Both carbon nanotubes (CNTs) and perfluorooctane sulfonate (PFOS) are used widely. There is considerable concern regarding their ecotoxicity. CNTs might interact with PFOS in water and result in different impacts compared with those after single exposures. To our knowledge, the developmental toxicity of PFOS in the presence of multi-walled carbon nanotubes (MWCNTs) in the early life stage of zebrafish (from 3 h post fertilization (hpf) to 96 hpf) was investigated for the first time in this study. The embryos and larvae were exposed to PFOS (0.2, 0.4, 0.8, and 1.6 mg/L), MWCNTs (50 mg/L), and a mixture of both. Compared with PFOS exposure, the adverse effects induced by PFOS on the hatching rate of zebrafish embryos and the heart rate and body length of zebrafish larvae were reduced in the presence of MWCNTs, and mortality and malformation were also alleviated. In addition, zebrafish larvae exposed to PFOS showed decreased activities of superoxide dismutase, catalase, and glutathione peroxidase, as well as decreased levels of reactive oxygen species and malondialdehyde, in the presence of MWCNTs, indicating that oxidative stress and lipid peroxidation was relieved. Thus, the presence of MWCNTs reduces the developmental toxicity of PFOS in the early life stage of zebrafish.

Benzene is a well-known occupational and environmental toxicant associated with cytopenia, which is characterized by a disorder in the peripheral blood cell counts. However, no effective preventive strategy has been developed yet to tackle the exposure to benzene in daily life. The aim of this study was to evaluate the protective effects of diallyl trisulfide (DATS) on benzene-induced haematopoietic damage and to reveal its potential mechanisms of action. In our study, male Sprague-Dawley rats were divided into six groups. Rats were administered with benzene (1.3 g/kg BW by gavage) to establish the benzene poisoning model, while the DATS treatment groups were treated with benzene plus DATS (15 mg/kg, 30 mg/kg, 45 mg/kg, respectively, by gavage) for 28 days. Our results demonstrated that the counts of peripheral blood WBC and RBC decreased to 31.0% and 79.2%, respectively, in the benzene poisoning model group compared to the control. However, blood cell counts were restored by DATS treatment (30 mg/kg, 45 mg/kg). The apoptosis rates of peripheral blood mononuclear cells (PBMCs) and bone marrow cells (BMCs) were increased to 274% and 284%, respectively, following benzene exposure. Furthermore, expression levels of Bcl-2, PI3K and p-Akt were downregulated and those of Bax were upregulated in both cell types. Moreover, the oxidative parameters (oxygen species, malonaldehyde) were significantly increased, while the non-enzymatic GSH/GSSG ratios and the activities of enzymatic antioxidants (superoxide dismutase, glutathione peroxidase and catalase) were decreased. Interestingly, DATS treatment can restore the WBC number by 267.1% and 304.8% while RBC number by 108.6% and 117.7% in 30,45 mg/k DATS treated groups. In summary, we demonstrated that benzene-induced cytopenia was related to the apoptosis of PBMCs and BMCs, and DATS treatment could prevent benzene-induced cytopenia by suppressing oxidative stress-mediated cell apoptosis via the PI3K/Akt pathway.

Using Artemia salina (A. salina) cysts (capsulated and decapsulated) and larvae [instar I (0–24 h), II (24–48 h) and III (48–72 h)] as experimental models, developmental toxicity of oxidized multi-walled carbon nanotubes (O-MWCNTs) was evaluated. Results revealed that hatchability of capsulated and decapsulated cysts was significantly decreased (p < 0.01) following exposure to 600 mg/L for 36 h. Mortality rates were 33.8, 55.7 and 40.7% for instar I, II and III larvae in 600 mg/L. The EC50 values for swimming inhibition of instar I, II and III were 535, 385 and 472 mg/L, respectively. Instar II showed the greatest sensitivity to O-MWCNTs, and followed by instar III, instar I, decapsulated cysts and capsulated cysts. Effects on hatchability, mortality and swimming were accounted for O-MWCNTs rather than metal catalyst impurities. Body length was decreased with the concentrations increased from 0 to 600 mg/L. O-MWCNTs attached onto the cysts, gill and body surface, resulting in irreversible damages. Reactive oxygen species, malondialdehyde content, total antioxidant capacity and antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase) activities were increased following exposure, indicating that the effects were related to oxidative stress. O-MWCNTs were ingested and distributed in phagocyte, lipid vesicle and intestine. Most of the accumulated O-MWCNTs were excreted by A. salina at 72 h, but some still remained in the organism. Data of uptake kinetics showed that O-MWCNTs contents in A. salina were gradually increased from 1 to 48 h and followed by rapidly decreased from 48 to 72 h with a range from 5.5 to 28.1 mg/g. These results so far indicate that O-MWCNTs have the potential to affect aquatic organisms when released into the marine ecosystems.

Intensive exploitation and transport of oil and derivatives are increasing the risk of coastal contamination by either dramatic disasters or diffuse sources. Tools for monitoring diffuse contamination, such as diesel oil that leaks from marine vessels are much needed. We experimentally tested the efficiency of antioxidant biomarkers as indicators of chronic exposure to diesel oil in a mudflat from the subtropical Bay of Paranaguá, in southern Brazil. We examined the effects of three successive diesel oil spills, with two weeks of recovery time between exposures, on the edible clam Anomalocardia flexuosa. Previous studies have highlighted its potential as a bioindicator species for diesel oil contamination in subtropical and tropical ecosystems. Endpoints measured in gill and digestive gland homogenates included the activity of antioxidant enzymes SOD, GPx, GST and levels of lipid peroxides. PAHs concentration in sediments and soft tissue were also quantified. GST and SOD were the most responsive biomarkers to the exposure. There were significant but non–cumulative departures from control levels in organisms from treated samples, which were, in all cases, more common 48 h after each experimental spill. Biomarker responses were more evident in the digestive gland than in gills. This work validated the short–term responsiveness of biomarkers as measures of repeated pulsed in situ exposure to low concentrations of diesel oil. For their routine implementation into monitoring programs for tropical estuaries our general recommendations are 1) to include several reference sites, 2) to analyze biomarker data using a logarithmic–scale and 3) to interpret deviations from “normal” activity as multiplicative interval differences.

The primary objective of this study was to understand the impact of monsoon and summer seasons on the Polychlorinated Biphenyls (PCB's) and petroleum hydrocarbon compounds (PHC's) load in Ennore estuary and how the physiological response of estuarine Scylla serrata inhabiting in this estuary changed with reference to antioxidant defense. Seasonal levels of PCB's and PHC's were assessed in the water along with their bioaccumulation in gills, hemolymph, hepatopancreas and ovary of S. serrata. Concentration of PCB's and PHC's in water and their bioaccumulation was found to be higher in summer season when compared to monsoon season. Enzymic antioxidant assays [superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione reductase (GR), glutathione-S-transferase (GST)]; non-enzymic antioxidant assays [glutathione (GSH), vitamin C, vitamin E] and macromolecular alterations [membrane lipid peroxidation (LPO), and DNA Damage (strand breaks)] were assessed in the gills, hemolymph and hepatopancreas of S. serrata. There was a significant (p<0.05) upregulation in lipid peroxidation activity and DNA damage activity collected during the summer season when compared to the pre- and post-monsoon seasons. On the contrary, the enzymic and non-enzymic antioxidants exhibited significant (p<0.05) down regulation in the gills, hemolymph, hepatopancreas and ovary of S. serrata. Oxidative stress biomarkers represented a significant (p<0.05) maximum in gills when compared to hemolymph and hepatopancreas of S. serrata. Present study provided scientific evidences of how the antioxidant defense status of S. serrata responded to PCB's and PAH's stress with reference to seasonal vicissitudes, which indirectly represented the environmental health conditions of the estuary.

The present study aimed to assess whether environmental 1-nitropyrene (1-NP) concentration will induce genotoxicity and oxidative damages in tilapia, lives in estuarine and brackish water. Tilapia were exposed to waterborne 1-NP. Cellular antioxidant enzyme activity of glutathione peroxidase and oxidative damage, i.e., lipid peroxidation, protein and DNA oxidation were used as biomarkers of oxidative stress, while the micronucleus test was used for evaluation of chromosomal damage and was used as an indication of genotoxicity. Results showed that all biomarkers for oxidative stress positively responded, and micronucleus and other nuclear abnormalities frequencies significantly increased (p<0.001). This study showed that environmentally relevant 1-NP concentration in test water (0.15ng/L) and in fish (3ng/kg) induced genotoxicity and oxidative stress. Micronuclei and other nuclear abnormalities were probably formed as a result of oxidative stress. In conclusion, exposure to lower waterborne 1-NP concentration can pose a risk to freshwater and estuarine organisms through accumulation.

A comprehensive approach to chemical accumulation and biological effects of short-term Cu exposure in juveniles of European seabass (Dicentrarchus labrax) has been achieved. Fish were exposed to 0.01–10mgL−1 nominal Cu concentrations for 24–96h. Metal concentrations in water and gills, liver, muscle and brain tissues were studied along with oxidative stress biomarkers (superoxide dismutase, catalase, glutathione peroxidase, lipid peroxidation). Induction of oxidative damage was observed in all the organs with differential antioxidant responses; gills appearing as the most sensitive from low environmentally water Cu concentrations as 0.01mgL−1. Histopathological alterations were also observed in liver and gills, even without a significant Cu accumulation.The results show that the combination of oxidative stress parameters, particularly lipid peroxidation and glutathione peroxidase activities, and histopathological alterations provide a good model fish and reliable early biomarkers for monitoring Cu pollution in seawater and might call for the protection agencies to revise the Cu environmental standards.

Polybrominated diphenyl ethers (PBDEs), a persistent organic pollutant are ubiquitous in aquatic ecosystems, which are causing serious environmental concerns. In this study, we chose BDE-47 as a representative PBDEs, to investigate its toxic effects on two microalgal species and the response of their antioxidant system. The results indicated Alexandrium minutum (a dinoflagellate) was more sensitive to BDE-47 than Dunaliella salina (a chlorophyte), as determined by growth rates, cellular structure and photosynthetic parameters. Cellular reactive oxygen species (ROS) levels were significantly elevated under the exposure of BDE-47 in both species, corresponding to an increase of superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR) activities, while glutathione peroxidase (GPX) activities decreased in D. salina and increased in A. minutum. The different enzymes responses between the two species indicated different mechanisms in their antioxidant system, and we deduced that A. minutum might have a higher efficiency for scavenging H2O2 than D. salina.

Ethanol consumption-induced oxidative stress that is a major etiological factor has been proven to play important roles in organs’ injury. In the present study, we investigated the protective effect of fish protein hydrolysate prepared from the heads and viscera of sardinelle (Sardinella aurita) (SPH) against the toxicity of ethanol on the liver and kidney of adult male rats. Animals were divided into four groups of six animals each: group C served as control, group Eth received 30 % ethanol solution at the dose of 3 g/kg body weight, group SPH received only 7.27 mg of SPH/kg body weight, and group Eth-SPH received ethanol and SPH simultaneously at the doses of 30 % and 7.27 mg/kg body weight, respectively. All groups were treated by gavage way for 15 days. Ethanol treatment decreased the defense enzymatic system including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), which increased after the co-administration of SPH. Malondialdehyde (MDA) and toxicity biomarker levels such as aspartate transaminase (AST) and alanine transaminase (ALT) and alcaline phosphatase (ALP) and gamma-glutamyl transaminase (GGT) activities were enhanced after chronic ethanol treatment and reduced by co-treatment with SPH. The histological examination of the liver and kidney confirmed biochemical changes in ethanol-treated rats and demonstrated the protective role of SPH.

The present work is to evaluate the neurotoxicity induced by pyrethroid insecticide “Deltamethrin” at 0.32 mg/kg/day in two main regions of the Wistar rat brain (hippocampus and striatum) and the protective effects of Quercetin at 10 mg/kg/day on this toxicity after 90 days of exposure. The assay of brain parameters showed that Deltamethrin caused a significant increase of mitochondrial metabolite level (proteins, lipids, and carbohydrates) and enzyme activity (glutathione S-transferase and superoxide dismutase); a decreased amount of mitochondrial glutathione level and catalase and glutathione peroxidase activities; and an increase of malondialdehyde (MDA) acid levels of the two regions. Furthermore, mitochondrial functional testing in the brains of treated rats exhibited a significant increase in permeability followed by a mitochondrial swelling. Instead, a statistically significant decrease in mitochondrial respiration (O₂ consumption) was recorded in the striatum and hippocampus. Our study showed that the pesticide caused a significant increase of the cytochrome c amount correlated with activation of neuronal apoptosis mechanisms by the significant increase of caspase-3 of hippocampus and striatum. In particular, the results of behavioral tests (open field, classic maze tests of sucrose, and Morris water maze) have significant changes, namely bad behavior of the treated rats, affecting the level of anxiety, learning, and memory, and general motor activity has mainly been shown in treated rats. In addition, the histological cuts clearly confirm cerebral necrosis in the hippocampus and the striatum caused by the pesticide. They allow us to consider the necrotic areas, black spots, reduction, and denaturation of these brain regions in the treated rats. On the other hand, we have studied the protective effects against the neurotoxicity of Deltamethrin (DLM). In this context, after the gavage of Quercetin at the dose of 10 mg/kg/day, we have noticed an improvement in the entire parameters: mitochondrial enzyme, metabolic, histological, and behavioral parameters. This confirmed the improvement of preventive and curative effect of Quercetin against free radicals induced by the DLM.