Antioxidant and lipid peroxidation responses in Mytilus galloprovincialis exposed to mixtures of benzo(a)pyrene and copper

Copper oxide nanoparticles exhibit variable response against enzymatic toxicity biomarkers of Moina macrocopa

Growing toxicity of nanomaterials to aquatic organisms is a major area of concern as it is destroying the carefully evolved aquatic ecosystem and food web. Copper oxide nanoparticles (CuONPs) are among the top industrially manufactured nanomaterials having multifaceted applications in medicine, agriculture, energy, water technology, and other areas. However, reports on detailed scientific understanding behind toxic effects of CuONPs on aquatic organisms are scant. The present work reports on the interaction of CuONPs of 10 ± 05 nm with an ecologically significant aquatic species, Moina macrocopa, at morphological and enzymatic levels. CuONPs were found to be severely toxic just within 48 h of exposure as seen from the lethal value (48 h LC50) of 0.137 ± 0.002 ppm. Profiling of enzymatic toxicity biomarkers indicated variable response of CuONPs on selected enzymes of M. macrocopa at two sub-lethal concentrations (0.013 to 0.039 ppm). While the activities of acetyl cholinesterase and digestive enzymes (trypsin, amylase) were found to be significantly (p < 0.001) lowered after exposure to CuONPs, the β-galactosidase activity was completely inhibited. Among the antioxidant enzymes that were assayed, superoxide dismutase and glutathione-S-transferase activity was found to increase (p > 0.001), while that of catalase decreased (p > 0.001, < 0.05) with increase in exposure to CuONPs. An upsurge of several folds was seen in the activity of alkaline phosphatase after exposure to CuONPs as compared to the control group. CuONPs accumulated in the gut region of M. macrocopa which provided an ideal environment for CuONP to interact and alter the enzymes in M. macrocopa. This report highlights the use of enzymes as sensitive biomarker to detect toxicity of trace amount of CuONPs in a very sensitive non-target crustacean species found in water bodies.

Bioaccumulation and biological effects of hydrogenated cement particles in the marine bivalve, Mytilusgalloprovincialis

The decommissioning and normal functioning of nuclear facilities can result in the production and release of airborne particles in the environment. Aquatic biota are expected to be exposed to these particles considering that nuclear facilities are often located near water bodies. Aerosols, such as cement dust, can interact with radionuclides as well as with heavy metals, and therefore elicit not only radiological impacts but also chemical toxicity. In the present study, we aimed to determine the effects of hydrogenated cement particles (HCPs) as a first step before evaluating any radiotoxicity of tritiated cement particles in the marine mussels, Mytilus galloprovincialis. Responses at different levels of biological organisation were assessed, including clearance rate (CR), tissue specific accumulation, DNA damage and transcriptional expression of key stress related genes. Acute (5 h) and medium-term, chronic (11 d) exposures to 1000 μg L-1 HCPs showed that bioaccumulation, assessed using Cu as a proxy and determined by inductively coupled plasma mass spectrometry, was time and tissue dependent. The highest levels of Cu were found in the digestive gland (DG) after 11 d. HCP exposure caused changes in the expression of oxidative and other stress-related genes, including mt20 in DG and gst and sod in the gill after 5 h exposure, while an overexpression of hsp70 in the gill was observed after 11 d. Genotoxic effects in haemocytes were observed after 11 d of HCP exposure. Multivariate analysis indicated that oxidative stress is the most probable factor contributing to overall physiological dysfunction. Our results provide a baseline to perform further studies employing tritiated cement particles. Specifically, future work should focus on the DG since only this tissue showed significant bioaccumulation when compared to the negative control.

Temperature influence on the sensitivity of Artemia franciscana to globally used pesticides - Oxyfluorfen and copper

Climate change further the world's human population increase is a mainstream political issue, and it's critical to search for solutions to produce enough food to feed everyone. Pesticides and fertilizers have been used as an easy solution to prevent pests and increase food production. Nevertheless, their overuse has dangerous effects on the ecosystems and communities. Oxyfluorfen (Oxy) and copper (Cu) based formulations are used as pesticides and widely applied on agricultural fields for crop protection. However, they have shown negative effects on non-target species. So, this work proposes to: a)determine the lethal concentration of Oxy and Cu to the zooplankton, Artemia franciscana, at different temperatures (15 °C, 20 °C and 25 °C); b)understand the biochemical impacts of these chemicals at the different temperatures scenarios, on A. franciscana and c)evaluate the impact of the climate changes, particularly the temperature increase, on this species sensitivity to the tested pesticides. Acute and sub-lethal bioassays with Oxy and Cu were performed at different temperatures to determine the lethal concentration of each chemical and to understand the effects of the compounds at different temperatures on the biochemical profiles of A. franciscana. Results showed an increase in chemicals toxicity with the temperature, and Oxy was revealed to be more noxious to A. franciscana than Cu; at a biochemical level, significant differences were observed among temperatures, with the biggest differences between the organisms exposed to 15 °C and 25 °C. Overall, a decrease in fatty acids (FA) and sugars was observed with the increase in Cu and oxyfluorfen concentrations. Different trends were observed with temperature increase, with FA increase in the organisms exposed to Cu and the opposite was observed in the ones exposed to oxyfluorfen. Sugar content decreases in the organisms exposed to oxyfluorfen with temperature increase and showed a non-linear behaviour in the ones exposed to Control and Cu treatments.

Assessing combined effects of long-term exposure to copper and marine heatwaves on the reef-forming serpulid Ficopomatus enigmaticus through a biomarker approach

Sessile benthic organisms can be affected by global changes and local pressures, such as metal pollution, that can lead to damages at different levels of biological organization. Effects of exposure to marine heatwaves (MHWs) alone and in combination with environmentally relevant concentration of copper (Cu) were evaluated in the reef-forming tubeworm Ficopomatus enigmaticus using a multi-biomarker approach. Biomarkers of cell membrane damage, enzymatic antioxidant defences, metabolic activity, neurotoxicity, and DNA integrity were analyzed. The exposure to Cu alone did not produce any significant effect. Exposure to MHWs alone produced effects only on metabolic activity (increase of glutathione S-transferase) and energy reserves (decrease in protein content). MHWs in combination with copper was the condition that most influenced the status of cell homeostasis of exposed F. enigmaticus. The combination of MHWs plus Cu exposure induced increase of protein carbonylation and glutathione S-transferase activity, decrease in protein/carbohydrate content and carboxylesterase activity. This study on a reef-forming organism highlighted the additive effect of a climate change-related stressor to metals pollution of marine and brackish waters.

Combined effects of diesel and air exposure on oxidative stress parameters of mussels Perna perna (Mytilidae, Bivalvia)

This study aimed to assess the combined effect of hypoxia and exposure to diesel on biochemical parameters of Perna perna mussels. Mussels previously kept for 48 h in clean seawater were submitted to hypoxia for 24 h followed by reoxygenation in clean seawater for 48 h. The same procedure was done but using seawater containing 0.01 mL/L of diesel, before and after hypoxia. Antioxidant enzymes as well as levels of glutathione and lipid peroxidation were measured in gills and digestive glands. The neutral red retention time assay was also evaluated in hemocytes. Results showed that cycles of air exposure and reoxygenation caused oxidative stress and antioxidant modulation in both the gills and digestive glands. The presence of diesel in water triggered additional modulation of antioxidants under hypoxia and reoxygenation stress, apparently enhancing the capacity of mussels to avoid lipid peroxidation.

Examining the subchronic (28-day) effects of aqueous Cd-BaP co-exposure on detoxification capacity and cardiac function in adult zebrafish (Danio rerio)

The present study aimed to examine the effects of environmentally relevant concentrations of cadmium (Cd) and Benzo[a]Pyrene (BaP) in the adult zebrafish (Danio rerio). To this end, fish were exposed to either 1 or 10 μg/L Cd or 0.1 or 1 μg/L BaP in isolation, or a co-exposure containing a mixture of the two toxicants. Our results showed extensive modulation of the expression of key antioxidant genes (GPx, SOD1, catalase), detoxifying genes (MT1, MT2, CYP1A1) and a stress biomarker (HSP70) differing between control, single toxicant groups and co-exposure groups. We additionally carried out histopathological analysis of the gills, liver, and hearts of exposed animals, noting no differences in tissue necrosis or apoptosis. Finally, we carried out ultrasonographic analysis of cardiac function, noting a significant decrease of E-wave peak velocity and end diastolic volume in exposed fish. This in turn was accompanied by a decrease in stroke volume and ejection fraction, but not cardiac output in co-exposed fish. The present study is the first to demonstrate that a subchronic aqueous exposure to a Cd-BaP mixture can extensively modulate detoxification capacity and cardiac function in adult zebrafish in a tissue-specific manner.

Metabolic Regulation of Copper Toxicity during Marine Mussel Embryogenesis

The development of new tools for assessing the health of cultured shellfish larvae is crucial for aquaculture industries to develop and refine hatchery methodologies. We established a large-volume ecotoxicology/health stressor trial, exposing mussel (Perna canaliculus) embryos to copper in the presence of ethylenediaminetetraacetic acid (EDTA). GC/MS-based metabolomics was applied to identify potential biomarkers for monitoring embryonic/larval health and to characterise mechanisms of metal toxicity. Cellular viability, developmental abnormalities, larval behaviour, mortality, and a targeted analysis of proteins involved in the regulation of reactive oxygen species were simultaneously evaluated to provide a complementary framework for interpretative purposes and authenticate the metabolomics data. Trace metal analysis and speciation modelling verified EDTA as an effective copper chelator. Toxicity thresholds for P. canaliculus were low, with 10% developmental abnormalities in D-stage larvae being recorded upon exposure to 1.10 μg·L-1 bioavailable copper for 66 h. Sublethal levels of bioavailable copper (0.04 and 1.10 μg·L-1) caused coordinated fluctuations in metabolite profiles, which were dependent on development stage, treatment level, and exposure duration. Larvae appeared to successfully employ various mechanisms involving the biosynthesis of antioxidants and a restructuring of energy-related metabolism to alleviate the toxic effects of copper on cells and developing tissues. These results suggest that regulation of trace metal-induced toxicity is tightly linked with metabolism during the early ontogenic development of marine mussels. Lethal-level bioavailable copper (50.3 μg·L-1) caused severe metabolic dysregulation after 3 h of exposure, which worsened with time, substantially delayed embryonic development, induced critical oxidative damage, initiated the apoptotic pathway, and resulted in cell/organism death shortly after 18 h of exposure. Metabolite profiling is a useful approach to (1) assess the health status of marine invertebrate embryos and larvae, (2) detect early warning biomarkers for trace metal contamination, and (3) identify novel regulatory mechanisms of copper-induced toxicity.

Assessing the impact of terbium on Mytilus galloprovincialis: Metabolic and oxidative stress responses

The increasing demand for electric and electronic equipment has led to a rise in potentially hazardous electronic waste, including rare-earth elements (REEs), such as terbium (Tb), which have been already detected in aquatic systems. This study investigated the biochemical effects of anthropogenic Tb on mussels over a 28-day period. The mussels were exposed to different concentrations of Tb (0, 5, 10, 20, 40 μg/L), and biomarkers related to metabolism, oxidative stress, cellular damage, and neurotoxicity were evaluated. Bioaccumulation of Tb in the mussels' tissue increased with exposure concentrations, but the bioconcentration factor remained similar between treatments. Exposure to Tb enhanced glycogen consumption and decreased metabolic capacity which could be seen as a physiological adaptation to limit Tb accumulation. Antioxidant defenses and glutathione S-transferases showed a more complex dose-response, with enzymatic responses increasing until 10 μg/L but then returning to control levels at 20 μg/L. At 40 μg/L, enzymatic responses were also enhanced but to a lower extent than at 10 μg/L. The presence of Tb had clearly an inhibitory effect on biotransformation enzymes such as carboxylesterases in a dose-dependent manner. Likely, thanks to biochemical and physiological adaptations, no cellular damage or neurotoxicity was observed in any treatments, confirming the mussels' ability to tolerate Tb exposure. Nevertheless, prolonged exposure to these concentrations could lead to harmful consequences when facing other environmental stressors, such as misallocating energy resources for growth, reproduction, and defense mechanisms.

Ecotoxicological and biochemical effects of a binary mixture of pesticides on the marine diatom Thalassiosira weissflogii in a scenario of global warming

Under the current scenario of global warming, it is ecologically relevant to understand how increased temperature influences the combined toxicity of pesticides to aquatic species. Hence, this work aims to: a) determine the temperature effect (15 °C, 20 °C and 25 °C) on the toxicity of two pesticides (oxyfluorfen and Copper (Cu)), on the growth of Thalassiosira weissflogii; b) assess whether temperature affects the type of toxicity interaction between these chemicals; and c) assess the temperature effect on biochemical responses (fatty acids (FA) and sugar profiles) of the pesticides on T. weissflogii. Temperature increased the tolerance of the diatoms to the pesticides with EC₅₀ values between 3.176 and 9.929 μg L^-1 for oxyfluorfen and 42.50-230.75 μg L^-1 for Cu, respectively, at 15 °C and 25 °C. The mixtures toxicity was better described by the IA model, but temperature altered the type of deviation from dose ratio (15 °C and 20 °C) to antagonism (25 °C). Temperature, as well as the pesticide concentrations, affected the FA and sugar profiles. Increased temperature increased saturated FA and decreased unsaturated FA; it also affected the sugar profiles with a pronounced minimum at 20 °C. Results highlight effects on the nutritional value of these diatoms, with potential repercussion on food webs.

The Lethal and Sub-Lethal Effects of Fluorinated and Copper-Based Pesticides-A Review

In recent decades, pollution levels have increased, mainly as a result of the intensive anthropogenic activities such industrial development, intensive agricultural practices, among others. The impact of metals and organic contaminants is, nowadays, a great concern to the scientific and political communities. Copper compounds are the main sold pesticides in Europe, as well as herbicides, including glyphosate. Diphenyl ethers are the second ones most sold. Glyphosate and copper compounds are intensively studied, but the opposite is seen in the case of diphenyl ethers, including fluorinated pesticides (e.g., oxyfluorfen). Some research has been performed to increase the knowledge about these contaminants, daily inputted on the aquatic systems and with dangerous effects at physical and biochemical levels on the organisms. A wide range of biomarkers (e.g., growth, survival, reproductive success, enzymatic activity, lipid metabolism) has been applied to determine the potential effects in many species. This review intends to: (a) perform a compilation of the knowledge in previous research about the action mode of organic (fluorinated-based herbicide) and inorganic (copper-based pesticides) contaminants; (b) carry out an information survey about the lethal and sub-lethal effects of the fluorinated-based pesticides, namely the oxyfluorfen and the copper-based pesticides, on aquatic species from different trophic levels, according to in vitro and in vivo studies; (c) understand the impact of oxyfluorfen and copper-based pesticides, considering their effects reported in in vitro studies and, simultaneously, the authorized concentrations by legal organizations and the effective concentrations of each pollutant found in the environment. The literature analyzed revealed noxious effects of Cu and oxyfluorfen to aquatic organisms, including freshwater and marine species, even when exposed to the reference as well as to environmental concentrations, thus highlighting the importance of more monitoring and ecotoxicological studies, to chemical pollutants and different species from different ecological niches, to sustain and improve the legislation.

Bioplastic leachates characterization and impacts on early larval stages and adult mussel cellular, biochemical and physiological responses

Bioplastics are promoted as safer alternatives to tackle the long-term persistence of conventional plastics. However, information on the potential release of additives and non-intentionally added substances (NIAS) in the surrounding environment is limited, and biological effects of the leachates have been little studied. Leachates produced from three bioplastics, i.e. compostable bags (CB), bio-polyethylene terephthalate bottles (bioPET) and polylactic acid cups (PLA), and a control polymeric material, i.e. rubber tire (TR), were examined. The chemical nature of bioplastic polyesters PET, PLA and poly (butylene adipate-co-terephthalate) (PBAT) in CB, was confirmed by analytical pyrolysis. Fragments were incubated in artificial sea water for 14 days at 20 °C in darkness and leachate contents examined by GC-MS and HPLC-MS/MS. Catalysts and stabilizers represented the majority of chemicals in TR, while NIAS (e.g. 1,6-dioxacyclododecane-7,12-dione) were the main components of CB. Bisphenol A occurred in all leachates at a concentration range 0.3-4.8 μg/L. Trace metals at concentrations higher than control water were found in all leachates, albeit more represented in leachates from CB and TR. A dose response to 11 dilutions of leachates (in the range 0.6-100%) was tested for biological effects on early embryo stages of Mytilus galloprovincialis. Embryotoxicity was observed in the whole range of tested concentrations, the magnitude of effect depending on the polymers. The highest concentrations caused reduction of egg fertilization (CB, bioPET, TR) and of larvae motility (CB, PLA, TR). TR leachates also provoked larvae mortality in the range 10-100%. Effects on adult mussel physiology were evaluated after a 7-day in vivo exposure to the different leachates at 0.6% concentration. Nine biomarkers concerning lysosomal functionality, neurotransmission, antioxidant and immune responses were assessed. All lysosomal parameters were affected, and serum lysozyme activity inhibited. Harmonized chemical and biological approaches are recommended to assess bioplastic safety and support production of sustainable bioplastics.

Ecotoxicity of Copper(I) Chloride in Grooved Carpet Shell (Ruditapes decussatus)

Copper (Cu) is a ubiquitous trace element in the aquatic environment, and is usually found at low levels. Copper environmental concentrations can be altered as a result anthropogenic activities. Shellfish are useful bioindicators to ensure adequate environmental monitoring. Thus, the aim of the present study was as follows: (a) determine the LC50 of copper(I) chloride in grooved carpet shell (Ruditapes decussatus) collected in the Santa Gilla lagoon (Sardinia, Italy), and (b) analyze the antioxidant biomarkers in digestive gland and gills of same specimens exposed to different concentrations of the above-mentioned metal (0.045, 0.45, and 0.90 mg/L) for 96 h. A withdrawal period of 96 h was considered for the treated clam, carrying out the same biochemical analyses, superoxide dismutase (SOD), catalase (CAT), selenium-dependent glutathione peroxidase (Se-GPx), glutathione S-transferases (GSTs), and total glutathione (GSH+2GSSG) in the two tissues. Different time and dose responses of the antioxidant biomarkers were recorded in the digestive glands and gills. Oxidative stress biomarkers highlighted the ability of Cu to induce oxidative stress in R. decussatus. Clam, following the withdrawal period of 96 h, has not been able to achieve the control levels of all biochemical markers in the digestive gland and gills. R. decussatus can be a suitable model to assess the ecotoxicity of copper in aquatic ecosystems. These findings may advance knowledge on the role and the effects of copper on oxidative stress biomarkers in grooved carpet shell. The metal ecotoxicity response can be useful to perform accurate biomarker-based monitoring programs using this bivalve species.

Effects of microplastics alone and with adsorbed benzo(a)pyrene on the gills proteome of Scrobicularia plana

Microplastics (MPs) are globally present in the marine environment, but the biological effects on marine organisms at the molecular and cellular levels remain scarce. Due to their lipophilic nature, MPs can adsorb other contaminants present in the marine environment, which may increase their detrimental effects once ingested by organisms. This study investigates the effects of low-density polyethylene (PE) MPs with and without adsorbed benzo[a]pyrene (BaP) in the gills proteome of the peppery furrow shell clam, Scrobicularia plana. Clams were exposed to PE MPs (11-13 μm; 1 mg L^-1) for 14 days. BaP was analyzed in whole clams' soft tissues, and a proteomic approach was applied in the gills using SWATH/DIA analysis. Proteomic responses suggest that virgin MPs cause disturbance by altering cytoskeleton and cell structure, energy metabolism, conformational changes, oxidative stress, fatty acids, DNA binding and, neurotransmission highlighting the potential risk of this type of MPs for the clam health. Conversely, when clam gills were exposed to MPs adsorbed with BaP a higher differentiation of protein expression was observed that besides changes in cytoskeleton and cell structure, oxidative stress, energy metabolism and DNA binding also induce changes in glucose metabolism, RNA binding and apoptosis. These results indicate that the presence of both stressors (MPs and BaP) have a higher toxicological risk to the health of S. plana.

The impact of temperature on lithium toxicity in the gastropod Tritia neritea

The most important use of lithium (Li) is in rechargeable batteries. The growing use of Li, incorrect disposal of Li-based applications, and inefficient recycling strategies for their elimination will result in the release of this metal into the aquatic systems. Alongside with the impacts caused by pollutants, organisms in coastal ecosystems are also facing environmental changes as those related with climate change scenarios, namely, seawater temperature rise. In this context, the present study aimed to evaluate the influence of temperature on Li toxicity, using the Nassariid gastropod Tritia neritea as model species. Metabolism and oxidative stress related biomarkers were evaluated after a 28-day exposure period. The results demonstrated that temperature enhanced the toxic impacts of Li, most probably due to snail increased sensitivity when under warming conditions. As a consequence of inefficient antioxidant and biotransformation capacity, lipid peroxidation was observed in Li-contaminated snails at 21 ºC, demonstrating a significant interaction between both factors. Regarding snails' metabolic capacity, Li did not affect snails, but a clear decrease on their metabolism was observed at increased temperature (with or without Li) which may limit snail defense capacity. Overall, the present findings demonstrated the impacts derived from Li towards marine intertidal gastropods, evidencing enhanced threats under predicted warming conditions. Considering the role of T. neritea in the ecosystem functioning, impacts on this species may greatly affect other populations and eventually the entire community.

Biocide vs. Eco-Friendly Antifoulants: Role of the Antioxidative Defence and Settlement in Mytilus galloprovincialis

Antifoulant paints were developed to prevent and reduce biofouling on surfaces immersed in seawater. The widespread use of these substances over the years has led to a significant increase of their presence in the marine environment. These compounds were identified as environmental and human threats. As a result of an international ban, research in the last decade has focused on developing a new generation of benign antifoulant paints. This review outlines the detrimental effects associated with biocide versus eco-friendly antifoulants, highlighting what are effective antifoulants and why there is a need to monitor them. We examine the effects of biocide and eco-friendly antifoulants on the antioxidative defence mechanism and settlement in a higher sessile organism, specifically the Mediterranean mussel, Mytilus galloprovincialis. These antifoulants can indirectly assess the potential of these two parameters in order to outline implementation of sustainable antifoulants.

Ecotoxicity in Hyriopsis bialatus of copper and zinc biocides used in metal-based antifouling paints

Biofouling is a costly burden for the shipping industry. Metal-based antifouling paints are widely used to protect submerged surfaces, but the release of metals from coatings and the recoating of hulls can leach large amounts of copper and zinc into aquatic environments, posing a risk for aquatic ecosystems and biodiversity. With this study, we studied the time-course metal accumulation and oxidative stress in the digestive gland and the gills of Hyriopsis bialatus, an Asian freshwater mussel, exposed to sublethal concentrations of cuprous chloride (50 and 5 µg/L) and zinc sulfate (1000 and 100 µg/L). Time-dependent accumulation was observed after exposure to copper, but zinc uptake was negligible. Integrated biomarker response (IBRv2) and statistical analysis of individual biomarker levels showed a greater biomarker response in the digestive gland and the gills after exposure to the higher concentration of CuCl and ZnSO₄. Both compounds elicited a biochemical response, especially in the digestive gland. Glutathione peroxidase activity was increased after exposure to both metals at both concentrations, suggesting a powerful defense against lipid peroxidation. The biological impact of zinc was less than that of copper, suggesting mitigated ecological pressure.

Effects of ocean acidification on the biochemistry, physiology and parental transfer of Ampelisca brevicornis (Costa, 1853)

Ocean acidification (OA) has received more attention in the marine research community in recent years than any other topic. Excess carbon dioxide makes the ocean more acidic, threatening marine ecosystems. There has been little research on the impact of OA on crustaceans, particularly on their physiological and potential ecosystem-level consequences. Thus, we investigated the impacts of OA on the physiological and biochemical characteristics of the estuarine amphipod Ampelisca brevicornis. Ovigerous amphipods were harvested from nature and maintained in the laboratory to produce juveniles, which were then further reared to obtain the mature adults (F0) and successive offspring (F1). For this study, four pH treatments (pH 8.1, 7.5, 7.0, and 6.5) mimicking future OA were evaluated to understand the physiological and biochemical effects on the organisms. The findings of this study suggest that A. brevicornis is more vulnerable to OA than was previously established in short-term trials. The survival was significantly reduced as pH decreased over time and a significant interaction between pH and time was observed. Survival was higher in F1 than in F0 juveniles and vice versa in terms of growth. Animal's physiological responses such as growth, burrowing behavior, locomotor activity, swimming speed, ventilation rate and reproductive performance were negatively influenced by acidification. These physiological characteristics can be linked to the oxidative stress induced by global change conditions because excess of free radicals degrade cell functioning, affecting species' biochemical and physiological performance. These alterations may have long-term negative impacts, with ecological consequences. The results of this study provide baseline information regarding the effect of OA on this keystone crustacean that may be useful in simulating the impacts of OA to develop different conceptual models for a better understanding of the consequences and implications of climate change in the future for managing marine ecosystems.

Influence of Particle Size on Ecotoxicity of Low-Density Polyethylene Microplastics, with and without Adsorbed Benzo-a-Pyrene, in Clam Scrobicularia plana

This study investigated the ecotoxicological effects of differently sized (4–6 µm and 20–25 µm) low-density polyethylene (LDPE) microplastics (MPs), with and without adsorbed benzo-a-pyrene (BaP), in clam Scrobicularia plana. Biomarkers of oxidative stress (superoxide dismutase—SOD; catalase—CAT), biotransformation (glutathione-S-transferases—GST), oxidative damage (lipid peroxidation—LPO) and neurotoxicity (acetylcholinesterase—AChE) were analysed in gills and digestive glands at different time intervals for a total of 14 days of exposure. In order to have a better impact perspective of these contaminants, an integrated biomarker response index (IBR) and Health Index were applied. Biomarker alterations are apparently more related to smaller sized (4–6 µm) MPs in gills and to virgin LDPE MPs in the digestive gland according to IBR results, while the digestive gland was more affected by these MPs according to the health index.

Elevated Temperature and Exposure to Copper Leads to Changes in the Antioxidant Defense System of the Reef-Building Coral Mussismilia harttii

The frequency and severity of coral bleaching events have increased in recent years. Global warming and contamination are primarily responsible for triggering these responses in corals. Thus, the objective of this study was to evaluate the isolated and combined effects of elevated temperature and exposure to copper (Cu) on responses of the antioxidant defense system of coral Mussismilia harttii. In a marine mesocosm, fragments of the coral were exposed to three temperatures (25.0, 26.6, and 27.3°C) and three concentrations of Cu (2.9, 5.4, and 8.6 μg/L) for up to 12 days. Levels of reduced glutathione (GSH) and the activity of enzymes, such as superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), and glutamate cysteine ligase (GCL), were evaluated on the corals and symbionts. The short exposure to isolated and combined stressors caused a reduction in GSH levels and inhibition of the activity of antioxidant enzymes. After prolonged exposure, the combination of stressors continued to reduce GSH levels and SOD, CAT, and GCL activity in symbionts and GST activity in host corals. GCL activity was the parameter most affected by stressors, remaining inhibited after 12-days exposure. Interesting that long-term exposure to stressors stimulated antioxidant defense proteins in M. harttii, demonstrating a counteracting response that may beneficiate the oxidative state. These results, combined with other studies already published suggest that the antioxidant system should be further studied in order to understand the mechanisms of tolerance of South Atlantic reefs.

Multi-biomarker approach in Mytilus galloprovincialis and Ruditapes decussatus as a predictor of pelago-benthic responses after exposure to Benzo[a]Pyrene

This study evaluated the biomarker responses indicative of exposure to Benzo[a] Pyrene (B[a]P) in Mytilus galloprovincialis and Ruditapes decussatus. A significant increase of the total oxyradical scavenging capacity (TOSC) was observed after seven days of exposure to two concentrations of B[a]P (100 and 300 μg.L^-1), in the digestive gland with the lowest concentration tested. The TOSC in the gills increased notably only after the exposure to 300 μg.L^-1 of B[a]P. Interestingly, the superoxide dismutase (SOD) and catalase (CAT) activities in gills and digestive gland on one hand and glutathione S-transferase (GST) in gills in the other, were positively correlated with the concentration of B[a]P with a significant induction noticed at the highest concentration. In contrast, a significant increase of the GST activity was observed in the digestive gland following the exposure of bivalves to 100 μg.L^-1. In pelagic (M. galloprovincialis) or benthic (R. decussatus) bivalves, the AChE activity decreased discernibly in digestive glands and gills with the increase of B[a]P concentrations as evidence of neurotoxic effects. In clams, the exposure to B[a]P was followed by a significant increase of Malondialdehyde level (MDA) in gills and digestive gland, this does not occur in gills of Mytilus galloprovincialis at the concentration of 100 μg.L^-1. Overall, the results found seems to indicate that the mussel was more suitable as a predictor tool of toxicity of B[a]P.

Sensitivity of midgut physiological parameters of Lymantria dispar L. larvae to benzo[a]pyrene in populations with different multigeneration contact to environmental pollutants

Accumulation of organic pollutants in the environment calls for sensing physiological parameters adequate to indicate the presence of contaminants and their effects on ecosystems. Evidence points to the importance of insect adaptations in their habitats for the assessment of sensitive biomarkers so we examined the influence of origin and multigenerational adaptations of the Lymantria dispar larvae to chronic benzo[a]pyrene (B[a]P) treatment under laboratory conditions. The main aim was to compare reactions of larvae from unpolluted and polluted forests using alkaline phosphatase (ALP), acid phosphatase (ACP), and carboxylesterase (CE) specific activities in the midgut, including electrophoretic isoform patterns; midgut expression levels of Hsp70, larval development time (DT), and midgut mass (MM), after chronic exposure to 5 and 50 ng of B[a]P/g dry food weight. The biomarker potential of these parameters regarding larval pre-exposure history to pollution was estimated by principal component analysis (PCA). B[a]P treatment resulted in inhibition of ALP activity, a rise of CE activity, and reduction of MM in larvae from the unpolluted forest, while the population from the polluted forest showed significant elevation of Hsp70 expression in the midgut, prolonged DT, and reduction of MM. PCA confirmed variations in responses of the selected parameters regarding population origin. The obtained results provide insight into insect population variability concerning physiological responses to pollutants. It is indicative that all investigated physiological parameters of L. dispar larvae showed origin-dependent responses to long-term presence of B[a]P, which may be of great importance in ecotoxicological research.

Efficacy and side effects of bio-fabricated sardine fish scale silver nanoparticles against malarial vector Anopheles stephensi

Mosquitoes are a great menace for humankind since they transmit pathogenic organisms causing Malaria, Dengue, Chikungunya, Elephantiasis and Japanese encephalitis. There is an urgent need to discover new and novel biological tools to mitigate mosquito-borne diseases. To develop bioinsecticides through newly developed nanotechnology is another option in the present research scenario. In this study we synthesize and characterize sardine fish scales with silver nitrate by adopting various instrumental techniques such as UV- and FTIR-spectroscopy, energy-dispersive X-ray (EDAX), X-ray diffraction analyses (XRD) and scanning electron microscopy (SEM). Toxicity bioassays were conducted with young developmental stages of mosquito vectors. Significant mortality appeared after different life stages of mosquito vectors (young larval and pupal instars were exposed to the nanomaterials). LC50 values were 13.261 ppm for young first instar larvae and 32.182 ppm for pupae. Feeding and predatory potential of G. affinis, before and after exposure to nanoparticles against mosquito larval (I & II) instars of the mosquitoes showed promising results in laboratory experiments. Feeding potential of mosquito fish without nanoparticle treatment was 79.7% and 70.55% for the first and second instar larval populations respectively. At the nanoparticle-exposed situation the predatory efficiency of mosquitofish was 94.15% and 84.3%, respectively. Antioxidant enzymes like (SOD), (CAT), and (LPO) were estimated in the gill region of sardine fish in control and experimental waters. A significant reduction of egg hatchability was evident after nanoparticle application. It became evident from this study that the nano-fabricated materials provide suitable tools to control the malaria vector Anopheles stephensi in the aquatic phase of its life cycle. This finding suggests an effective novel approach to mosquito control.

Acute benzo[a]pyrene exposure induced oxidative stress, neurotoxicity and epigenetic change in blood clam Tegillarca granosa

The blood clam (Tegillarca granosa) is being developed into a model bivalve mollusc for assessing and monitoring marine pollution on the offshore seabed. However, the information on the response of blood clam to PAHs, an organic pollutant usually deposited in submarine sediment, remains limited. Herein, we employed multiple biomarkers, including histological changes, oxidative stress, neurotoxicity and global DNA methylation, to investigate the effects of 10 and 100 μg/L Bap exposure on the blood clams under laboratory conditions, as well as the potential mechanisms. Acute Bap exposure can induce significant morphological abnormalities in gills as shown through hematoxylin–eosin (H.E) staining, providing an intuitive understanding on the effects of Bap on the structural organization of the blood clams. Meanwhile, the oxidative stress was significantly elevated as manifested by the increase of antioxidants activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and glutathione-s-transferase (GST), lipid peroxidation (LPO) level and 8-hydroxy-2′-deoxyguanosine (8-OHdG) content. The neurotoxicity was also strengthened by Bap toxicity manifested as inhibited acetylcholinesterase (AChE) and choline acetyltransferase (ChAT) activities. In addition, the global DNA methylation level was investigated, and a significant DNA hypomethylation was observed in Bap exposed the blood clam. The correlation analysis showed that the global DNA methylation was negatively correlated with antioxidants (SOD, CAT and POD) activities, but positively correlated choline enzymes (AChE and ChAT) activities. These results collectively suggested that acute Bap exposure can cause damage in gills structures in the blood clam possibly by generating oxidative stress and neurotoxicity, and the global DNA methylation was inhibited to increase the transcriptional expression level of antioxidants genes and consequently elevate antioxidants activities against Bap toxicity. These results are hoped to shed some new light on the study of ecotoxicology effect of PAHs on marine bivalves.

Effects of Copper Oxide Nanoparticles on Immune and Metabolic Parameters of Galleria mellonella L

In this study, the effects of dietary CuO nanoparticles (NPs) on metabolic enzyme activity, biochemical parameters, and total (THC) and differential hemocyte counts (DHC) were determined in Galleria mellonella larvae. Using concentrations of 10, 100, 1000 mg/L and the LC10 and LC30 levels of CuO NPs, we determined that the NPs negatively impacted metabolic enzyme activity and biochemical parameters in larval hemolymph. Compared with the control, the greatest increase in THC was observed in larvae fed on diets with 100 mg L^-1 of CuO NPs. Plasmatocytes and granulocytes were among the most numerous hemocytes in all treatments. These results suggest that dietary CuO NPs effects the metabolic metabolism and immune system of G. mellonella and provide indirect information regarding the toxic effects of CuO NPs in mammalian immune system given similarities between mammalian blood cells and insect hemocytes.

Biochemical Effects of Two Pesticides in Three Different Temperature Scenarios on the Diatom Thalassiosira weissflogii

The exponential increase of the human population demands the overuse of fertilizers and pesticides in agriculture practices to suppress food production needs. The excessive use of these chemicals (fertilizers and pesticides) can comport deleterious effects to the ecosystems, including aquatic systems and communities. Oxyfluorfen is a fluorine-based herbicide, and its application has increased, since it is seen as an alternative to control glyphosate-resistant weeds. Copper sulfate is an inorganic pesticide based on copper which is being used in several chemical formulations, and it is the second main constituent of fungicides. Besides the known effects of such products in organisms, climatic changes pose an additional issue, being a main concern among scientists and politicians worldwide, since these alterations may worsen ecosystems’ and organisms’ sensitivity to stress conditions, such as the exposure to pollutants. Thalassiosira weissflogii (Grunow) G. A. Fryxell & Hasle, 1977 plays an important role in aquatic food webs as a primary producer and an essential food source to zooplankton. Thus, alterations on the diatom’s abundance and nutritional value may lead to consequences along the trophic chain. However, few studies have evaluated the biochemical impacts of oxyfluorfen and copper sulfate exposure on diatoms. This study intends to (1) evaluate the effects on the growth rate of both contaminants on T. weissfloggi at three temperatures, considering the actual scenario of climatic changes, and (2) assess biochemical changes on the diatom when exposed to the chemicals at different temperatures. To achieve these aims, the marine diatom was exposed to the two chemicals individually at different temperatures. The results showed an increase in the growth rate with increasing temperatures. Oxyfluorfen exhibited higher toxicity than copper sulfate. At the biochemical level, the microalgae were greatly affected when exposed to oxyfluorfen at 20 °C and 25 °C and when exposed to copper sulfate at 15 °C. Moreover, a general increase was observed for the polysaccharide content along the copper sulfate and oxyfluorfen concentrations. Therefore, the contaminants show the ability to interfere with the diatom growth and the nutritive value, with their effects dependent on the temperature.

The Nrf2 molecule trigger antioxidant defense against acute benzo(a)pyrene exposure in the thick shell mussel Mytilus coruscus

The NF-E2-related factor 2 (Nrf2), an ubiquitous, evolutionarily conserved transcription factor, acts as a major sensor of oxidative stress in cells. In the present study, a Nrf2 homolog was newly identified in the thick shell mussel Mytilus coruscus. Accordingly, its functional role in antioxidant defense in response to acute benzo(a)pyrene (Bap) exposure was assessed. The newly identified McNrf2 affiliated to traditional Nrf2 family through Blast, multiple alignment and phylogenetic analysis. After acute exposure to Bap, antioxidants including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathine reductase (GR) were significantly induced in gills and digestive glands at both mRNA and enzymatic levels, and the expression of McNrf2 mRNA was also up-regulated. The analysis of correlating the expression of McNrf2 and the mRNA levels of these antioxidant genes showed positive ties, indicating that Nrf2 was needed for protracted induction of such genes. Further, the recombinant McNrf2 was produced through pET-32a prokaryotic system. After 50 μg/L Bap exposure, ROS generation and LPO level in gills of Nrf2 over-expressed mussels significantly decreased compared to Nrf2 wild-type mussels, as well as reduced ROS production in digestive glands. Collectively, these results show that Nrf2 pathway can provide protection from oxidative stress triggered by Bap in the thick shell mussel.

The effects of co-exposure of graphene oxide and copper under different pH conditions in Manila clam Ruditapes philippinarum

Carbon nanomaterials (CNM), such as graphene oxide (GO), have been the focus of study in several areas of science mostly due to their physical-chemical properties. However, data concerning the potential toxic effects of these CNM in bivalves are still scarce. When present in the aquatic systems, the combination with other contaminants, as well as pH environmental variations, can influence the behavior of these nanomaterials and, consequently, their toxicity. Thus, the main goal of this study was to evaluate the effect of exposure of clam Ruditapes philippinarum to GO when acting alone and in the combination with copper (Cu), under two pH levels (control 7.8 and 7.3). A 28-day exposure was performed and metabolism and oxidative stress-related parameters were evaluated. The effects caused by GO and Cu exposures, either isolated or co-exposed, showed a direct and dependent relationship with the pH in which the organisms were exposed. In clams maintained at control pH (7.8), Cu and GO + Cu treatments showed lower lipid peroxidation (LPO) and lower electron transport system (ETS) activity, respectively. In clams maintained at low pH, glutathione-S-transferases (GSTs) activities were increased in Cu and Cu + GO treatments, whereas reduced glutathione (GSH) levels were increased in Cu treatment and ETS activity was higher in GO + Cu. Thus, it can be observed that clams responses to Cu and GO were strongly modulated by pH in terms of their defense system and energy production, although this does not result into higher LPO levels.

Environmental Fate of Multistressors on Carpet Shell Clam Ruditapes decussatus: Carbon Nanoparticles and Temperature Variation

Ruditapes decussatus is a native clam from the Southern Europe and Mediterranean area, relevant to the development of sustainable aquaculture in these regions. As sessile organisms, bivalves are likely to be exposed to chemical contaminations and environmental changes in the aquatic compartment and are widely used as bioindicator species. Carbon-based nanomaterials (CNTs) use is increasing and, consequently, concentrations of these contaminants in aquatic systems will rise. Therefore, it is imperative to assess the potential toxic effects of such compounds and the interactions with environmental factors such as water temperature. For this, we exposed R. decussatus clams to four different water temperatures (10, 15, 20 and 25 °C) in the presence or absence of CNTs for 96 h. Different parameters related with oxidative stress status, aerobic metabolism, energy reserves and neurotoxicity were evaluated. The relationship and differences among water temperatures and contamination were highlighted by principal coordinates analysis (PCO). CNTs exposure increased oxidative damage as protein carbonylation (PC) in exposed clams at 10 °C. Higher temperatures (25 °C) were responsible for the highest redox status (ratio between reduced and oxidized glutathione, GSH/GSSG) observed as well as neurotoxic effects (acetylcholinesterase—AChE activity). Antioxidant defenses were also modulated by the combination of CNTs exposure with water temperatures, with decrease of glutathione peroxidase (GR) activity at 15 °C and of glutathione S-transferases (GSTs) activity at 20 °C, when compared with unexposed clams. Clams energy reserves were not altered, probably due to the short exposure period. Overall, the combined effects of CNTs exposure and increasing water temperatures can impair R. decussatus cellular homeostasis inducing oxidative stress and damage.

Copper sulphate impact on the antioxidant defence system of the marine bivalves Cerastoderma edule and Scrobicularia plana

Anthropogenic activities, such as agriculture and industrial activities, are a main source of pollution contributing for the degradation of water quality and thus affecting the living organisms of aquatic systems. Copper is widely used at these practices being often released into the aquatic systems and may cause negative effects in its communities. This study proposes to determine the effects of copper in the antioxidant defence system of two size classes (big and small sizes) of Scrobicularia plana and Cerastoderma edule, two marine bivalve species with commercial interest. It was observed the behaviour activity of the organisms during the exposure to copper sulphate (CS) and was determined the enzymatic activities of glutathione-S-transferases (GST), glutathione reductase (GR) and glutathione peroxidase (GPx) (both selenium-dependent (SeGPx) and total (tGPx)) in the muscle tissue (foot). Lipid peroxidation (LPO) was evaluated through thiobarbituric acid reactive substances (TBARS) measurement in the foot. Changes in the behaviour and enzymatic activity were observed. Lipid peroxidation was observed at C. edule and S. plana big and small size classes, respectively, according to TBARS levels. The foot showed to be a good tissue to be used in biochemical analysis to detect the presence of toxicants.

The influence of temperature and salinity on the impacts of lead in Mytilus galloprovincialis

Mussels, such as the marine bivalve Mytilus galloprovincialis are sentinels for marine pollution but they are also excellent bioindicators under laboratory conditions. For that, in this study we tested the modulation of biochemical responses under realistic concentrations of the toxic metal Lead (Pb) in water for 28 days under different conditions of salinity and temperature, including control condition (temperature 17 ± 1.0 °C and salinity 30 ± 1.0) as well as those within the range expected to occur due to climate change predictions (± 5 in salinity and + 4 °C in temperature). A comprehensive set of biomarkers was applied to search on modulation of biochemical responses in terms of energy metabolism, energy reserves, oxidative stress and damage occurrence in lipids, proteins as well as neurotoxicity signs. The application of an integrative Principal Coordinates Ordination (PCO) tool was successful and demonstrated that Pb caused an increase in the detoxification activity mainly evidenced by glutathione S-transferases and that the salinities 25 and 35 were, even in un-exposed mussels, responsible for cell damage seen as increased levels of lipid peroxidation (at salinity 25) and oxidised proteins (at salinity 35).

The effects of benzo[a]pyrene on the composition of gut microbiota and the gut health of the juvenile sea cucumber Apostichopus japonicus Selenka

The gut microbiota is essential for health and physiological functions in the host organism. However, the toxicological evaluation of environmental pollutants on the gut microbiota is still insufficient. In the present study, the juvenile sea cucumber Apostichopus japonicus was exposed for 14 days to Benzo[a]pyrene (BaP), which is a model polycyclic aromatic hydrocarbon (PAH), at four different concentrations (0, 0.5, 5, and 25 μg/L). We analyzed the intestinal microbial community of A. japonicas using 16S rRNA gene amplicon sequencing. Our results demonstrate that BaP exposure caused alterations to the microbiome community composition in sea cucumbers. At the phylum level, Planctomycetes were significantly more abundant in BaP exposure groups at 14 d compared with the control group, and the abundance of Proteobacteria and Bacteroidetes increased while the abundance of Firmicutes decreased following BaP exposure. At the genus level, multiple beneficial and autochthonous genera declined in the BaP treatment groups compared to the control, including Lactococcus, Bacillus, Lactobacillus, Enterococcus, Leuconostoc and Weissella; however, a bloom of alkane-degrading bacteria was found in BaP-exposed guts and included Lutibacter, Pseudoalteromonas, Polaribacter, Rhodopirellula and Blastopirellula. Furthermore, histological morphology, enzymatic activity and gene expression analysis revealed that BaP exposure also negatively impacted gut structure and function and presented as inflammation or atrophy, oxidative stress and immune suppression in sea cucumber intestines. Collectively, these findings provide insights into the toxic effects of BaP exposure on A. japonicas associated with intestinal microbiota and health.

Food-type may jeopardize biomarker interpretation in mussels used in aquatic toxicological experimentation

To assess the influence of food type on biomarkers, mussels (Mytilus galloprovincialis) were maintained under laboratory conditions and fed using 4 different microalgae diets ad libitum for 1 week: (a) Isochrysis galbana; (b) Tetraselmis chuii; (c) a mixture of I. galbana and T. chuii; and (d) a commercial food (Microalgae Composed Diet, Acuinuga). Different microalgae were shown to present different distribution and fate in the midgut. I. galbana (≈4 μm Ø) readily reached digestive cells to be intracellularly digested. T. chuii (≈10 μm Ø and hardly digestible) was retained in stomach and digestive ducts for long times and extracellularly digested. Based on these findings, it appeared likely that the presence of large amounts of microalgal enzymes and metabolites might interfere with biochemical determinations of mussel's biomarkers and/or that the diet-induced alterations of mussels' digestion could modulate lysosomal and tissue-level biomarkers. To test these hypotheses, a battery of common biochemical, cytological and tissue-level biomarkers were determined in the gills (including activities of pyruvate kinase, phosphoenolpyruvate carboxykinase and cytochrome c oxidase) and the digestive gland of the mussels (including protein, lipid, free glucose and glycogen total content, lysosomal structural changes and membrane stability, intracellular accumulation of neutral lipids and lipofuscins, changes in cell type composition and epithelial thinning, as well as altered tissue integrity). The type of food was concluded to be a major factor influencing biomarkers in short-term experiments though not all the microalgae affected biomarkers and their responsiveness in the same way. T. chuii seemed to alter the nutritional status, oxidative stress and digestion processes, thus interfering with a variety of biomarkers. On the other hand, the massive presence of I. galbana within digestive cells hampered the measurement of cytochemical biomarkers and rendered less reliable the results of biochemical biomarkers (as these could be attributed to both the mussel and the microalgae). Research to optimize dietary food type, composition, regime and rations for toxicological experimentation is urgently needed. Meanwhile, a detailed description of the food type and feeding conditions should be always provided when reporting aquatic toxicological experiments with mussels, as a necessary prerequisite to compare and interpret the biological responses elicited by pollutants.

Biomarkers responses in Manila clam, Ruditapes philippinarum after single and combined exposure to mercury and benzo[a]pyrene

Physiological and biochemical responses in bivalves exposed to pollutants have proved a valuable tool to assess the health of organisms in aquatic ecosystems. The single and combined effects of mercury (Hg²⁺, 2 and 10 μg/L) and benzo[a]pyrene (BaP, 3 μg/L) on physiological and biochemical biomarkers in Manila clam, Ruditapes philippinarum were evaluated. Results showed that significant higher oxygen consumption (OR) and ammonia-N excretion rates (NR) together with significant lower ingestion rates (IR) were observed for the 10 μg/L Hg²⁺ or 3 μg/L BaP treatments compared to controls (P < 0.05). However, clam NR decreased significantly in response to the binary mixtures of 10 μg/L Hg²⁺ and 3 μg/L BaP (P < 0.05). Moreover, the levels of superoxide dismutase (SOD), catalase (CAT), glutathione-s-transferases (GSTs), glutathione (GSH), acetylcholinesterase (AChE) and malondialdehyde (MDA) in the hepatopancreas of clams were induced substantially, whereas glycogen (GLY) contents were suppressed dramatically after Hg²⁺ and BaP exposure. Additionally, the integrated biomarker response (IBR) values measured showed significant increases in combination treatments and they were much higher than that in the Hg²⁺ treatment. This study will provide further information on the defense mechanism in the Manila clam after exposure to marine pollutants and may help evaluate the quality of the aquatic environment.

The effect of copper and chlorpyrifos co-exposure on biomarkers in the marine mussel Mytilus galloprovincialis

Metals and organophosphorous pesticides commonly co-occur in marine environment, but the effect of their mixtures on non-target organisms is still poorly understood. This study investigated the combined effect of the essential metal copper (Cu) and organophosphorous pesticide chlorpyrifos (Chp) in mussels (Mytilus galloprovincialis) after short-term exposure to their sublethal concentrations. Mussels were exposed for four days to 5 and 15 μg L^-1 Cu and 0.05 and 5 μg L^-1 Chp, and to their binary mixtures. The investigated biomarkers, namely acetylcholinesterase activity (AChE), glutathione S-transferase activity (GST), metallothioneins content (MTs) and lipid peroxide levels (LPO) displayed unspecific and inconsistent response patterns that varied depending on the concentration of chemicals and composition of mixtures. The exposure to Cu or Chp alone did not induce AChE activity changes, whereas only Cu provoked a significant GST activity increase. Exposure to lower and higher concentration of Chp resulted in MTs content and LPO level increase, respectively. Response of biomarkers to mixtures was generally inconsistent. Data integration by IBR index and PCA revealed different stress levels for given exposure conditions, but no explicit differentiation between single and joint exposures was found. The present results showed that low and environmentally relevant concentrations of Cu and Chp in mixtures may result in a detectable biological response, stressing the need for further investigation of joint effects of widespread marine contaminants in sentinel organisms.

Contaminant accumulation and biological responses in Atlantic cod (Gadus morhua) caged at a capped waste disposal site in Kollevåg, Western Norway

The aim of this study was to assess whether fish in Kollevåg, a sheltered bay on the western coast of Norway, previously utilized as a waste disposal site, could be affected by environmental contaminants leaking from the waste. Farmed, juvenile Atlantic cod (Gadus morhua) were caged for six weeks at three different locations in Kollevåg bay and at one reference location. Sediments and cod samples (bile and liver) were analyzed for polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), brominated flame retardants (BFRs), per-and polyfluoroalkyl substances (PFASs) and polycyclic aromatic hydrocarbon (PAH) metabolites, revealing a contamination gradient at the four stations. Furthermore, hepatosomatic index (HSI) and Fulton's condition factor (CF) were significantly lower in cod caged closest to the disposal site. Levels and activities of biomarker proteins, such as vitellogenin (Vtg), metallothionein (Mt), and biotransformation and oxidative stress enzymes, including cytochrome P450 1a and 3a (Cyp1a, Cyp3a), glutathione s-transferase (Gst) and catalase (Cat), were quantified in blood plasma and liver tissue. Hepatic Cat and Gst activities were significantly reduced in cod caged at the innermost stations in Kollevåg, indicating modulation of oxidative stress responses. However, these results contrasted with reduced hepatic lipid peroxidation. Significant increases in transcript levels were observed for genes involved in lipid metabolism (fasn and acly) in cod liver, while transcript levels of ovarian steroidogenic enzyme genes such as p450scc, cyp19, 3β-hsd and 20β-hsd showed significant station-dependent increases. Cyp1a and Vtg protein levels were however not significantly altered in cod caged in Kollevåg. Plasma levels of estradiol (E2) and testosterone (T) were determined by enzyme immunoassay (EIA) and showed elevated E2 levels, but only at the innermost station. We conclude that the bay of Kollevåg did not fullfill adequate environmental condition based on environmental quality standards (EQSs) for chemicals in coastal waters. Following a six weeks caging period, environmental contaminants accumulated in cod tissues and effects were observed on biomarker responses, especially those involved in reproductive processes in cod ovary.

Copper Bioaccumulation Kinetics in Swan Mussel, Anodonta cygnea (Linnaeus, 1758) During Waterborne Exposure to CuO Nanoparticles

This study was conducted to investigate bioaccumulation of copper in two internal organs (mantle and foot) of swan mussel, Anodonta cygnea (Linnaeus, 1758) in exposure to copper oxide nanoparticles (CuO NPs). Basal concentration of Cu in the mantle (3.15 ± 1.09 µg g^-1 DW) was significantly (p < 0.05) lower than the foot (5.43 ± 1.54 µg g^-1 DW). At the end of the exposure period, the highest concentration of Cu in both organs belonged to the highest exposure concentration. Calculated bioconcentration factor (BCF) values showed significant (p < 0.05) higher values for the mantle in each day and each exposure concentration (except the lowest exposure concentration) than the foot. For both organs, the highest and lowest BCFs occurred at the lowest and highest exposure concentrations, respectively. Cu concentration in both organs was significantly (p < 0.05) decreased after day 4. Based on the results, it was obvious that exposure to sub-lethal concentrations of CuO NPs would lead to the significant accumulation of copper in mantle and foot that may have adverse effects on this organism.

Molecular cloning and characterization of two genes encoding peroxiredoxins from freshwater bivalve Anodonta woodiana: Antioxidative effect and immune defense

Members of Prx family function as an important players in host defense against oxidative stress, and modulate immune responses. In the current study, two complete Prx sequences were isolated from bivalve Anodonta woodiana and respectively named AwPrx4a and AwPrx4b. Regulative characterizations of AwPrx4a and AwPrx4b derived from perfluorooctanesulfonate (PFOS), perfluoroocanoic acid (PFOA), lipopolysaccharide (LPS) and polyinosinic:polycytidylic (Poly I:C) challenge in hepatopancreas, gill and hemocytes were measured by quantitative real-time PCR, respectively. The full-length cDNA of AwPrx4a had an open reading frame ORF of 588 bp encoding 196 amino acids. Two highly conserved Prxs signature motifs were observed in deduced amino acid sequence, one was FYPLDFTFACPTEI, and the other was GEVCPA. Complete cDNA sequence of AwPrx4b was comprised of a 5' untranslated region (UTR) of 120 nucleotides, a 426 bp ORF which was encoded 142 amino acids, and a long 3'-UTR of 412 nucleotides. Expressions of AwPrx4a and AwPrx4b showed a significant up-regulation pattern in groups at lower concentration treatment of PFOS and PFOA, a biphasic profile in groups with a higher concentration treatment. Compared with that of control group, expressions of AwPrx4a and AwPrx4b were significantly induced by LPS and Poly I:C treatment in the hepatopancreas, gill and hemocytes. These results indicate up-regulations of AwPrx4a and AwPrx4b expression are associated with eliminating oxidative stress derived from PFOS and PFOA administration as well as enhancing immune defense against LPS and Poly I:C challenge.

Experimental exposure of blue mussels (Mytilus galloprovincialis) to high levels of benzo[a]pyrene and possible implications for human health

Polycyclic aromatic hydrocarbons (PAHs) are lipophilic compounds able to accumulate in the food chain. Mussels showed to bioaccumulate contaminants, such as PAHs, so that recurrent consumption of such contaminated food represents a risk for human health. This study was aimed to elucidate if acute exposure of Mediterranean blue mussel (Mytilus galloprovincialis), a bivalve of great economic importance in several countries, to a PAH, benzo[a]pyrene (B[a]P), at doses able to induce cytochrome P450 1A (CYP1A) and pathological changes in mussel gills, can produce accumulation in soft tissue. We explored the cytotoxic effects (cell viability, DNA laddering, and glutathione levels) of in vitro exposure of human peripheral blood mononuclear cells (PBMCs) to organic extracts obtained from blue mussels previously exposed for 12 and 72h via water to B[a]P (0.5-1mg/L). In our experimental conditions, B[a]P induced CYP1A induction and morphological changes in mussel gills and a significant B[a]P accumulation in soft tissue. Conversely, exposing PBMCs to organic extracts obtained from contaminated mussels, resulted in a significant reduction of cell viability and cell glutathione content, and in an increase in DNA laddering. This confirms that consumption of mussels from B[a]P polluted waters might affect human health. Our data lead us to suggest that CYP1A activity in mussel gills may be useful (more than the amount of detected PAHs in the mussel edible tissue) as a marker in assessment of risk for health of consumers exposed to PAHs through ingestion of shellfish.

Transcriptomic approach: A promising tool for rapid screening nanomaterial-mediated toxicity in the marine bivalve Mytilus edulis-Application to copper oxide nanoparticles

The extensive development of nanotechnologies will inevitably lead to the release of nanomaterials (NMs) in the environment. As the aquatic environments represent the ultimate sink for various contaminants, it is highly probable that they also constitute a reservoir for NMs and hence aquatic animals represent potential targets. In a regulatory perspective, it is necessary to develop tools to rapidly screen the impact of NMs on model organisms, given that the number of NMs on the market will be increasing. In this context High Throughput Screening approaches represent relevant tools for the investigation of NM-mediated toxicity. The objective of this work was to study the effects of copper oxide nanoparticles (CuONPs) in the marine bivalve Mytilus edulis, using a transcriptomic approach. Mussels were exposed in vivo to CuONPs (10 μg·L^-1CuO NPs) for 24 h and analysis of mRNA expression levels of genes implicated in immune response, antioxidant activities, cell metabolism, cell transport and cytoskeleton was investigated by qPCR on hemocytes and gills. Results showed common effects of CuONPs and its ionic counterpart. However, greater effects of CuONPs on GST, SOD, MT, Actin, ATP synthase gene expressions were observed compared to ionic form indicating that toxicity of CuONPs is not solely due to the release of Cu²⁺. Even though M. edulis genome is not fully characterized, this study provides additional knowledge on the signaling pathways implicated in CuONP-mediated toxicity and demonstrates the reliability of using a qPCR approach to go further in the cellular aspects implicated in response to NPs in marine bivalves.

Hydrogen-rich water alleviates the toxicities of different stresses to mycelial growth in Hypsizygus marmoreus

In plants, hydrogen gas (H₂) enhances tolerance to several abiotic stresses, including salinity and heavy metals. However, the effect of H₂ on fungal growth under different stresses remains largely unclear. In this study, hydrogen-rich water (HRW) was employed to characterize physiological roles and molecular mechanisms of H₂ in the alleviation of three different stresses in basidiomycete Hypsizygus marmoreus. Our results showed that HRW treatment, of which the H₂ concentration was 0.8 mM, significantly reduced the toxicities of CdCl₂, NaCl and H₂O₂, leading to significantly improved mycelial growth and biomass. These beneficial effects could be attributed to a significantly decreased formation of malondialdehyde (MDA). Besides, HRW treatment significantly increased the activities of antioxidants (SOD, CAT and GR) as well as the gene expressions of these antioxidants (SOD, CAT, and GR) at the mRNA level. In vivo detection of reactive oxygen species (ROS), including H₂O₂ and O₂⁻, as well as lipid peroxidation provided further evidence that HRW could significantly improve tolerances of CdCl₂, NaCl and H₂O₂. Furthermore, pyruvate kinase was activated in the mycelia treated with HRW, along with its induced gene expression, suggesting that HRW treatment enhanced the glucose metabolism. Taken together, our findings suggested that the usage of HRW could be an effective approach for contaminant detoxification in H. marmoreus, which was similar with the effects of HRW in plants, and such effects could be also beneficial in entire agricultural system.

Sublethal effects in Perinereis gualpensis (Polychaeta: Nereididae) exposed to mercury-pyrene sediment mixture observed in a multipolluted estuary

Sediment-living organisms can be subjected to a multi-pollution condition due to an increase in the diversity of contaminants. Sediment mixtures of Mercury (Hg) and some polycyclic aromatics hydrocarbons like Pyrene (Pyr) are common in heavily industrialized coastal zones. In the present study, greater than (>) and less than (<) probable effect concentration levels (PELs) of Hg and Pyr were assessed using spiked sediments in order to determine combined (Hg + Pyr) effects in uptake, metabolization and oxidative balance in the polychaete Perinereis gualpensis at short and medium-term exposure. Hg + Pyr significantly influenced the uptake/kinetics of Hg and Pyr metabolite 1-OH-pyrene in polychaete tissues during the exposure time compared with separate treatments of each analyte (p < 0.05). Both the Hg-only and Pyr-only exposures significantly influenced both enzymatic and non-enzymatic responses respect to control groups (p < 0.05). The Hg-only treatment showed the worst scenario related to the activation and subsequent inhibition of glutathione S- transferase (GST) and peroxidase (GPx) activities, high levels of Thiol-groups (SH-groups), low antioxidant capacity (ACAP) and enhanced lipid peroxidation (TBARS) in the last days of exposure (p < 0.05). In contrast, ragworms exposed to Hg + Pyr showed a significant increase in both enzymatic and non-enzymatic activity during the first days of exposure and the absence of lipid peroxidation during the whole experiment. Our results suggest different oxidative stress scenarios in P. gualpensis when exposed to >PEL Hg concentration with <PEL Pyr in sediments. Results also reveal the importance of the exposure time, endpoints involved as well as of the contaminant monitoring during the whole experiments in assessing the interactive effects of the contaminant mixture.

Characteristics and proteomic analysis of pyrene degradation by Brevibacillus brevis in liquid medium

Polycyclic aromatic hydrocarbons (PAHs) are widely spread in various ecosystems and are of great concern due to their potential toxicity, mutagenicity and carcinogenicity. Bioremediation has been proposed as an effective approach to remove PAHs. In this study, the physiological responses and proteome of Brevibacillus brevis under exposure to pyrene, a four-ring compound from PAHs family, were investigated. The changes of cell viability of B. brevis were observed during the degradation of pyrene by means of flow cytometry. The results indicated that pyrene stimulated superoxide dismutase (SOD) activity from 93.9 to 100.6 U mg^-1 prot, whereas inhibited catalase (CAT) activity from 29.1 to 20.3 U mg^-1 prot. The main compositions of B. brevis changed during pyrene degradation, with the proportion of unsaturated fatty acids increased by 13.4%. In addition, we performed a proteomic approach (two-dimensional gel electrophoresis and MALDI-TOF/TOF-MS) in order to explore how B. brevis survived upon treatment with pyrene. It was showed that the expression of 13 proteins increased whereas 10 other decreased after pyrene-treatment. The differentially expressed proteins were identified and the results indicated that they were involved in multiple biological processes including energy metabolism, biosynthesis, transmembrane transport and oxidative stress. Overall, these findings offered a new insights into the cellular response strategy developed by B. brevis to overcome the pyrene stress.

Response a chronic effects of PBDE-47: Up-regulations of HSP60 and HSP70 expression in freshwater bivalve Anodonta woodiana

Heat shock proteins (HSPs) play an important role in adaption of environmental stress by protein folding, membrane translocation, degradation of misfolded proteins and other regulatory processes. Our previous study showed oxidative stress generated from polybrominated diphenyl ether-47 (PBDE-47) could cause an acute toxicity on freshwater bivalve Anodonta Woodiana, but the effect of chronic toxicity need to be elucidated. In order to further investigate the chronic effect of PBDE-47, clams A. Woodiana were randomly divided into the PBDE-47 treated group administrated with PBDE-47 at a concentration 3.36 μg/L and control group treated with a similar volume dimethyl sulfoxide. Two complete HSP sequences were isolated from A. Woodianaa and respectively named AwHSP60 and AwHSP70. They were widely distributed in foot, gill, hepatopancreas, adductor muscle, heart, hemocytes and mantle. Administration of PBDE-47 could result in a significant up-regulation of AwHSP60 and AwHSP70 expressions in the hepatopancreas, gill and hemocytes. In the hepatopancreas, compared with that of control group, mRNA level of AwHSP60 increased more than 89.9% (P < 0.05) from day 1-15, AwHSP70 increased more 2.79 times (P < 0.01). In the gill, during experiment observed, expression of AwHSP60 increased more 2.09 times (P < 0.01) in contrasted with that of control group. Significant up-regulation of AwHSP70 expression showed a reversed U shape. In the hemocytes, AwHSP60 and AwHSP70 expressions of PBDE-47 treated group respectively increased more 2.09 times (P < 0.05) and 1.81 times (P < 0.05) compared with that of control group. These results indicated that up-regulations of AwHSP60 and AwHSP70 expression are contribute to enhancing adaption of bivalve A. Woodiana exposed to PBDE-47 treatment.

Variations of biomarkers response in mussels Mytilus galloprovincialis to low, moderate and high concentrations of organic chemicals and metals

The changes of acetylcholinesterase activity (AChE), metallothioneins content (MTs), catalase activity (CAT) and lipid peroxidation (LPO) were assessed after 4 days exposure of mussels Mytilus galloprovincialis to a wide range of sublethal concentrations of chlorpyrifos (CHP, 0.03-100 μg/L), benzo(a)pyrene (B(a)P, 0.01-100 μg/L), cadmium (Cd, 0.2-200 μg/L) and copper (Cu, 0.2-100 μg/L). The activity of AChE in the gills decreased after exposure to CHP and Cu, whereas no change of activity was detected after exposure to B(a)P and Cd. Both induction and decrease of MTs content in digestive gland occurred after exposure to CHP and B(a)P, while a marked increase was evident at highest exposure concentrations of Cd. The content of MTs progressively decreased of MTs with increasing concentration of Cu. CAT activity and LPO in the gills did not change after exposure to any of the chemicals. The results demonstrate different response profile in relation to the type of chemical compound, and highlight the potential implications for evaluation of biological effect of contaminants in marine environment. Furthermore, the AChE activity in the gills and MTs content in the digestive gland could be modulated by CHP and Cu at environmentally relevant concentrations indicating the potential risks of short-term transient mussels exposure that may occur due to run-off from land or accidental releases.

Evaluation of the multiple biomarkers on identification of the vulnerable coastal pollution hotspots

This paper presents multiple biomarkers on metal accumulation and its impacts along the Chennai to Puducherry, southeast coast of India using bivalves as bioindicators. In this regard, water samples and Perna viridis were collected from three stations and the accumulation of metals and its biological impacts were assessed. Among the three sampling stations, the maximum accumulation was noticed in Ennore (S1) than the Puducherry (S3) followed by Kovalam (S2). Mean accumulation pattern of metals in Perna viridis was found to be in the following order Zn > Cu > Ni > Cr > Pb > Cd, which were in close match with the metal concentration in seawater at respective site. The ambient metal concentration and behavior of multiple biomarkers were positively correlated indicating that the uptake of metals might induce biological changes, particularly in the internal organs, thus significantly affecting health of the aquatic organisms. P. viridis provides reliable information concerning the adverse effects and reflects the integrated effects of all contaminants. Thus, study confirmed that Ennore (S1) coast is highly vulnerable for significant pollution, in terms of metal toxicity in the study area. Overall investigation revealed that metal enrichment was observed close to the major urban areas in the S1 and S2 which were associated with industrialized areas. The assessment of multiple biomarkers on metal accumulation was the first step in determining the trophic transfer factors on marine foot web, which can be evaluated in the future based on this study.

Response of selenium-dependent glutathione peroxidase in the freshwater bivalve Anodonta woodiana exposed to 2,4-dichlorophenol,2,4,6-trichlorophenol and pentachlorophenol

2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP), and pentachlorophenol (PCP) pose a health risk to aquatic organism and humans, and are recognized as persistent priority pollutants. Selenium dependent glutathione peroxidase (Se-GPx) belongs to the family of selenoprotein, which acts mainly as an antioxidant role in the cellular defense system. In the current study, a Se-GPx full length cDNA was cloned from Anodonta woodiana and named as AwSeGPx. It had a characteristic codon at 165TGA167 that corresponds to selenocysteine(Sec) amino acid as U44. The full length cDNA consists of 870 bp, an open reading frame (ORF) of 585 bp encoded a polypeptide of 195 amino in which conserved domain (68LGFPCNQF75) and a glutathione peroxide-1 GPx active site (32GKVILVENVASLUGTT47) were observed. Additionally, the eukaryotic selenocysteine insertion sequence (SECIS) was conserved in the 3'UTR. The AwSeGPx amino acid sequence exhibited a high similarity with that of other Se-GPx. Real-time PCR analysis revealed that AwSeGPx mRNA had a widely distribution, but the highest level was observed in hepatopancreas. AwSeGPx mRNA expression was significantly up-regulated in hepatopancreas, gill and hemocytes after 2,4-DCP, 2,4,6-TCP and PCP exposure. Under similar environment, clams A. woodiana showed a more sensitive to PCP than that of 2,4-DCP and 2,4,6-TCP. These results indicate that AwSeGPx plays a protective role in eliminating oxidative stress derived from 2,4-DCP, 2,4,6-TCP and PCP treatment.

Molecular cloning, characterization, and the response of Cu/Zn superoxide dismutase and catalase to PBDE-47 and -209 from the freshwater bivalve Anodonta woodiana

Polybrominated diphenyl ethers-47 (PBDE-47) and -209 are significant components of total PBDEs in water and can catalyze the production of reactive oxygen species (ROS) in the organisms. Anti-oxidant enzymes play an important role in scavenging the high level of ROS. In the current study, two full-length cDNAs of Cu/Zn superoxide dismutase (CuZnSODs) and catalase (CAT) were isolated from freshwater bivalve Anodonta woodiana by rapid amplification of cDNA ends approach and respectively named as AwSOD and AwCAT. The nucleotide sequence of AwSOD cDNA had an open reading frame (ORF) of 465 bp encoding a polypeptide of 155 amino acids in which signature 1 GKHGFHVHEFGDNT and signature 2 GNAGARSACGVI of SODs were observed. Deduced amino acid sequence of AwSOD showed a significant similarity with that of CuZnSODs. AwCAT had an ORF 1536 bp encoding a polypeptide of 512 amino acids which contains a conserved catalytic site motif, and a proximal heme-ligand signature motif of CATs. The time-course expressions of AwSOD and AwCAT in hepatopancreas were measured by quantitative real-time PCR. Expressions of AwSOD and AwCAT showed a significant up-regulation in groups at a low concentration treatment of PBDE-47, a biphasic pattern in groups with a high concentration treatment. Administration of PBDE-209 could result in an up-regulation of AwSOD and AwCAT expressions with time- and dose-dependent matter. These results indicate that up-regulations of AwSOD and AwCAT expression of hepatopancreas of freshwater bivalve A. woodiana contribute to eliminate oxidative stress derived from PBDE-47 and -209 treated.

Ocean acidification increases copper toxicity differentially in two key marine invertebrates with distinct acid-base responses

Ocean acidification (OA) is expected to indirectly impact biota living in contaminated coastal environments by altering the bioavailability and potentially toxicity of many pH-sensitive metals. Here, we show that OA (pH 7.71; pCO2 1480 μatm) significantly increases the toxicity responses to a global coastal contaminant (copper ~0.1 μM) in two keystone benthic species; mussels (Mytilus edulis) and purple sea urchins (Paracentrotus lividus). Mussels showed an extracellular acidosis in response to OA and copper individually which was enhanced during combined exposure. In contrast, urchins maintained extracellular fluid pH under OA by accumulating bicarbonate but exhibited a slight alkalosis in response to copper either alone or with OA. Importantly, copper-induced damage to DNA and lipids was significantly greater under OA compared to control conditions (pH 8.14; pCO2 470 μatm) for both species. However, this increase in DNA-damage was four times lower in urchins than mussels, suggesting that internal acid-base regulation in urchins may substantially moderate the magnitude of this OA-induced copper toxicity effect. Thus, changes in metal toxicity under OA may not purely be driven by metal speciation in seawater and may be far more diverse than either single-stressor or single-species studies indicate. This has important implications for future environmental management strategies.