Bisphenol a (BPA) aggravate the adverse effect on physiological and biochemical response in freshwater mussel potomida littoralis.

Bisphenol A (BPA) is a chemical compound extensively employed in plastic manufacturing, and this pollutant has been detected in diverse aquatic organisms, notably bivalves. In order to comprehend the ecological and toxicological consequences of BPA Bisphenol A in these organisms, it is essential to examine the physiological and biochemical effects and identify areas where our understanding is lacking. This knowledge is crucial for determining the environn ental threat posed by bisphenol A and assisting decision-makers in establishing the appropriate priorities. This investigation aimed to assess the impact of BPA on the biochemical and physiological parameters of the freshwater mussel Potomida littoralis. In a laboratory setting, mussels were subjected to two different levels of BPA (20 and 100 µg/L) for a duration of 21 days. Filtration rate was calculated from the clearance of neutral red, fed to mussels at different BPA concentrations. The mussel's filtration rate capacity declined as BPA exposure intensified, potentially due to the mussel's attempt to close its valves and minimize BPA absorption, thus preventing cellular damage. In the digestive gland tissue, key antioxidant and detoxification defenses, including catalase (CAT) activity, glutathione-S-transferase (GST) activity, and levels of H2O2 and glutathione (GSH), were activated, particularly at the 100 µg/L BPA concentration. This activation helped protect against lipid damage at higher BPA concentrations. This study underscores the significance of preventing and regulating BPA release into the environment to avert detrimental consequences for aquatic ecosystems.

The pharmaceutical triclosan induced oxidative stress and physiological disorder in marine organism and nanoparticles as a potential mitigating tool.

Environmental research plays a crucial role in formulating novel approaches to pollution management and preservation of biodiversity. This study aims to assess the potential harm of pharmaceutical triclosan (TCS) to non-target aquatic organism, the mussel Mytilus galloprovincialis. Furthermore, our study investigates the potential effectiveness of TiO2 and ZnO nanomaterials (TiO2 NPs and ZnO NPs) in degrading TCS. To ascertain the morphology, structure, and stability of the nanomaterials, several chemical techniques were employed. To evaluate the impact of TCS, TiO2 NPs, and ZnO NPs, both physiological (filtration rate (FR) and respiration rate (RR)), antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST)) activities and malondialdehyde (MDA) contents were measured in M. galloprovincialis gills and digestive gland. The mussel's responses varied depending on the contaminant, concentration, and organ, underscoring the significance of compiling these factors in ecotoxicity tests. The main toxic mechanisms of TCS and ZnO NPs at a concentration of 100 µg/L were likely to be a decrease in FR and RR, an increase in oxidative stress, and increased lipid peroxidation. Our findings indicate that a mixture of TCS and NPs has an antagonist effect on the gills and digestive gland. This effect is particularly notable in the case of TCS2 = 100 µg/L combined with TiO2 NP2 = 100 µg/L, which warrants further investigation to determine the underlying mechanism. Additionally, our results suggest that TiO2 NPs are more effective than ZnO NPs at degrading TCS, which may have practical implications for pharmaceutical control in marine ecosystems and in water purification plants. In summary, our study provides valuable information on the impact of pharmaceuticals on non-target organisms and sheds light on potential solutions for their removal from aqueous environments.

Doping zinc oxide and titanium dioxide nanoparticles with gold induces additional oxidative stress, membrane damage, and neurotoxicity in Mytilus galloprovincialis: Results from a laboratory bioassay.

BACKGROUND: While previous studies have provided insights into the effects of zinc oxide (ZnO) and titanium dioxide (TiO2) nanoparticles (NPs) on aquatic organisms, there is still a substantial amount of information lacking about the possible effects of their doped counterparts. The goal of the current work was to address this gap by examining Mytilus galloprovincialis reaction to exposure to doped and undoped nanoparticles. METHODS: Two concentrations (50 or 100 µg/L) of undoped ZnO and TiO2 NPs, as well as their gold (Au) doped counterparts, were applied on mussels for 14 days, and the effects on biomarkers activities in digestive glands and gills were assessed by spectrophotometry. RESULTS: The NPs were quasi-spherical in shape (below 100 nm), stable in seawater, and with no aggregation for both doped and undoped forms. Analytical results using inductively coupled plasma atomic emission spectroscopy indicated the uptake of NPs in mussels. Furthermore, it was found that biometal dyshomeostasis could occur following NP treatment and that doping the NPs aggravated this response. At the biochemical level, exposure to undoped NPs caused membrane damage, neurotoxic effect, and changes in the activities in the gills and digestive glands of superoxide dismutase, catalase, and glutathione-S-transferase, in a concentration and organ-dependent manner. CONCLUSION: Doping ZnO NPs and TiO2NPs with Au induced additional oxidative stress, membrane damage, and neurotoxicity in mussels.

Are iron ore microparticles toxic for the European clam Ruditapes decussatus? Response elements from biomarker activities and in silico modeling.

Inevitably, high concentrations of iron, the most widely produced ore globally, can be found in aquatic environments. To assess the toxicity of iron on aquatic organisms, Ruditapes decussatus specimens were subjected to microparticles derived from two types of iron ore (hematite and magnetite) at four different concentrations (0.5, 1, 1.5, and 5 g/L). The findings revealed that both types of iron ore were absorbed by clams in a concentration-dependent manner. Biomarkers analysis demonstrated significant and organ-specific impacts on the health of the clams caused by these microparticles, which was further supported by computational analyses on bioavailability. Within seven days of exposure, changes were observed in the activities of several enzymes, including catalase, acetylcholinesterase, and glutathione S-transferases, as well as in the rate of lipid peroxidation in both the digestive gland and gills. This study provides an environmental perspective on the toxicological effects of iron ore microparticles.

Possible Interaction between ZnS Nanoparticles and Phosphonates on Mediterranean Clams Ruditapes decussatus.

This study aims to evaluate the toxicity of ZnS nanoparticles (ZnS NP50 = 50 µg/L and ZnS NP100 = 100 µg/L) and diethyl (3-cyano-1-hydroxy-2-methyl-1-phenylpropyl)phosphonate or P (P50 = 50 µg/L and P100 = 100 µg/L) in the clams Ruditapes decussatus using chemical and biochemical approaches. The results demonstrated that clams accumulate ZnS NPs and other metallic elements following exposure. Moreover, ZnS NPs and P separately lead to ROS overproduction, while a mixture of both contaminants has no effect. In addition, data showed that exposure to P100 resulted in increased levels of oxidative stress enzyme activities catalase (CAT) in the gills and digestive glands. A similar trend was also observed in the digestive glands of clams treated with ZnS100. In contrast, CAT activity was decreased in the gills at the same concentration. Exposure to ZnS100 and P100 separately leads to a decrease in acetylcholinesterase (AChE) levels in both gills and digestive glands. Thus, AChE and CAT after co-exposure to an environmental mixture of nanoparticles (ZnS100) and phosphonate (P100) did not show any differences between treated and non-treated clams. The outcome of this work certifies the use of biomarkers and chemical assay when estimating the effects of phosphonate and nanoparticles as part of an ecotoxicological assessment program. An exceptional focus was given to the interaction between ZnS NPs and P. The antioxidant activity of P has been demonstrated to have an additive effect on metal accumulation and antagonistic agents against oxidative stress in clams treated with ZnS NPs.

Effects of an Endocrine Disruptor Triclosan on Ruditapes decussatus: Multimarker and Histological Approaches.

The aim of this work was to study the ecotoxicological effects of an endocrine disruptor triclosan on the clam Ruditapes decussatus. The bivalves were exposed to three concentrations of this biocide (C1 = 100 ng/L, C2 = 200 ng/L and C3 = 500 ng/L) for three and seven days. The impact was assessed at the gills and digestive glands, through activities of an antioxidant defense biomarker (Gluthatione S-Transferase, GST), a damage biomarker (Malondialdehyde, MDA), and a neurotoxicity biomarker (Acetylcholinesterase, AChE). Furthermore, histological traits were approached in different organs to evaluate any possible alteration induced by triclosan. It appears from this study that both gills and digestive glands responded discernibly to triclosan and effects were concentration-dependent. The stressed clams showed a significant increase in their GST and MDA activities in gills and digestive glands compared to controls for both time slots considered. In turn, the AChE activity was clearly inhibited in both organs in a time dependent way. The histological study made it possible to observe several structural pathologies caused by triclosan in the gills and the digestive gland. These alterations consisted mainly of inflammatory reactions, malformations of the lamellae and fusion of the gill filaments, degeneration of the connective tissue, and the erosion of the gill cilia with the appearance of certain severe alterations (cell necrosis and apoptosis), which can thus cause a malfunction of the gills and eventually lead to a reduction in oxygen consumption and a disruption of the osmoregulation for bivalves. Alterations in the digestive gland have also been detected, mainly by epithelial alterations, thinning of the tubules, and alteration of the basal cell membrane which can impair the ability of clams to absorb food. At germinal cells, several damages were observed in the oocytes which probably disturbed the reproductive function and the fertility of the clams. The damages observed in female gonads were caused by the cytolysis of a large number of oocytes through autophagy and necrosis at 200 ng triclosan/L. Moreover, at 500 ng triclosan/L, hemocytic infiltration was observed in acini and apoptotic bodies reflected in the fragmentation of more than 90% of oocytes.

Protective effect of the Spirulina platensis against toxicity induced by Diuron exposure in Mytilus galloprovincialis.

Diuron herbicide is widely used for weeds control in many kinds of cultivations. It reaches the waterbodies through various fate routes and can adversely threaten non-target organism. The current study was carried out to evaluate the antioxidant activity of Spirulina as feed additive against the toxicity of Diuron concentrations (40 and 80 µg/L) on the edible mollusk Mytilus galloprovincialis during seven days of exposure. Oxidative stress biomarkers were applied on mussel gills and digestive gland, investigating changes in enzymes activities such as catalase (CAT), Glutathione-S-transferase (GST) and Acetylcholinesterase (AChE) and the Malondialdehyde level (MDA). The obtained results show that diuron altered oxidative stress biomarkers in both organs, gills and digestive gland. Performed principle component analysis (PCA) highlighted relationship between biomarkers involved in functional response. Spirulina platensis supplemented diet (1 mg/L), completely ameliorated diuron-induced oxidative stress in mussel tissues. Thus, Spirulina seems to be a promising microalgae and eco-friendly tool helping the health recovery of aquatic animals subjected to environmental stressors.

This study provided recent and new data on the impact of Diuron in marine bivalve and the protective effect of Spirulina against Diuron-induced oxidative stress. The results of our study suggest that the antioxidant potential of Spirulina should be strongly candidate for the phytoremediation of Diuron-aquatic contaminated.

Toxicity assessment of organophosphorus in Ruditapes decussatus via physiological, chemical and biochemical determination: A case study with the compounds γ-oximo- and γ-amino-phosphonates and phosphine oxides.

Organophosphorus derivatives are widely used in human health care and have been detected in aquatic ecosystems. These compounds may pose significant risks to non-target exposed organisms and only limited studies are available on bioconcentration and the effects of organophosphorus derivatives on marine organisms. The aim of this work was to evaluate the possible toxic effects of two concentrations (20 and 40 µg/L) of γ-oximo- and γ-amino-phosphonates and phosphine oxides in mediterranean clams Ruditapes decussatus exposed for 14 days using different biomarkers and the changes of filtration and respiration rate. The use of clams in ecotoxicity evaluation is thus mandatory to assess the feasibility of assessing oxidative stress on R. decussatus after being exposed to γ-oximo- and γ-amino-phosphonates and phosphine oxides. The oxidative status was analyzed by measuring oxidative stress biomarkers RNS and ROS production in mitochondria, superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferases (GSTs), lipid peroxidation (LPO) and acetylcholinesterase (AChE), whose alteration was indicative of organophosphorus exposure, in both gills and digestive gland of the clams. No significant alterations in RNS, ROS production, SOD, CAT and AChE activities and MDA content were observed in both organs of clams treated with γ-oximophosphine oxides. It was possible then to hypothesize that γ-oximophosphine oxides may have probably exerted an incomplete alteration of antioxidant defenses and damage, which was changed by the activation of defense mechanisms. On the contrary, oxidative stress parameters were changed after exposure to γ-amino-phosphonates and phosphine oxides. In addition, metals accumulation, filtration and respiration rates were altered following exposure to all the studied organophosphorus compounds.

Au-TiO2 nanoparticles exposure induced oxidative stress and neurotoxicity in rat.

CONTEXT: The Au-TiO2NPs have a wide range of applications and can easily enter the cells. Due to their properties, they can cause toxicity. OBJECTIVE: It was aimed to test the toxic effects of Au-TiO2 NPs in the brain, heart, kidney and liver of rats in this work. MATERIALS AND METHODS: All used rats in this work were treated using diverse concentrations (doses) of NPs (100 and 200 mg/kg bw) for 21 days. SOD, CAT, AChE activities and MDA, H2O2, NO contents were evaluated in different organs. RESULTS: The Au-TiO2 NPs exposure induced biochemical changes in different organs of rats in view of oxidative stress and neurotoxicity by the alteration of the activity of the enzyme of neurotransmitter (AChE activity). CONCLUSION: The Au-TiO2 NPs have the potential to interact with rat's biochemical status and cause undesirable effects. One of those damaging effects was oxidative stress and neurotoxicity. CLINICAL SIGNIFICANCE: The study signifies the impact of usage of Au-TiO2 NPs in the medical field for further exploration.

The protective effect of Hibiscus sabdariffa calyxes extract against cypermethrin induced oxidative stress in mice.

Cypermethrin (Cyp) is a kind of pyrethroids compound that is broadly used against different species of insects and pests. Cyp can also elicit a range of neurotoxic, immunotoxic, genotoxic and reproductive toxic effects on various experimental organisms. The aim of this study was to evaluate the protective effects of Hibiscus sabdariffa against the toxicity damage induced by Cyp exposure. The Hibiscus sabdariffa calyxes extract was given to mice (200-500 mg/kg bw). The mice, which were treated with Cyp and Hibiscus sabdariffa, were divided into six groups of six mice each. Groups I, IV and VI were used as control and groups II CYP control (20 mg/kg body weight)., groups III and V were treated with Hibiscus sabdariffa extract (200 and 500 mg/kg body weight) plus (20 mg/kg body weight) for 21 days Furthermore, HPLC was used to identify the compound fraction. This result showed Cyp -induced biochemical changes in all organs of mice. Cyp caused decreased CAT activity, inhibition of AChE activity and increased the levels of H2O2 and MDA in brain, heart, liver and kidney. Hibiscus sabdariffa exhibited antioxidant effect and significantly attenuated the neurotoxicity of Cyp. Hibiscus sabdariffa exhibits neuroprotective effects and can be an effective and novel alternative approach to reduce the risk caused by pyrethroid compound.

Facile synthesis of Cu-doped ZnO nanoparticle in triethyleneglycol: photocatalytic activities and aquatic ecotoxicity.

A new synthetisis method of Cu-doped ZnO nanoparticles is presented in this work, this novel approach allow one to produce Zinc oxide nanocristal owing to a modified Polyol process that makes use of triethyleneglycol (TREG) as a solvent. The structure and morphology of the nanoparticles were characterized by high-resolution transmission electron microscopy (HRTEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), N2 adsorption study, UV-Vis diffuse reflectance spectroscopy, inductively coupled plasma optical emission spectroscopy and Raman spectroscopy. The lightly doped Zn1-xCuxO photocatalysts consisted in a novel nanorods structure of Zn0.9990Cu0.0010O nanoparticles. Taking the photocatalytic degradation of diuron under solar light as liquid phase test reaction, the lightly doped Zn0.9990Cu0.0010O nanorods photocatalysts showed strongly enhanced photocatalytic activity when compared to the bare ZnO counterpart. The apparent rate constant value of Zn0.9990Cu0.0010O was 22 times higher than that of pure ZnO. In order to study the environmental risk of Cu-ZnO, clams Ruditapes decussatus were exposed to Cu-ZnOC1 = 0.5 mg/L, Cu-ZnOC2 = 1 mg/L and Cu-ZnO C3 = 5 mg/L. Catalase (CAT) activities, malondialdehyde (MDA) content and acetylcholinesterase (AChE) activity were determined in gills and digestive gland of treated and untreated clams. Thus, no significant effects were detected in the gills of exposed clams after 7 days compared to control. Thus, MDA level and CAT activity showed significant differences in digestive glands of groups treated by the highest concentration of Cu-ZnO NPs compared to the control. No adverse effects on AChE activity was detected after Cu-ZnO NPs exposure. These results demonstrated that, although Cu-ZnO NPs is not acutely toxic to Ruditapes decussatus, it does exert oxidative stress on clams. These results are encouraging for the Cu-ZnO NPs use in variety of applications due to its high photocatalytic and low environmental toxicity.

Metal accumulation, biochemical and behavioral responses on the Mediterranean clams Ruditapes decussatus exposed to two photocatalyst nanocomposites (TiO2 NPs and AuTiO2NPs).

Nanoparticle decoration with noble metal represents a promising alternative to improve their photocatalytic and photovoltaic properties. However, toxicity can be influenced by such modification, as the bioavailability of these substances may be influenced. To understand how decoration influences the NP impacts in marine ecosystems, we exposed suspension-feeding clams, Ruditapes decussatus, to two photocatalyst nanocomposites, TiO2 NPs and AuTiO2 NPs, over 2 concentrations, 50 µg L-1and 100 µg L-1, in a laboratory experiment. Accumulation of Au and Ti in gills and digestive gland was noted in clams after exposure to TiO2 NPs and AuTiO2 NPs using inductively coupled plasma optic emission spectroscopy (ICP-OES). TiO2 and AuTiO2 NPs alter the behavior of the clams Ruditapes decussatus by reducing filtration and respiration rates. Furthermore, the highest concentration of TiO2NPs induces an overproduction of H2O2 in gills and digestive gland and NO production only in gills. Superoxide dismutase (SOD), Catalase (CAT), Glutathione-S-transferase (GST) and acetylcholinesterase (AChE) activities were induced in gills and digestives gland in concentration and nanocomposite type dependent manner. Decorated form presented higher Malondialdehyde (MDA) levels in gills and digestive gland than the undecorated form, suggesting different mechanisms of action that may be mediated through oxidative stress. In conclusion, the considered parameters could represent reliable biomarkers for the assessment of NP toxicity on R. decussatus as biological biomonitoring model. In addition, based on the obtained results, nanoparticle decoration influences the toxicity of metal nanoparticles in marine organism.

Gold Octahedra nanoparticles (Au_0.03 and Au_0.045): Synthesis and impact on marine clams Ruditapes decussatus.

The increased use of gold nanoparticles (AuNPs) in several applications has led to a rise in concerns about their potential toxicity to aquatic organisms. In addition, toxicity of nanoparticles to aquatic organisms is related to their physical and chemical properties. In the present study, we synthesize two forms of gold octahedra nanoparticles (Au_0.03 and Au_0.045) in 1.3-propandiol with polyvinyl-pyrrolidone K30 (PVPK30) as capping agent using polyol process. Shape, size and optical properties of the particles could be tuned by changing the molar ratio of PVP K30 to metal salts. The anisotropy in nanoparticles shape shows strong localized surface plasmon resonance (SPR) in the near infrared region of the electromagnetic spectrum. Environmental impact of Oct-AuNPs was determined in the marine bivalve, Ruditapes decussatus exposed to different concentrations of Au_0.03 and Au_0.045. The dynamic light scattering showed the stability and resistance of Au_0.03 and Au_0.045 in the natural seawater. No significant modification in vg-like proteins, MDA level and enzymatic activities were observed in treated clams with Au_0.03 even at high concentration. In contrast, Au_0.045 induced superoxide dismutase (SOD), catalase (CAT), glutathione transferase (GST) activities, in a concentration dependent manner indicating defense against oxidative stress. Enhanced lipid peroxidation represented by malondialdehyde content confirmed oxidative stress of Au_0.045 at high concentration. These results highlight the importance of the physical form of nanomaterials on their interactions with marine organisms and provide a useful guideline for future use of Oct-AuNPs. In addition, Vitellogenin is shown not to be an appropriate biomarker for Oct-AuNPs contamination even at high concentration. We further show that Oct-AuNPs exhibit an important antioxidant response without inducing estrogenic disruption.

Toxicity assessment of ZnO-decorated Au nanoparticles in the Mediterranean clam Ruditapes decussatus.

The synthesis of hybrid nanomaterials has greatly increased in recent years due to their special physical and chemical properties. However, information regarding the environmental toxicity associated with these chemicals is limited, in particular in the aquatic environment. In the present study, an experiment was performed in which the marine bivalve (Ruditapes decussatus) was exposed for 14days to 2 concentrations of zinc oxide-decorated Au nanoparticles (Au-ZnONPs: Au-ZnONP50=50µg/L; Au-ZnONP100=100µg/L). The stability and resistance of Au-ZnONPs in the natural seawater were assessed by combining transmission electron microscopy and dynamic light scattering. Inductively coupled plasma-atomic emission spectroscopy revealed uptake of these nanoparticles within clams and their ability to induce metallic deregulation. The results obtained indicate that Au-ZnONPs induce biochemical and histological alterations within either the digestive gland or gill tissues at high concentration. This was deduced from the significant increase in H2O2 level, superoxide dismutase and catalase activities and malondialdehyde content. Furthermore, the toxicity of Au-ZnO nanoparticles was linked with the increase of intracellular iron and calcium levels in both tissues. Histological alterations in gill and digestive gland were more pronounced with Au-ZnONP100 and this is likely related to oxidative mechanisms. Gill and digestive gland are differentially sensitive to Au-ZnONPs if the exposure concentration is higher than 50µg/L. In conclusion, the parameters considered here could constitute reliable biomarkers for evaluation of hybrid nanoparticles toxicity in environmental model organisms. In addition, based on the results obtained, gill and digestive gland of R. decussatus could be proposed as models to detect harmful effects of hybrid nanoparticles.

Neuroprotective Activity of Grape Seed and Skin Extract Against Lithium Exposure Using Proteomic Research.

Lithium (Li) has raised scientific concern because it represents a serious problem threatening human health. This study aimed firstly at analyzing and potentially quantifying the impact of Li and grape seed and skin extract (GSSE) separately and, secondly, describing the possible neuroprotective activity of GSSE against Li toxicity. To this end, rats were exposed for 30 days to different Li concentrations (0, 2, and 100 mg/kg bw), to GSSE (4000 mg/kg bw), and to binary mixture of Li and GSSE. Liquid chromatography (HPLC-MS/MS) analysis used for GSSE showed that 15 phenolic compounds are present in the extract. Significant modifications of proteins were detected in the brain using proteomics research after treatment. Proteins were successfully identified by a linear ion trap-Orbitrap mass spectrometer. These proteins can be roughly related to oxidative stress, glycolysis, signaling pathway, and inflammation. Additionally, proteins involved in cell junction such as myosin, spectrin, tubulin, ERM-binding phosphoprotein, and dynein were also affected by Li exposure. Dose response was detected for most expressed proteins after Li treatment. In contrast, GSSE induced the expression and/or the stabilization of some proteins changed after Li treatment in the brain showing its neuroprotective activity. These data demonstrate that proteomic analysis is a powerful tool to provide valuable insights into mechanisms of toxicity of Li in the nervous system of Wistar rats. To our knowledge, this is the first evidence of using GSSE as neuroprotective model against Li toxicity. These findings provide impetus for future investigation on GSSE against other toxic chemicals.

Effects of antifouling booster biocide Irgarol 1051 on the structure of free living nematodes: a laboratory experiment.

A mesocosm experiment was conducted to evaluate the effects of Irgarol on nematode diversity, composition and trophic structure. Sediment samples were experimentally contaminated using four increasing Irgarol concentrations [I1 (11.5 ng g(-1)), I2 (35 ng g(-1)), I3 (105 ng g(-1)) and I4 (315 ng g(-1))] and compared to non-contaminated sediments (controls). Nematode diversity as the number of nematodes species (S) and species richness (d) was significantly lower in all Irgarol treatments than in the controls while the evenness (J') increased significantly in I4 treated mesocosms. The nematode species composition significantly changed following Irgarol concentrations. Paracomesoma dubiun and Terschellingia longicaudata appeared as "tolerant" species to the highest Irgarol concentration. Additionally, Chromadorina germanica and Microlaimus cyatholaimoides appeared as "opportunistic" species. In contrast, Daptonema normandicum seemed to be a "sensitive" species to Irgarol contamination. Irgarol modified also the nematode trophic structure where the relative abundance of deposit feeders decreased significantly in all the treatments compared to control mesocosms and optional predators decreased only in treated mesocosms with I3. Epigrowth feeders increased significantly in treated mesocosms with I3 and I4 and the microvores increased with I1 and decreased with I4. The relative abundance of ciliate consumers appeared unaffected by the presence of Irgarol contamination. Our results open new perspectives on the potential impact of antifouling booster biocide Irgarol 1051 on nematode biodiversity and functional diversity as trophic structures.

Diastereomeric and enantiomeric selective accumulation of cypermethrin in the freshwater mussel Unio gibbus and its effects on biochemical parameters.

Synthetic pyrethroids are a family of chiral pesticides with a large number of stereoisomers. Cypermethrin (CYP) is used in a variety of agricultural crops, but also has public health and veterinary uses. In this work, the freshwater mussel (Unio gibbus) was chosen to evaluate the stereoselectivity of CYP through the use of gas chromatography with mass-spectrometry. The effects of CYP on mussels were examined by measuring neurotoxicity and oxidative stress biomarkers during its uptake. The investigation was performed under laboratory conditions using nominal CYP concentrations C1=100 µg/L and C2=150 µg/L over 96 h. Preferential bioaccumulation of cis-CYP isomers was observed. Furthermore, enantiomeric characterization revealed enantioselective accumulation, most probably related to mussel metabolism. Antioxidant enzyme activities (superoxide dismutase (SOD), and catalase (CAT)), and levels of reduced glutathione (GSH) and malondialdehyde (MDA) were determined in digestive gland after 4 days of exposure. CYP significantly inhibited acetylcholine esterase activity, by 51% and 57%, respectively, in mussels treated with 100 and 150 µg/L doses. The highest and lowest CYP concentrations elicited an increase of 67 and 63%, respectively, in SOD activity compared to the controls, while CAT activity was increased by 65 and 73%. A statistically significant decrease in GSH levels (40%) was observed only with the highest CYP concentration tested (150 µg/L). In addition, lipid peroxidation was significantly higher (67%) than in controls. These results provided information on CYP-enantioselective uptake and potential biomarkers that could be effectively applied for the biomonitoring of freshwater ecosystem.

Impact of the biocide Irgarol on meiofauna and prokaryotes from the sediments of the Bizerte lagoon-an experimental study.

The biocide Irgarol 1051 has been reported to have negative effects on a large number of living components including non-target organisms, but information on its impact on the marine meiofauna and benthic prokaryotes is completely lacking. Here, we report the results of long-term experimental studies in which we determined the effects of increasing Irgarol concentrations (from 11.5 to 315 ng g(-1) sediment dry weight) on meiofauna and benthic prokaryotes. We found that this biocide had a significant impact on meiofauna abundance, even at the lowest concentrations, causing a drastic decline in the abundance of nematodes (the dominant meiofaunal taxon) and an increase of the relative importance of oligochaetes. Even if no direct effects of Irgarol were found on prokaryotic abundance and biomass, the molecular fingerprinting analyses (automated ribosomal intergenic spacer analysis) showed that the prokaryotic diversity was significantly altered by the biocide. The results of the present study indicate that Irgarol 1051 in marine sediments has a significant impact on the smallest eukaryotic and microbial components also at very low concentrations (ca 12 ng g(-1)).

Effects of anthracene on filtration rates, antioxidant defense system, and redox proteomics in the Mediterranean clam Ruditapes decussatus (Mollusca: Bivalvia).

This study aimed at analyzing the impact of a toxic polyaromatic hydrocarbon (PAH), anthracene (ANT), on Ruditapes decussatus collected from a Tunisian coastal lagoon (Bizerte Lagoon). Filtration rates, several antioxidant enzymes--superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione transferase (GST)--as well as indices of protein oxidation status were determined in various tissues of this bivalve. Specimens were exposed to 100 µg/L of ANT for 2 days. ANT levels were evaluated using HPLC and were detected in the gill and digestive gland at different amounts. ANT exposure altered the behavior of bivalves by changing the siphon movement and decreasing filtration rate significantly. The enzymatic results indicated that ANT exposure affected the oxidative stress status of the gills of R. decussatus. In addition, modification of proteins was detected in the gills using redox proteomics after ANT treatment. Three protein spots were successfully identified by matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry (MALDI-TOF-MS). These proteins can be roughly related to muscle contraction function. In contrast, no significant modification of enzymatic and protein responses was detected in the digestive gland after ANT treatment. These data demonstrate that combined behavioral and biochemical analyses are a powerful tool to provide valuable insights into possible mechanisms of toxicity of anthracene in R. decussatus. Additionally, the results highlight the potential of the gill as a valuable candidate for investigating PAH toxicity.

Acute toxicity of cypermethrin on the freshwater mussel Unio gibbus.

Cypermethrin is a synthetic pyrethroid insecticide used worldwide in agriculture, home pest control, food stuff protection and disease vector control. We investigate the potential of cypermethrin to induce oxidative stress and enzyme activities within the gills of freshwater mussel Unio gibbus. This study was carried out under laboratory conditions using two nominal cypermethrin concentrations C1 (100µg/L) and C2 (150µg/L) during 96h. The measured concentrations of cypermethrin using GC-MS-MS in the treatment aquariums were respectively 59.7 µg/L and 97.5µg/L. Antioxidant enzyme activities (superoxide dismutase (SOD) and catalase (CAT)) as well as H2O2, malondialdehyde (MDA) and protein carbonyl (PCO) levels were assessed. An exposure during 96h induced the SOD activity at the highest concentration. The CAT activity and H2O2 level were increased significantly (P<0.05) in gills following a dose-dependent profile. Cypermethrin also generated an increase in malondialdehyde (MDA) levels reaching the highest value at the high concentration. The considered parameters can be used as biomarkers of exposure to cypermethrin. Freshwater mussel U. gibbus can be potentially employed in biomonitoring surveys of such threatened ecosystems.