-NP/kg/day group and an increase of GSI for the 50mg 4-n-NP/kg/day group were observed. Physical maturation (incisives and eyes) were likewise affected. In open field (OF) tests, females were more active than males. In the first OF (PND 36), a treatment effect was observed only for males, particularly for the high dose group, which became as active as females. The second OF (PND 71) showed few differences between groups (treated vs control), the gender difference whatever the dose was not abolished. In the Morris Water Maze test, the study of the first 30s showed that females (200mg/kg/day) were mainly affected. Their performances were improved by 4-n-NP. These effects were particularly important for the first short-term memory test and observed to a lesser extent in the second evaluation of the long-term memory (PND 69). These data showed that perinatal 4-n-NP exposure induced behavioral and neuro-developmental impairments from 50mg/kg/day.