Bioaccumulation and biochemical responses in the peppery furrow shell Scrobicularia plana exposed to a pharmaceutical cocktail at sub-lethal concentrations.

Pharmaceutical drugs in the aquatic medium may pose significant risk to non-target organisms. In this study, the potential toxicity of a mixture of three compounds commonly detected in marine waters (ibuprofen, ciprofloxacin and flumequine) was assessed, by studying bioaccumulation, oxidative stress and neurotoxicity parameters (catalase CAT, superoxide dismutase SOD, glutathione reductase GR, glutathione S-transferase GST, lipid peroxidation LPO, glutathione peroxidase GPX, metallothionein MT and acetylcholinesterase AChE) in the clam Scrobicularia plana. Temporal evolution of selected endpoints was evaluated throughout an exposure period (1, 7 and 21 days) followed by a depuration phase. The accumulation of all drugs was fast, however clams showed the ability to control the internal content of drugs, keeping their concentration constant throughout the exposure and reducing their content after 7 days of depuration. The induction of biochemical alterations (SOD, CAT, LPO, MT, AChE) was observed in gills and digestive gland probably related to an imbalance in the redox state of clams as a consequence of the exposure to the drug mixture. These alterations were also maintained at the end of the depuration week when the high levels of SOD, CAT, GST and LPO indicated the persistence of oxidative stress and damage to lipids despite the fact that clams were no longer exposed to the mixture.

Assessment of pharmaceutical mixture (ibuprofen, ciprofloxacin and flumequine) effects to the crayfish Procambarus clarkii: A multilevel analysis (biochemical, transcriptional and proteomic approaches).

The knowledge about the effects of pharmaceuticals on aquatic organisms has been increasing in the last decade. However, due to the variety of compounds presents in the aquatic medium, exposure scenarios and exposed organisms, there are still many gaps in the knowledge on how mixtures of such bioactive compounds affect exposed non target organisms. The crayfish Procambarus clarkii was used to analyze the toxicity effects of mixtures of ciprofloxacin, flumequine and ibuprofen at low and high concentrations (10 and 100 µg/L) over 21 days of exposure and to assess the recovery capacity of the organism after a depuration phase following exposure during additional 7 days in clean water. The crayfish accumulated the three compounds throughout the entire exposure in the hepatopancreas. The exposure to the mixture altered the abundance of proteins associated with different cells functions such as biotransformation and detoxification processes (i.e. catalase and glutathione transferase), carbohydrate metabolism and immune responses. Additionally changes in expression of genes encoding antioxidant enzymes and in activity of the corresponding enzymes (i.e. superoxide dismutase, glutathione peroxidase and glutathione transferase) were reported. Alterations at different levels of biological organization did not run in parallel under all circumstances and can be related to changes in the redox status of the target tissue. No differences were observed between control and exposed organisms for most of selected endpoints after a week of depuration, indicating that exposure to the drug mixture did not produce permanent damage in the hepatopancreas of P. clarkii.

Combination of HPLC with organic and inorganic mass spectrometry to study the metabolic response of the clam Scrobicularia plana to arsenic exposure.

Arsenic is a toxic element extensively studied in the marine environment due to differential toxicological effects of inorganic and organic species. In the present work, the bivalve Scrobicularia plana was exposed to AsV (10 and 100 µg/L) for 14 days to evaluate the metabolic perturbations caused by this element. Arsenic speciation and metabolomic analysis were performed in the digestive gland of the bivalve using two complementary analytical platforms based on inorganic and organic mass spectrometry. It has been observed the greater presence of the innocuous specie arsenobetaine produced in this organism as defense mechanism against arsenic toxicity, although significant concentrations of methylated and inorganic arsenic were also present, depending on the level of arsenic in aqueous media. Complementarily, a metabolomic study based on mass spectrometry and statistical discriminant analysis allows a good classification of samples associated to low and high As(V) exposure in relation to controls. About 15 metabolites suffer significant changes of expression by the presence of As(V): amino acids, nucleotides, energy-related metabolites, free fatty acids, phospholipids and triacylglycerides, which can be related to membrane structural and functional damage. In addition, perturbation of the methylation cycle, associated with the increase of homocysteine and methionine was observed, which enhance the methylation of toxic inorganic arsenic to less toxic dimethylarsenic.

Assessing lead toxicity in the clam Ruditapes philippinarum: Bioaccumulation and biochemical responses.

Lead (Pb) is a non-essential metal. Its occurrence in the environment is related principally to anthropogenic contamination. Pb is toxic to aquatic organisms and can provoke damage to membranes and inhibit the activity of essential enzymes. The filter-feeding, Manila clam Ruditapes philippinarum is widely used as a biomonitor organism to assess metal toxicity. Among biomarkers related to the Pb toxicity, the enzymatic activity of δ-aminolevulinic acid dehydratase (δ-ALAD) has been adopted as a specific tool. Metallothionein (MT), lipid peroxidation (LPO) and antioxidant enzymes activities, such as catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione S-transferase (GST) and superoxidase dismutase (SOD) have also been employed to assess the toxic effect of metals. Two target tissues, the gills and the digestive gland, were selected to examine biomarker responses. In order to assess the effects of Pb accumulation and the mechanisms involved in the recovery from it, clams were exposed at two Pb levels (10 and 100 µg/L) for 7 days and were later maintained in clean water for 7 days as a depuration period. Pb accumulation was dependent on the exposure concentration and higher Pb levels were observed in the gills compared to the digestive gland. Inhibition of δ-ALAD, GST and SOD and the induction of MT and LPO over the exposure period were observed in the gills and the digestive gland of R. philippinarum. The depuration period showed a continuous inhibition of the δ-ALAD activity and induction of MT and LPO in both tissues. These results demonstrate that lead induced an exposure effect and the 7 days of depuration were not sufficient to recover the basal health status of the clams.

ROI-scavenging enzyme activities as toxicity biomarkers in three species of marine microalgae exposed to model contaminants (copper, Irgarol and atrazine).

There is a need to develop efficient tools to prevent damage to marine ecosystems due to pollution. Since microalgae play a key role in marine ecosystems, they are considered potentially useful for quick and sensitive toxicity bioassays. In this study an integrative analysis has been carried out of the anti-oxidant enzyme activities of marine microalgae species. Three marine microalgae species (Cylindrotheca closterium, a benthic diatom; Phaeodactylum tricornutum, a diatom which has been used as model organism in toxicity bioassays; and Rhodomonas salina, a cryptophyceae which is considered to present a certain level of heterotrophy) were exposed to selected concentrations of three model pollutants: copper (5 and 10µg L(-1)), atrazine (25 and 50µg L(-1)) and Irgarol (0.5 and 1.0µg L(-1)). These pollutant concentrations are environmentally relevant for coastal ecosystems, and have been selected for checking the efficiency of the reactive oxygen intermediate (ROI) scavenging enzyme system of these organisms. Superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APx) and glutathione peroxidase (GPx) activities were measured at the end of 24h exposure. The integrated biomarker response (IBR) index - in our case for oxidative stress - has been employed to evaluate the ROI-scavenging enzyme system for each species and each treatment. In general, the SOD and CAT enzyme activities measured were higher in exposed populations than in controls, whereas APx and GPx activities showed the opposite trend. These microalgae showed significant responses of oxidative stress biomarkers at environmentally relevant concentrations for the assayed pollutants and short exposure periods, conditions that most other model organisms cannot match. Therefore microalgae present clear advantages over other species for their prospective employment in an "early warning system".

Accumulation, biochemical responses and changes in the redox proteome promoted by Ag and Cd in the burrowing bivalve Scrobicularia plana.

Silver (Ag) and cadmium (Cd) are non-essential metals that, as a result of natural processes and human activities, reach the aquatic environment where they interact with biota inducing potential toxic effects. To determine the biological effects of these metals on the endobenthic bivalve Scrobicularia plana, specimens were exposed to Ag and Cd at two concentrations, 5 and 50 µg∙L-1, for 7 days in a controlled microcosm system. The levels of the metals were measured in the seawater, sediments and clam tissues. The possible toxic biological effects of Ag and Cd were studied using a battery of biochemical biomarkers that are responsive to oxidative stress: superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione-S-transferase (GST) activities, and metallothioneins (MTs) and lipid peroxidation (LPO) levels. Since both metals have been linked to oxidative stress, redox modifications to proteins were studied by differential isotopic labelling of the oxidised and reduced forms of cysteines (Cys). An accumulation of metals was observed in the digestive gland and gills following exposure, together with the activation of enzyme activities (SOD for the Cd exposure; SOD, CAT, GST, and GR for the Ag exposure). The MT and LPO levels (after individual exposure to Ag and Cd) increased, which suggests the existence of antioxidant and detoxification processes to mitigate the toxic oxidative effects of both metals. The redox proteomic analysis identified 771 Cys-containing peptides (out of 514 proteins), of which 195 and 226 changed after exposure to Ag and Cd, respectively. Bioinformatics analysis showed that exposure to metal affects relevant functional pathways and biological processes in S. plana, such as: "cellular respiration" (Ag), "metabolism of amino acids" and "synthesis and degradation of proteins" (Ag and Cd), "carbohydrate metabolism" and "oxidative stress" (Cd). The proteomic approach implemented here is a powerful complement to conventional biochemical biomarkers, since it evaluates changes at the protein level in a high-throughput unbiased manner, thus providing a general appraisal of the biological responses altered by exposure to the contaminants.

Ions and nanoparticles of Ag and/or Cd metals in a model aquatic microcosm: Effects on the abundance, diversity and functionality of the sediment bacteriome.

Metals can be adsorbed on particulate matter, settle in sediments and cause alterations in aquatic environments. This study assesses the effect of Ag and/or Cd, both in ionic and nanoparticle (NP) forms, on the microbiome of sediments. For that purpose, aquatic controlled-microcosm experiments were exposed to an environmentally relevant and at tenfold higher doses of each form of the metals. Changes in the bacteriome were inferred by 16S rDNA sequencing. Ionic Ag caused a significant decrease of several bacterial families, whereas the effect was opposite when mixed with Cd, e.g., Desulfuromonadaceae family; in both cases, the bacteriome functionalities were greatly affected, particularly the nitrogen and sulfur metabolism. Compared to ionic forms, metallic NPs produced hardly any change in the abundance of microbial families, although the α-biodiversity of the bacteriome was reduced, and the functionality altered, when exposed to the NPs´ mixture. Our goal is to understand how metals, in different forms and combinations, released into the environment may endanger the health of aquatic ecosystems. This work may help to understand how aquatic metal pollution alters the structure and functionality of the microbiome and biogeochemical cycles, and how these changes can be addressed.

How and when service beneficiaries' gratitude enriches employees' daily lives.

Conventional research on gratitude has focused on the benefits of expressing or experiencing gratitude for the individual. However, recent theory and research have highlighted that there may too be benefits associated with receiving others' gratitude. Grounded in the Work-Home Resources model, we develop a conceptual model to understand whether, how, and for whom service providers (i.e., healthcare professionals) benefit from receiving service beneficiaries' (i.e., patients) gratitude in their daily work. We hypothesize that perceived gratitude from service beneficiaries enhances service providers' relational energy at work, which spills over to benefit their family lives later in the day. In addition, we hypothesize that the effect of gratitude on relational energy and its subsequent spillover effect to the family are contingent on employees' occupational identity. Two experience sampling studies with data collected from healthcare professionals and their spouses for two consecutive weeks (each) provided support for our hypothesized model. We conclude by discussing the theoretical and practical implications of our work. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Are habitable clean areas in heterogeneously contaminated landscapes functioning as escape zones for fish populations to alleviate stress?

Environmental contamination is a problem that reduces the quality of ecosystems and may make them unsuitable to accommodate life. As many ecosystems are connected, some organisms avoid the stress from continuous exposure to contaminants by moving towards less disturbed areas. However, the landscapes in which organisms move might vary regarding the concentrations of contaminants, in the form of gradients or patches of contamination. Therefore, although it is expected that organisms prefer clean areas, their sporadic contact with contamination should not be ignored, as the greater the probability of being in contact with contaminated areas, the higher the stress. The aim of this study was to assess how the stress (cortisol levels) of zebrafish (Danio rerio) varies as a consequence of heterogeneity in the chemical composition of the habitats and the presence of uncontaminated areas in this heterogeneous landscape. Zebrafish were exposed to heterogeneous contamination scenarios containing different concentrations of copper along a free-choice multi-compartmented system, in which they were able to flee from the most contaminated areas. Fish escaped from the most contaminated areas with an avoidance by 50% of population (AC50) at concentrations of 41 (copper gradient scenario), 25 (spatially limited contamination scenario) and 69 (highly contaminated scenario) µg/L. Higher cortisol levels were observed in the populations exposed to homogeneously contaminated and highly contaminated (by copper) scenarios (both with no acceptable clean area to flee to). In summary, the uncontaminated areas might be crucial for the spatial dynamics of fish populations in a chemically heterogeneous landscape due to their role as escape zones to alleviate stress.

Single and joint effects of cadmium and selenium on bioaccumulation, oxidative stress and metabolomic responses in the clam Scrobicularia plana.

Selenium (Se) is a vital trace element for many living organisms inclusive of aquatic species. Although the antagonistic action of this element against other pollutants has been previously described for mammals and birds, limited information on the join effects in bivalves is available. To this end, bivalves of the species Scrobicularia plana were exposed to Se and Cd individually and jointly. Digestive glands were analysed to determine dose-dependent effects, the potential influence of Se on Cd bioaccumulationas well as the possible recover of the oxidative stress and metabolic alterations induced by Cd. Selenium co-exposure decreased the accumulation of Cd at low concentrations. Cd exposure significantly altered the metabolome of clams such as aminoacyltRNA biosynthesis, glycerophospholipid and amino acid metabolism, while Se co-exposure ameliorated several altered metabolites such asLysoPC (14:0), LysoPE (20:4), LysoPE (22:6), PE (14:0/18:0), PE (20:3/18:4) andpropionyl-l-carnitine.Additionally, Se seems to be able to regulate the redox status of the digestive gland of clams preventing the induction of oxidativedamage in this organ. This study shows the potential Se antagonism against Cd toxicity in S. plana and the importance to study join effects of pollutants to understand the mechanism underlined the effects.

The antibacterials ciprofloxacin, trimethoprim and sulfadiazine modulate gene expression, biomarkers and metabolites associated with stress and growth in gilthead sea bream (Sparus aurata).

The high consumption and subsequent input of antibacterial compounds in marine ecosystems has become a worldwide problem. Their continuous presence in these ecosystems allows a direct interaction with aquatic organisms and can cause negative effects over time. The objective of the present study was to evaluate the effects of exposure to three antibacterial compounds of high consumption and presence in marine ecosystems (Ciprofloxacin CIP, Sulfadiazine SULF and Trimethoprim TRIM) on the physiology of the gilthead sea bream, Sparus aurata. Plasma parameters, enzymatic biomarkers of oxidative stress and damage and expression of genes related to stress and growth were assessed in exposed S. aurata specimens. For this purpose, sea bream specimens were exposed to individual compounds at concentrations of 5.2 ± 2.1 µg L-1 for CIP, 3.8 ± 2.7 µg L-1 for SULF and 25.7 ± 10.8 µg L-1 for TRIM during 21 days. Exposure to CIP up-regulated transcription of genes associated with the hypothalamic-pituitary-thyroid (HPT) (thyrotropin-releasing hormone, trh) and hypothalamic-pituitary-interrenal (HPI) axes (corticotropin-releasing hormone-binding protein, crhbp) in the brain, as well as altering several hepatic stress biomarkers (catalase, CAT; glutathione reductase, GR; and lipid peroxidation, LPO). Similar alterations at the hepatic level were observed after exposure to TRIM. Overall, our study indicates that S. aurata is vulnerable to environmentally relevant concentrations of CIP and TRIM and that their exposure could lead to a stress situation, altering the activity of antioxidant defense mechanisms as well as the activity of HPT and HPI axes.

Stress under the sun: Effects of exposure to low concentrations of UV-filter 4- methylbenzylidene camphor (4-MBC) in a marine bivalve filter feeder, the Manila clam Ruditapes philippinarum.

UV filters are a class of emerging contaminants with an annual estimated production of 10,000 tons worldwide that continuously enter aquatic environments. Among UV filters, 4-methylbenzylidenecamphor (4-MBC) is an organic camphor derivative used in the cosmetic industry for its ability to protect the skin against UV, specifically UV B radiation. Individuals of the Japanese clam, Ruditapes philippinarum, were exposed to 4-MBC at environmentally relevant and slightly higher concentrations (nominal: 0, 1, 10, 100 µg L-1) using a semi-static exposure system over a 7-days period followed by a 3-days depuration period (total 10 days) where no 4-MBC was added to the tanks. Assessed mortality reached up to 100 % at the highest exposure concentration and a LC50 value of 7.71 µg·L-14-MBC was derived. Environmental risk assessment carried out in a site specific environment, the Cadiz bay in the south of Spain, revealed a potential risk produced by the presence of 4-MBC. Digestive glands tissues were analysed for differential expression of genes encoding proteins involved in the stress response (SOD, MT, GST, EIF1, BCL2, TP53, CAT, 18S, GADPH, GPX, GADD45, THIO9) by RT-qPCR for relative quantification. Results showed that the presence of 4-MBC at environmentally relevant concentrations induced the expression of genes that encode for antioxidant enzymes (GST) and for proteins related to the inhibition of apoptosis (BCL2) and cellular stress (GADD), suggesting a physiological stress response.

Lead toxicity on a sentinel species subpopulation inhabiting mangroves with different status conservation.

Lead is a priority pollutant introduced in the aquatic environment by different sources commonly located in estuarine regions, such as ports, marinas and industries. Environmental agencies around the world set the maximum allowable concentration of lead in effluents, surface water and sediment, but few studies reported its accumulation and chronic toxicity in mangrove benthic invertebrates using concentrations believed to be safe. In the case of Brazilian mangrove environments, Ucides cordatus is a crab species of choice to be used in bioaccumulation studies. We have assessed biomarkers' responses (DNA strand breaks, micronucleated cells, metallothioneins, enzymatic activity of aminolevulinic acid dehydratase and neutral red retention time) and the total bioaccumulation in six tissues of U. cordatus crabs resident to mangrove areas under different conservation status during a 28-day period bioassay. We also investigated Pb subcellular partition and biomarkers' responses using a supposedly safe concentration (10 µg L-1). During the Pb exposure, the highest concentration of Pb was observed in crab gills. Crabs also showed a high ability to allocate Pb in detoxified forms. Multivariate analysis pointed out that bioaccumulation (total, active and detoxified) is linked to biomarkers. Even in supposedly safe dosage, U. cordatus triggered its defense mechanisms expressing more metallothioneins and presented relevant cyto-genotoxic damage. Our data suggest the development of biological tolerance to Pb in crabs from polluted areas. Our results provided a new insight about lead toxicity even at concentrations considered environmentally safe, which could support new strategies to manage estuarine areas considering their respective conservation status.

Assessing the effect of human pharmaceuticals (carbamazepine, diclofenac and ibuprofen) on the marine clam Ruditapes philippinarum: An integrative and multibiomarker approach.

The presence of pharmaceuticals in the aquatic ecosystem has become a topic of growing interest in recent years. In this study, the marine clam Ruditapes philippinarum was exposed during 14 days to concentrations close to those found in the environment: (15 µg L-1) of carbamazepine (CBZ), diclofenac (DCF) and ibuprofen (IBU), three pharmaceuticals widely used worldwide and commonly found within the aquatic environment. Additionally, exposure was followed by a depuration phase (7 days). A battery of biomarkers (superoxide dismutase SOD, catalase CAT, glutathione reductase GR, total glutathione peroxidase T-GPx, glutathione transferase GST, lipid peroxidation LPO, acetylcholinesterase AChE and metallothionein MT) was evaluated throughout the exposure and depuration. The Integrated Biomarker Response index was calculated with all selected biomarkers and used as a complementary tool in the evaluation of the organisms' health status. Exposure induced changes in the clams' biochemical responses that led to the hypothesis of the harmful role of the pharmaceuticals resulting in negative effects (changes in enzyme activities, LPO and MT levels, related to ROS production) particularly after short-term exposure. However, the clams showed the ability to cope with these imbalances by recovering their general oxidative status by the end of exposure.

Biochemical response of the clam Ruditapes philippinarum to silver (AgD and AgNPs) exposure and application of an integrated biomarker response approach.

Silver is a ubiquitous metal in the marine environment which can be accumulated by marine organisms. In order to assess the effect of dissolved silver (AgD) and AgNPs in R. philippinarum, the organisms were exposed to 20 µg L-1 of AgD and AgNPs (15 nm) over 7 days. Bioaccumulation of the metal and oxidative and detoxification biomarkers were studied in control and exposed clams. Ag was accumulated in gills and digestive glands. Results for biochemical biomarkers (superoxide dismutase, catalase and glutathione reductase activity, lipid peroxidation and metallothionein provoked a general increase in the integrated biomarker response index (IBR) values) indicating the induction of oxidative stress in the clams exposed to both Ag treatments. Therefore, the presence of Ag forms at the tested concentration in the aquatic medium represent a risk for R. philippinarum.

Mangrove metal pollution induces biological tolerance to Cd on a crab sentinel species subpopulation.

Metals are persistent pollutants, able to accumulate in the biota and magnify in trophic web. In the specific case of cadmium contamination, it has been the subject of considerable interest in recent years because of its biological effects and it is one of major pollutant in estuarine areas. Ucides cordatus is considered a mangrove local sentinel crab species in Brazil and there are previous studies reporting crab subpopulations living from pristine to heavily metal impacted areas in São Paulo coast (Southeastern Brazil). Taking into account the background knowledge about these subpopulations, we proposed the hypothesis that crabs from a highly polluted mangrove (Cubatão - CUB) have developed biological tolerance to cadmium compared to animals from an Environmental Protected Area (Jureia - JUR). Aiming to verify this hypothesis, we have investigated total bioaccumulation and subcellular partition of Cd, besides biomarkers' responses during a long-term exposure bioassay (28 days, with weekly sampling) using a supposedly safe Cd concentration (0.0022 mg L-1). Specimens from the pristine area (JUR) accumulated higher total Cd, as such as in its biologically active form in gills. Animals living in the polluted site (CUB) presented higher amounts of Cd in the mainly detoxifying tissue (hepatopancreas), which could be considered a pathway leading to tolerance for this metal. Multivariate analysis indicated that bioaccumulation (active, detoxified and total Cd) is linked to geno-cytotoxic damages. CUB subpopulation was considered more tolerant since it presented proportionally less damage and more capacity to allocate Cd in the main detoxifying forms and tissues.

Evaluation of acute effects of four pharmaceuticals and their mixtures on the copepod Tisbe battagliai.

The individual and combined toxicities of acetaminophen, carbamazepine, diclofenac and ibuprofen have been examined in neonate nauplii (<24 h-old) of the harpacticoid copepod Tisbe battagliai. Based on acute toxicity data (LC50) obtained, diclofenac was the most toxic compound with an LC50 value of 9.5 mg·L(-1); this is between 5 and 7 times lower than the LC50 value for acetaminophen, carbamazepine and ibuprofen (67.8 mg·L(-1), 59 mg·L(-1) and 49.7 mg·L(-1) respectively). The environmental risk posed by the selected pharmaceuticals was assessed by calculating risk quotients (RQs) based on MEC (the highest exposure concentration of the compound in the medium)/PNEC (predicted no effect concentration) ratios. Results suggest that, at environmental concentrations, none of the compounds is harmful for the aquatic environment (low or no risk). Toxicity data obtained for mixtures were compared with predictions derived from three different models: Concentration Addition (CA), Independent Action (IA) and Combination Index (CI). The classical modeling approaches CA and IA failed to predict the observed mixture toxicity, thus indicating that single compound toxicity data are not sufficient to predict toxicity of drug mixtures on Tisbe species. However, the use of the CI seems to provide better predictions of pharmaceutical toxicity.

Toxic effects of cisplatin cytostatic drug in mussel Mytilus galloprovincialis.

Antineoplastic drugs used in chemotherapy were detected in aquatic environment: despite the very low concentrations (ng L(-1) to ug L(-1)), due to their potent mechanism of action they could have adverse effects on non-target aquatic organisms particularly under chronic exposure. Cisplatin (CDDP) is one of the most effective anticancer drug currently in use but information on its ecotoxicological effects is very limited. In this study, Mytilus galloprovincialis was used to investigate the toxic effects related to CDDP exposure. Mussels were exposed to cisplatin (100 ng L(-1)) for 14 days: antioxidant (superoxide dismutase, catalase, total and selenium-dependent glutathione peroxidase) and phase II (glutathione-S-transferase) enzymes activities, oxidative damage (lipid peroxidation), genotoxicity (DNA damage) and neurotoxicity (acetylcholinesterase) was evaluated. Results indicate that CDDP at tested concentration induce changes in the antioxidant capacity, oxidative stress in target organs (digestive gland and gills) as well as DNA damage in mussel hemocytes and neurotoxicity representing a risk for non-target organisms.

Citrate gold nanoparticle exposure in the marine bivalve Ruditapes philippinarum: uptake, elimination and oxidative stress response.

Gold nanoparticles (AuNPs) are considered an important nano-sized component of the twenty-first century. Due to their unique physical and chemical properties, they are being used and developed for a wide range of promising applications in medicine, biology and chemistry. Notwithstanding their useful aspects, in recent years concern has been raised over their ability to enter cells, organelles and nuclei and provoke oxidative stress. In a laboratory-based experiment, the non-target marine bivalve Ruditapes philippinarum was used as a model organism. Uptake, elimination and molecular effects under short-term and sub-chronic exposure conditions to an environmental relevant concentration (0.75 µg L(-1)) of weakly agglomerating citrate AuNPs (∼20 nm) were studied. Our results demonstrate that at the tested concentration, the particles are readily taken up into the digestive gland > gills and can produce significant changes (p < 0.05) in oxidative stress and inflammatory response markers, as measured by phase II antioxidant enzymes and q-PCR gene expression analysis. However, the overall magnitude of responses was low, and oxidative damage was not provoked. Further, a significant elimination of Au from the digestive tract within a 7-day purification period was observed, with excretion being an important pathway. In conclusion, short-term and sub-chronic exposure to an environmental relevant concentration of citrate-stabilized AuNPs cannot be considered toxic to our model organism, while some further consideration should be given to chronic exposure effects.