Acetylcholinesterase (AChE) activity measurement is widely used as a specific biomarker of neurotoxic effects. The aim of this study was to evaluate AChE activity in a host fish (the cod) and its acanthocephalan parasite Echinorhynchus gadi from the southern Baltic. AChE activity in hosts and parasites was inversely related: the highest cod AChE activity corresponded to the lowest E. gadi enzymatic activity and vice versa (“mirror effect”). This is the first report on the simultaneous application of this biomarker in cod and its acanthocephalan parasites. Results obtained for the host–parasite system are complementary and provide comprehensive information about the response of this biomarker. Analysis of the system allows for detection of a greater number of factors influencing AChE activity in the marine environment than separate analysis of the host and parasites. Thus, AChE activity measurement in a host–parasite system may be considered to be a promising tool for biomonitoring.

To evaluate the health status at six different study areas, we used the generalized linear model approach with selected biochemical markers in resident fish from uncontaminated and contaminated sites. We also confirmed the independence between the biochemical indices and the morphometric indices including the hepato-somatic index (HSI), gonado-somatic index (GSI), and condition factor (CF) in fish from the sampling areas. The effect of area on the presence of biotransformation markers (ethoxyresorufin-O-deethylase activity; EROD) was significantly high in Masan Bay. The area with the greatest effect on acetylcholinesterase (AChE) activity was Jindong Bay, while there was no significant effect of GSI, HSI, CF, and sex in the EROD model and HSI, CF and sex in the AChE model. These results clarify that fish from Masan, Gwangyang and Jindong Bay were affected by pollutant stress, and the analysis of sensitive biochemical responses allowed for an improved interpretation of the results.

The ecological relevance of polychaetes coupled with their easy culture and maintenance in the laboratory, has led them to become increasingly used in marine ecotoxicological studies, raising the need to validate frequently applied monitoring tools at various biological levels. The present study was aimed to characterize the cholinesterases (ChE) activity in the polychaete Capitella teleta, using three substrates (acetylthiocholine iodide, propionylthiocholine iodide, and S-butyrylthiocholine iodide) and four known inhibitors (eserine hemisulfate, BW284c51, iso-OMPA and chlorpyrifos-oxon). Results showed that most of the measured cholinesterase activity was acetylcholinesterase (AChE). Inhibition of enzyme kinetic experiments denoted that sensitivity of C. teleta’s ChE to the organophosphorous metabolite chlorpyrifos-oxon (IC50=60.72nM) was analogous to some fish species. This study highlights the relevance of ChE characterization before its use as a biomarker in ecotoxicology and biomonitoring studies.

In order to assess the environmental quality of the Bizerte lagoon (Tunisia), biomarker and contaminant levels were measured in Mediterranean mussels (Mytilus galloprovincialis) from five selected sites. Persistent organic pollutants (POPs) were quantified in whole body and enzyme activities such as acetylcholinesterase (AChE), catalase (CAT) and glutathione S-transferase (GST) in gills. Despite the relatively low levels of organic contaminants, the selected biomarkers responded differently according to the pollution level at the different sites. GST and AChE activities were correlated with the amount of DDTs in mussel tissues. These two enzymatic activities were also correlated to temperature and pH. No significant difference was observed for CAT activity. Principal component analysis showed a clear separation of sampling sites in three different assemblages which is consistent with POP body burden in mussels. Our results confirmed the usefulness of combining biomarker and chemical analyses in mussels to assess chemical pollution in the Bizerte lagoon.

The Tubarão River rises in Santa Catarina, Brazil, and has been historically affected by coal mining activities around its springhead. To evaluate its water conditions, an investigation regarding a possible decontamination gradient associated with the increased river flow toward the estuary, as well as the influence of seasonality over this gradient was performed through a series of biomarkers (vitellogenin, comet assay, lipid peroxidation, protein carbonylation, gluthatione, gluthatione S-transferase, acetylcholinesterase, light microscopy in liver, and scanning electron microscopy in gills) and chemical analysis (polycyclic aromatic hydrocarbons (PAHs) in bile and metal analysis in sediment) in the cichlid Geophagus brasiliensis. Two collections (summer and winter) were made in four distinct sites along the river, while sediments were sampled between those seasons. As expected, the contamination linked exclusively to mining activities was not observed, possibly due to punctual inputs of contaminants. The decontamination gradient was not observed, although seasonality seemed to have a critical role in the responses of biomarkers and availability of contaminants. In the summer, the fish presented higher histopathological damages and lower concentrations of PAHs, while in the winter they showed both higher genetic damage and accumulation of PAHs. The Tubarão suffers impacts from diverse activities, representing health risks for wild and human populations.

It now is widely recognised that the global temperature is rising, a phenomenon which could alter the effects of pollution on wildlife. In order to assess the role of temperature and exposure to chlorine due to cooling water discharges, a battery of metabolic, oxidative stress and histological parameters were evaluated in Mytilus galloprovincialis after 15 and 30 days at 15 °C and at two increased temperatures (+5 and +10 °C). Diverse gill pathologies such as haemolymphatic sinus dilatation, an increased number of mucocytes and granulocytes as well as a lower number of cilia were observed after 30 days exposure at higher temperatures. Protein, amino acid, triglyceride and fatty acid levels decreased when the temperature increased, as a consequence of higher energetic demand. Similarly, acetylcholinesterase, catalase and glutathione S-transferase activities showed an inhibition at higher temperatures, although gill lipid peroxidation levels remained unaffected. Our results suggest that increased temperatures induce deterioration in the health status of the mussels and in their defensive capacity against a polluted environment.

Modern society grapples with large amounts of household waste. The anaerobic digestion of this waste offers a promising source for energy-rich biogas production but generates high toxic effluents that require treatment before reuse or disposal into the environment. This study aimed to investigate three techniques, namely coagulation/flocculation, electro-coagulation, and activated sludge, in terms of efficiency in the treatment of these effluents. It also aimed to assess their toxicity effects on the germination and growth of durum wheat Triticum aestivum L. seeds before and after 6 days of treatment. Activated sludge was most efficient in reducing chemical oxygen demand, turbidity, and conductivity (95.7 %, 15.8 %, and 37.5 %, respectively). The effluent treated with this technique induced a marked delay in germination (low mean time of germination) and a significant reduction in the percentages of seed germination and root and leaf growths. It was also noted to strongly induce lipid peroxidation in roots and leaves, which presumably explained the germination/growth inhibition of the wheat seeds. The effluent also induced marked lipid peroxidation effects and strongly inhibited the activities of butyrylcholinesterase in mice bone marrows. The effluent shows a high ability to inhibit the growth of three microalgae; these endpoints are useful tools to biomonitor the physico-chemical quality of this wastewater. Overall, while no significant alterations were observed in terms of animal and vegetable toxicities when the effluent was treated by coagulation/flocculation, activated sludge treatment proved efficient in reducing the toxicities induced by the untreated effluents. The results indicate that the application of this technique is promising with regards to attaining efficient, eco-friendly, and cost-effective strategies for the management and treatment of household waste.

This study was aimed to analyze the alteration of membrane protein profiles in Aplysia juliana Quoy & Gaimard (A. juliana) pleural–pedal ganglia under MP exposure. Both the results of GC–MS analysis and the activity assay of acetylcholinesterase (AChE), superoxide dismutase (SOD), catalase (CAT) reveal that MP toxicological effects on Aplysia left and right pleural–pedal ganglia are different under 7 and 14 days of exposure. Therefore, Aplysia were subjected for exposure at two concentrations (1 and 2 mg/l) of MP for 7 and 14 days for membrane proteomic study. As a result, 19 and 14 protein spots were differentially expressed in A. juliana left pleural–pedal ganglia under 7 and 14 days treatment, and 20 and 14 protein spots found with differential expressions in their right ganglia under the same treatment, respectively. Several proteins with expression variations were detected from both the left and right pleural–pedal ganglia; however, most proteins have distinctive expressions, indicating different mechanisms might be involved in initiating MP toxicology in left and right ganglia. Among the total differential protein spots obtained, 29 proteins were classed as membrane proteins. These proteins are mainly involved in the metabolism process, cell redox homeostasis, signal transduction, immunology, intracellular transport and catalysis, indicating MP toxicity in mollusks seems to be complex and diverse. Some differentially expressed proteins were further confirmed by Western blotting and quantitative real-time PCR. These results might provide renovated insights to reveal the mechanism of MP-induced neurotoxicity, and the novel candidate biomarkers might have potential application for environmental evaluation of MP pollution level.

This study examined the influence of increasing temperatures in spring and summer on biochemical biomarkers in Mytilus galloprovincialis mussels sampled from Bizerte lagoon (northern Tunisia). Spatial and seasonal variations in a battery of seven biomarkers were analyzed in relation to environmental parameters (temperature, salinity, and pH), physiological status (condition and gonad indexes), stress on stress (SoS), and chemical contaminant levels (heavy metals, polycyclic aromatic hydrocarbons (PAHs), and PCBs) in digestive glands. Integrated biological response (IBR) was calculated using seven biomarkers (acetylcholinesterase (AChE), benzo[a]pyrene hydroxylase (BPH), multixenobiotic resistance (MXR), glutathione S-transferase (GST), catalase (CAT), malondialdehyde (MDA), and metallothioneins (MT). Seasonal variations in biological response were determined during a critical period between spring and summer at two sites, where chemical contamination varies by a factor of 2 for heavy metals and a factor 2.5 for PAHs. The analysis of a battery of biomarkers was combined with the measurement of physiological parameters at both sites, in order to quantify a maximum range of metabolic regulation with a temperature increase of 11 °C between May and August. According to our results, the MT, MDA, CAT, and AChE biomarkers showed the highest amplitude during the 11 °C rise, while the BPH, GST, and MXR biomarkers showed the lowest amplitude. Metabolic amplitude measured with the IBR at Menzel Abdelrahmen—the most severely contaminated station—revealed the highest metabolic stress in Bizerte lagoon in August, when temperatures were highest 29.1 °C. This high metabolic rate was quantified for each biomarker in the North African lagoon area and confirmed in August, when the highest IBR index values were obtained at the least contaminated site 2 (IBR = 9.6) and the most contaminated site 1 (IBR = 19.6). The combined effects of chemical contamination and increased salinity and temperatures in summer appear to induce a highest metabolic adaptation response and can therefore be used to determine thresholds of effectiveness and facilitate the interpretation of monitoring biomarkers. This approach, applied during substantial temperature increases at two sites with differing chemical contamination, is a first step toward determining an environmental assessment criteria (EAC) threshold in a North African lagoon.

Due to their broad-spectrum antimicrobial activity, silver nanoparticles (AgNPs) have been used in a large number of commercial and medical products. Such proliferated AgNP production poses toxicological and environmental issues which need to be addressed. The present study aimed to investigate the effects of AgNPs on acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), important enzymes in areas of neurobiology, toxicology and pharmacology. Three different AgNPs, prepared by the chemical reduction using trisodium citrate, hydroxylamine hydrochloride (Cl-AgNPs), and borohydride following stabilization with poly(vinyl alcohol), were purified and characterised with respect to their sizes, shapes and optical properties. Their inhibition potential on AChE and BChE was evaluated in vitro using an enzyme assay with o-nitrophenyl acetate or o-nitrophenyl butyrate as substrates, respectively. All three studied AgNPs were reversible inhibitors of ChEs. Among tested nanoparticles, Cl-AgNP was found to be the most potent inhibitor of both AChE and BChE. Although the detailed mechanism by which the AgNPs inhibit esterase activities remains unknown, structural perturbation of the enzyme may be the common mode of ChE inhibition by AgNPs.