Induction of micronuclei and nuclear abnormalities in Oreochromis niloticus following exposure to petroleum refinery and chromium processing plant effluents

Effects of urban streams on muscle non-protein thiols, gill and liver histopathology in zebrafish (Danio rerio) assessed by active biomonitoring

Aquatic biota are exposed to toxic substances resulting from human activities, reducing environmental quality and can compromise the health of the organisms. This study aimed to employ Danio rerio as an environmental bioindicator, analyzing the effects of water from distinct urban aquatic environments. An active biomonitoring system was set up to compare the temporal dynamics of histological biomarkers for gill and liver and the patterns of non-protein thiols (NPSH) in muscle in specimens exposed for 3, 6, and 12 days. Three large urban basins in the city of Campo Grande (Midwest of Brazil) were selected. Two sites are in a very populous area (i.e Lagoa and Bandeira) and another on in an area with agricultural activities (i.e Anhanduí). All the streams displayed distinct qualitative characteristics. The presence of metals, including Mn, Zn, Fe, and Al, as well as pH, temperature, and dissolved oxygen, accounted for 38% of the variability (PC1), while total solids, conductivity, ammonia, nitrite, and explained 24 % (PC2). Degree tissue changes index (DTC) in gill and the concentration of NPSH increased in all streams during 3, 6 and 12 days of exposure. DTC in liver increases in all exposure times in most populous stream (i.e Lagoa and Bandeira). Histopathological evidence in the gill, including proliferation, desquamation, and necrosis of the primary lamellar epithelium; fusion and aneurysms in the secondary lamellar epithelium were observed after three days of exposure. Degenerative nuclear figures were noted in the liver after three days of exposure, followed by hepatocellular hypertrophy, lipidosis, and necrosis at twelve days. Our findings showing time-dependent effects of urban aquatic environments in histopathological (i.e DTC) and biochemical biomarkers in zebrafish. The biomonitoring model enabled a comparison of the temporal dynamics of various health markers, using zebrafish as bioindicator. Future studies might use this experimental model and biomarkers for environmental biomonitoring program.

Assessing haematological parameters and probable toxicity analysis in two coastal fish species at harbouring areas of Digha coastal belt, West Bengal, India

Coastal ecosystems are vital for maintaining the biodiversity and human livelihoods, but they are increasingly subjected to anthropogenic pressures, including pollution from various sources. Present work intends to assess the possible threats in coastal ecosystem as well as coastal fish species, in particular, through haematological parameters caused due to exposure of environmental contaminants like polycyclic aromatic hydrocarbons (PAHs), potentially toxic metals (PTMs), etc. This study analysed the haematological parameters and probable toxicity levels in two important coastal fish species, viz., Mystus sp. and Mugil sp. widely available in Digha coastal belt. Different haematological parameters, such as WBCs (White Blood Cells), Lym (Lymphocytes), Gran (Granulocytes), Mid (Monocytes), RBCs (Red Blood Cells), HCT (Haematocrit) value, MCV (Mean Corpuscular Volume), MCH (Mean Corpuscular Haemoglobin), MCHC (Mean Corpuscular Haemoglobin Concentration), RDW- CV (Red Cells Distribution Width-Co-efficient of Variation), RDW- SD (Red Cells Distribution Width-Standard Deviation), PLT (Total Platelet Count), MPV (Mean Platelet Volume), PDW- SD (Platelet Distribution Width-Standard Deviation), PDW- CV (Platelet Distribution Width-Co-efficient of Variation), PCT (Plateletcrit), PLCR (Platelet Large Cell Ratio), PLCC (Platelet Large Cell Count) and many others were measured directly through Erba H360 Haematology Analyser, simultaneously air dried blood smear was stained by Haematoxylin-Eosin(H-E) and Giemsa stain for assessing morphometric alterations of RBCs, WBCs, platelets as well as to determine the differential counts of WBCs by observing through Leica DM2000 microscope. Evidence of several abnormalities in the erythrocyte's nucleus (ENAs) and the abundance of abnormal celled erythrocytes (ECAs), carcinoma (lymphoproliferative disorder, polycythaemia vera, Hodgkin lymphoma and non-Hodgkin lymphoma), elevation of WBCs content, Lym %(Lymphocyte percentage), Eo(Eosinophils), monocytes, HCT and gross depletion of Ne(Neutrophils), basophils, and PLCR levels indicated a sign of major impact of contamination to two intoxicated fishes which may also affect the human being through food chain and may result into leukaemia in mammalian species, finally. However, comprehensive evaluation of the long-term impacts of the contaminants like PAHs and/or PTMs, etc., on fish populations, human health risk and coastal ecosystem is required to be addressed.

Hematological and genotoxic biomarkers in a natural population of freshwater turtles Trachemys dorbigni (Duméril & Bibron, 1835) (Testudines: Emydidae) living in an urban area in Southern Brazil

The present study aimed to report the morphometric and hematological indices and genotoxicity of a free-life population of D'Orbigny's slider turtles (Trachemys dorbigni) living in an urban area in Southern Brazil. For that, 16 specimens were randomly captured in an urban canal that receives irregular releases of wastewater. Biometrics and external visual changes were analyzed, such as turtle shell deformities, and the presence of parasites. Blood samples were collected to evaluate the hematological profile and the presence of micronuclei and other erythrocyte nuclear abnormalities as potential mutagenic and genotoxic effects. Water physicochemical parameters were also measured. Organisms with ectoparasites (31.25%) and small carapace deformations (56.25%) were observed, but maximum carapace length and weight were considered normal for the species according to the literature. The blood profile indicated low hemoglobin and hematocrit and a high number of total leukocytes, particularly eosinophils which characterize parasitic infections. A frequency of 0.12% for the micronucleus was considered basal, but the frequency of other erythrocyte abnormalities was evident, mainly of blebbed nuclei (63.79%), indicating chromosomal damage in the early stage. The results of this study suggest that natural populations of chelonian inhabiting urbanized areas are impacted by anthropogenic activities in the surrounding environment. Furthermore, it provides comprehensive data which can serve as a comparative model for environmental monitoring studies involving turtles.

Experimentally exposed toxic effects of long-term exposure to environmentally relevant concentrations of CIP in males and females of the silver catfish Rhamdia quelen

Ciprofloxacin (CIP) is an antibiotic commonly used in human and veterinary medicine. It is present in the aquatic environment, but we still know very little about its effect on non-targeted organisms. This study aimed to evaluate the effects of long-term exposure to environmental CIP concentrations (1, 10, and 100 μg.L^-1) in males and females of Rhamdia quelen. After 28 days of exposure, we collected the blood for the analysis of hematological and genotoxic biomarkers. Additionally, we measured 17 β-estradiol and 11 keto-testosterone levels. After the euthanasia, we collected the brain and the hypothalamus to analyze acetylcholinesterase (AChE) activity and neurotransmitters, respectively. The liver and gonads were assessed for biochemical, genotoxic, and histopathological biomarkers. At 100 μg.L^-1 CIP, we observed genotoxicity in the blood, nuclear morphological changes, apoptosis, leukopenia, and a reduction of AChE in the brain. In the liver was observed oxidative stress and apoptosis. At 10 μg.L^-1 CIP, leukopenia, morphological changes, and apoptosis were presented in the blood and a reduction of AChE in the brain. Apoptosis, leukocyte infiltration, steatosis, and necrosis occurred in the liver. Even at the lowest concentration (1 μg.L^-1), adverse effects such as erythrocyte and liver genotoxicity, hepatocyte apoptosis, oxidative stress, and a decrease in somatic indexes were observed. The results showed the importance of monitoring CIP concentrations in the aquatic environment that cause sublethal effects on fish.

Genotoxicity effects in freshwater fish species associated with gold mining activities in tropical aquatic ecosystems

The main aim of this study was to investigate total mercury (THg), methylmercury (MeHg) and arsenic (As) concentrations, and their genotoxic effects on fish species in freshwater habitats impacted by gold mining activities in the Mojana and Bajo Cauca regions (Northern Colombia). A total of 255 individuals of Prochilodus magdalenae (PM) and Hoplias malabaricus (HM) were collected in different areas of northern Colombia, 205 in the exposed groups: Mojana 1 (61), Mojana 2 (81) and Bajo Cauca (63); and 50 individuals in the control group. Dorsal muscle was analysed for pollutants and blood to perform micronucleus (MN) and erythrocytic nuclear alterations (ENA) tests. The results of the MN revealed statistically significant (p < 0.05) genetic damage in both PM (Mojana 1 = 29.7 ± 14.2; Mojana 2 = 25 ± 6.25; Bajo Cauca= 26.6 ± 10.6) and in HM (Mojana 1 = 17.7 ± 7.8; Mojana 2 = 20.4 ± 6.3; Bajo Cauca= 20.8 ± 9.8) compared to the control group (PM= 10.5 ± 3.6; HM= 9.1 ± 3.9). Likewise, the frequency of ENA was statistically higher in the exposed groups compared to the control group (p < 0.05). On the other hand, the concentrations of THg, MeHg and As found in tissue samples were significantly higher (p < 0.05) compared to the control group, being the Bajo Cauca region the area of highest risk due to high concentrations of THg (651.2 ± 344.5 μg/kg for HM and 678.5 ± 983.9 μg/kg for PM) and MeHg (504.6 ± 220.9 μg/kg for HM and 606.8 ± 886.4 μg/kg for PM). Results showed that mean THg values for both species in Bajo Cauca exceeded the WHO maximum limit (set in 500 μg Hg/kg) in fish for human consumption. Results suggest that DNA damage in erythrocytes is associated with the presence of Hg, MeHg and As, coming from mining activities.

Altered transcriptional levels of autophagy-related genes, induced by oxidative stress in fish Channa punctatus exposed to chromium

Chromium has been detected in various water bodies as a harmful metallic stressor to aquatic organisms. This study aimed to investigate the mechanism associated with autophagy, oxidative stress, and genotoxicity after chromium (Cr⁶⁺) exposure (1/20th of 96 h-LC50, 1/10th of 96 h-LC50, and 1/5th of 96 h-LC50 of Cr⁶⁺) of common food fish Channa punctatus. The mRNA levels of autophagy-related genes ATG5, LC3, GABARAP, and mTOR were assessed in the liver and kidney tissue of fish. An upregulation of ATG5, LC3, and GABARAP was observed in both liver and kidney tissue samples, while mTOR showed transcriptional downregulation in both the tissue samples. This depicts autophagic vesicle formation due to stress signals. All the studied oxidative stress markers SOD, CAT, GSH, GR, and GPx showed an increase in the activity level of treated groups in a dose-dependent manner. Particularly, SOD and CAT have shown a significant elevation in activity level. ROS levels in blood cells increased significantly (p < 0.05) in all the treated groups (groups II, III, and IV) in a time-dependent manner as compared to the control (group I). There was a significant induction in MN frequency in all the treated groups. The highest frequency of micronuclei induced by Cr⁶⁺ was recorded in group IV after 28 days of exposure period. Collectively, it can be concluded that the information about Cr⁶⁺-induced oxidative stress-mediated autophagy in vital organs of fish Channa punctatus remains largely obscure hitherto; to fill the aforesaid gap, this study was undertaken, which gives a snapshot for the mechanisms of autophagy induced by Cr⁶⁺ in fish. HIGHLIGHTS: • Chronic exposure to Cr⁶⁺ induces eco-toxicological manifestations in a fish Channa punctatus. • Altered transcriptional profile of autophagy-related genes suggests autophagic vesicle formation due to stress signals. • Increased activity levels of oxidative stress biomarkers reveal that Cr⁶⁺ annihilates antioxidative defense system in fish. • Genotoxicity due to chromium exposure is evident by increased frequency of MN in red blood cells of fish. • The information presented in this study is helpful to get an insight into the mechanism of Cr⁶⁺-induced oxidative stress-mediated induction of autophagy in the liver and kidney of Channa punctatus.

Toxicity evaluation of the combination of emerging pollutants with polyethylene microplastics in zebrafish: Perspective study of genotoxicity, mutagenicity, and redox unbalance

Despite the toxicity of microplastics (MPs) in freshwater fish has been demonstrated in previous studies, their effects when mixed with other pollutants (organic and inorganic) are poorly understood. Thus, we aimed to test the hypothesis that the association of polyethylene MPs (PE-MPs) to a mix of emerging pollutants induces more adverse genotoxic, mutagenic, and redox unbalance effects in adult zebrafish (Danio rerio), after 15 days of exposure. Although the accumulation of MPs in animals was greater in animals exposed to PE-MPs alone, erythrocyte DNA damage (comet assay) and the frequency of erythrocytic nuclear abnormalities (ENAs) evidenced in zebrafish exposed to PE-MPs alone were as pronounced as those observed in animals exposed to the mix of pollutant (alone or in combination with MPs), which constitutes the big picture of the current study. Moreover, we noticed that such effects were associated with an imbalance between pro-and antioxidant metabolism in animals, whose activity of superoxide dismutase (SOD) and catalase (CAT) was assessed in different organs which were not sufficient to counterbalance the production of reactive oxygen species [hydrogen peroxide (H₂O₂)] and nitrogen [nitric oxide (NO)] evaluated. The principal component analysis (PCA) also revealed that while the antioxidant activity was more pronounced in the brain and liver of animals, the highest production of H₂O₂ was perceived in the gills and muscles, suggesting that the biochemical response of the animals was organ-dependent. Thus, the present study did not demonstrate antagonistic, synergistic, or additive effects on animals exposed to the combination between PE-MPs and a mix of pollutants in the zebrafish, which reinforces the theory that interactions between pollutants in aquatic ecosystems may be as complex as their effects on freshwater ichthyofauna.

Low concentrations of ciprofloxacin alone and in combination with paracetamol induce oxidative stress, upregulation of apoptotic-related genes, histological alterations in the liver, and genotoxicity in Danio rerio

Nowadays, there are countless articles about the harmful effects of paracetamol (PCM) in non-target organisms. Nonetheless, information regarding the toxicity of ciprofloxacin (CPX) and the CPX-PCM mixture is still limited. Herein, we aimed to evaluate the hepatotoxic and genotoxic effects that ciprofloxacin alone and in combination with paracetamol may induce in Danio rerio adults. For this purpose, we exposed several D. rerio adults to three environmentally relevant concentrations of PCM (0.125, 0.250, and 0.500 μg/L), CPX (0.250, 0.500, and 1 μg/L), and their mixture (0.125 + 0.250, 0.250 + 0.500, and 0.500 + 1 μg/L) for 96 h. The blood samples showed CPX alone and in combination with PCM damaged the liver function of fish by increasing the serum levels of liver enzymes alanine aminotransferase and alkaline phosphatase. Moreover, our histopathological study demonstrated liver of fish suffered several tissue alterations, such as congestion, hyperemia, infiltration, sinusoidal dilatation, macrovascular fatty degeneration, and pyknotic nuclei after exposure to CPX alone and in combination with PCM. Concerning oxidative stress biomarkers and the expression of genes, we demonstrated that CPX and its mixture, with PCM, increased the levels of antioxidant enzymes and oxidative damage biomarkers and altered the expression of Nrf1, Nrf2, BAX, and CASP3, 6, 8, and 9 in the liver of fish. Last but not least, we demonstrated CPX alone and with PCM induced DNA damage via comet assay and increased the frequency of micronuclei in a concentration-dependent manner in fish. Overall, our results let us point out CPX, even at low concentrations, induces hepatotoxic effects in fish and that its combination with PCM has a negative synergic effect in the liver of this organism.

Sublethal biochemical, histopathological and genotoxicological effects of short-term exposure to ciprofloxacin in catfish Rhamdia quelen

Ciprofloxacin (Cipro) is commonly detected in water worldwide, however, the ecotoxicological effects to aquatic biota is still not fully understood. In this study, using multiple biomarkers, it was investigated sublethal effects of short-term exposure to Cipro concentrations (1, 10 and 100 μg.L^-1) in the Neotropical catfish Rhamdia quelen compared to non-exposure treatment (Control). After 96 h of exposure, the fishes were anesthetized for blood collection to hematological and genotoxicity biomarkers analysis. After euthanasia, the brain and muscle were sampled for biochemical biomarkers analyses. Gills, liver and posterior kidney for genotoxicity, biochemical and histopathological biomarkers analysis and anterior intestine for histopathological biomarkers analysis. Genotoxicity was observed in all tissues, regardless of the Cipro concentrations. Hematological alterations, such as reduction of the number of erythrocytes and leucocytes, as well as in hematocrit concentration and histopathological damages, such as reduction of microridges in gill epithelium and necrosis in liver and posterior kidney, occurred mainly at 100 μg.L^-1. In addition, at 100 μg.L^-1, Cipro increased antioxidant system activity (Catalase in liver and posterior kidney). These results demonstrated that under short-term exposure, Cipro causes toxic effects in R. quelen that demands attention and surveillance of environmental aquatic concentrations of this antibiotic.

In vivo assessment of genotoxic effects in Cyprinus carpio L., 1758 (Teleostei: Cyprinidae) exposed to selected metal(oid)s

Heavy metals and metalloids originating from industrial, agricultural, and urban wastes and increasing in aquatic ecosystems cause genotoxic damage to fish species. This study aimed to determine the potential genotoxic effects of mixtures of aluminum, arsenic, and manganese in Cyprinus carpio. The effects of the mixtures on erythrocyte cells of C. carpio were examined using the comet assay, micronucleus test, and erythrocytic nuclear abnormalities in two groups after exposure to three doses of the mixtures (Group A; Dose 1: 0.3 + 0.1 + 0.02 mg/L, Dose 2: 0.6 + 0.2 + 0.04 mg/L, Dose 3: 0.9 + 0.3 + 0.06 mg/L and Group B; Dose 1: 1 + 3 +0.1 mg/L, Dose 2: 2 + 6 + 0.2 mg/L, Dose 3: 3 + 9 + 0.3 mg/L). Experimental groups were formed according to the permissible limits specified in the Turkish Surface Water Quality Regulation (TSWQR). The results of comet assay parameters such as tail DNA %, tail moment, and olive tail moment confirmed the genotoxic effect of metal(oid)s mixtures on erythrocyte cells compared with control groups and showed that DNA damage increased with increasing the concentrations. The micronucleus and other nuclear abnormalities such as blebbed nuclei, notched nuclei, eightshaped nuclei, lobed nuclei, and binucleated cells were detected in the erythrocyte cells exposed to the mixtures. Consequently, it was found that the frequency of micronucleus and erythrocytic nuclear abnormalities significantly increased in the erythrocyte cells exposed to metal(oid) concentrations compared to control groups. These results show the existence of potential genotoxicity in C. carpio even at the minimum values specified in the TSWQR after exposure to the mixtures.

Assessment of toxicity in the freshwater tadpole Polypedates maculatus exposed to silver and zinc oxide nanoparticles: A multi-biomarker approach

Nanoparticles (NPs), especially silver nanoparticles (Ag NPs) and zinc oxide nanoparticles (ZnO NPs), are widely used in various industrial applications and are released into the surrounding environment through industrial and household wastewater. They have enormous toxic effects on aquatic animals and amphibians. In the current study, a multi-biomarker approach was used to assess toxicity on Polypedates maculatus (P. maculatus) tadpoles collected from a freshwater pond and exposed to sub-lethal concentrations of Ag-NPs (1, 5 and 10 mg L^-1) and ZnO-NPs (1, 10 and 50 mg L^-1). A significant bioaccumulation of silver (Ag) and Zinc (Zn) was observed in the blood, liver, kidney and bones in comparison to control tadpoles. Blood parameters (Red blood cells (RBC), Hematocrit (Htc), White blood cells (WBC), monocytes, lymphocytes and neutrophils), immunological markers (ACH50, lysozyme, total Ig, total protein, albumin, and globulin), biochemical markers (glucose, cortisol, cholesterol, triglycerides, alanine transaminase (ALT), asparatate transaminase (AST), alkaline phosphatase (ALP), urea and creatinine) and the oxidative stress marker (LPO) of serum were increased significantly (p < 0.05) in Ag/ZnO-NPs exposed groups when compared to the control groups. The levels of mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), mean corpuscular volume (MCV) and haemoglobin (Hb) in the ZnO NP-exposed groups were significantly different from those in the control group. Antioxidant (SOD and CAT) levels were significantly declined in the treatment groups. Based on the results, Ag/ZnO-NPs are toxic to aquatic organisms and amphibians at sub-lethal concentrations. The species P. maculatus can be used as a bioindicator for the nanomaterial (NM) contamination of freshwater systems.

Mercuric chloride-induced oxidative stress, genotoxicity, haematological changes and histopathological alterations in fish Channa punctatus (Bloch, 1793)

The present study was undertaken to investigate the adverse effects of mercuric chloride (HgCl₂ ) overload in the fish Channa punctatus. Two sublethal test concentrations of HgCl₂ (1/20th and 1/10th of 96 h LC₅₀ i.e., 0.03 mg l^-1 (low concentration) and 0.07 mg l^-1 (high concentration), respectively, were used for exposure. Blood, liver and kidney tissues of the control and exposed specimens were sampled at intervals of 15, 30, and 45 days to assess alterations in oxidative stress, genotoxicity haematological parameters and histopathology. Significant changes in Hb%, RBC count, WBC count, antioxidant enzyme activity, i.e., superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) and glutathione reductase (GR), were recorded. Micronuclei (MN) induction, nuclear abnormalities (NAs) and histopathological alterations were also observed in the exposed fish. Significant (P < 0.05) increase in the activities of SOD, CAT, GSH and GR was observed. After 45 days, a decrease in the level of GSH and GR was noticed which suggests an undermined anti-oxidative defence system in the fish exposed to HgCl₂ . Histological examination of the liver and kidney showed serious tissue injury and histological alterations. Significant increases in MN and NA frequencies reveal the DNA damage in erythrocytes of fish, and haematological changes show the toxicological potential of HgCl₂ . The observed changes in the antioxidant defence system, genotoxicity and haematological and histological changes in the present study provide the most extensive insight into HgCl₂ stress in C. punctatus.

Protective efficacy of naringenin against cadmium-induced redox imbalance in Labeo rohita: an integrated biomarker approach

The protective efficacy of dietary naringenin (NG) has been investigated against the toxicity caused by cadmium chloride (CdCl₂) using biomarkers of oxidative stress in the liver, gills and kidney of Labeo rohita. The fish were exposed to environmentally relevant concentrations of CdCl₂ (0.37 and 0.62 mg/L) and simultaneously orally administered with NG (50 mg/kg bw/day) for 60 days. Tissue (gills, liver and kidney) samples were collected on days 15, 30 and 60 of the experiment and analysed for endogenous antioxidants and oxidative stress biomarkers. CdCl₂ exposure for 15 and 30 days induced the development of adaptive mechanism as demonstrated by the enhanced activities of superoxide dismutase, catalase, glutathione peroxidase and glutathione-S-transferase in all three tissues. However, on the 60th day, CdCl₂-induced oxidative damage was stipulated by a decline in the enzyme activities and reduced glutathione (GSH) content significantly (p < 0.05) below control levels along with enhanced levels of lipid peroxidation. Oral administration of NG in toxicant exposed fish significantly restored the altered levels of antioxidants, oxidative enzymes and lipid peroxidation. Besides, integrated biomarker response (IBR) analysis was applied by combining all the biomarkers to indicate the overall stress response index. IBR analysis confirmed the altered levels of biomarkers, the oxidative stress induced by CdCl₂ exposure and the ameliorative potential of NG. The present study suggested that NG might have protective role against Cd-induced oxidative insult which might be ascribed to the ability of NG to chelate metals and scavenge free radicals.

Genotoxicity, oxidative stress and lysozyme induction in Clarias gariepinus chronically exposed to water-soluble fraction of burnt tire ash

The safety of aquatic ecosystems has been compromised by numerous anthropogenic activities, especially leachates from non-point source toxicants, leaching into aquatic systems. This study evaluated the toxicity of the water-soluble fractions (WSFs) of burnt tire ash (BTA) on Clarias gariepinus via a battery of integrated biomarkers. Juvenile C. gariepinus were exposed to sublethal (0.56, 1.12, and 2.24 g/L) concentrations of BTA, derived from 11.2 g/L median lethal concentration (96 LC₅₀), at duration intervals of 1, 14, and 28 days, followed by a recovery trial that lasted for 14 days. Serum biochemical parameters, antioxidant enzyme activities of the gill and liver, lysozymes activity and erythron profile were assessed. The findings of the present study revealed that BTA-WSF induced prominent alterations on biochemical parameters, lysozymes activity and antioxidant enzymes activities in the exposed fish. Furthermore, toxicant exposure promoted oxidative stress, cellular damage and genotoxicity (erythrocytic nuclear and cellular abnormalities) in the exposed fish. In general, a post-exposure trial showed partial recovery from the exposure effects of the toxicant, following the evident modifications of serum enzymes and erythron pathopathology in the experimental model. Biomonitoring of BTA, using sentinel aquatic species such as C. gariepinus, provides insights into the ecotoxicological potency of this toxicant.

Aquatic concentration and risk assessment of pharmaceutically active compounds in the environment

Pharmaceutically active compounds are increasingly detected in raw and treated wastewater, surface water, and drinking water worldwide. These compounds can cause adverse effects to the ecosystem even at low concentrations and, to assess these impacts, toxicity tests are essential. However, the toxicity data are scarce for many PhACs, and when available, they are dispersed in the literature. The values of pharmaceuticals concentration in the environment and toxicity data are essential for measuring their environmental and human health risks. Thus this review verified the concentrations of pharmaceuticals in the aquatic environment and the toxicity related to them. The risk assessment was also carried out. Diclofenac, naproxen, erythromycin, roxithromycin, and 17β-estradiol presented a high environment risk and 17α-ethinylestradiol presented a high human health risk. This shows the potential of these pharmaceuticals to cause adverse effects to the ecosystem and humans and establishes the necessity of their removal through advanced technologies.

Chromium Exposure Causes Structural Aberrations of Erythrocytes, Gills, Liver, Kidney, and Genetic Damage in Striped Catfish Pangasianodon hypophthalmus

Heavy metal pollution due to anthropogenic activities poses a great threat to aquatic organisms. The present study was conducted to evaluate the cytotoxic and genotoxic effects of hexavalent chromium (potassium dichromate) on hemato-biochemical, histo-pathological, and genetical changes in striped catfish Pangasianodon hypophthalmus. Three sub-lethal doses (0.8, 1.6, and 3.2 mg/L) of chromium (Cr) were selected and fish were exposed in vivo contrasting with a control (0 mg/L) for 30 days. The study revealed that various hemato-biochemical parameters showed a significant decrease in hemoglobin (Hb), red blood cells (RBCs), and blood glucose content, whereas white blood cells (WBCs) significantly increased in Cr exposed fish. Frequencies of all forms of structural abnormalities of erythrocytes (erythrocytic cellular abnormalities; ECA, erythrocytic nuclear abnormalities; ENA and erythroblasts; Ebs) were significantly increased in higher two test concentrations (1.6 and 3.2 mg/L) when compared to control. Differential leucocyte count exhibited significant increase in neutrophil and decrease in lymphocytes in the highest Cr treated group. The severity of various histo-pathological changes in the gills, liver, and kidney were increased considerably with the increase of Cr concentrations. Similarly, the amount of DNA (ng/μl) decreased significantly in blood and tissues of different vital organs where the liver showed the highest decline compared to control in a concentration-dependent manner. Taken altogether, P. hypophthalmus is susceptible to Cr and can be used as a bio-indicator to assess aquatic metal pollution.

Impacts of wildfires in aquatic organisms: biomarker responses and erythrocyte nuclear abnormalities in Gambusia holbrooki exposed in situ

Wildfires are an environmental concern due to the loss of forest area and biodiversity, but also because their role as drivers of freshwater systems contamination by metals. In this context, the fish Gambusia holbrooki was used as a model, deployed for in situ exposure in watercourses standing within a recently burnt area and further assessment of toxic effects. The fish were exposed during 4 days at four different sites: one upstream and another downstream the burnt area and two within the burnt area. Biochemical biomarkers for oxidative stress and damage were assessed. The extent of lipoperoxidative damage was monitored by quantifying malondialdehyde and DNA damage evaluated through erythrocyte nuclear abnormalities observation. Chemical analysis revealed higher metal levels within the burnt area, and exposed fish consistently showed pro-oxidative responses therein, particularly an increase of gill glutathione peroxidase and glutathione reductase activity, the records doubling compared to samples from sites in the unburnt area; also the activity of glutathione-S-transferases comparatively increased (by 2-fold in the liver) in samples from the burnt area, and malondialdehyde was produced twice as much therein and in samples downstream the burnt area reflecting oxidative damage. Consistently, the frequency of erythrocyte nuclear abnormalities was higher at sites within and downstream the burnt area. This study supports the use of sensitive oxidative stress and genotoxicity biomarkers for an early detection of potentially noxious ecological effects of wildfires runoff.

Cytotoxic effects of wildfire ashes: In-vitro responses of skin cells

Wildfires are a complex environmental problem worldwide. The ashes produced during the fire bear metals and PAHs with high toxicity and environmental persistence. These are mobilized into downhill waterbodies, where they can impair water quality and human health. In this context, the present study aimed at assessing the toxicity of mimicked wildfire runoff to human skin cells, providing a first view on the human health hazardous potential of such matrices. Human keratinocytes (HaCaT) were exposed to aqueous extracts of ashes (AEA) prepared from ash deposited in the soil after wildfires burned a pine or a eucalypt forest stand. Cytotoxicity (MTT assay) and changes in cell cycle dynamics (flow cytometry) were assessed. Cell viability decreased with increasing concentrations of AEA, regardless of the ash source, the extracts preparation method (filtered or unfiltered to address the dissolved or the total fractions of contaminants, respectively) or the exposure period (24 and 48 h). The cells growth was also negatively affected by the tested AEA matrices, as evidenced by a deceleration of the progress through the cell cycle, namely from phase G0/G1 to G2. The cytotoxicity of AEA could be related to particulate and dissolved metal content, but the particles themselves may directly affect the cell membrane. Eucalypt ash was apparently more cytotoxic than pine ash due to differential ash metal burden and mobility to the water phase. The deceleration of the cell cycle can be explained by the attempt of cells to repair metal-induced DNA damage, while if this checkpoint and repair pathways are not well coordinated by metal interference, genomic instability may occur. Globally, our results trigger public health concerns since the burnt areas frequently stand in slopes of watershed that serve as recreation sites and sources of drinking water, thus promoting human exposure to wildfire-driven contamination.

Morphological, behavioral and genotoxic effects of glyphosate and 2,4-D mixture in tadpoles of two native species of South American amphibians

Pesticide contamination is an important factor in the global decline of amphibians. The herbicides glyphosate and 2,4-D are the most applied worldwide. These herbicides are often found in surface waters close to agricultural areas. This study aims at evaluating the chronic effects caused by glyphosate + 2,4-D mixture in Boana faber and Leptodactylus latrans tadpoles. The combined solution of the glyphosate and 2,4-D, in 5 different concentrations, was applied for 168 h. Herbicide mixtures did not affect the survival of the exposed tadpoles but growth and swimming activity were altered; besides causing several damages in the mouth and intestine. The erythrocytes showed micronuclei and other nuclear abnormalities. There is an ecological risk in the exposure of tadpoles of B. faber and L. latrans from the mixture of glyphosate + 2,4-D. Therefore, the approach used in this study provides important information on how commonly used pesticides can affect non-target organisms.

Cytotoxicity and mutagenicity of the waters of the Marrecas River (Paraná, Brazil) to bullfrogs (Lithobates catesbeianus)

Animals have a long history of assessing ecosystem responses to environmental disturbances, and amphibians stand out for presenting themselves as good animal model and bioindicators of environmental quality. The main purpose of the present work was to investigate the cellular effects of contamination of waters of the Marrecas River, located in the southwest of the state of Paraná, Brazil. Therefore, the objective of the present study was to investigate and monitor the cytotoxic and mutagenic effect, with bullfrog tadpoles, and to discuss these effects with land use along this hydrographic basin. Mutagenic effects were determined by micronucleus assay, and cytotoxicity by other nuclear changes, such as segmented cells, binucleated cells, cells with buds and reniform cells. Water samples were obtained at nine sites along the Marrecas River, covering areas with rural and urban hydrological contribution. For each site, four samples were collected, along the years 2017 and 2018, encompassing the four seasons (summer, autumn, winter, and spring). The results showed mutagenic and cytotoxic effect in four sampling sites, and only cytotoxic effect in other four sites. These effects may be due, possibly, to the use of different agrochemicals across the hydrographic basin region, which have predominant hydrological contributions from crops. Data of this study indicate the presence of cytotoxic and mutagenic contaminants in the waters of the Marrecas River, which can generate environmental problems on the river fauna/flora, and can also affect the local population health.

Haematological, biochemical, enzymological and histological responses of Labeo rohita exposed to methyl orange dye solution treated with Oedogonium subplagiostomum AP1

The present investigation is an attempt to assess the impact of untreated methyl orange and Oedogonium subplagiostomum AP1 treated methyl orange dye solutions on Labeo rohita. The behavioural response, mortality, haematological (red blood corpuscles (RBC), packed cell volume (PCV), haemoglobin (Hb), white blood corpuscles (WBC), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC)), biochemical (plasma glucose and protein), enzymological (aspartate amino transaminases (AST) and alanine amino transaminases (ALT)) and histological examination (gills, liver and kidney) of Labeo rohita are exposed to untreated and treated methyl orange dye solutions were assessed on 7th day. The fish exposed to tap water and treated dye solution showed normal behavioural response whereas abnormal behaviour was noted in fish exposed to untreated dye solution. Similar trend was recorded in the mortality rate of the fishes. Fish exposed to untreated dye solution showed reduction in RBC, PCV, Hb, MCHC, plasma glucose and plasma protein, increased level of WBC, MCV and MCH and also alteration in AST and ALT thereby indicating the toxicity of the dye. No such reduction and alteration were observed in haematological, biochemical and enzymological levels of fishes exposed to tap water and treated dye solution indicating the non-toxic nature of the degraded metabolites of dye. Histological examination of fishes exposed to methyl orange dye revealed necrosis and haemorrhage in the gills and hepatocytes, congested and shrunken glomeruli in kidney thereby indicating the toxicity of the dye. The histoarchitecture of control and algae-treated fishes showed no structural changes indicating the non-toxic nature of the degraded metabolites of the dye. The results concluded that methyl orange dye solution treated with O. subplagiostomum AP1 can be explored for aquacultural purposes owing to its non-toxic nature.

Evaluation of the genotoxic and cytotoxic effects of exposure to the herbicide 2,4-dichlorophenoxyacetic acid in Astyanax lacustris (Pisces, Characidae) and the potential for its removal from contaminated water using a biosorbent

The genotoxic and cytotoxic effects of 2,4-dichlorophenoxyacetic acid (2,4-D) on specimens of Astyanax lacustris were evaluated using different biomarkers. Additionally, this study evaluated the efficiency of an activated carbon filter made from the husks green coconut, which was used as a biosorbent to remove 2,4-D dissolved in the water, and the potential effectiveness of this procedure for the reduction of the toxic effects of this compound on A. lacustris. Three sublethal concentrations of 2,4-D (10, 20, and 40 mg L^-1) were tested over 24, 48, and 72 h, and their effects on Astyanax lacustris were evaluated using chromosomal aberration test, the mitotic index, the frequency of micronuclei and nuclear alterations, and the comet assay. Exposure to 2,4-D increased the frequency of chromosomal aberrations, reduced the mitotic index, and caused significant levels of nuclear modification in some of the treatments, in comparison with the negative control. The comet assay revealed DNA damage (classes 1-3) at all 2,4-D concentrations, reaching significant levels in the 20 mg L^-1 (48 h) and 40 mg L^-1 (72 h) treatments. The coconut husk biosorbent was highly effective for the removal of 2,4-D and the fish exposed to the water decontaminated by this filter had low levels of cellular alteration. The findings of the present study demonstrated, for the first time, the genotoxic and cytotoxic effects of 2,4-D in Astyanax lacustris, as well as suggests the potential application of a biosorbent for the effective decontamination of water contaminated with pesticides.

Geno-cytotoxicity and congenital malformations produced by relevant environmental concentrations of aluminum, diclofenac and their mixture on Cyprinus carpio. An interactions study

Several studies highlight the presence of aluminum and diclofenac in water bodies around the world and their ability to induce oxidative stress and a negative effect on biomolecules in several aquatic species. However, studies evaluating the toxic effect of mixtures of these contaminants are scarce. The objective of this work was to determine the genotoxic, cytotoxic and embryotoxic effect of the mixture of aluminum and diclofenac at environmentally relevant concentrations on Cyprinus carpio. Juveniles of Cyprinus carpio were exposed to 0.31 μg L^-1 of diclofenac, 24.45 mg L^-1 of aluminum, and a mixture of both contaminants at the same concentrations for 12, 24, 48, 72 and 96 h. After the exposure time the liver, gills and blood were extracted and the following biomarkers were evaluated: micronucleus frequency, comet assay, caspase activity and TUNEL test. On the other hand, Cyprinus carpio embryos were exposed to diclofenac (0.31 μg L^-1), aluminum (0.06 mg L^-1) and their mixture at the same concentrations and exposure time. Microscopic observation was performed to evaluate embryonic development at 12, 24, 48, 72 and 96 h. Diclofenac (0.31 μg L^-1) induces significant increases in micronucleus frequency with respect to control (p < 0.05), in all tissues. Aluminum (24.45 mg L^-1) significantly increases DNA damage index in liver and blood cells with respect to control (p < 0.05). All treatments increase caspases activity in all tissues with respect to control (p < 0.05). Diclofenac increases the percentage of TUNEL-positive cells in liver and blood; while aluminum and the mixture increases it significantly in gills and blood with respect to the control (p < 0.05). The mixture significantly delays embryonic development, while aluminum and the mixture significantly increase teratogenic index with respect to control (p < 0.05). In conclusion, exposure to environmental concentrations of aluminium, diclofenac and their mixture induces genotoxic damage, cell death by apoptosis and negative effects on the development of Cyprinus carpio and the toxic response is modified by the interaction of the xenobiotics.

Tissue-specific genotoxicity and antioxidant imbalance of titanium dioxide nanoparticles (NPTiO2) and inorganic lead (PbII) in a neotropical fish species

The aquatic environment is the major recipient of wastes containing nanoparticles and other contaminants. Titanium dioxide nanoparticles (NPTiO₂) are one of the most produced and used nanoparticle worldwide. This study investigated the toxicity of NPTiO₂, as well as the toxicity interaction between NPTiO₂ and lead (Pb), in response to genetic and biochemical biomarkers using freshwater fish Rhamdia quelen, as an animal model. The results showed genotoxicity in blood and kidney tissues. No effect of NPTiO₂ alone or in co-exposure with Pb on liver genotoxicity were observed. Alterations in the antioxidant hepatic enzymes activities, as well as alterations in glutathione levels indicated that NPTiO₂ alone or in co-exposure with Pb can cause antioxidant imbalance. The lipid peroxidation was also raised after exposure to NPTiO₂. In general, the results of this study indicated that both NPTiO₂ alone and their co-exposure with Pb are capable of producing significant toxic effects in short-term exposure.

Micronuclei in Fish Erythrocytes as Genotoxic Biomarkers of Water Pollution: An Overview

Freshwater and marine water bodies receive chemical contaminants from industrial, agricultural, urban, and domestic wastes. Eco-genotoxicity assays are useful tools to assess the cumulative genotoxicity of these pollutants. Fish are suitable indicators for biomonitoring of mutagenic and carcinogenic pollution.In this review, we present a complete overview of the studies performed so far using the micronucleus test in peripheral erythrocytes of fish exposed to polluted water. We have listed all the species of fish used and the geographical distribution of the investigations. We have analyzed and discussed all technical aspects of using this test in fish, as well as the advantages and disadvantages of the different experimental protocols. We have reported the results of all studies. This assay has become, for years, one of the simplest, fastest, and most cost-effective for assessing genotoxic risk in aquatic environments. However, there are still several factors influencing the variability of the results. Therefore, we have given indications and suggestions to achieve a standardization of experimental procedures and ensure uniformity of future investigations.

Bisphenol A and Bisphenol S Induce Endocrine and Chromosomal Alterations in Brown Trout

Bisphenol A is a widely used compound found in large amount of consumer products. As concerns have been raised about its toxicological and public health effect, the use of alternatives to bisphenol A are now increasing. Bisphenol S is one of the analogues being used as a replacement for bisphenol A despite the fact that little is known about the effects of bisphenol S on living organisms. In this study, we investigated the potential endocrine and genotoxic effects of bisphenol A and bisphenol S in juvenile brown trout (Salmo trutta). The fish were exposed to the compounds for either 2 weeks or 8 weeks via sustained-release cholesterol implants containing doses of 2 mg/kg fish or 20 mg/kg fish of the substances. The effects on the thyroid hormone levels and the estrogenic disrupting marker vitellogenin were evaluated, along with the genotoxic markers micronucleated cells and erythrocyte nuclear abnormalities. An increase in plasma vitellogenin was observed in fish exposed to the high dose of bisphenol A for 2 weeks. At this experimental time the level of the thyroid hormone triiodothyronine (T3) in plasma was elevated after bisphenol S exposure at the high concentration, and paralleled by an increase of micronucleated cells. Moreover, bisphenol A induced an increase of micronuclei frequency in fish erythrocytes after the exposure at the lowest dose tested. Taken together the results indicate that both bisphenol A and its alternative bisphenol S cause endocrine disrupting and genotoxic effects in brown trout, although suggesting two different mechanisms of damage underlying bisphenol A and bisphenol S activity.

Naphthenic acids are key contributors to toxicity of heavy oil refining effluents

Oil refining produces vast quantities of wastewater with harmful contaminants that can be released back into the environment with a possible risk of toxicity to aquatic wildlife and human populations. Hence the importance of adequate wastewater treatment to achieve safe effluents that protect both ecological and human health. However, some refining effluents are linked to serious pollution problems even after treatment, partly because little progress has been made in determining the causative agents of the observed biological effects, resulting in non-targeted treatment. Here, we followed an effect-directed analysis (EDA) approach using Aliivibrio fischeri as biosensor to show that naphthenic acids (NAs) are important components of refining wastewater resulting from the processing of heavy crude oil. Furthermore, we demonstrate that besides mixture effects, NAs have a significant contribution to the toxicity exerted by these effluents. Profiling of the NA mixture was conducted using high resolution liquid chromatography-Orbitrap, which evidenced that O₂ NAs corresponded to 90% of the NAs detected. Our findings contrast with previous reports where classic NAs have been found between 15% and 72% and could explain the significant biological effects observed in A. fischeri. This study broadens the body of evidence pointing at mixture effects and low-concentration pollutants as the cause of toxicity from RWW, in addition to NAs resulting from the processing of heavy crude oil. Our results can serve as a starting point for setting better effluent discharge standards relevant to oil refining wastewater resulting from heavy crude oil and help improve wastewater treatment plants to reduce effluent toxicity.

Chlorpyrifos levels within permitted limits induce nuclear abnormalities and DNA damage in the erythrocytes of the common carp

The organophosphate pesticide chlorpyrifos (CPF) is defined as a priority pollutant in surface freshwaters according to Directive 2013/39/EU of the European Parliament. The focus of this study was to assess the potential cytotoxic and genotoxic effects of permissible CPF levels on juvenile forms of the common carp. We found that low-level CPF exposure did not induce elevated levels of micronuclei, but significantly increased the frequency of total nuclear abnormalities (NAs) proportional to dose and time; notched, blebbed, lobed and eight-shaped nuclei, nuclear buds, nuclear bridges and binucleated cells were all detected. Decreased frequencies of polychromatic erythrocytes (PCEs) and DNA damage detected by comet assay were also observed, confirming the cytotoxic and genotoxic effects of CPF. Altogether, these data (1) demonstrate that CPF is toxic even at permissible levels, possessing considerable genotoxic and cytotoxic potential in peripheral erythrocytes of exposed fish and (2) validate the assessment of NAs, PCEs and comet assay performance as sensitive biomarkers for the early detection of CPF pollution. These findings can be applied to guide environmental risk assessment and biomonitoring programs.

Micronucleus test in tadpole erythrocytes: Trends in studies and new paths

The micronucleus test has been applied for more than three decades in tadpoles, generating an early warning of environmental quality. In this study, we reviewed 48 articles on the micronucleus test in tadpoles, published between 1987 and 2018. The findings reveal that pesticides have been the main topic discussed in the induction of micronucleus and other nuclear abnormalities in anuran larvae to the detriment of the widespread use of compounds used in agriculture. In addition to pesticides, a number of other xenobiotic agents have been targeted for genotoxic damage, such as heavy metals, radiation and wastewater. An appeal is reported to environmental contaminants, which when released naturally into the environment or because of human activities may contaminate aquatic habitats, threatening populations of tadpoles that depend on these environments for their survival. Larvae can bioaccumulate these contaminants that cause progressive impacts, ranging from DNA damage to metamorphosis delays, as well as malformations. We found that Argentina is the main driving force for the application of this test in anuran larvae along with Brazil. Different erythrocyte malformations have been reported for the erythrocyte nuclear abnormalities test, binucleated cells, nuclear buds, notched, lobed, reniform, nuclear bebbled, anucleated, picnotic and apoptotic cells are the most cited. In summary, the presence of chemical or physical agents, along with other disturbances of the habitat, can have a significant impact on the life history of the species, contributing to the decline of anuran populations.

An imazethapyr-based herbicide formulation induces genotoxic, biochemical, and individual organizational effects in Leptodactylus latinasus tadpoles (Anura: Leptodactylidae)

Genotoxic, biochemical, and individual organizational effects on Leptodactylus latinasus tadpoles were evaluated after exposure to an imazethapyr (IMZT)-based commercial herbicide formulation, Pivot® H (10.59% IMZT). A determination of the value of the lethal concentration (LC50) was determined as a toxicological endpoint. Alterations in animal behavior and morphological abnormalities as well as cholinesterase (ChE), catalase (CAT), and glutathione S-transferase (GST) activities were employed as individual sublethal endpoints. Micronuclei frequencies (MNs), binucleated cells (BNs), blebbed nuclei (BLs), lobed nuclei (LBs), notched nuclei (NTs), erythroplastids (EPs), and evaluation of DNA strand breaks were employed as genotoxic endpoints. All biomarkers were evaluated after 48 and 96 h of exposure to concentrations of IMZT within 0.07-4.89 mg/L. LC50_96h values of 1.01 and 0.29 mg/L IMZT were obtained for Gosner stages 25 and 36, respectively. Irregular swimming, diamond body shape, and decreased frequency of keratodonts were detected at both sampling times. Results showed that IMZT increased GST activity and MN frequency at 48 and 96 h of exposure. Other nuclear abnormalities were also observed in the circulating erythrocytes of tadpoles, i.e., NT and BL values after 48 h, and LN, BL, and EP values after 96 h. Finally, results showed that IMZT within 0.07-0.22 mg/L increased the genetic damage index in tadpoles exposed for both exposure times (48 and 96 h). This study is the first to report the sublethal biochemical effects of IMZT in anurans and is also the first report using L. latinasus tadpoles as a bioindicator for ecotoxicological studies.

Effects of water-accommodated fraction of diesel fuel on seahorse (Hippocampus reidi) biomarkers

The present work aimed to investigate the effects of acute (12, 24, 48 and 96 h) and subchronic (168 and 336 h) exposure of seahorse, Hippocampus reidi to water-accommodated fraction (WAF) of diesel fuel on biotransformation parameters, antioxidant defenses and DNA integrity. In addition, a recovery experiment was performed, where the organisms remained in absence of the contaminant for 336 h, after WAF exposure for 168 h (totaling 504 h). At the end of each experimental protocol, the concentration of pyrene-, benzo(a)pyrene- and naphthalene-type metabolites in bile, hepatic activity of glutathione-S-transferase (GST), superoxide dismutase (SOD), and catalase (CAT), as well as lipid peroxidation (LPO) levels in hepatocytes, were analyzed, in addition to the DNA damage and the micronucleus (MN) test in the peripheral blood. It was observed that both acute and subchronic WAF exposure affected the investigated parameters in different ways. In general, the exposed groups presented higher mean values for the investigated parameters if compared with their respective controls. After the recovery experiment, the mean values of PAH metabolites, LPO, DNA damage and MN frequency were significantly lower than those of animals exposed for 168 h, indicating that the recovery period was appropriately long for the evaluated biomarkers return to the control levels. The results indicated that the selected H. reidi biomarkers proved to be adequate and complementary tools in determining the first impacts of acute and subchronic exposure caused by WAF of diesel fuel in fish, as well as their recovery in clean water.

Genotoxic and cytotoxic alterations induced by environmentally-relevant concentrations of amoxicillin in blood cells of Cyprinus carpio

Amoxicillin (AMX) is a pharmaceutical widely employed in human and veterinary medicine worldwide. Its wide production and use has led to this pharmaceutical being released into the environment in concentrations that range from ng L^-1 to μg L^-1. Previous studies have demonstrated that this antibiotic generates toxic effects, amongst which alterations to embryonic development and oxidative stress in aquatic organisms, is noteworthy. Nonetheless, it is necessary to characterize the risks that this pharmaceutical represents for species of economic interest such as Cyprinus carpio, in a more precise manner. The aim of this work was to demonstrate if AMX, at environmentally-relevant concentrations, is capable of inducing genotoxic/cytotoxic alterations in C. carpio. In order to evaluate genotoxicity, the comet assay and micronucleus test were used; in order to determine cytotoxic effects, caspase-3 activity and the TUNEL assay were carried out. The results showed that the effects of the biomarkers had their maximum at 72 h; considering the DNA damage in the comet assay, 0.039 μg L^-1 resulted in a 29% increase compared to control, and 1.67 μg L^-1 caused a 40% increase; micronucleus frequency increased by 205% in C1 and by 311% in C2 when compared to control; compared to control, caspase-3 activity increased 262% in C1 and 787% in C2; for the TUNEL assay, DNA fragmentation increased by 86% in C1 and 120% in C2 compared to control. The results showed that environmentally-relevant concentrations, AMX was capable of generating DNA damage and cytotoxic effects in blood cells of the common carp.

Alterations to DNA, apoptosis and oxidative damage induced by sucralose in blood cells of Cyprinus carpio

Sucralose (SUC) is an organochlorine that is used as a common sweetener in different dietary products around the world. Its extended use and production have led to this product is released into the environment in concentrations ranging from ng L^-1 to μg L^-1 in surface waters, groundwaters, wastewater treatment plants and ocean waters. A previous study carried out by our research team demonstrated that SUC is capable of inducing oxidative stress in Cyprinus carpio at environmentally-relevant concentrations. The aim of this study was to evaluate if SUC was capable of inducing alterations to DNA, apoptosis, and oxidative damage in the blood cells of C. carpio. Carps were exposed to two environmentally-relevant concentrations (0.05 and 155 μg L^-1) of SUC, and the following biomarkers were determined: comet assay, micronucleus test (MN), caspase-3 activity, TUNEL assay, hydroperoxide content, lipid peroxidation level, protein carbonyl content and superoxide dismutase and catalase activities. Results obtained showed that SUC is capable of inducing DNA damage. A maximum increase of 35% and 23% were observed for c1 and c2, respectively in the comet assay; increases of 586% and 507.7% for c1 and c2, respectively, were found at 72 h through the MN test. The activity of caspase-3 showed a greater response for c1 and c2 at 96 h, with 271% and 493.5%, respectively. TUNEL assay also showed the highest response at 96 h, with 51.8 for c1 and 72.9 for c2; c1 y c2 were able to induce oxidative stress with the highest expression at 72 h. A correlation between DNA damage biomarkers, apoptosis and plasma levels of SUC in both concentrations were observed. With the data obtained, we can conclude that SUC, at environmentally-relevant concentrations, was capable of generating DNA alterations, apoptosis and oxidative stress in blood cells in common carp.

Acute exposure to environmentally relevant concentrations of benzophenone-3 induced genotoxicity in Poecilia reticulata

The organic UV filter benzophenone-3 (BP-3), widely used in the commercial formulations of sunscreens and personal care products, is considered an emerging pollutant and has been associated with several human and environmental health concerns. However, knowledge about their mode of action and ecotoxicity on aquatic biota is scarce. In this scenario, the objective of this work was to evaluate the genotoxic, mutagenic, and erythrotoxicity effects of BP-3 in the guppy Poecilia reticulata after acute exposure. Adult females of P. reticulata were exposed to three non-lethal and environmentally relevant concentrations of BP-3 (10, 100, and 1000 ng L^-1) during 96 h of exposure, and the somatic parameter [Fulton condition factor (K)], genotoxicity (comet assay), mutagenicity [micronucleus (MN) and erythrocyte nuclear abnormalities (ENA) tests] and erythrotoxicity parameters (such as total cell area and nucleus-cytoplasmic ratio) were analyzed. Results showed that the general physiological condition (K value) of fish was not affected by acute exposure to BP-3. However, BP-3 induced DNA damage at 100 and 1000 ng L^-1 and increased the frequency of total ENA at 1000 ng L^-1, specially lobed nucleus, when compared to control group, indicating its genotoxic and mutagenic effects. Furthermore, the BP-3 did not induce significant changes in the total cell area and nucleus-cytoplasmic ratio. In summary, results showed that the BP-3 at environmentally relevant concentration was genotoxic to freshwater fish P. reticulata, confirming its environmental risk.

Light microscopic studies to evaluate fish scales as non-invasive indicators of heavy metal-contaminated waters

Heavy metal pollution in aquatic bodies is a matter of serious concern for aquatic fauna and human health. This study evaluated the effect of heavy metals on structural aberrations in fish scales of freshwater Indian major carp Labeo rohita. Scales from two size groups-lesser than and equal to 40 cm and greater than 40 cm-collected from three markets of Ludhiana district for a period of 6 months were assessed. The values of Pb, Zn and Cr in fish scales exceeded the permissible limits. Structural alterations such as distorted focus, damaged and eroded circuli, distorted pattern of circuli, damaged margins of scales, dispersed chromatophores, disorganised radii and damaged tubercles were observed on the dorsal surface of scales using light microscopy. It is postulated that heavy metals would be responsible for structural anomalies on scales as their accumulation was higher in larger fishes which have been exposed to metals for longer duration. These observations clearly suggest that fish scales are effective non-invasive indicator of water quality where fish have been reared and cultured.

Determination of genotoxic and antigenotoxic effects of wild-grown Reishi mushroom (Ganoderma lucidum) using the hen's egg test for analysis of micronucleus induction

The micronucleus (MN) technique is commonly used for genotoxicity testing. The hen's egg test (HET) for analysis of MN induction (HET-MN) is an inexpensive, rapid and simple genotoxicity assay that is compatible with animal protection and ethical considerations. Ganoderma lucidum (Curtis) P. Karst is known also as reishi mushroom and mushroom of immortality. It has long been used to treat disorders including fungal infections, influenza, common cold, hepatitis, diabetes, high cholesterol and cancer in many countries including China and Japan. G. lucidum strengthens the immune system and reduces the side effects of chemo- and radiotherapy. We investigated the possible genotoxic and antigenotoxic effects of the aqueous extract of wild-grown G. lucidum from Turkey using the HET-MN test. Three different doses of aqueous extract of G. lucidum, 50 µg/egg vitamin C as an antigenotoxic agent and 50 µg/egg cyclophosphamide as a genotoxic compound were injected separately or together into fertilized chicken eggs at incubation day 8. Embryonic peripheral blood smears were prepared and stained with a modified May-Grünwald-Giemsa method on incubation day 11. The frequencies of MN and nuclear abnormalities in erythrocytes were determined using light microscopy. Although the aqueous extract G. lucidum exhibited no genotoxic effect, it did exhibit an antigenotoxic effect. Our findings suggest that G. lucidum extract is a valuable natural antigenotoxic agent.

Genotoxic Evaluation in Tadpoles Associated with Agriculture in the Central Cerrado, Brazil

Many agricultural practices cause environmental degradation that affects the cellular integrity of anurans. In the present study, we provided in situ data of Dendropsophus minutus, Physalaemus cuvieri, and Scinax fuscovarius collected in soybean/corn and conservation units in the Brazilian Cerrado. The in situ data showed no significant variation in the micronucleus frequency between the sites, only the reniform cells had a higher rate for the agricultural environment. A combined analysis of all nuclear erythrocyte abnormalities (ENAs = nuclear buds, reniform nuclei, apoptotic cell, binucleated, and anucleated cells) was recorded higher frequencies in farmland. Overall, Scinax fuscovarius was considered the best potential bioindicator for soybean/corn plantations. Finally, we recommend expanding the micronucleus test for in situ studies to expand our understanding of the sensitivity of native anuran species and provide a more systematic assessment of the adverse effects of environmental pollutants on wildlife.

Cypermethrin induction of DNA damage and oxidative stress in zebrafish gill cells

Cypermethrin (CYP) is a synthetic pyrethroid insecticide, used to control pests in domestic, industrial and agricultural environments. According to recent reports, it is one of the most common contaminants in freshwater aquatic systems. The aim of this study was to evaluate its potential genotoxic effect and the activation of the superoxide dismutase (SOD) and catalase (CAT) systems of adult zebrafish gill cells after in vivo exposure. The comet assay (CA) demonstrated that gill cells are sensitive to DNA damage after in vitro exposure to hydrogen peroxide (H₂O₂), showing a dose-dependent response. We also found an increase in DNA damage of gill cells following a dose- and time-dependent treatment with CYP. Moreover, it was verified that SOD and CAT activities significantly increased after exposure to 0.6 µg/L CYP, both during six and nine days. The same treatment caused a significant up-regulation of the mRNA levels of Mn-sod and cat genes. These data indicate that CYP causes gill cell's DNA damage and oxidative stress, modifying the activities of the enzymes responsible for maintaining ROS balance, as well as in their corresponding gene expression levels.

Overview of the toxic effects of titanium dioxide nanoparticles in blood, liver, muscles, and brain of a Neotropical detritivorous fish

The toxicity of titanium dioxide nanoparticles (TiO₂ -NP) in the blood, liver, muscle, and brain of a Neotropical detritivorous fish, Prochilodus lineatus, was tested. Juvenile fish were exposed to 0, 1, 5, 10, and 50 mg L^-1 of TiO₂ -NP for 48 hours (acute exposure) or 14 days (subchronic exposure) to evaluate changes in hematology, red blood cell (RBC) genotoxicity/mutagenicity, liver function (reactive oxygen species (ROS) production, antioxidant responses, detoxification, and histopathology), acetylcholinesterase (AChE) activity in muscles and brain, and Ti bioaccumulation. TiO₂ -NP did not cause genetic damage to RBC, but acutely decreased white blood cells (WBC) and increased monocytes. Subchronically, RBC decreased, mean cell volume and hemoglobin increased, and WBC and lymphocytes decreased. Therefore, NP has the potential to affect immune system and increase energy expenditure, reducing the fish's ability to avoid predator and to resist pathogens. In the liver, acute exposure decreased ROS and increased glutathione (GSH) content, while subchronic exposure decreased superoxide dismutase activity and increased glutathione-S-transferase (GST) activity and GSH content. GSH and GST seem to play an essential role in metabolizing NP and ROS, likely increasing hepatocytes' metabolic rate, which may be the cause of observed cell hypertrophy, disarrangement of hepatic cords and degenerative morphological alterations. Although most studies indicate that the kidney is responsible for metabolizing and/or eliminating TiO₂ -NP, this study shows that the liver also has a main role in these processes. Nevertheless, Ti still accumulated in the liver, muscle, and brain and decreased muscular AChE activity after acute exposure, showing neurotoxic potential. More studies are needed to better understand the biochemical pathways TiO₂ -NP are metabolized and how its bioaccumulation may affect fish homeostasis and survival in the environment.

Antioxidant imbalance and genotoxicity detected in fish induced by titanium dioxide nanoparticles (NpTiO2) and inorganic lead (PbII)

Titanium dioxide nanoparticles (NpTiO₂) are the most widely-used nanoparticle type and the adsorption of metals such as lead (PbII) onto their surface is a major source of concern to scientists. This study evaluated the effects of the associated exposure to both types of contaminant, i.e., lead (a known genotoxic metal) and NpTiO₂, in a freshwater fish (Astyanax serratus) through intraperitoneal injection for an acute assay of 96 h. The effects of this exposure were evaluated using the comet assay, DNA diffusion assay and piscine micronucleus test, as well as the quantification of antioxidant enzymes (SOD, CAT, and GST) and metallothioneins. Our findings indicate that co-exposure of PbII with NpTiO₂ can provoke ROS imbalances, leading to DNA damage in the blood and liver tissue of A. serratus, as well as modifying erythropoiesis in this species, inducing necrosis and changing the nuclear morphology of the erythrocytes.

Sex-biased regulation of respiratory burst, phagocytic activity and plasma immune factors in lined seahorse (Hippocampus erectus) after subchronic benzo[a]pyrene exposure

Both wild and aquacultured seahorses are currently under great threat from marine pollution, notably from the potent contaminant and carcinogen benzo[a]pyrene (BaP). However, very little data are available regarding the immunomodulating effects of BaP in seahorses. Therefore, in this study, we exposed lined seahorses (Hippocampus erectus) for 7 d to BaP at three dosages (0.5, 5, and 50 μg/L) to evaluate sexual dimorphism in immune response. We measured eight immune parameters in the blood, including respiratory burst (RB), phagocytic activity (PA), monocytes/leucocytes, immunoglobulin M, complement 3, complement, interferon-a, and interleukin-2. Male seahorses had significantly higher parameters than females, except in terms of monocytes/leucocytes (P < 0.05). Although flow cytometry showed that RB and PA variation per BaP dose were roughly similar across sexes, RB and PA exhibited distinct patterns. Additionally, fluorescence intensity and leucocyte percentage were positively correlated in PA but not RB for all treatment and sex combinations. Through ELISA, we showed that the other six parameters had complex responses that nevertheless varied in a BaP-dosage and sex-dependent manner. Overall, adult male seahorses had higher immunocompetence than females before BaP exposure, and sexual dimorphism continued to be apparent during BaP exposure. Furthermore, all eight parameters were sensitive to BaP. Based on these results, we highly recommend H. erectus as a sentinel species for crude contamination, whereas PA and RB are valuable bioindicators of marine contaminants such as BaP.

Lack of mutagenicity, genotoxicity and developmental toxicity in safety assessment tests of Lactobacillus mali APS1

Lactobacillus (L.) mali APS1 isolated from sugary kefir grains has been proven to affect energy and glucose homeostasis. However, without proper safety assessment it cannot be recommended as probiotics for human consumption. For genotoxicity, the Ames test showed no mutagenic effect of L. mali APS1 in the presence or absence of S9 mix metabolic activation. In-vitro mammalian chromosomal aberration test showed that the number of Chinese hamster ovary cells with abnormal chromosomes was <5% after L. mali APS1 treatment. Moreover, L. mali APS1 showed no risk of genotoxicity potential compared to the control. L. mali APS1 administration did not cause significant (p>0.05) changes in body weight, the number of reticulocytes, or in the occurrence percentage of micronucleus in Imprinting Control Region (ICR) mice. Based on the absence of maternal or fetal effects at any dosage level investigated, the teratogenicity could be defined as greater than 1,670 mg/kg b.w./day for maternal general toxicity and fetal development when L. mali APS1 was orally administered by gavage to pregnant SD rats during gestation days 6 to 15.

Enteric nervous system analyses: New biomarkers for environmental quality assessment

The gastrointestinal tract (GIT) of fish is a target of contaminants since it can absorb these substances. We evaluated the morphophysiological alterations in the GIT of Sphoeroides testudineus collected in two estuaries presenting differences in their environmental quality (NIA and IA). The intestine was analyzed for histological and neuronal changes; liver and gills for biochemical markers; muscle tissues for neurotoxicity and peripheral blood for genotoxic damage. The results showed alterations in the GIT of the animals collected in the IA, such as muscle tunica and goblet cell density reduction, increased intraepithelial lymphocytes density and changes in neuronal density. Furthermore, changes were observed in MTs and LPO in the gills. Thus, we suggest that TGI is functioning as a barrier that responds to ingested contaminants, in order to reduce their absorption and translocation. Thus, alterations in morphophysiological and enteric neurons in S. testudineus can be used as biomarkers of environmental contamination.

Evaluation of multiwalled carbon nanotubes toxicity in two fish species

Carbon Nanotubes are among the most promising materials for the technology industry. Their unique physical and chemical proprieties may reduce the production costs and improve the efficiency of a large range of products. However, the same characteristics that have made nanomaterials interesting for industry may be responsible for inducing toxic effects on the aquatic organisms. Since the carbon nanotubes toxicity is still a controversial issue, we performed tests of acute and subchronic exposure to a commercial sample of multiwalled carbon nanotubes in two fish species, an exotic model (Danio rerio) and a native one (Astyanax altiparanae). Using the alkaline version of the comet assay on erythrocytes and the piscine micronucleous, also performed on erythrocytes, it was verified that the tested carbon nanotubes sample did not generate apparent genotoxicity by means of single/double DNA strand break or clastogenic/aneugenic effects over any of the species, independently of the exposure period. Although, our findings indicate the possibility of the occurrence of CNTs-DNA crosslinks. Apparently, the sample tested induces oxidative stress after subchronic exposure as shown by activity of superoxide dismutase and catalase. The data obtained by the activity levels of acetylcholinesterase suggests acute neurotoxicity in Astyanax altiparanae and subchronic neurotoxicity in Danio rerio.

A comprehensive review on chromium induced alterations in fresh water fishes

Chromium is considered as one of the most common ubiquitous pollutants in the aquatic environment, but the pure metallic form is absent naturally. There are three oxidation states in case of Chromium viz., Cr (II), Cr (III), Cr (VI). Among which Cr (II) is most unstable. Cr (III) and Cr (VI) are the stable oxidation state of Chromium in the environment. Being one of the commonly used metals Chromium and its particulates enter the aquatic medium through effluents discharged from different industries like textiles, tanneries, electroplating workshops, ore mining, dyeing, printing-photographic and medical industries. Among these, hexavalent chromium is considered as the most toxic form because it readily passes cellular membranes and then reduced to trivalent form. This trivalent chromium combines with several macromolecules including genetic material inside the cytosol, and is ultimately exposes the toxic and mutagenic alterations due of chromium toxicity. Chromium is taken up either through gastrointestinal tract or respiratory tract. The amount varies depending upon the medium and the form of chromium. In this review, an attempt has been made to accumulate the mammoth available data regarding impact of chromium on fresh water fishes into a systematic representation. The main objective of the review is to provide a future guideline for the scientific community and public officials involved in health risk assessment and management ensuring a better environmental condition for human health.

Diffuse sources of contamination in freshwater fish: Detecting effects through active biomonitoring and multi-biomarker approaches

Aquatic organisms are usually exposed to a mixture of xenobiotics that may exert a large effect even in low concentrations, and when information is obtained exclusively from chemical analyses the prediction of the deleterious effects is potentially hindered. Therefore, the application of complementary monitoring methods is a priority. Here, in addition to chemical analyses, an active biomonitoring study using multiple biomarker responses in Nile tilapia Oreochromis niloticus was conducted to assess the effects of a contamination gradient along four reservoirs in Iguaçu River. Chemical analysis in the muscle showed high levels of metals in fish from the reservoir closest to an industrialized and environmentally degraded area, however fish exposed to all studied reservoirs showed hepatic alterations (necrosis and inflammatory processes). Also, significant variations of biochemical biomarkers were observed with no clear indication of contamination gradient, since an indicative of higher impact was found in an intermediary reservoir, including high concentrations of biliary polycyclic aromatic hydrocarbons (PAHs). However, nuclear morphological alterations (NMA) were less frequent at the same reservoir. Thus, the multi-biomarker approach allied to active biomonitoring is a practical and important tool to assess deleterious effects of contamination in freshwater, providing data for monitoring and conservation protocols.

Aberrations of the peripheral erythrocytes and its recovery patterns in a freshwater teleost, silver barb exposed to profenofos

The present experiment was conducted to explicate the genotoxic effects of profenofos, an organophosphate insecticide, on the erythrocytes of silver barb (Barbonymus gonionotus). Silver barb were exposed to a solution of 10% and 50% of lethal concentrations (LC₅₀) of profenofos as sub-lethal concentrations at different days (1, 7, 15, and 30 d), along with a control (0% profenofos). Subsequent recovery patterns were assessed allowing the fish exposed to profenofos free water for the same period that they were exposed to profenofos. Our results revealed that with the progression of time and concentration, fish exposed to profenofos showed significantly (p < .05) higher level of erythrocytic nuclear abnormalities (ENA) such as micronuclei, bi-nuclei, degenerated nuclei, notched nuclei, nuclear bridge and nuclear buds, as well as erythrocytic cellular abnormalities (ECA) such as echinocytic, elongated, fusion, spindle, tear-drop and twin shaped cells. After exposure, the silver barb recovered spontaneously, and the abnormal erythrocytic parameters were normalized with a concentration- and duration-dependent fashion. Therefore, these abnormalities and their recovery can be used to assess the toxic levels of pesticides on aquatic organisms. There is great potential to use this technique as in vivo to predict susceptibility of aquatic animals to environmental pollution.