Cadmium effects on ros production and DNA damage via adrenergic receptors stimulation: role of Na+/H+ exchanger and PKC

Genotoxicity and metabolic changes induced via ingestion of virgin and UV-aged polyethylene microplastics by the freshwater fish Perca fluviatilis

The present study aims to compare and assess the toxicity induced by aged (irradiated with ultraviolet radiation for 120 days) polyethylene microplastics (PE-MPs) in comparison to virgin (non-irradiated) ones, after feeding the freshwater fish Perca fluviatilis. To this end, MPs mediated genotoxicity was assessed by the investigation of micronucleus nuclear abnormalities frequency in fish blood, and the degree of DNA damage in the liver and muscle tissues, while metabolic alterations were also recorded in both tissues. Results showed that both virgin and aged PE-MPs induced signaling pathways leading to DNA damage and nuclear abnormalities, as well as metabolites changes in all tissues studied. Metabolic changes revealed that the metabolism of nucleic acids, energy, amino acids, and neurotransmitters was more disrupted in the liver and by aged PE-MPs compared to muscles. Fish fed with aged PE-MPs exhibited greater DNA damage, while blood cells of fish fed with virgin PE-MPs seemed to be more vulnerable to nuclear abnormalities in relation to those fed with aged PE-MPs. Moreover, aged PE-MPs induced more acute overall effects on the metabolic profiles of fish tissues, and initiated stronger stress responses, inflammation, and cellular damages in fish tissues in relation to virgin ones. Characterization of both virgin and aged MPs revealed that the latter exhibited lower crystallinity and melting point, more irregular shapes and higher moiety of oxygen and carbonyl groups, which could be attributed for their observed higher toxicity. The research outcomes provide significant insights for advancing toxicological investigations in this field.

Physiological and biochemical response in green mussel Perna viridis subjected to continuous chlorination: Perspective on cooling water discharge criteria

Heavy infestation by Perna viridis has been observed in the sub-seabed seawater intake tunnel and CWS of a tropical coastal power station in-spite of continuous low dose chlorination regime (0.2 ± 0.1 mg L-1) (CLDC), indicating periodical settlement and growth. Continuous arrival of mussels (colonized in the sub seabed tunnel intake section) at the pump house indicated that the mussels were able to tolerate and survive in a chlorinated environment, for varying time periods and were dislodged when they become weak and subsequent death, leading to flushing out of the system. In the present study, effect of continuous chlorination [0.2 mg L-1 (in-plant use); 0.5 mg L-1 (shock dose) & 1.0 mg L-1 (high levels)] was evaluated on mussels to assess; (a) time taken for mortality, (b) action of chlorine on physiological, genetic, metabolic and neuronal processes. 100% mortality of mussels was observed after 15 (0.2 mg L-1); 9 (0.5 mg L-1) and 6 days (1.0 mg L-1) respectively. Extended valve closure due to chlorination resulted in stress, impairing the respiratory and feeding behavior leading to deterioration in mussel health. Pseudofaeces excretion reduced to 68% (0.2 mg L-1); 10% (0.5 mg L-1) and 89% (1.0 mg L-1) compared to controls. Genotoxicity was observed with increase in % tail DNA fraction in all treatments such as 86% (0.2 mg L-1); 76% (0.5 mg L-1) and 85% (1.0 mg L-1). Reactive Oxygen Species (ROS) stress biomarkers increased drastically/peaked within the first 3 days of continuous chlorination with subsequent quenching by antioxidant enzymes. Gill produced highest generation of ROS; 38% (0.2 mg L-1); 97% (0.5 mg L-1); 98% (1.0 mg L-1). Additionally, it was shown that 84% (0.2 mg L-1), 72% (0.5 mg L-1), and 80.4% (1.0 mg L-1) of the neurotransmitter acetylcholinesterase activity was inhibited by chlorine at the nerve synapse. The cumulative impact of ROS generation, neuronal toxicity, and disrupted functions weakens the overall health of green mussels resulting in mortality.

Recent Trends and Developments in Multifunctional Nanoparticles for Cancer Theranostics

Conventional anticancer treatments, such as radiotherapy and chemotherapy, have significantly improved cancer therapy. Nevertheless, the existing traditional anticancer treatments have been reported to cause serious side effects and resistance to cancer and even to severely affect the quality of life of cancer survivors, which indicates the utmost urgency to develop effective and safe anticancer treatments. As the primary focus of cancer nanotheranostics, nanomaterials with unique surface chemistry and shape have been investigated for integrating cancer diagnostics with treatment techniques, including guiding a prompt diagnosis, precise imaging, treatment with an effective dose, and real-time supervision of therapeutic efficacy. Several theranostic nanosystems have been explored for cancer diagnosis and treatment in the past decade. However, metal-based nanotheranostics continue to be the most common types of nonentities. Consequently, the present review covers the physical characteristics of effective metallic, functionalized, and hybrid nanotheranostic systems. The scope of coverage also includes the clinical advantages and limitations of cancer nanotheranostics. In light of these viewpoints, future research directions exploring the robustness and clinical viability of cancer nanotheranostics through various strategies to enhance the biocompatibility of theranostic nanoparticles are summarised.

Differentiation in the expression of toxic effects of polyethylene-microplastics on two freshwater fish species: Size matters

The built up of microplastic (MPs) remains is shaping a new aquatic habitat and imposes the necessity for research of the effects that these relatively new pollutants exert on organisms, environment, and human health. The purpose of the present study was to verify if there is a particle-size dependence of fish response to MPs. Thus, we exposed two freshwater fish species, the zebrafish (Danio rerio) and perch (Perca fluviatilis) for 21 days to polyethylene microplastics (PE-MPs) sized 10-45 μm and 106-125 μm. Thereafter, in the liver and gills tissues, biochemical and molecular parameters and the metabolic profile were examined. Ex-vivo characterization by ATR-FTIR spectroscopy exhibited increased concentration of 10-45 μm PE-MPs in the liver of the two fish species while 106-125 μm PE-MPs mostly concentrated in fish gills. The penetration of PE-MPs to fish and the induced oxidative stress triggered changes in lipid peroxidation, DNA damage and ubiquitination and furthermore stimulated signal transduction pathways leading to autophagy and apoptosis. The smaller PE-MPs were more potent in inducing alterations to all the latter parameters measured than the larger ones. Tissue response in both fish seems to depend on the parameter measured and does not seem to follow a specific pattern. Our results showed that there is no clear sensitivity of one fish species versus the other, against both sizes of PE-MPs they were exposed. In perch the metabolic changes in gills were distinct to the ones observed in liver, following a size dependent pattern, indicating that stress conditions are generated through different mechanisms. All the parameters employed can be suggested further as biomarkers in biomonitoring studies against PE-MPs.

Application of land snail Helix lucorum for evaluation of genotoxicity of soil pollution

Application of native species as sentinels allows environmental scientists to determine real genotoxic impact of environmental pollutants. The present study aims at investigating the DNA damage in the land snail Helix lucorum as a biomarker of soil pollution. For this reason, the genotoxic impact of contaminated soil on H. lucorum, collected from different polluted areas, was investigated using the comet assay in haemocytes and digestive gland cells. An increase in DNA damage was found in the snails sampled from polluted sites compared with the reference one. Strong correlations between DNA damage in haemocytes and digestive gland cells with the level of contamination indicate pollution-induced genotoxic effects in both tissues. At the same time, the digestive gland was more sensitive towards pollutants compared with haemolymph. A direct relationship between concentrations of Cu, As and Mo in soil and the number of damaged cells for hаemolymph and digestive gland tissue was found. However, the data obtained reflect the total genotoxicity of all pollutants in the studied areas. Significant correlations between the DNA damage measured by the comet assay and metal contents in soil indicate that it is a suitable biomarker in ecotoxicological studies. Our results indicate the effectiveness of H. lucorum in biomonitoring of environmental pollution.

Emerging Roles of Green-Synthesized Chalcogen and Chalcogenide Nanoparticles in Cancer Theranostics

The last few decades have seen an overwhelming increase in the amount of research carried out on the use of inorganic nanoparticles. More fascinating is the tremendous progress made in the use of chalcogen and chalcogenide nanoparticles in cancer theranostics. These nanomaterials, which were initially synthesized through chemical methods, have now been efficiently produced using different plant materials. The paradigm shift towards the biogenic route of nanoparticle synthesis stems from its superior advantages of biosafety, eco-friendliness, and simplicity, among others. Despite a large number of reviews available on inorganic nanoparticle synthesis through green chemistry, there is currently a dearth of information on the green synthesis of chalcogens and chalcogenides for cancer research. Nanoformulations involving chalcogens such as sulfur, selenium, and tellurium and their respective chalcogenides have recently emerged as promising tools in cancer therapeutics and diagnosis. Similar to other inorganic nanoparticles, chalcogens and chalcogenides have been synthesized using plant extracts and their purified biomolecules. In this review, we provide an up-to-date discussion of the recent progress that has been made in the plant-mediated synthesis of chalcogens and chalcogenides with a special focus on their application in cancer theranostics.

Toxicity and Functional Tissue Responses of Two Freshwater Fish after Exposure to Polystyrene Microplastics

Microplastics (MPs)' ingestion has been demonstrated in several aquatic organisms. This process may facilitate the hydrophobic waterborne pollutants or chemical additives transfer to biota. In the present study the suitability of a battery of biomarkers on oxidative stress, physiology, tissue function and metabolic profile was investigated for the early detection of adverse effects of 21-day exposure to polystyrene microplastics (PS-MPs, sized 5-12 μm) in the liver and gills of zebrafish Danio rerio and perch, Perca fluviatilis, both of which are freshwater fish species. An optical volume map representation of the zebrafish gill by Raman spectroscopy depicted 5 μm diameter PS-MP dispersed in the gill tissue. Concentrations of PS-MPs close to the EC50 of each fish affected fish physiology in all tissues studied. Increased levels of biomarkers of oxidative damage in exposed fish in relation to controls were observed, as well as activation of apoptosis and autophagy processes. Malondialdehyde (MDA), protein carbonyls and DNA damage responses differed with regard to the sensitivity of each tissue of each fish. In the toxicity cascade gills seemed to be more liable to respond to PS-MPs than liver for the majority of the parameters measured. DNA damage was the most susceptible biomarker exhibiting greater response in the liver of both species. The interaction between MPs and cellular components provoked metabolic alterations in the tissues studied, affecting mainly amino acids, nitrogen and energy metabolism. Toxicity was species and tissue specific, with specific biomarkers responding differently in gills and in liver. The fish species that seemed to be more susceptible to MPs at the conditions studied, was P. fluviatilis compared to D. rerio. The current findings add to a holistic approach for the identification of small sized PS-MPs' biological effects in fish, thus aiming to provide evidence regarding PS-MPs' environmental impact on wild fish populations and food safety and adequacy.

Adverse effects polystyrene microplastics exert on zebrafish heart - Molecular to individual level

In the present study the effects of sublethal concentrations of polystyrene microplastics (PS-MPs) on zebrafish were evaluated at multiple levels, related to fish activity and oxidative stress, metabolic changes and contraction parameters in the heart tissue. Zebrafish were fed for 21 days food enriched with PS-MPs (particle sizes 3-12 µm) and a battery of stress indices like DNA damage, lipid peroxidation, autophagy, ubiquitin levels, caspases activation, metabolite adjustments, frequency and force of ventricular contraction were measured in fish heart, parallel to fish swimming velocity. In particular, exposure to PS-MPs caused significant decrease in heart function and swimming competence, while enhanced levels of oxidative stress indices and metabolic adjustments were observed in the heart of challenged species. Among stress indices, DNA damage was more vulnerable to the effect of PS-MPs. Our results provide evidence on the multiplicity of the PS-MPs effects on cellular function, physiology and metabolic pathways and heart rate of adult fish and subsequent effects on fish activity and fish fitness thus enlightening MPs characterization as a potent environmental pollutant.

Insights into the toxicity of biomaterials microparticles with a combination of cellular and oxidative biomarkers

Considering that the extensive biomedical, pharmaceutics, cosmetic and other industrial applications of biomaterials (BMs) is of great concern nowadays, regarding their environmental risk, the present study aimed to investigate the effects of four BMs, poly(ε-caprolactone) (PCL), poly(butylene succinate) (PBSu), chitosan (CS) and modified chitosan (succinic acid grafted chitosan) (CS-Suc) in the form of microplastics (particle sizes less than 1 mm) on biochemical parameters of snails Cornu aspersum hemocytes. Due to the absence of knowledge about the environmentally relevant concentrations of BMs, snails were initially treated through their food with a wide range of nominal concentrations of each BM to define the half maximal effective concentration (NRRT₅₀), according to the destabilization degree of hemocytes' lysosomal membranes (by mean of neutral red retention time/NRRT assay). Thereafter, snails were treated with each BM, at concentrations lower than the estimated NRRT₅₀ values in all cases, for periods up to 15 days. After the end of the exposure period, a battery of stress indices were measured in hemocytes of challenged snails. According to the results, all parameters tested in BMs-treated snails statistically differed from those measured in BMs-free snails, thus indicating the pro-oxidant potential of BMs, as well as their ability to affect animals' physiology. The most considerable effect in most cases seems to be caused by modified chitosan and PCL, while chitosan appears to be the least toxic. A common response mechanism of snails' blood cells against the 4 BMs used in the present study was shown. After exposure to each of the studied BMs a significant augmentation in protein carbonyls, MDA equivalents and DNA damage, while a significant reduction in NRRT values was determined in the snails hemocytes, in relation to the unexposed animals. From the biochemical parameters examined, MDA equivalents and DNA damage seem to be more susceptible than the other parameters studied, to respond to BMs effect, with MDA to react with more sensitivity to PCL and CS, while DNA damage to CS-Suc and PBSu. Our results could suggest the simultaneous use of the latter biomarkers in biomonitoring studies of terrestrial ecosystems against the specific BMs.

Ethyl isopropyl amiloride decreases oxidative phosphorylation and increases mitochondrial fusion in clonal untransformed and cancer cells

Many cancer cells, regardless of their tissue origin or genetic landscape, have increased expression or activity of the plasma membrane Na-H exchanger NHE1 and a higher intracellular pH (pHi) compared with untransformed cells. A current perspective that remains to be validated is that increased NHE1 activity and pHi enable a Warburg-like metabolic reprogramming of increased glycolysis and decreased mitochondrial oxidative phosphorylation. We tested this perspective and find it is not accurate for clonal pancreatic and breast cancer cells. Using the pharmacological reagent ethyl isopropyl amiloride (EIPA) to inhibit NHE1 activity and decrease pHi, we observe no change in glycolysis, as indicated by secreted lactate and intracellular pyruvate, despite confirming increased activity of the glycolytic enzyme phosphofructokinase-1 at higher pH. Also, in contrast to predictions, we find a significant decrease in oxidative phosphorylation with EIPA, as indicated by oxygen consumption rate (OCR). Decreased OCR with EIPA is not associated with changes in pathways that fuel oxidative phosphorylation or with mitochondrial membrane potential but occurs with a change in mitochondrial dynamics that includes a significant increase in elongated mitochondrial networks, suggesting increased fusion. These findings conflict with current paradigms on increased pHi inhibiting oxidative phosphorylation and increased oxidative phosphorylation being associated with mitochondrial fusion. Moreover, these findings raise questions on the suggested use of EIPA-like compounds to limit metabolic reprogramming in cancer cells.

Toxicity assessment and comparison of the land snail's Cornu aspersum responses against CuO nanoparticles and ZnO nanoparticles

The goal of the present study was to examine the effects of ZnO NPs and CuO NPs on Cornu aspersum land snail, enlightening their cytotoxic profile. ZnO NPs and CuO NPs were synthesized and thoroughly characterized. Α series of concentrations of either ZnO NPs or CuO NPs were administered in the feed of snails for 20 days. Thereafter, neutral red retention assay was conducted, in order to estimate NRRT50 values. Subsequently, snails were fed with NPs concentrations slightly lower than the concentrations that were corresponding to the NRRT50 values, i.e. 3 mg·L^-1 ZnO NPs and 6 mg·L^-1 CuO NPs, for 1, 5, 10 and 20 days. Both NPs agglomerates were detected in hemocytes by Transmission Electron Microscopy. Moreover, both effectors resulted to toxicity in the snails' hemocytes. The latter was shown by changes in the NRRT50 values, increased reactive oxygen species (ROS) production, lipid peroxidation, DNA integrity loss, protein carbonyl content, ubiquitin conjugates and cleaved caspases conjugates levels compared to the untreated animals. Although ZnO NPs exhibited higher toxicity, as indicated by the NRRT50 values, both NPs affected similarly a wide range of the cellular parameters mentioned above. The latter parameters could constitute sensitive biomarkers in biomonitoring studies of terrestrial environment against nanoparticles.

Effects of seawater acidification and cadmium on the antioxidant defense of flounder Paralichthys olivaceus larvae

Increasing atmospheric carbon dioxide has led to a decrease in the pH of the ocean, which influences the speciation of heavy metals and consequently affects metal toxicity in marine organisms. To investigate the effects of seawater acidification and metals on the antioxidant defenses of marine fishes, the flounder Paralichthys olivaceus, was continuously exposed to cadmium (Cd; control, 0.01 and 0.15 mg L^-1) and acidified seawater (control (pH 8.10), 7.70 and 7.30) for 49 days from embryogenesis to settlement. The results demonstrated that both Cd and acidified seawater could induce oxidative stress and consequently cause lipid peroxidation (LPO) in the larvae. Antioxidants (i.e., superoxide dismutase, SOD; catalase, CAT; reduced glutathione, GSH; glutathione S-transferase, GST; glutathione peroxidase, GPx; and glutathione reductase, GR) functioned to defend the larvae against oxidative damage. Overall, Cd induced (SOD, GST and GSH) or inhibited (CAT and GPx) the enzymatic activities or contents of all the selected antioxidants except for GR. The antioxidants responded differently to seawater acidification, depending on their interaction with the metal. Similarly, the mRNA expressions of the antioxidant-related genes were upregulated (sod, gr and gst) or downregulated (cat and gpx) in response to increasing Cd exposure. Seawater acidification did not necessarily affect all of the biomarkers; in some cases (e.g., SOD and sod, GR and gr), Cd stress may have exceeded and masked the stress from seawater acidification in regulating the antioxidant defense of the larvae. The integrated biomarker response (IBR) was enhanced with increasing levels of the stressors. These findings support the hypothesis that seawater acidification not only directly affects the antioxidant defense in flounder larvae but also interacts with Cd to further regulate this defense. This study has ecological significance for assessing the long-term impacts of ocean acidification and metal pollution on the recruitment of fish populations in the wild.

Common mechanisms activated in the tissues of aquatic and terrestrial animal models after TiO2 nanoparticles exposure

Titanium dioxide nanoparticles (TiO₂-NPs) are among the most popular manufactured and widely used nanoparticles. They are released into the environment, affecting terrestrial and aquatic ecosystems, with unexpected consequences to organisms and human health. The present study investigates the mediated toxicity imposed to the freshwater fish species, zebrafish (Danio rerio) and the prussian carp (Carassius gibelio), and to the terrestrial land snail Cornu aspersum, after their exposure to sublethal concentrations of TiO₂-NPs. Oxidative, proteolytic, genotoxic and apoptotic parameters in fish liver and gills, as well as on snail hemocytes were studied and the swimming performance was estimated in order to (a) estimate and suggest the most susceptible animal, and (b) propose a common battery of biomarkers as the most suitable indicator for biomonitoring studies against TiO₂-NPs. Our in vivo experiments demonstrated that NPs induced detrimental effects on animal physiology and swimming behavior, while no general pattern was observed in species and tissues responsiveness. Generally, TiO₂-NPs seemed to activate a group of molecules that are common for aquatic as well as terrestrial animals, implying the existence of a conserved mechanism. It seems that after exposure to TiO₂-NPs, a common mechanism is activated that involves the stimulation of immune system with the production of ROS, damage of lysosomal membrane, protein carbonylation, lipid peroxidation, DNA damage, following proteolysis by ubiquitin and finally apoptosis. Thus, the simultaneous use of the latter biomarkers could be suggested as a reliable multi parameter approach for biomonitoring of aquatic and terrestrial ecosystems against TiO₂-NPs.

Escherichia coli-based synthesis of cadmium sulfide nanoparticles, characterization, antimicrobial and cytotoxicity studies

The present research describes the synthesis of cadmium sulfide (CdS) nanoparticles from Escherichia coli under the influence of bacterial enzyme sulphate reductase and study on their cytotoxicity for applications in cancer therapy. Escherichia coli cells were used to synthesize CdS nanoparticles under different concentrations of cadmium chloride and sodium sulfide. The morphology of the nanoparticles was analysed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) was used for elemental analysis of nanoparticles. Fourier-transform infrared spectroscopy analysis (FTIR) was performed to assess the functional groups of the nanoparticles. Crystalline nature of nanoparticles was assessed using powder X-ray diffraction (XRD). Antibacterial studies of CdS nanoparticles were carried out on foodborne pathogens and cytotoxicity studies were carried out on Mus musculus skin melanoma (B16F10) and human epidermoid carcinoma (A431) cell lines. CdS nanoparticle showed more cytotoxic effect on cancer cells compared with standard 5-aminolevulinic acid (5-ALA). The Escherichia coli-synthesized CdS nanoparticles showed highest zone of inhibition in the ratio 4:1 of cadmium chloride and sodium sulfide on all tested bacterial strains. The nanoparticles were also tested for haemolytic activity on RBC cells, which exhibited lower cytotoxicity than sodium dodecyl sulphate which was used as positive control. The cytotoxicity of CdS nanoparticles assessed on A431 cells showed an inhibition of 81.53% at 100 μM concentration while the cytotoxicity assessed on B16F10 cells showed an inhibition of 75.71% at 200 μM concentration which was much efficient than 5-ALA which showed an inhibition of 31.95% at a concentration against B16F10 cells and 33.45% against A431 cells at a concentration of 1 mM. Cadmium sulfide nanoparticles were thus found to be highly toxic on cancer cells compare with standard anticancerous drug 5-ALA.

Magnetite nanoparticles effects on adverse responses of aquatic and terrestrial animal models

Among pollutants, nanoparticles (NPs) consist a potential environmental hazard, as they could possibly harm the aquatic and terrestrial ecosystems while having unpredictable repercussions on human health. Since monitoring the impact of NPs on aquatic and terrestrial life is challenging, due to the differential sensitivities of organisms to a given nanomaterial, the present study examines magnetite nanoparticles' mediated toxicity in different animal models, representing distinctive environments (terrestrial and aquatic). Oxidative, proteolytic and genotoxic effects were evaluated on the hemocytes of the snail Cornu aspersum; in addition to those, apoptotic effects were measured in gills and liver of the zebrafish Danio rerio, and the prussian carp Carassius gibelio. All biochemical parameters studied increased significantly in animals after 8 days exposure to NPs. Inter-species and inter-tissues differences in responses were evident. Our results suggest a common toxicity response mechanism functioning in the tissues of the three animals studied that is triggered by magnetite NPs. The simultaneous use of these parameters could be established after further investigation as a reliable multi-parameter approach for biomonitoring of terrestrial and aquatic ecosystems against magnetite nanoparticles. Additionally, the results of our study could contribute to the design of studies for the production and rational utilization of nanoparticles.

Resveratrol alleviate the injury of mice liver induced by cadmium sulfide nanoparticles

Cadmium sulfide nanoparticle (Nano-CdS) is a kind of important semiconductor material with special photochemistry property. With the Nano-CdS being widely used, the security problems it caused have been catching more and more attention. This study aims to explore the possible mechanism of liver injury induced by Nano-CdS and whether resveratrol can reduce the damage. In this study, male BALB/C mice were treated with Nano-CdS with a diameter of 20 to 30 nm and a length of 80 to 100 nm. It turned out that the mice liver inflammatory cells infiltrated, the liver tissue and the ultrastructure changed; The activities of T-AOC and GSH were suppressed (n = 6, P < 0.05) and the content of lipid peroxide (MDA) increased (n = 6, P < 0.05). Besides, Nano-CdS decreased the mRNA expression level of Sirt1 and FoxO1 genes in liver tissue (n = 3, P < 0.05). All the changes in the index were reversed by resveratrol. The mRNA expression level of FoxO3a showed no significant difference between the control group and the Nano-CdS group. But under the protection of resveratrol, the mRNA expression level of FoxO3a was higher than that in the control and Nano-CdS groups (n = 3, P < 0.05). Results suggest that Nano-CdS can cause oxidative damages to liver tissues in mice, in which process that the Sirt1 and FoxO1 genes may participate, and the damage can be reversed by resveratrol which may be a potential cure for oxidative damage to nanomaterials.

Trace metals and oxidative status in soft tissues of caged mussels (Aulacomya atra) on the North Patagonian coastline

This study investigated metal accumulation and oxidative effects in mantle, gill and digestive gland of the ribbed mussel Aulacomya atra from the Argentinean North Patagonian coastline. Mussels were transplanted over an 18-month period from a site with low anthropogenic impact to a harbor site with higher seawater concentration of aluminum, chromium, copper, manganese, nickel and zinc. Total trace metal concentration in seawater did not change throughout the 18-month transplant in either site. A. atra bioaccumulated metals in digestive gland, gills and mantle at different levels. Digestive gland had the highest concentration of metals, especially towards the end of the transplant experiment in the harbor area. Mussels transplanted to the harbor site experienced an upregulation in their antioxidant system, which likely explains the lack of oxidative damage to lipids despite higher metal accumulation. These results demonstrate that A. atra selectively accumulates metals from the water column and their prooxidant effects depend on the tissue antioxidant defenses and the exposure time.

Seawater Acidification Reduced the Resistance of Crassostrea gigas to Vibrio splendidus Challenge: An Energy Metabolism Perspective

Negative physiological impacts induced by exposure to acidified seawater might sensitize marine organisms to future environmental stressors, such as disease outbreak. The goal of this study was to evaluate if ocean acidification (OA) could reduce the resistance capability of the Pacific oyster (Crassostrea gigas) to Vibrio splendidus challenge from an energy metabolism perspective. In this study, the Pacific oyster was exposed to OA (pH 7.6) for 28 days and then challenged by V. splendidus for another 72 h. Antioxidative responses, lipid peroxidation, metabolic (energy sensors, aerobic metabolism, and anaerobic metabolism) gene expression, glycolytic enzyme activity, and the content of energy reserves (glycogen and protein) were investigated to evaluate the environmental risk of pathogen infection under the condition of OA. Our results demonstrated that following the exposure to seawater acidification, oysters exhibited an energy modulation with slight inhibition of aerobic energy metabolism, stimulation of anaerobic metabolism, and increased glycolytic enzyme activity. However, the energy modulation ability and antioxidative regulation of oysters exposed to seawater acidification may be overwhelmed by a subsequent pathogen challenge, resulting in increased oxidative damage, decreased aerobic metabolism, stimulated anaerobic metabolism, and decreased energy reserves. Overall, although anaerobic metabolism was initiated to partially compensate for inhibited aerobic energy metabolism, increased oxidative damage combined with depleted energy reserves suggested that oysters were in an unsustainable bioenergetic state and were thereby incapable of supporting long-term population viability under conditions of seawater acidification and a pathogen challenge from V. splendidus.

Insights into the toxicity of iron oxides nanoparticles in land snails

The use of manufactured nanoparticles (NPs) is spreading rapidly across technology and medicine fields, posing concerns about their consequence on ecosystems and human health. The present study aims to assess the biological responses triggered by iron oxide NPs (IONPs) and iron oxide NPs incorporated into zeolite (IONPZ) in relation to oxidative stress on the land snail Helix aspersa in order to investigate its use as a biomarker for terrestrial environments. Morphology and structure of both NPs were characterized. Snail food was supplemented with a range of concentrations of IONPs and IONPZ and values of the hemocyte lysosomal membranes' destabilization by 50% were estimated by the neutral red retention (NRRT50) assay. Subsequently, snails were fed with NPs concentrations equal to half of the NRRT50 values, 0.05 mg L^-1 for IONPs and 1 mg L^-1 for IONPZ, for 1, 5, 10 and 20 days. Both effectors induced oxidative stress in snails' hemocytes compared to untreated animals. The latter was detected by NRRT changes, reactive oxygen species (ROS) production, lipid peroxidation estimation, DNA integrity loss, measurement of protein carbonyl content by an enzyme-linked immunoabsorbent assay (ELISA), determination of ubiquitin conjugates and cleaved caspases conjugates levels. The results showed that the simultaneous use of the parameters tested could constitute possible reliable biomarkers for the evaluation of NPs toxicity. However, more research is required in order to enlighten the disposal and toxic impact of iron oxide NPs on the environment to ensure their safe use in the future.

Ocean acidification stimulates alkali signal pathway: A bicarbonate sensing soluble adenylyl cyclase from oyster Crassostrea gigas mediates physiological changes induced by CO2 exposure

Ocean acidification (OA) has been demonstrated to have severe effects on marine organisms, especially marine calcifiers. However, the impacts of OA on the physiology of marine calcifiers and the underlying mechanisms remain unclear. Soluble adenylyl cyclase (sAC) is an acid-base sensor in response to [HCO₃^-] and an intracellular source of cyclic AMP (cAMP). In the present study, an ortholog of sAC was identified from pacific oyster Crassostrea gigas (designated as CgsAC) and the catalytic region of CgsAC was cloned and expressed. Similar to the native CgsAC from gill tissues, the recombinant CgsAC protein (rCgsAC) exhibited [HCO₃^-] mediated cAMP-forming activity, which could be inhibited by a small molecule KH7. After 16days of CO₂ exposure (pH=7.50), the mRNA transcripts of CgsAC increased in muscle, mantle, hepatopancreas, gill, male gonad and haemocytes, and two truncated CgsAC forms of 45kD and 20kD were produced. Cytosolic CgsAC could be translocated from the cytoplasm and nuclei to the membrane in response to CO₂ exposure. Besides, CO₂ exposure could increase the production of cAMP and intracellular pH of haemocytes, which was regulated by CgsAC (p<0.05), suggesting the existence of a [HCO₃^-]/CgsAC/cAMP signal pathway in oyster. The elevated CO₂ could induce an increase of ROS level (p<0.05) and a decrease of phagocytic rate of haemocytes (p<0.05), which could be inhibited by KH7. The results collectively suggest that CgsAC is an important acid-base sensor in oyster and the [HCO₃^-]/CgsAC/cAMP signal pathway might be responsible for intracellular alkalization effects on oxidative phosphorylation and innate immunity under CO₂ exposure. The changes of intracellular pH, ROS, and phagocytosis mediated by CgsAC might help us to further understand the effects of ocean acidification on marine calcifiers.

Human pharmaceuticals in the marine environment: Focus on exposure and biological effects in animal species

Marine waters have been poorly investigated for the occurrence of pharmaceutical contamination. Recent data confirm that pharmaceuticals occur widely in marine and coastal environments; therefore, assessment of potential risk to marine species needs further efforts. The present study represents the first extensive review of pharmaceutical contamination in marine environments addressing the effects on the marine biota analyzed at the molecular, cellular, and individual levels. Because pharmaceuticals differ from conventional pollutants, being designed to interact with specific physiological pathways at low doses, the most recent evidence on modes of action and physiological alterations on marine animal species are discussed. Data on spatial distributions of pharmaceuticals in waters and sediments, as well as bioaccumulation rates, are also presented. The present review also seeks to expand knowledge of how the quality of coastal and marine environments could be efficiently monitored to anticipate possible health and environmental risks.

Toxicity assessment and comparison between two types of iron oxide nanoparticles in Mytilus galloprovincialis

Nanoparticles (NPs), due to their increased application and production, are being released into the environment with unpredictable impact on the physiology of marine organisms, as well as on entire ecosystems and upcoming effects on human health. The aim of the present study was to evaluate and compare the oxidative responses of the mussel Mytilus galloprovincialis after exposure to iron oxide NPs and to iron oxide NPs incorporated into zeolite for 1, 3 and 7 days. Our results showed that both effectors induced changes on animal physiology by causing oxidative stress in hemocytes of exposed mussels compared to control animals. This was shown by the significant increase in reactive oxygen species (ROS) production, protein carbonylation, lipid peroxidation, ubiquitin conjugates and DNA damage. In addition an increase in prooxidant levels as measured by the prooxidant-antioxidant balance (PAB) assay was observed in exposed mussels' hemolymph. The results show that ROS, DNA damage, protein and lipid oxidation, ubiquitin conjugates and PAB could constitute, after further investigation, reliable biomarkers for the evaluation of pollution or other environmental stressors. In addition, more studies are needed in order to ensure the safety of these NPs on various biomedical applications, since it is critical to design NPs that they meet the demands of application without causing cellular toxicity.

Effects of environmental hypercapnia and metal (Cd and Cu) exposure on acid-base and metal homeostasis of marine bivalves

Elevated CO2 levels reduce seawater pH and may affect bioavailability of trace metals in estuaries. We studied the interactive effects of common metal pollutants (50 μg l(-1) Cd or Cu) and PCO2 (~395, 800 and 2000 μatm) on metal levels, intracellular pH, expression of metal binding proteins and stress biomarkers in estuarine bivalves Crassostrea virginica (oysters) and Mercenaria mercenaria (hard clams). Cd (but not Cu or hypercapnia) exposure affected the acid-base balance of hemocytes resulting in elevated intracellular pH. Cd and Cu exposure led to the increase in the tissue metal burdens, and metal accumulation was reduced by elevated PCO2 in the mantle but not hemocytes. No change was found in the intracellular free Cd(2+), Cu(2+) or Fe(2+) during Cu or Cd exposure indicating that these metals are bound to intracellular ligands. Free Zn(2+) content in oyster hemocytes was suppressed by Cd and Cu exposure and below the detection limits in clam hemocytes, which went hand-in-hand with the elevated mRNA expression of metallothioneins and ferritin in Cd- and Cu-exposed bivalves, enhanced by hypercapnia. The metal-binding and antioxidant mechanisms of oysters and clams were sufficient to effectively maintain intracellular redox status, even though metal exposure combined with moderate hypercapnia (~800 μatm PCO2) led to the elevated production of reactive oxygen species in hemocytes. Overall, while hypercapnia modulates metal accumulation, binding capacity and oxidative stress in estuarine bivalves, the physiological effects of elevated CO2 are mild compared to the effects of other common stressors.

Genotoxicity and Cytotoxicity of Cadmium Sulfide Nanomaterials to Mice: Comparison Between Nanorods and Nanodots

Cadmium sulfide (CdS) nanomaterials (such as CdS nanodots or nanorods) are widely used in optical, electronic, and biological applications. Large-scale production and use of these materials will likely result in accidental and incidental releases, which raise concerns about their potential environmental and human-health impacts. Most studies on toxicity of Cd-containing nanomaterials have focused on nanodots, and the relative toxicity of Cd-containing nanorods is not well understood. Here, we compared genotoxicity and cytotoxicity of CdS nanorods (30-50 nm diameter, 500-1100 nm length) and cubic CdS nanodots (3-5 nm) in mice by examining total cadmium accumulation in organs, acute toxicity, DNA damage, spermatozoon viability and abnormality, kidney and liver damage, and oxidative stress. Compared with (smaller) nanodots, nanorods resulted in relatively low bioaccumulation, acute toxicity, and damage to spermatozoa and the tested organs. Differences in toxicity between CdS nanodots and nanorods could not be fully explained by differences in their metal ion (Cd²⁺) release patterns, based on control tests with mice gavaged with dissolved CdCl₂ at equivalent concentrations. This underscores that toxicity of metallic nanomaterials could not be solely predicted based either on their elemental composition or on the amount of ions released before receptor intake. Particle morphology (including size) may also need to be considered.

Inhibition of DNA methylation attenuates low-dose cadmium-induced cardiac contractile and intracellular Ca(2+) anomalies

(1) Cadmium is a human carcinogen with unfavourable health impacts probably associated with its DNA methylation property. Recent data suggest that environmental cadmium exposure is associated with the incidence of myocardial infarction and peripheral arterial disease. Nonetheless, the effect of chronic cadmium exposure on cardiac contractile function remains unknown. (2) The present study was designed to examine the impact of low-dose cadmium exposure on cardiac contractile function and intracellular Ca2+ homeostasis. Adult male mice were exposed to cadmium for 4 weeks (20 nmol/kg, i.p. every other day for 4 weeks) with or without the DNA methylation inhibitor 5-aza-2'-deoxyctidene (5-AZA; 0.25 mg/kg, i.p., twice a week for 6 weeks, starting at the same time as cadmium administration). Cardiac contractile and intracellular Ca2+ properties were analysed, including echocardiographic left ventricular parameters, fractional shortening (FS), peak shortening (PS) amplitude, maximal velocity of shortening/relengthening (±dL/dt), time to PS (TPS), time to 90% relengthening (TR90 ), electrically stimulated increases in intracellular Ca2+ and intracellular Ca2+ decay. (3) Cadmium exposure depressed FS, PS, ±dL/dt and electrically stimulated increases in intracellular Ca2+ without affecting TPS, TR90 , intracellular Ca2+ levels or the decay rate. The effects of cadmium were significantly attenuated (PS) or blocked altogether (all other parameters) by 5-AZA. Cadmium exposure led to overt interstitial fibrosis (collagen deposition), which was mitigated by 5-AZA treatment. Western blot analysis revealed that cadmium exposure and/or 5-AZA treatment had no effect on the expression of intercellular adhesion molecule-1, tumour necrosis factor-α and cleaved caspase 3, suggesting a relatively minor role of proinflammatory cytokines and apoptosis in the cardiac responses to cadmium and 5-AZA. (4) Together, our data demonstrate, for the first time, direct cardiac depressant effects following cadmium exposure, which may be rescued by inhibition of DNA methylation.

Oxidative stress parameters induced by exposure to either cadmium or 17β-estradiol on Mytilus galloprovincialis hemocytes. The role of signaling molecules

The aim of the present study was to determine and compare the possible effects of exposure to an estrogen, 17β-estradiol and to a metal, cadmium on oxidative parameters of Mytilus galloprovincialis hemocytes and to elucidate the signaling pathways that probably mediate the studied effects exerted by these two chemicals. In addition, it was of interest to investigate if the studied parameters could constitute biomarkers for aquatic pollution monitoring. Our results suggest that micromolar concentrations of either cadmium or 17β-estradiol affected the redox status of mussels by modulating oxidative parameters and antioxidant enzymes gene expression in mussel M. galloprovincialis hemocytes. In particular, our results showed that treatment of hemocytes with either 5 μM of cadmium chloride or with 25 nM of 17β-estradiol for 30 min caused significant increased ROS production; this led to oxidative damage exemplified by significant increased DNA damage, protein carbonylation and lipid peroxidation, as well as increased mRNA levels of the antioxidant enzymes catalase (CAT), superoxide dismoutase (SOD) and glutathione S-transferase (GST). Furthermore, our results suggest that either cadmium or 17β-estradiol signal is mediated either through one of the already known pathways initiated by photatidyl-inositol 3-kinase (PI3K) and reaching Na(+)/H(+) exchanger (NHE) probably through protein kinase C (PKC) or a kinase-mediated signaling pathway that involves in most of the cases NHE, PKC, Ca(2+)-dependent PKC isoforms, PI3-K, NADPH oxidase, nitric oxide (NO) synthase, c-Jun N-terminal kinase (JNK) and cyclic adenosine-3'-5'-monophosphate (cAMP). Our results also attribute a protective role to cAMP, since pre-elevated intracellular cAMP levels inhibited the signal induced by each exposure. Finally, since aquatic invertebrates have been the most widely used monitoring organisms for pollution impact evaluation in marine environments and taking under consideration the positive correlation obtained between the studied parameters, we can suggest the simultaneous use of these oxidative stress parameters offering an effective early warning system in biomonitoring of aquatic environments.

Environmental and human risk assessment of landfill leachate: an integrated approach with the use of cytotoxic and genotoxic stress indices in mussel and human cells

The present study investigates leachate hazardous effects on marine biota and human cells, with the use of a battery of assays, both under in vivo and in vitro conditions. According to the results, mussels exposed for 4 days to 0.01 and 0.1% (v/v) of leachate showed increased levels of DNA damage and micronuclei (MN) frequencies in their hemocytes. Similarly, enhanced levels of DNA damage were also observed in hemocytes treated in vitro with relevant concentrations of leachate, followed by a significant enhancement of both superoxide anions (O₂(-)) and lipid peroxidation products (malondialdehyde/MDA). On the other hand, human lymphocyte cultures treated with such a low concentrations of leachate (0.1, 0.2 and 1%, v/v), showed increased frequencies of MN formation and large MN size ratio, as well as decreased cell proliferation, as indicated by the use of the cytokinesis block micronucleus (CBMN) assay and Cytokinesis Block Proliferation Index (CBPI) respectively. These findings showed the clear-cut genotoxic and cytotoxic effects of leachate on both cellular types, as well as its potential aneugenic activity in human lymphocytes.

Short-term acute hypercapnia affects cellular responses to trace metals in the hard clams Mercenaria mercenaria

Estuarine and coastal habitats experience large fluctuations of environmental factors such as temperature, salinity, partial pressure of CO2 ( [Formula: see text] ) and pH; they also serve as the natural sinks for trace metals. Benthic filter-feeding organisms such as bivalves are exposed to the elevated concentrations of metals in estuarine water and sediments that can strongly affect their physiology. The effects of metals on estuarine organisms may be exacerbated by other environmental factors. Thus, a decrease in pH caused by high [Formula: see text] (hypercapnia) can modulate the effects of trace metals by affecting metal bioavailability, accumulation or binding. To better understand the cellular mechanisms of interactions between [Formula: see text] and trace metals in marine bivalves, we exposed isolated mantle cells of the hard clams (Mercenaria mercenaria) to different levels of [Formula: see text] (0.05, 1.52 and 3.01 kPa) and two major trace metal pollutants - cadmium (Cd) and copper (Cu). Elevated [Formula: see text] resulted in a decrease in intracellular pH (pHi) of the isolated mantle cells from 7.8 to 7.4. Elevated [Formula: see text] significantly but differently affected the trace metal accumulation by the cells. Cd uptake was suppressed at elevated [Formula: see text] levels while Cu accumulation has greatly accelerated under hypercapnic conditions. Interestingly, at higher extracellular Cd levels, labile intracellular Cd(2+) concentration remained the same, while intracellular levels of free Zn(2+) increased suggesting that Cd(2+) substitutes bound Zn(2+) in these cells. In contrast, Cu exposure did not affect intracellular Zn(2+) but led to a profound increase in the intracellular levels of labile Cu(2+) and Fe(2+). An increase in the extracellular concentrations of Cd and Cu led to the elevated production of reactive oxygen species under the normocapnic conditions (0.05 kPa [Formula: see text] ); surprisingly, this effect was mitigated in hypercapnia (1.52 and 3.01 kPa). Overall, our data reveal complex and metal-specific interactions between the cellular effects of trace metals and [Formula: see text] in clams and indicate that variations in environmental [Formula: see text] may modulate the biological effects of trace metals in marine organisms.

Influence of cadmium on the morphology and functionality of haemocytes in the compound ascidian Botryllus schlosseri

In order to get insights into the effects of cadmium (Cd) on cell morphology and functions, we exposed haemocytes of the colonial ascidian Botryllus schlosseri to sub-lethal concentrations of CdCl(2). Results indicate that Cd hampers haemocyte spreading and phagocytosis in a dose-dependent way, through the alteration of the actin cytoskeleton. In addition, the metal decreases the stability of the internal membranes, as revealed by the Neutral Red assay. The fraction of cells showing positivity for the lysosomal enzyme acid phosphatase is also reduced in the presence of Cd, whereas the number of cells responsive to the Annexin-V assay and showing chromatin condensation increases, suggesting a metal-dependent induction of apoptosis in exposed cells. As Cd is a known cause of oxidative stress, the decrease in the percentage of cells positive to the assay for superoxide anion, observed at low Cd concentrations, is indicative of the synthesis of metal-chelating molecules, such as metallothioneins, whereas, the increase at high Cd concentrations suggests a depletion of the cell reducing redox potential.

Antioxidant and pro-oxidant challenge of tannic acid in mussel hemocytes exposed to cadmium

The present study investigates the antioxidant and pro-oxidant behavior of tannic acid (TA) in hemocytes of mussel Mytilus galloprovincialis, in the presence or the absence of cadmium (Cd). TA at concentrations up to 20 μM, primarily found to be no toxic (in terms of cell viability, superoxide anions, nitric oxide and lipid peroxidation products currently estimated), significantly diminished the cytotoxic and oxidative effects induced by the metal (50 and/or 100 μM) in all cases. On the other hand, higher concentrations of TA (40 and 60 μM) were toxic, thus enhancing Cd-mediated cytotoxic and oxidative effects. The present study showed TA beneficiary properties in hemocytes of mussels, at least at low concentrations, while TA at concentrations higher than 20 μM could serve as an excellent oxidized substrate, thus enhancing toxic effects either alone or with the presence of micromolar concentrations of non transition metals, such as Cd.

Biomarkers in marine mussels, Mytilus galloprovincialis, exposed to environmentally relevant levels of the pesticides, chlorpyrifos and penoxsulam

The present study examines the influence of environmentally relevant concentrations of two pesticides, chlorpyrifos and penoxsulam on mussel physiological status. For this reason, lysosomal membrane stability (LMS), reactive oxygen species (ROS), DNA damage, protein carbonylation (PCC) and antioxidant capacity (TAC) in hemaolymph and hemocytes of the mussels was measured. Mussels were exposed to a range of concentrations of the pesticides chlorpyrifos and penoxsulam and the response of animals to the destabilization of lysosomal membrane in hemocytes (LMS) was studied. Subsequently, the half maximal effective concentration (EC50) for both pesticides was calculated. The animals were subsequently exposed for 0, 1, 3, 5, 7, 15 and 30 days to 10 times less concentration than EC50 of each pesticide (0.05 μg/l) and changes in LMS, ROS, DNA damage, protein carbonylation and antioxidant capacity of mussels was evaluated. Our results showed a significant change in the response of mussels for all parameters tested after 30 days exposure, in relation to the controls. The pesticides at the environmental concentrations used induced changes to the animal physiology through causing oxidative stress and lysosomal abnormalities and their usage in the agriculture demands great care. In addition, the results show that ROS, DNA damage, protein carbonylation and antioxidant capacity could constitute, after further investigation, reliable biomarkers for the evaluation of pollution or other environmental stressors.

Evidence for phosphatidylinositol-3-OH-kinase (PI3-kinase) involvement in Cd-mediated oxidative effects on hemocytes of mussels

This study investigated phosphatidylinositol-3-OH-kinase (PI3-kinase) involvement in the induction of cadmium-mediated oxidative effects on hemocytes of mussel Mytilus galloprovincialis. PI3-kinase was investigated with the use of wortmannin, a specific covalent inhibitor of PI3-kinase. Moreover, phorbol-myristate acetate (PMA), a well-known protein kinase C (PKC)-mediated NADPH oxidase and nitric oxide (NO) synthase stimulator, was also used for elucidating PI3-kinase involvement during the respiratory burst process in challenge hemocytes. According to the results, cells pre-treated with non-toxic concentrations of wortmannin (1 and/or 50 nM, as revealed by neutral red retention assay) for 15 min, showed a significant attenuation of cadmium ability (at concentration of 50 μM) to promote cell death, superoxide anion (O(2)(-)) production, NO generation and lipid peroxidation (in terms of malondialdehyde equivalents). On the other hand, wortmannin-treated cells showed a significant attenuation of PMA ability to induce NO generation but not O(2)(-) production. These findings reveal that PI3-kinase could lead to a PKC-independent induction of NO synthase activity in cells faced with pro-oxidants, such as cadmium, while its activation could be fundamental for the regulation of NAPDH oxidase activity, probably through a PKC-dependent signaling pathway.

Effects of organic contaminants in reactive oxygen species, protein carbonylation and DNA damage on digestive gland and haemolymph of land snails

The present study focused on early responses of land snails Eobania vermiculata to organic environmental contaminants, by investigating the use of a newly-established method for the measurement of protein carbonylation as a new biomarker of terrestrial pollution, as well as by measuring the ROS production and the DNA damage. Land snails were exposed to different concentrations of chlorpyrifos, parathion-methyl or PAHs in vivo or in vitro in the laboratory. The susceptibility of exposed snails was increased in relation to oxidative stress induced by contaminants tested. A statistically significant increase in ROS production, protein carbonylation and DNA damage was revealed in the snails treated with pollutants, compared to the untreated ones. The results indicated the effectiveness of measuring ROS production and DNA damage and reinforce the application of the present ELISA method in organic terrestrial pollution biomonitoring studies.

Effect of 17β-estradiol on adhesion of Mytilus galloprovincialis hemocytes to selected substrates. Role of alpha2 integrin subunit

The process of hemocyte adhesion to extracellular matrix (ECM) proteins plays a crucial role in cell immunity. In most of these interactions between ECM proteins and cells, integrins are involved. The results of the present study showed that incubation of Mytilus galloprovincialis hemocytes with 17β-estradiol caused significant increased adhesion of hemocytes to ECM proteins and specifically to laminin-1, collagen IV and oxidized collagen IV, in relation to control cells. The adhesion of hemocytes to oxidized collagen was significantly higher than to either collagen IV or to laminin-1. In accordance with this, inhibition of either NADPH oxidase or nitric oxide (NO) synthase attenuated 17β-estradiol effect on hemocyte adhesion, suggesting that the high levels of free radicals, produced after 17β-estradiol effect, could contribute to the high adhesion of hemocytes to laminin-1 and collagen IV. The implication of ROS was further confirmed by the use of the oxidant rotenone, which caused elevation of cell adhesion in relation to control and by the antioxidant NAC which attenuated 17β-estradiol effect. The mechanism of 17β-estradiol induced adhesion to laminin-1, collagen IV and oxidized collagen IV involves a large number of intracellular components, as Na+/H+ exchanger (NHE), all isoforms of protein kinase C (PKC), phosphatidylinositol-3-kinase (PI3K) and c-jun N-terminal kinase (JNK) as well as alpha2 integrin subunit. Maintenance of high cyclic adenosine-3'-5'-monophosphate (cAMP) levels caused non significant higher adhesion of hemocytes to ECM proteins in relation to control cells. Our results showed that 17β-estradiol caused a significant increase in α₂ integrin subunit levels, which was reduced after inhibition of NHE, PI3K, PKC, NO synthase, NADPH oxidase and JNK. In addition, our results showed that apart from 17β-estradiol, high cAMP and high ROS levels caused significantly higher induction of α₂ integrin subunit levels in relation to control. Our results imply a potential involvement of cAMP in immune responses of Mytilus hemocytes, which needs further investigation.

In vivo and in vitro effects of metals in reactive oxygen species production, protein carbonylation, and DNA damage in land snails Eobania vermiculata

Heavy metals are known to induce oxidative damage by way of enhancement of intracellular reactive oxygen species (ROS) production, which often preludes the onset of alterations, such as protein carbonylation and DNA damage. In this study, our aim was to examine the early responses of land snails Eobania vermiculata to environmental contaminants by investigating the use of a modified enzyme-linked immunosorbent assay (ELISA) assay for the measurement of protein carbonylation as a new biomarker of terrestrial pollution as well as by measuring ROS production and DNA damage. Land snails were treated with heavy metals-cadmium, lead, or copper-in vivo (15 or 40 ppm) for 25 days or in vitro (0.5, 5, 50 or 500 μM) for 30 min in the laboratory, and the previously mentioned biomarkers were determined in digestive gland and haemolymph of the treated animals. A statistically significant increase in ROS production, protein carbonylation, and DNA damage was shown in the snails treated with pollutants compared with the untreated snails. The results indicate the effectiveness of measuring ROS production and DNA damage, as well as using the present ELISA method, as sensitive tools of terrestrial pollution biomonitoring studies. Statistically significant correlations among the previously mentioned techniques further enhance their role as promising biomarkers in terrestrial pollution studies.

The β-blocker propranolol affects cAMP-dependent signaling and induces the stress response in Mediterranean mussels, Mytilus galloprovincialis

Widespread occurrence of pharmaceuticals is reported in aquatic systems, posing concerns for the health of aquatic wildlife and a theoretical risk to humans. A recent concept was developed for the identification of highly active compounds amongst the environmental pharmaceuticals, based on their mode of action, the homology between human targets and possible targets in the environment, and the importance of the affected pathway for the target species. In line with this approach, this study investigated whether propranolol (PROP) affects the cAMP-dependent pathway in Mediterranean mussels, Mytilus galloprovincialis. PROP is a prototypical β-adrenoceptor antagonist, and these receptors exist in bivalves and show gross pharmacological properties similar to their mammalian counterparts. PROP also acts as a 5-HT1 receptor antagonist, which is the sole 5-HT receptor reported in bivalves to date. Importantly, β-adrenoceptor and 5HT-1 receptor subtypes are positively and negatively coupled to cAMP-mediated signaling, respectively. PROP was administered as either l-PROP or dl-PROP. A wide range of concentrations was tested including low (0.3, 3 and 30ng/L) and high (300ng/L) environmental ranges, and a concentration 5-fold above the maximum reported environmental level (30,000ng/L). After a 7-day exposure, mussel cAMP levels and PKA activities were significantly reduced in digestive gland, increased in mantle/gonads and unaffected in gills. Similar patterns were observed for the mRNA expression of the ABCB1 gene encoding the membrane transporter P-glycoprotein, hypothesised to be under PKA modulation. The effects on the digestive gland are consistent with PROP blocking β-adrenoceptors. The observed increased cAMP levels in the mantle/gonad tissue support PROP blocking 5-HT1 receptors. Catalase and glutathione-S tranferase were differently affected by PROP in the two tissues. Mussel haemocyte lysosome membrane stability, a sensitive biomarker of animal health status, was concentration-dependently reduced following PROP exposure. Our observations provide evidence for PROP affecting cell signaling in M. galloprovincialis. Moreover, the chemical interacts with specific and evolutionally conserved biochemical pathways for which it was designed. The mode of action of PROP in mussels is related with its therapeutic properties in humans, based upon these conserved human targets. It also induced a stress response, and all these effects were displayed at the lowest concentrations tested.

Olive oil mill wastewater toxicity in the marine environment: alterations of stress indices in tissues of mussel Mytilus galloprovincialis

This study investigated the impact of olive mill wastewater (OMW) as a pollutant of the marine environment, via the detection of stress indice alterations in mussels Mytilus galloprovincialis. Due to the absence of data concerning the levels of OMW in the receiving waters, mortality test (96h) was first performed in order to estimate the range of OMW concentration where no mortality occurs. OMW concentrations ranging from 0.01 to 0.1% (v/v) showed no increased mortality and thus were used for the determination of pre-pathological alterations in tissues of mussels. In particular, mussels exposed to either 0.1 or 0.01% (v/v) OMW for 5 days showed significant alterations of stress indices in their tissues. Specifically, decreased neutral red retention (NRR) assay time values, inhibition of acetylcholinesterase (AChE) activity, as well as a significant increase of micronucleus (MN) frequency and DNA damage were detected in haemolymph/haemocytes and gills, compared with values measured in tissues of control mussels. The results of the present study showed that OMW disposal into the marine environment could induce pre-pathological alterations in marine organisms, before severe disturbances, such as disease, mortality, or population changes occur.

The content of elements in rainwater and its relation to the frequency of hospitalization for atrial fibrillation in Opole Voivodship, Poland, during 2000-2002

The elemental composition of rainwater is a suitable indirect indicator of the presence of chemical elements in airborne dust. As such, rainwater is considered a suitable monitor for environmental or natural pollution. The yearly content of chemical elements in rainwater may be considered a good indicator for determining the influence of these environmental factors on human body. We decided to investigate the relationship between chemical elements in rainwater and the frequency of hospitalizations for atrial fibrillation (I48, ICD10) on the population of the region of Opole Voivodship, Poland during the years 2000-2002. The voivodship or province has a population of one million and is divided into 12 counties that have between 44,000 and 151,000 inhabitants. We calculated the yearly average number of hospitalizations by reasons of atrial fibrillation per 10,000 inhabitants in particular counties. The average content of the chosen chemical elements in kilograms per hectare per year was calculated for each county individually and the data evaluated by means of Spearman's correlation coefficient. There is a high positive correlation between chromium in rainwater and hospital admissions for atrial fibrillation (r = 0.62) and mild positive correlation with cadmium (r = 0.57), lead (r = 0.57), zinc (r = 0.50), and chloride (r = 0.48). There are no significant differences between male and female patients. The biological activities of these elements, which may include enhanced adrenergic stimulation, remodeling of calcium or other ion channels, or the cytotoxic effects of hexavalent chromium may explain the positive correlations here reported.

Involvement of Na+/H+ exchanger and respiratory burst enzymes NADPH oxidase and NO synthase, in Cd-induced lipid peroxidation and DNA damage in haemocytes of mussels

This study investigated cadmium-induced oxidative and genotoxic effects, such as lipid peroxidation and disturbance of DNA integrity (DNA damage) in haemocytes of mussel Mytilus galloprovincialis and the possible involvement of Na+/H+ exchanger (NHE), and/or the main enzymes of respiratory burst, NADPH oxidase and nitric oxide (NO) synthase, in the induction of Cd toxic effects. In order to verify the role of either NHE, or NADPH oxidase and NO synthase in Cd-mediated toxicity, inhibitors such as ethyl-N-isopropyl-amiloride (EIPA), diphenyleneiodonium chloride (DPI) and NG-nitro-L-arginine methyl ester (L-NAME) were used in each case. Moreover, phorbol-myristate acetate (PMA), a well-known protein kinase C (PKC)-mediated NADPH oxidase and NO synthase stimulator, as well as hydrogen peroxide (H2O2), a well-known genotoxic agent, was also used for elucidating the modulation of signaling molecules within cells, thus leading to the induction of lipid peroxidation and DNA damage. The results of the present study showed that micromolar concentrations of Cd (0.05-50 microM) could enhance both lipid peroxidation and DNA damage, possible via a PKC-mediated signaling pathway with the involvement of NHE, thus leading to the induction of NADPH oxidase and NO synthase activity, since inhibition of either NHE, or NADPH oxidase and NO synthase activity, significantly attenuates Cd-induced toxic effects in each case.

Effects of vibrio challenge on digestive gland biomarkers and antioxidant gene expression in Mytilus galloprovincialis

In bivalve molluscs, responses to bacterial infection have been largely characterized in terms of both functional responses and gene expression in the immune cells, the hemocytes. The effects of bacterial challenge at the tissue level, where bacterial infection may cause stressful conditions, have not been so far specifically investigated. Biomarkers are widely utilised to evaluate the health status of bivalves, from the molecular to the organism level, in response to both natural and anthropogenic stressors. In this work, the effects of in vivo challenge with heat-killed vibrio species, Vibrio splendidus LGP32 and Vibrio anguillarum (ATCC19264), on different biomarkers in the digestive gland of the marine bivalve Mytilus galloprovincialis were investigated. Mussels were injected with either vibrio and tissues sampled at 3, 6 and 24 h post injection (p.i.). Lysosomal biomarkers, such as lysosomal membrane stability (LMS) and lipofuscin accumulation, as well as specific activities of antioxidant enzymes (catalase and glutathione transferase-GST) were evaluated. Moreover, the expression of antioxidant molecules (catalase, GST-pi and metallothioneins MT10 and MT20) was determined by quantitative RT-PCR. Both V. splendidus and V. anguillarum significantly affected all parameters measured, to a different extent and at different times p.i. Interestingly, whereas both vibrios induced lysosomal membrane destabilisation and increases in the activities of antioxidant enzymes, distinct responses were observed in terms of lysosomal lipofuscin accumulation and expression of antioxidant molecules. In particular, V. splendidus induced a general increase in the transcription of antioxidant genes, indicating that Mytilus digestive gland can mount an efficient antioxidant response towards this vibrio species. On the other hand, a general down-regulation or no effect was observed with V. anguillarum. The lack of this response was reflected in stronger oxidative stress conditions in the digestive gland of mussels challenged with V. anguillarum, as indicated by higher levels of lysosomal lipofuscin observed at longer times p.i. Overall, these data indicate that lysosomal and oxidative stress biomarkers could be usefully applied in order to monitor early changes in the health status of bivalves induced by bacteria. Moreover, the results support the hypothesis that host responses to bacteria may be taken into account when interpreting biomarker data in ecotoxicological studies.

Cyclic AMP signaling in bivalve molluscs: an overview

The cyclic AMP (cAMP)-dependent signaling accounts for the control of cellular cascades involved in many physiological functions, and a wealth of information is available on the cAMP system that operates in mammalian cells. Nevertheless, cAMP has a central role also in nonmammalian vertebrates and invertebrates. The present review aims at examining the information available on bivalve molluscs, from the first studies carried out in the early 1980s to the last progresses made in the present days. The major focus is on the structural and operational characteristics of the main actors of the signaling pathway, i.e., adenylyl cyclase, G proteins, and protein kinase A, and on the role played by the cyclic nucleotide on smooth muscle, heart, gills, gonads, and metabolism regulation. Moreover, recent evidence regarding the cAMP system as a target of environmental stress factors are discussed. It will become clear that cAMP does play a wide and important role in bivalve physiology. Several issues have been sufficiently clarified, although investigated only in a few model species. However, further fundamental aspects remain unknown, mainly regarding molecular features and interactions with other signaling pathways, thus requiring further elucidation.

Cadmium-induced hormetic effect in differentiated Caco-2 cells: ERK and p38 activation without cell proliferation stimulation

Cadmium (Cd) is a toxic metal that enters the food chain. Following oral ingestion, the intestinal epithelium may in part protect against Cd toxicity but is also a target tissue. Using human enterocytic-like Caco-2 cells, we have previously shown differences in sensitivity to Cd according to the differentiation status. The present study focuses on Cd effects on differentiated cells. Concentration and time-dependent increases in MTT (3-[4,5-dimethyl-2-thiazol-2-yl]-2,5-diphenyltetrazolium bromide assay) activity were observed in post-confluent cultures exclusively, with a twofold maximal stimulation in 21-day-old cells exposed to 10 microM Cd for 24 h. No concomitant increase in [methyl-(3)H] thymidine incorporation was noted and Cd did not modify cell distribution in the cell-cycle phases. However, Cd-induced increase in MTT activity was inhibited by cycloheximine as well as by inhibitors of ERK1/2 and p38, but not by that of JNK. Consistently, Cd increased the levels of ERK1/2 and p38 phosphorylation. Inhibition of Ras-GTP or PI3K enhanced the stimulatory effect of Cd, whereas mTOR inhibition had no effect. Inhibition of G protein-phospholipase and PKC decreased MTT stimulation. These results show a hormesis-like stimulation of Cd on MTT activity in differentiated intestinal cells exclusively. This effect is not related to cell proliferation but more likely to increased protein synthesis which involves ERK1/2 and p38 cascades and possibly PLC-beta signaling pathways. Because growth-related differentiation of intestinal cells is linked to the selective and sequential activation of MAPKs, the impacts that these Cd-induced perturbations in signaling pathways may have on intestinal functions clearly deserve to be investigated.

Frequency of hospitalization for angina pectoris, stroke, and peripheral venous thrombosis and its relationship to elements in rainwater in Opole Voivodship, Poland, during 2000-2002

The content of elements in rainwater is an indirect indicator of its occurrence in air dust. This is sometimes referred to as rain fallout and is investigated in applied environmental pollution monitoring schemes. The annual content of elements in rainwater may be recognized as good index for assessing influence of those environmental factors on human body. The possible relationship between the concentrations of selected elements in rainwater and the frequency of hospitalization by reason of angina pectoris, stroke, and peripheral venous thrombosis was investigated in the Opole Voivodship (Poland) area during the period 2000-2002. There is a relatively high or partly significant correlation between frequency of hospitalization by reason of these conditions and content of lead, cadmium, chromium, zinc, and chloride in rainwater. Significant gender-dependent differences were observed only in peripheral venous thrombosis, where important correlations with lead, cadmium, and chromium were found only in men.

The role of signalling molecules on actin glutathionylation and protein carbonylation induced by cadmium in haemocytes of mussel Mytilus galloprovincialis (Lmk)

This study investigated the role of Na(+)/H(+) exchanger (NHE) and signalling molecules, such as cAMP, PKC, PI 3-kinase, and immune defence enzymes, NADPH oxidase and nitric oxide synthase, in the induction of protein glutathionylation and carbonylation in cadmium-treated haemocytes of mussel Mytilus galloprovincialis. Glutathionylation was detected by western blot analysis and showed actin as its main target. A significant increase of both actin glutathionylation and protein carbonylation, were observed in haemocytes exposed to micromolar concentration of cadmium chloride (5 micromol l(-1)). Cadmium seems to cause actin polymerization that may lead to its increased glutathionylation, probably to protect it from cadmium-induced oxidative stress. It is therefore possible that polymerization of actin plays a signalling role in the induction of both glutathionylation and carbonylation processes. NHE seems to play a regulatory role in the induction of oxidative damage and actin glutathionylation, since its inhibition by 2 micromol l(-1) cariporide, significantly diminished cadmium effects in each case. Similarly, attenuation of cadmium effects were observed in cells pre-treated with either 11 micromol l(-1) GF-109203X, a potent inhibitor of PKC, 50 nmol l(-1) wortmannin, an inhibitor of PI 3-kinase, 0.01 mmol l(-1) forskolin, an adenylyl cyclase activator, 10 micromol l(-1) DPI, a NADPH oxidase inhibitor, or 10 micromol l(-1) L-NAME, a nitric oxide synthase inhibitor, suggesting a possible role of PKC, PI 3-kinase and cAMP, as well as NADPH oxidase and nitric oxide synthase in the enhancement of cadmium effects on both actin glutathionylation and protein carbonylation.

Modelling interactions of acid-base balance and respiratory status in the toxicity of metal mixtures in the American oyster Crassostrea virginica

Heavy metals, such as copper, zinc and cadmium, represent some of the most common and serious pollutants in coastal estuaries. In the present study, we used a combination of linear and artificial neural network (ANN) modelling to detect and explore interactions among low-dose mixtures of these heavy metals and their impacts on fundamental physiological processes in tissues of the Eastern oyster, Crassostrea virginica. Animals were exposed to Cd (0.001-0.400 microM), Zn (0.001-3.059 microM) or Cu (0.002-0.787 microM), either alone or in combination for 1 to 27 days. We measured indicators of acid-base balance (hemolymph pH and total CO(2)), gas exchange (Po(2)), immunocompetence (total hemocyte counts, numbers of invasive bacteria), antioxidant status (glutathione, GSH), oxidative damage (lipid peroxidation; LPx), and metal accumulation in the gill and the hepatopancreas. Linear analysis showed that oxidative membrane damage from tissue accumulation of environmental metals was correlated with impaired acid-base balance in oysters. ANN analysis revealed interactions of metals with hemolymph acid-base chemistry in predicting oxidative damage that were not evident from linear analyses. These results highlight the usefulness of machine learning approaches, such as ANNs, for improving our ability to recognize and understand the effects of sub-acute exposure to contaminant mixtures.

The potential role of cAMP as a pollution biomarker of terrestrial environments using the land snail Eobania vermiculata: correlation with lysosomal membrane stability

The present study investigates the role of the signal transduction molecule cAMP, and the lysosomal membrane stability (LMS), as biomarkers of terrestrial environmental pollution using the land snail Eobania vermiculata. Snails were exposed to different concentrations of heavy metals (Cd, Pb and Cu) and organic pollutants (chlorpyrifos, parathion-methyl and PAHs) in laboratory conditions for 25 days. In addition, snails were collected from various sites located at different distances away from two polluted areas in northern Greece (the road Agiou Dimitriou in Thessaloniki city and a lignite power station in the district of Kozani). The results of the current investigation showed significantly increased levels of cAMP in the digestive gland of snails, as well as decreased LMS values in all experimental groups compared to control animals. In support of our data, cAMP levels were significantly negatively correlated with the conventional biomarker LMS, thus encouraging the use of cAMP as a new potential stress index in terrestrial pollution biomonitoring studies.

Production of superoxides and nitric oxide generation in haemocytes of mussel Mytilus galloprovincialis (Lmk.) after exposure to cadmium: a possible involvement of Na(+)/H(+) exchanger in the induction of cadmium toxic effects

The present study investigates cadmium (Cd) ability to enhance superoxides (O(2-)) and nitric oxide (NO) production (as nitrites) in haemocytes of mussel Mytilus galloprovincialis as well as the possible involvement of Na(+)/H(+) exchanger (NHE) in the induction of NADPH oxidase and NO synthase activity. PMA, a well-known PKC-mediated NADPH oxidase as well as NO synthase stimulator was also used, in order to verify Cd effects on both O(2-) and NO generation. According to the results of the present study, micromolar concentrations of Cd (0.05, 5, 10 and 50 microM) seemed to enhance O(2-) and NO generation in haemocytes of mussels. Moreover, O(2-) and NO generation in haemocytes exposed to Cd could be enhanced by its ability to induce reactive oxygen species (ROS) but respiratory burst activation as well. Inhibition of NO synthase with 10 microM l-NAME, significantly attenuated Cd ability to enhance O(2-) production and diminished NO generation, thus leading to the suggestion that Cd toxic effects, started at concentration of 50 muM, could enhance NADPH oxidase and NO synthase stimulation in haemocytes of mussels. NHE seems to play a regulatory role in the induction of either O(2-) or NO generation in haemocytes exposed to the metal, since its inhibition with the use of 10 microM EIPA significantly decrease both O(2-) and NO production. The involvement of NHE in the induction of O(2-) and NO generation, probably via PKC-mediated NADPH oxidase and NO synthase activation, is likely to be crucial to haemocytes exposed to heavy metals, such as Cd.