The micronucleus test in piscine erythrocytes

Effect on growth and development of common toad (Rhinella arenarum) tadpoles in environment related to fluorite mine

Fluorite mining activities have been scarcely evaluated so far and the potential effect of this activity on larval stages is poorly known. Thus, studies addressing the effect of contaminants present in water bodies on the health of amphibian larvae are crucial information for their conservation and constitute a warning sign of environmental modification. This study aims to evaluate the effects of natural and artificial surface waters associated with a fluorite mine on the early life stages of Rhinella arenarum. Using microcosms, we assessed four sites with different degrees of disturbance by the fluorine mine: Vallecitos stream (undisturbed); Cerros Negros upstream of mining camp (low disturbance); Cerros Negro downstream of mining camp (medium disturbance); Decantation Ponds (high disturbance). For 65 days we measured different endpoints at different periods of tadpole development. The highest mortality of tadpoles was observed in the Decantation Ponds. In the same way, larval body condition was lower at Decantation Ponds throughout the study, due mainly to the lower weight. A significant decrease in growth and development was observed in Cerros Negro downstream of the mining camp and Decantation Ponds. No significant differences in growth, development and mortality were observed for the other two sites. At the metamorphic climax we observe a lower body condition and a reduced recruitment of individuals in Decantation Ponds. This study allowed us to assess the effect on larvae of R. arenarum of fluorite mining wastewater compared with other near-natural sites. Given the potentially negative synergic effects of mixed water pollutants on tadpoles, this study suggests that chronic exposure to fluorite mining water may significantly impact the adult amphibian population structure, thus altering population viability. Therefore, we propose to monitor the correct functioning of the mine and especially of Decantation Ponds to avoid discharges into the natural streams.

Evidence of genotoxicity, neurotoxicity, and antioxidant imbalance in silver catfish Rhamdia quelen after subchronic exposure to diisopentyl phthalate

Diisopentyl phthalate (DiPeP) is a plasticizer with significant offer and application in Brazilian industries. This is attributed to its origin, which is closely linked to the refining process of sugarcane for ethanol production in the country. In this work, we developed a model for trophic exposure to environmentally relevant doses (5, 25, and 125 ng/g of DiPeP) to identify possible target tissues and toxic effects promoted by subchronic exposure to DiPeP in a Neotropical catfish species (Rhamdia quelen). After thirty days of exposure, blood, liver, kidney, brain, and muscle were collected and studied regarding DNA damage in blood cells and biochemical analyses. The kidney was the most affected organ, as in the head kidney, genotoxicity was evidenced in all groups exposed to DiPeP. Besides, the caudal kidney showed a reduction in the superoxide dismutase and glutathione peroxidase activities as well as a reduced glutathione concentration. In the liver, exposure to 125 ng/g of DiPeP increased glutathione S-transferase activity and reduced glutathione levels. In muscle, acetylcholinesterase (AChE) was reduced. However, in the brain, an increase in AChE activity was observed after the exposure to lowest doses. In contrast, a significant reduction of brain AChE activity after exposure to the highest dose was detected. The pronounced genotoxicity observed in head kidney cells is of concern, as it may compromise different functions performed by this organ (e.g., hematopoiesis, immune and endocrine functions). In our study, DiPeP proved to be a compound of environmental concern since we have evidenced its nephrotoxic and neurotoxic potential even in low doses.

The goby fish Sicydium spp. as valuable sentinel species towards the chemical stress in freshwater bodies of West Indies

Implementation of the European Water Framework Directive in tropical areas such as the French West Indies (FWI) requires to select relevant aquatic sentinel species for investigating the ecological status of surface waters. The present work aimed to study the biological response of the widespread fish Sicydium spp. towards river chemical quality in Guadeloupe island through a set of proper biomarkers. During a 2-year survey, the hepatic EROD activity, the micronucleus formation and the level of primary DNA strand breaks in erythrocytes were measured respectively as an enzymatic biomarker of exposure and genotoxicity endpoints in fish living upstream and downstream of two chemically-contrasted rivers. Hepatic EROD activity was shown to be variable along the time but always significantly higher in fish from the most contaminated river (Rivière aux Herbes) compared to the low contaminated one (Grande Rivière de Vieux-Habitants). Fish size did not influence EROD activity. Female fish exhibited a lower EROD activity compared to males depending on the catching period. We observed significant temporal variation in micronucleus frequency and primary DNA damage level measured in fish erythrocytes that did not depend on the fish size. Micronucleus frequency and to a lesser extent DNA damage were significantly higher in fish from the Rivière aux Herbes compared to the Grande Rivière de Vieux-Habitants. Our results argue for the interest of using Sicydium spp. as sentinel species to assess river quality and chemical pressures in FWI.

Mitigating the nephrotoxic impact of hexavalent chromium in Ctenopharyngodon idellus (grass carp) with Boerhavia diffusa (punarnava) leaf extract

In Ctenopharyngodon idellus, the ameliorative influence of rutin-containing leaf extract of Boerhavia diffusa was assessed against chronic exposure to hexavalent chromium. For this, alterations in chromium accumulation, oxidative stress, kidney function markers, histopathology (light and transmission electron microscopy), and transcriptional profiling (Nrf2 and MT2) were examined. RP-HPLC analysis confirmed the presence of rutin (90.45 ± 0.98 mg/g) in the ethanolic leaf extract of the plant. LD₅₀ of the extract to the fish was beyond 5000 mg/kg b.w. The fish was subjected to a sublethal concentration of hexavalent chromium (5.30 mg/L) accompanied by a dose of 250 mg/kg b.w./day of extract in the diet for the experimental duration of 45 days. The extract alone did not generate any adverse consequences in the nephric tissue. Chronic exposure to hexavalent chromium damaged tissue irreparably, demonstrated by elevated levels of kidney function markers (blood urea nitrogen and creatinine) and altered histoarchitecture (DTC value of 78.02 ± 10.5). The metal exposure increased chromium accumulation and malondialdehyde (MDA) and decreased the reduced glutathione (GSH) levels, the activity of antioxidant enzymes (superoxide dismutase, catalase and glutathione-S-transferase) and gene expression in the tissue. The co-supplementation of leaf extract with metal exposure revealed a tissue architecture with normal to slight modifications, and the level of kidney markers, antioxidants, and genes expressed in a normalized range. Principal component analysis created two components with antioxidants (GSH, SOD, CAT, and GST) revealing a negative correlation with the second component comprising MDA, DTC, and chromium concentration. It can be concluded that B. diffusa leaves are safe additives in the fish diet and possess an ameliorative capacity for renal injury incurred by hexavalent chromium.

Nano-titanium dioxide induced genotoxicity and histological lesions in a tropical fish model, Nile tilapia (Oreochromis niloticus)

This study evaluated potential genotoxic and histopathological effects of nano-TiO₂ (0.1, 0.5 and 1 mg/L) in Nile tilapia over 7, 14 and 21 days of exposure. Bulk TiO₂ (1 mg/L) along with controls was used for comparison. Comet assay revealed that nano-TiO₂ can induce erythrocytic DNA damage in a concentration dependent manner. However, micronuclei induction was observed only at the lowest concentration. Elevated organ damage indices indicate nano-TiO₂ induced histological alterations in liver and intestine. Severe histological alterations induced by nano-TiO₂ in the fish were necrosis of hepatic parenchyma and intestinal mucosa. Bulk TiO₂ exposure had no effect on the histological structure of the intestine but increased liver damage indices and erythrocytic DNA damage compared to the controls indicating dissolved form of TiO₂ is not biologically inert. More research efforts are needed to generate in vivo toxicity data on realistic levels of nano-TiO₂ and bulk TiO₂ for environmental risk assessments.

Micronuclei in embryos of eight seabird species in northwestern Mexico: a biomarker of exposure to coastal pollution?

The micronucleus (MN) test may be used to evaluate genome instability in birds and the potential of different species to function as biomarkers of genotoxicity. However, little is known regarding genome instability in seabird embryos or the instability present among embryonic development stages. Therefore, the present study aimed to describe the frequencies of micronucleated erythrocytes (MNE) and micronucleated polychromatic erythrocytes (MNPCE) in blood samples collected from the embryos of eight seabird species nesting on the coast of Sinaloa, Mexico. An additional description of blood cell maturation along with embryo development during incubation was conducted based on the proportion of polychromatic erythrocytes (PCE), and the potential relationships between metals (Hg and Cd concentrations in egg content) and the MN frequencies in embryo blood were evaluated. The PCE proportion appears to decline as incubation advances (initial stage > intermediate stage > advanced stage), and the values varied between species (Suliformes/Pelecaniformes < Charadriiformes: Laridae), which may be related to differences among incubation periods and reproductive strategies. Interspecific variation in the MNPCE frequency was found in embryos showing advanced development, which could be related to both variations in life-history traits and ecological factors and not Hg or Cd exposure. The genomic instability values in this study are the first to be reported for embryos of seabird species nesting in a subtropical coastal region.

Comparative chemical analysis, mutagenicity, and genotoxicity of Petroleum refinery wastewater and its contaminated river using prokaryotic and eukaryotic assays

Concern on the toxicity of final wastewater generated by the petroleum refining industry has increased in recent years due to the potential health threats associated with their release into the waterways. This study determined the mutagenic and genotoxic potential of petroleum refinery wastewater and a receiving river using the Ames fluctuation test on Salmonella typhimurium strains TA100 and TA98, SOS chromotest on Escherichia coli PQ37, and piscine peripheral micronucleus (MN) assay. Analyses of the physicochemical parameters, heavy metal, and organic contents of the samples were also performed. Ames test result showed that the two tested samples were mutagenic with TA100 strain as the more responsive strain for both the refinery wastewater and the river sample in terms of the calculated mutagenic index. A similar result was obtained in the SOS chromotest; however, the E. coli PQ37 system recorded a slightly higher sensitivity for detecting genotoxins than the Salmonella assay in the two samples. MN data showed induction of a concentration-dependent significant (p < 0.05) increase in the frequency of MN by both samples when compared with the negative control. Generally, the refinery wastewater induced the highest mutagenicity and genotoxicity compared to the river sample in the three assays used. Haemoglobin, platelets, red blood cells, mean corpuscular volume, total white blood cells, heterophils, haematocrit, and eosinophils reduced significantly with increased lymphocytes, basophils, mean corpuscular haemoglobin, and mean corpuscular haemoglobin concentration in fishes exposed to both samples. Total petroleum hydrocarbon, benzene, toluene, phenol index, polycyclic aromatic hydrocarbons, cadmium, mercury, nickel, lead, and vanadium contents analysed in the samples were believed to be responsible for the observed genotoxicity and mutagenicity. The findings of this study revealed that petroleum refinery wastewater is a potential mutagenic and genotoxic risk to the environment.

Bats and pollution: Genetic approaches in ecotoxicology

Environmental pollution drives the decline of species and, as flying mammals, bats can be considered to be excellent indicators of environmental quality, and the analysis of genetic biomarkers in these animals can provide important parameters for the assessment of environmental health. This review verifies the trends in pollution research, in particular, the use of genetic markers in the study of bats, based on a literature search of the Web of Science and Scopus platforms. Sixteen publications were identified during the search, which focused on the timeframe between 1996 and March 2022, including investigations of the effects of heavy metals, agricultural pesticides, and radiation. The studies were based primarily on the application of biomarkers for genotoxic analysis, including the comet assay, micronucleus test, and the Polymerase Chain Reaction (PCR). Only 55 bat species have been investigated up to now, that is, 4% of the 1447 currently recognized. In general, bats exposed to polluted environments presented a higher frequency of genotoxic and mutagenic damage than those sampled in clean environments. Given the importance of the diverse ecological functions provided by bats, including pest control, pollination, and seed dispersal, it is increasingly necessary to investigate the damage caused to the health of these animals exposed to areas with high concentrations of contaminants. Although genetic biomarkers have been used to investigate physiological parameters in bats for more than two decades, then, many knowledge gaps remain, worldwide, in terms of the number of species and localities investigated.

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.

Reproductive Toxicity and Recovery Associated With 4-Non-ylphenol Exposure in Juvenile African Catfish (Clarias garepinus)

Although, the effects of 4-non-ylphenol (4-NP) on fish's reproductive hormones were assessed in several studies using adult models, however, the effect of this endocrine disruptor on immature fish's reproductive hormones was not addressed commonly. We aimed to study the apoptosis induction, hematotoxicity, reproductive toxicity, and the recovery associated with 4-NP exposure in juvenile African catfish [Clarias garepinus) using some hormones [17β-estradiol (E2), testosterone (T), follicle-stimulating hormone (FSH), and luteinizing hormone (LH)] and gonad histology as biomarkers. The toxic effects of 4-NP have been studied in many animal models, but there is still limited knowledge about the dose-dependent damage caused by 4-NP exposure in juvenile Clarias gariepinus. A healthy juvenile C. gariepinus was categorized into four groups (n = 3/group; three replicates in each group). The first group was the control, and the other three groups were subjected to 4-NP concentrations as 0.1, 0.2, and 0.3 mg/L for 15 days; they were left for a recovery period of another 15 days. The reproductive hormones of C. gariepinus exposed to 4-NP for 15 days exhibited significant variations between the treatment groups and the control (P < 0.05), which were evident in E2 and T-values, whereas FSH, LH, total protein, and lipid peroxidation values showed non-significant differences among all groups at P < 0.05. Such a situation referred to the fact that the 15-day recovery period was insufficient to remove the impacts of 4-NP doses in concern. The trend of dose-dependent increase/decrease was recorded for T, E2, FSH, and LH. The histopathological alterations of 4-NP treated in gonad tissues were recorded in juvenile C. gariepinus, reflecting their sensitivity to 4-NP estrogenic-like effects. Overall, our results investigate that recovery has improved the reproductive toxicity caused by 4-NP in juvenile C. garepinus. Significant variations between the treated groups and the control group (P < 0.05) were evident in hematological parameters except for hemoglobin (Hb), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC). The parameters exhibiting significance decreased with such increased doses [red blood cells (RBCs), hematocrit (Hct), and white blood cells (WBCs)]. Similar patterns of significant variations toward the increase or decrease were recorded following the 15-day recovery period. Apoptotic frequency in erythrocytes and brain cells has increased significantly with increased 4-NP exposure, indicating that 4-NP caused cytotoxic effects, such as apoptosis in a dose-dependent manner. However, these cellular alterations greatly decreased after the 15-day recovery period.

In vivo genotoxic effects of commercial grade cypermethrin on fish peripheral erythrocytes

The study explicates the genotoxic effects of commercial grade cypermethrin on peripheral erythrocytes of Catla catla, chronically exposed to two environmentally relevant concentrations. The fish was treated with sub-lethal concentrations 0.12 μg/L and 0.41 μg/L (1/10th and /1/3rd of 96 h LC₅₀ ) of cypermethrin for 45 days. DNA damage in the exposed fish was assessed using alkaline comet assay, presence of micronuclei (MN), erythrocyte nuclear and cytoplasmic abnormalities. Exposure to cypermethrin induced a dose-dependent increase in percent DNA damage, micronucleus frequency and erythrocyte abnormalities. Nuclear anomalies such as notched nuclei, lobed nuclei, bridged nuclei, and deformed nuclei; and cytoplasmic anomalies like anisochromasia, vacuolated cytoplasm, lobed cells, and echinocytes were observed. The findings revealed the genotoxic potential of commercial formulations pyrethroid cypermethrin at concentrations found in the environment and their potential deleterious effects on nontarget aquatic organisms.

Malathion-Induced Hematoxicity and Its Recovery Pattern in Barbonymus gonionotus

An experiment was conducted to assess malathion-induced hematological responses of Barbonymus gonionotus (silver barb) and its recovery patterns in malathion-free water. Fish (45 days old) were exposed to two sublethal concentrations, namely, 25% and 50% (i.e., 3.78 and 7.56 ppm) of LC₅₀ (15.13 ppm) of malathion for 28 days, followed by a postexposure recovery period for the same time. The hematological parameters were examined after 1, 7, 14, 21, and 28 days of exposure as well as after the postexposure recovery time. Except in the case of the control group (0% of malathion), the obtained results revealed that malathion exposure resulted in significantly (p < 0.05) higher prevalence and severity of micronucleus and lower values of Hb, PCV, and RBC and significantly higher values of WBC in a concentration- and time-dependent manner. The values of blood glucose, MCV, MCH, and MCHC showed mixed trends during the experiment. During the recovery period, all blood parameters (micronucleus, glucose, Hb, PCV, RBC, WBC, MCV, MCH, and MCHC) partially recovered, which means that the recovery period was not long enough for the organisms to recover from the previous exposure. The study thus confirms that hematology is a sensitive indicator for fish to detect toxicity caused by different chemicals. Changes in these parameters can provide useful information about environmental conditions and risk assessment of aquatic organisms.

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.

Indigenous Fish-Based Assessment of Genotoxic Potentials of the Helong Reservoir in Guangzhou, China

The present study was conducted to assess the genotoxic potential of water from the Helong Reservoir, which was designated as a strategic drinking water source by the Guangdong Provincial Government of China in October 2016. Four kinds of common indigenous fish samples (Labeo rohita, Cirrhinus molitorella, red tilapia, and Oreochromis niloticus) were collected at 6 sampling sites during the period from July to November 2020. Fish from the clean drinking water source of the upper reaches of the Liuxihe Reservoir in Guangzhou were collected as the control. Both the alkaline single cell gel electrophoresis assay and the micronucleus test were used to detect DNA damage and the micronucleus rate in erythrocytes of fish samples, respectively. The results indicated that there was a significant increase in comet tail length, Olive tail moment, and micronucleus rates of all fish samples compared with those of the control (p < 0.05). The order of sensitivity to DNA damage and micronucleus formation was Labeo rohita > Cirrhinus molitorella > red tilapia > Oreochromis niloticus. The results of the 2 kinds of experiments were in perfect agreement with each other. We conclude that there are obvious genotoxic effects from the water in the Helong Reservoir. As a strategic drinking water source, the safety of the Reservoir water quality should be considered. The local government should put the restoration of the Helong Reservoir water quality on the agenda as soon as possible. Environ Toxicol Chem 2021;40:1919-1927. © 2021 SETAC.

Mutagenicity and genotoxicity in juvenile African catfish, Clarias gariepinus exposed to formulations of glyphosate and paraquat

The aquatic ecosystem is under increasing pressure from environmental contaminants due to anthropogenic activities. This study investigated the potential of glyphosate and paraquat to induce DNA damage and other cell abnormalities in juvenile African Catfish, Clarias gariepinus. Juvenile fish were exposed for 96 h to 0.36, 0.48, 0.60, 0.72 and 0.84 mg/L glyphosate; and 0.018, 0.037, 0.055, 0.110 and 0.221 mg/L paraquat. Following the exposure, the fish liver and blood were analysed for DNA damage and micronucleus respectively. DNA damage was analysed using comet assay while the micronucleus test was used for assessing nuclear abnormalities. Both herbicides induced DNA damage in fish, with paraquat exhibiting higher toxicity. The severity in liver DNA damage was observed to be dependent on concentration. The herbicides triggered formation of micronuclei, bean-shaped cells, lobed nuclei, and apoptosis in blood cells of fish. Both herbicides also increased the frequency of occurrence of these cell abnormalities in erythrocytes and showed mutagenic potential in fish. Glyphosate and Paraquat both have mutagenic potentials in fish and this is a reflection of the threat these contaminants pose to fish and other forms of aquatic life in our natural water bodies. Low concentrations of these herbicides should be encouraged when usage is inevitable.

Exposure to a contaminated tropical freshwater (Awba Dam) in Ibadan, Nigeria, induced cytogenotoxicity and haemato-pathological changes in Clarias gariepinus

Awba reservoir serves the purpose of water supply in the University of Ibadan, Nigeria. Recent reports on pollution status have focused on toxicological implication of contaminants in this reservoir. But none is on genetic and systemic toxicity of the water in fish. We investigated cytogenotoxicity of Awba Dam water (ADW) on Clarias gariepinus using piscine micronucleus (MN) assay. Haematological and histopathological changes were also evaluated. Bi-monthly composite water samples were collected from the reservoir from July to October, 2018. The water was used to cultivate juvenile C. gariepinus in the laboratory for 1-4 months, and tap water was used as the negative control. Peripheral blood erythrocytes from the caudal veins of C. gariepinus were used for the monthly MN assessment. There was significant (p < 0.05) induction of MN and other erythrocyte nuclear abnormalities in C. gariepinus within the period of study. There were variations in the haematological indices and pathological alterations in sections of the gill, liver and kidney of C. gariepinus. The levels of some heavy metals in ADW were above standard permissible limits and might have contributed to the observed cytogenetic and systemic disruptions. These findings may be used by the concerned authorities to evolve management strategies for the reservoir's health and biologic resources.

Distortion of micronuclei and other peripheral erythrocytes caused by fenitrothion and their recovery assemblage in zebrafish

The experiment was explicated to investigate the fenitrothion persuaded genotoxicity in the peripheral erythrocytes of zebrafish (Danio rerio) through in vivo exposures (10 %, 20 % and 40 % of LC50 of fenitrothion, i.e., 0.8, 1.6, and 3.2 mg/L, respectively) for variable periods (1, 3, and 7 days) and its subsequent post-exposure recuperation array in pesticide-free water for similar intervals was also evaluated. With the exception of the control group (0% of fenitrothion), the obtained results pointed out that with the promotion of time and concentrations, fenitrothion induced significantly (p < 0.05) higher prevalence and severity of erythrocytic nuclear abnormalities (ENA) such as- notched, micronucleus, nuclear bridges, blebbed, binucleated, nuclear bud and also erythrocytic cellular abnormalities (ECA) such as - echinocytic, elongated, tear-drop, crescentic, twin, fusion, and spindle-shaped cells. Recuperation data stated that zebrafish cured spontaneously and aberrated erythrocytic anomalies in all treatments were renormalized according to the concentration and duration dependence. Hence, we concluded that fenitrothion has a dangerous effect on the zebrafish, and this technology can be used to anticipate the sensitivity of aquatic animals to environmental pollution.

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.

Integrated ecotoxicological assessment of the complex interactions between chlorpyrifos and glyphosate on a non-target species Cnesterodon decemmaculatus (Jenyns, 1842)

Pesticide mixtures are frequent in freshwaters systems around the world, threatening the biota exposed to these conditions. The aim of this study was to determine the single and joint effect of two widely used pesticides in southern South America on a widely distributed fish species. In a 96-h assay, individuals of Cnesterodon decemmaculatus were exposed to 0.84 nL/L and 8.4 nL/L of Clorfox and 0.2 mg/L and 2 mg/L of Roundup Max, commercial formulations of chlorpyrifos and glyphosate, respectively. Also, there were four mixture treatments with all the possible combinations of both pesticides. A multi-level approach was carried out to assess their effects covering the following relevant biomarkers: behavior (immobile time, line crossings and average speed), somatic conditions (Fulton condition factor and hepatosomatic index), serum parameters (cortisol levels, lactate dehydrogenase (LDH), and creatine phosphokinase activity (CPK)), brain and muscle acetylcholinesterase and cytological characteristics (micronuclei frequency and nuclear abnormalities in erythrocytes). Our results showed that Clorfox exposures affect behavioral parameters, serum cortisol, and nuclear characteristics of erythrocytes. Roundup Max affects only the cortisol levels whereas mixture treatments have an effect on behavioral parameters, cortisol levels, LDH and CPK activities, and nuclear characteristics of erythrocytes. Potentiation was the main interaction at the lowest concentrations of both pesticides whereas antagonism occurred at the highest concentrations of both pesticides. These results are highly significant since they arise from an integrated ecotoxicological assessment at several levels of biological organization but even more important is that the potentiated effects of the mixtures we registered are environmentally relevant concentrations.

Titanium dioxide nanoparticles-induced cytogenotoxicity and alterations in haematological indices of Clarias gariepinus (Burchell, 1822)

The application of titanium dioxide (TiO₂) nanoparticles (NPs) in the manufacturing of consumer products has increased tremendously and with the potential to induce deleterious effects on aquatic biota. There have been reports on metal oxide NP toxicity in aquatic organisms, however, information on cytotoxicity and genotoxicity of TiO₂ NPs on the African catfish, Clarias gariepinus, is scarce. In this study, we investigated the genotoxicity and haematotoxicity of TiO₂ NPs in C. gariepinus using the micronucleus (MN) assay and haematological analysis, respectively. Juvenile C. gariepinus were exposed to 6.25, 12.5, 25.0, 50.0 and 100.0 mg L^-1 concentrations of TiO₂ NPs for 7 and 28 days. Benzene (0.05 mL L^-1) and dechlorinated tap water were used as positive and negative controls, respectively. Data of the MN showed a significant (p < 0.05) concentration-dependent increase in the frequency of MN at both exposure periods in comparison to negative control. Red blood cells, haematocrit, platelets and heterophils significantly reduced with an increased mean corpuscular haemoglobin concentration and lymphocytes at the 7-day exposure period, while in the 28-day exposure period, mean cell volume, mean corpuscular haemoglobin and lymphocytes had a significant increase in comparison with the negative control. This study indicates that TiO₂ NPs induced cytogenetic and haematological alterations in C. gariepinus and is of relevance in biodiversity and aquatic health management.

Genotoxicity induced by hexavalent chromium leading to eryptosis in Ctenopharyngodon idellus

The initiation of eryptosis as a result of genotoxic action of Cr(VI), seen through micronucleus and comet assay in the peripheral erythrocytes of Ctenopharyngodon idellus was evaluated through RT-qPCR. For this, fish was exposed to sublethal concentration of hexavalent chromium (5.30 and 10.63 mg/L), and the blood was sampled on different endpoints (15, 30 and 45 days). Accumulation of chromium in the erythrocytes was also studied, which depicted a significant increase in toxicant concentration and time dependent manner. Both concentrations of hexavalent chromium induced DNA damage, visible in the form of comet tails. The presence of micronuclei in the erythrocytes was accompanied with occurrence of nuclear bud (NBu), lobed nucleus (Lb), notched nucleus (Nt), vacuolated nucleus (Vn), binucleated cell (Bn) as nuclear abnormalities; and acanthocytes (Ac), echinocytes (Ec), notched cells (Nc), microcytes (Mc) and vacuolated cytoplasm (Vc) as cytoplasmic abnormalities. The expression of genes related to intrinsic apoptotic pathway induced by Cr(VI) presented significant (p < 0.05) upregulation in the expression of p53, Bax, Apaf-1, caspase9 and caspase3, and downregulation of Bcl2; inferring the initiation of apoptotic pathway. The ration of Bax and Bcl2 also appended the apoptotic state of the erythrocytes. From the present investigation, it can be concluded that genotoxicity induced by hexavalent chromium lead to eryptosis in C. idellus.

Chitosan grafting onto single-walled carbon nanotubes increased their stability and reduced the toxicity in vivo (catfish) model

The present work was aimed to develop the tissue benign, modified acid-functionalized single-walled carbon nanotube (COOH-SWCNT) chitosan (CS) hybrid (COOH-SWCNT-CS). Chitosan-nanotube hybrids were characterized by Fourier-transform infrared spectroscopy (FTIR), Thermogravimetry Analysis (TGA), Raman spectroscopy, Emission Gun-Scanning Electron Microscopes (FEG-SEM), Transmission Electron Microscopy (TEM) and Energy-dispersive X-ray spectroscopy (EDS). Micronuclei test of blood cells, comet assay of liver tissue and histological analysis of liver and kidney tissues were conducted after different treatments to evaluate the toxicity. Fish receiving COOH-SWCNT developed more numbers of micronuclei than COOH-SWCNT-CS treatments. Similarly, more DNA damage was observed in fish injected with nanotubes alone than chitosan hybrid groups. Histological observations revealed severe liver cell damage at higher concentrations of COOH-SWCNT whereas, in COOH-SWCNT-CS, no such damage was observed. However, kidney tissue remained unaffected in all groups. The study suggests that the nanohybrid developed will be safe and useful for delivery of micro or macro biomolecules in fish and higher animals.

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.

Ecotoxicological Analyses of Springs of a Brazilian Northeast Conservation Unit

Ecotoxicological assessment is an useful tool to evaluate toxicity of pollutants on aquatic organisms. In the present study, we evaluated the lethal effect, micronucleus frequency and histological changes in gills of fish species Danio rerio exposed to water from two sources of a Conservation Unit. We performed acute tests, Micronucleus Test in blood cells and histological analysis of gills. As results, the springs had no lethal toxic effects on the species. Nuclear alterations were present in erythrocytes in organisms exposed to water from the two sampled sites. As well, we found moderate to severe gill abnormalities generating the impairment of respiratory vital functions of these organisms. This study indicates that the water of the springs does not present lethal toxic effect but damage in gills for species from short exposure time.

Geophagus brasiliensis (Teleostei: Cichlidae) as an indicator of toxicity of ornamental stone processing wastes

Massive exploitation of geological resources may lead to environmental issues due to the inadequate disposal of the processing wastes, which are potentially hazard to terrestrial and aquatic environments. To evaluate the toxic effects ornamental stones processing wastes (OSPW), Geophagus brasiliensis fish were contaminated with different concentrations of OSPW (250, 500, 750 and 1000 mg/L). The contaminated aquarium water showed increased total hardness and Ca, Na, K, Mg and Mn content, which lead to bioconcentration of Na⁺, K⁺ and Mg²⁺ in G. brasiliensis gills. The highest concentration of OSPW induced slight to moderate histopathological lesions in gills of exposed fish, such as structural detachment, hyperplasia of the lamellar epithelium and incomplete fusion of several lamellae. Micronucleus and comet assays revealed a dose-dependent genotoxic damage in fish exposed to the contaminant. The biochemical analysis revealed a slight increase in catalase and reduction in superoxide dismutase activities in exposed fish, indicating that OSPW affects the oxidative stress of G. brasiliensis. The no observed effect concentration (NOEC) and lowest observed effect concentration (LOEC) parameters indicate that low concentrations of OSPW (even under 250 mg/L) may be detrimental to exposed organisms by causing oxidative damage. This study demonstrates the toxic potential of OSPW in G. brasiliensis, even in short-term exposure, revealing some morphologic and molecular parameters that may be used as biomarkers in monitoring aquatic ecosystems contaminated with this effluent.

Protective effect of p53 knockout on 4-nonylphenol-induced nephrotoxicity in medaka (Oryzias latipes)

In the past few decades, environmental pollutants have become common because of misused nonionic surfactants and detergents. Nonylphenol ethoxylates (NPs) are one of the most important contaminants of water. Therefore, the present study aimed to investigate the protective blocking effect of apoptosis (deficient P53 gene) on 4-nonylphenol (4-NP)-induced nephrotoxicity of medaka (Oryzias latipes). We divided 36 fish into six groups: two different control groups of wild type (Wt; Hd-rR) control and p53 (-/-) control, and four different treated with 4-nonylphenol (50 μg/L and 100 μg/L) for 15 days. Histology, immunochemistry, and TUNEL assays confirmed that 4-NP causes nephrotoxicity. Our results showed that 4-NP administration significantly disturbed the kidney structure and function and 4-NP-treated fish showed dilated glomerular vessels, had less glomerular cellular content, decreased expression of glomerular proteins, and an increased level of apoptosis compared with a Wt control group (P < 0.05). As p53 is an apoptotic inducer, some protection in p53-deficient medaka was found as nephrotoxic effects of 4-NP were minimized significantly. Our study demonstrated for the first time to our knowledge that 4-NP induces apoptosis, causing nephrotoxicity in medaka. We found that blocking apoptosis blocking was able to protect the kidney from the toxic effects of 4-NP.

Toxic effects of ornamental stone processing waste effluents on Geophagus brasiliensis (Teleostei: Cichlidae)

The ornamental stone industry generates considerable amounts of waste (OSPW), which may eventually reach natural environments and impact the local ecosystem. The aim of this study was to compare the toxic effects of two OSPW effluents in Geophagus brasiliensis: i) leachate effluent from a lagoon in an OSPW landfill (LE) and ii) decanted effluent from an ornamental stone processing industry (DE). G. brasiliensis were submitted to acute contamination with both OSPW effluents. After contamination, the gills were extracted for evaluation of histopathological alterations and ion concentration, while the liver underwent catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD) and glutathione s-transferase (GST) enzyme activity analysis. An induced biomarker response (IBRv2) index was determined to correlate the multi-biomarker response in G. brasiliensis. Fish gills exposed to DE showed increased concentration of Ca²⁺, Mg²⁺, Na⁺, and K⁺ when compared to those treated with LE. Histopathological lesions were observed in gills of animals exposed to both effluents. Micronucleus and comet assay were significantly greater in fish exposed to DE, when compared to those contaminated with LE. The evaluation of the enzymatic activity of CAT, GPx and SOD indicate greater oxidative stress in DE and LE-exposed fish, while GST activity was not altered. DE showed an IBRv2 value almost two-times higher in relation to LE, indicating that this waste may present higher toxic potential. The results demonstrate that both contaminants led to substantial toxic effects in G. brasiliensis, although the decanted waste induced the most remarkable responses in G. brasiliensis.

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.

Pyrethrum extract encapsulated in nanoparticles: Toxicity studies based on genotoxic and hematological effects in bullfrog tadpoles

The environment receives about 2.7 kg.ha^-1 annually of pesticides, used in crop production. Pesticides may have a negative impact on environmental biodiversity and potentially induce physiological effects on non-target species. Advances in technology and nanocarrier systems for agrochemicals led to new alternatives to minimize these impacts, such as nanopesticides, considered more efficient, safe and sustainable. However, it is important to evaluate the risk potential, action and toxicity of nanopesticides in aquatic and terrestrial organisms. This study aims to evaluate genotoxic and hematological biomarkers in bullfrog tadpoles (Lithobates catesbeianus) submitted to acute exposure (48 h) to pyrethrum extract (PYR) and solid lipid nanoparticles loaded with PYR. Results showed increased number of leukocytes during acute exposure, specifically eosinophils in nanoparticle-exposed groups, and basophil in PYR-exposed group. Hematological analysis showed that PYR encapsulated in nanoparticles significantly increased the erythrocyte number compared to the other exposed groups. Data from the comet assay indicated an increase in frequency of the classes that correspond to more severe DNA damages in exposed groups, being that the PYR-exposed group showed a high frequency of class-4 DNA damage. Moreover, erythrocyte nuclear abnormalities were triggered by short-time exposure in all treatments, which showed effects significantly higher than the control group. These results showed genotoxic responses in tadpoles, which could trigger cell death pathways. Concluding, these analyses are important for applications in assessment of contaminated aquatic environments and their biomonitoring, which will evaluate the potential toxicity of xenobiotics, for example, the nanoparticles and pyrethrum extract in frog species. However, further studies are needed to better understand the effects of nanopesticides and botanical insecticides on non-target organisms, in order to contribute to regulatory aspects of future uses for these systems.

Genotoxicity induced by widely used pesticide binary mixtures on Caiman latirostris (broad-snouted caiman)

In this study, we investigated the effects of three binary mixtures of pesticide formulations commonly used in soybean crop: Cypermethrin Atanor® (25% -CYP), Chlorpyrifos Lorsban 48E® (48% -CPF) and Glyphosate Roundup® Full II (66.2% -GLY) on broad-snouted caiman (Caiman latirostris) hatchlings exposed by voluntary immersion under controlled condition. Genotoxicity was evaluated in peripheral blood erythrocytes through the micronucleus (MN) test and other nuclear abnormalities (NAs) and besides, growth of caiman was analyzed in each experimental group. The results showed that pesticide formulations tested, at concentrations similar to those recommended for application in the field, induced an increase in the frequency of micronucleus (FMN; p = 0.001) and Notched nuclei (NN; p = 0.010) in the mixture CYP + CPF, while an increase in the frequency of buds and NN was observed in the mixture of GLY + CYP (pbuds = 0.016 and pNN = 0.021), compared to the vehicle control (VC). On the contrary, a possible antagonistic action was observed between the components in the mixture GLY + CPF. Growth was not affected in any exposed groups (p > 0.05). There was a clutch effect in the frequency of binucleated erythrocytes (BiN; p = 0.011), total length (TL; p = 0.001) and snout-vent length (SVL; p = 0.031). Biomarkers used in this study are considered important predictive tools for the evaluation of xenobiotics. In this study, we demonstrated genotoxicity of pesticide mixtures under conditions that simulate the real situation of exposure suffered by caiman and other wild species in Argentina.

Experimental modeling of the acute toxicity and cytogenotoxic fate of composite mixtures of chromate, copper and arsenate oxides associated with CCA preservative using Clarias gariepinus (Burchell 1822)

Concurrent occurrence of chromium (Cr), copper (Cu) and arsenic (As) from chromated copper arsenate (CCA) wood preservative in aquatic ecosystems demands that their joint-actions in eliciting toxic effects be assessed for adequate understanding of the health risk they may pose to biota. Clarias gariepinus was exposed to As₂O₃ , CrO₃ and CuO and their composite mixtures (1:1 and 1:1:1) at various concentrations (0 – 600 mg/L) for 96-h to determine the acute toxicity using OECD (1992) protocol. C. gariepinus was then exposed to sub-lethal concentrations corresponding to 6.25, 12.5, 25.0, 50.0 and 100% of the 96-h LC₅₀ for 7 days to assess the cytogenotoxic effects using piscine micronucleus (MN) test. The 96-h LC₅₀ showed that the metals/metalloid demonstrated differential interactions in a concentration dependent pattern. The 96-h LC₅₀ showed that Cr was the most toxic while Cu and As:Cu were indeterminate (Cr > Cr:Cu > As:Cr > As > As:Cr:Cu > Cu = As:Cu indeterminate). Isobologram and synergistic ratio (SR) models predicted antagonistic interaction between Cu:Cr and As:Cr and synergism between As:Cu in the causation of morbidity and mortality of C. gariepinus. Interaction factor model predicted antagonism as common interactive mechanism among the metal/metalloid mixtures in the induction of MN and abnormal nuclear erythrocytes in C. gariepinus. Predicted interactions among the three metals/ metalloid were largely antagonism and synergism towards the induction of acute toxicity and cytogenotoxicity. The models employed herein may be useful in establishing environmental safe limits for mixtures of metals/metalloids against the induction of acute toxicity and DNA damage in lower aquatic vertebrates.

Water temperature and acid pH influence the cytotoxic and genotoxic effects of aluminum in the freshwater teleost Astyanax altiparanae (Teleostei: Characidae)

The toxicity of metals, including aluminum (Al), can be potentiated by temperature and acid pH, a concern in view of the current global warming scenario. The aim of this study was to evaluate the bioconcentration of Al in the testes and semen of Astyanax altiparanae and the potential of this metal, at different environmental temperatures and acid pH, to cause cytotoxicity and genotocixity in erythrocytes and spermatozoa. A. altiparanae males were divided into nine experimental groups: at each of three different water temperatures (20, 25 and 30 °C), the fish were exposed to a neutral pH, an acid pH and acidic water containing Al (0.5 mg.L^-1). The fish were subjected to subacute, semi-static exposure and sampled at 24 and 96 h. After each exposure period the comet assay (blood and semen) and micronucleus test (blood) were performed. Bioconcentration of Al was evaluated in the testes and semen. Exposure time and temperature influenced the Al bioconcentration pattern in the testes. Al concentration in the semen was higher in fish exposed at 20 and 25 °C (24 h). The DNA fragmentation score for the semen and blood was higher in fish exposed to Al at 20 (24 h) and 30 °C (96 h). The frequency of nuclear abnormalities in erythrocytes was higher in the group exposed to Al at 30 °C (96 h). It was concluded that Al bioconcentrates in the testes and semen of A. altiparanae at different temperatures and is potentially cytotoxic and genotoxic to erythrocytes and spermatozoa in this species.

Influence of Land Use and Cover on Toxicogenetic Potential of Surface Water from Central-West Brazilian Rivers

The objective of this study was to evaluate toxicogenetic potential of surface water samples from rivers of center-west Brazil and analyze the influence of land use and cover and physicochemical parameters in genetic damage. Samples were collected during winter (June) and summer (November) at sampling sites from Dourados and Brilhante Rivers (Mato Grosso do Sul/Brazil). The toxicogenetic variables, including chromosomal alterations, micronuclei, and mitotic index, were analyzed in meristematic cells of Allium cepa; and micronuclei, nuclear abnormalities, and DNA strand breaks (arbitrary units, AU_T) were analyzed in erythrocytes of Astyanax lacustris. The rivers presented physicochemical values outside the Brazilian laws, which can be a characteristic of human pollution (domestic sewage and local agriculture). The results of A. cepa test suggest that the water samples from Dourados and Brilhante rivers exerted significant (p < 0.05) cytotoxic and genotoxic effects, in both periods of collection, especially alterations in mitotic index. In blood cells of A. lacustris, genotoxic effect of the water samples from the rivers also was observed as significant nuclear abnormalities, DNA breaks (UA_T), in both sampling periods, compared with the negative control. Spearman correlation analyses revealed that data of land use and cover and physicochemical parameters were statistically correlated with DNA damages in bioassays. This study demonstrates toxicogenetic potential of water samples from Dourados and Brilhante rivers; furthermore, the type of land use and land cover and physicochemical parameters were revealed to have influence on toxicogenetic damage.

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.

Temperature affects the toxicity of lead-contaminated food in Geophagus brasiliensis (QUOY & GAIMARD, 1824)

Lead is toxic to fish, and its toxicity can be aggravated by the water temperature. Geophagus brasiliensis populations are geographically widespread and thus live in areas with different temperatures. The objective of this work was to evaluate the effects of lead-contaminated feed in fish (Geophagus brasiliensis) exposed to different temperatures. A factorial experiment was performed with two temperatures (25 and 28°C), and two feeds (control and lead contaminated - 60 mg/kg) for a sum of four treatments (25°C, Control = 25/C; 25°C, 60 mg/kg = 25/60; 28°C, Control = 28/C and 28°C, 60 mg/kg = 28/60). Analyses of the lead accumulation, oxidative stress and genotoxic damage were performed. The gills and liver showed increased lead concentrations in fish receiving lead-contaminated food at both temperatures. The lead concentrations in the intestines and muscles of fish exposed to the 25/60 treatment was greater than it was in fish exposed to the 25/C treatment. The enzyme response in the gills and the micronuclei count increased in fish exposed to the 25/60 treatment. Higher temperatures can be a beneficial factor for Geophagus brasiliensis because they can hinder the absorption of lead, thereby reducing the damage caused to the organism.

Radio-protective dosimetry of Pangasius sutchi as a biomarker, against gamma radiation dosages perceived by genotoxic assays

Exposure to ionizing radiation is harmful to any living organism. It may cause varying levels of genetic mutation or ultimately death. Synthetic compounds have been used to counteract the hazardous effect of radiation on the live cells, but the possibility of these synthetic compounds being harmful to the organism being treated also exists. Herbal formulations are thus being explored as a possible alternative for the synthetic radioprotectant. Induction of DNA damage in fishes caused by ionizing radiation and its protection by phytocompounds is a hardly studied topic. In this study, we analyzed the radioprotective effect of Gymnema sylvestre leaves extract (GS) and its active compound gymnemagenin (GG) against different doses of gamma radiation (⁶⁰Co) on the freshwater fish Pangasius sutchi. The radioprotective efficacy was assessed by micronuclei and alkaline comet assays. The freshwater fish P. sutchi was pre-treated with intramuscular injection (IM) of amifostine (83.3 mg/kg of B.W.), GS (25 mg/kg of B.W.) and GG (0.3 mg/kg of B.W.), 1 h prior to the gamma radiation. The fishes were exposed to LD₃₀, LD₅₀ and LD₇₀ of gamma radiation and the protection activities were assessed by analyzing the number of micronuclei (MN) and erythrocytic abnormalities in the blood after 2, 4, 8, 16 and 32 days after exposure. Compared to the irradiated fishes, frequency of erythrocytic abnormalities were decreased in response to the radio-protection in the amifostine treated groups for all three doses of gamma radiation (LD₇₀ - 77.62%), (LD₅₀ - 80.11%) and (LD₃₀ - 82.30%); GS (LD₇₀ - 62.66%), (LD₅₀ - 69.74%) and (LD₃₀ - 70.81%); and GG (LD₇₀ - 49.42%), (LD_{50 -} 53.43%) and (LD₃₀ - 58.42%). Similarly, a significant radio-protective effect in terms of decremented DNA damage was observed using the comet assay after post exposure. The percentage of protection noted for amifostine was (LD₇₀ - 58.68%), (LD₅₀ - 64.52%) and (LD₃₀ - 74.40%); GS (LD₇₀ - 53.84%), (LD₅₀ - 59.02%) and (LD₃₀ - 65.97%); GG (LD₇₀ - 49.85%), (LD₅₀ - 52.56%) and (LD₃₀ - 64.30%). From the current study, we can conclude that the radioprotective efficacy of the GS is similar to the synthetic compound (amifostine) and also greater than the bioactive compound (GG). The synergetic effect of the plant extract which leads to a better protection than the bioactive compound must be further studied. MN and Comet assays can easily identify the damage due to radiation exposure and thus can be used as predictive biomarkers for aquatic organisms exposed to radiation.

Anxiety-associated behavior and genotoxicity found in adult Danio rerio exposed to tebuconazole-based commercial product

The effects of different concentrations of commercial product based on tebuconazole, on adults of Danio rerio, were evaluated through novel tank diving test and micronucleus and comet assay tests. A total of 320 adult D. rerio were divided into eight tanks and exposed to concentrations of 0; 100; 200 and 300 μg/L the commercial product based on tebuconazole, with their respective replicates at 24, 72 and 96 h. The results showed a behavioral deviation of zebrafish and a significant (p < 0.05) increase in DNA damage as a function of exposed time and different concentrations of the commercial product in relation to the negative control. The results obtained in this study allow to conclude that tebuconazole has effects on adults of Danio rerio, inducing genotoxicity and mutagenicity, as well as altering neurological functions related to the change in the behavior of adults.

Metal loads and biomarker suite responses in a tropical carnivorous fish indicative of anthropogenic impacts in a Southeastern Brazilian lagoon

Tropical coastal lagoons are highly productive environments exhibiting high biodiversity. However, the use of these ecosystems by local communities is of concern, since this generally leads to environmental degradation. The Imboassica coastal lagoon, located in Macaé city, in Northern Rio de Janeiro, is an important ecosystem in the state, however, already displaying signs of anthropogenic impacts. Carnivorous fish Hoplias malabaricus specimens were sampled from this impacted site, as well as from a reference area. Fish from Imboassica Lagoon presented lower condition factor, lower cholinesterase activity, and higher percentage of erythrocyte micronuclei when compared to fish from the reference site. Metals in fish from Imboassica Lagoon were always higher than Encantada Lagoon, with some seasonal differences, where some metals were higher in the rainy season compared to the dry season in muscle tissue, with the exception of Cu, Fe, Sr, and Zn; and in the liver, except for Ba, Cd, Cr, Ni, and Sr. Cr and Mn in the edible muscle portion of the fish were higher than the limits established by Brazilian and International legislations as permissible for human consumption, thus leading to concerns regarding public health risks for the local population that use fish as their main protein source.

Effects of benzo[a]pyrene on the blood and liver of Physalaemus cuvieri and Leptodactylus fuscus (Anura: Leptodactylidae)

Benzo[a]pyrene (BaP) is a bio-accumulative toxic compound found in the atmosphere, water, and soil that may affect the life cycle of amphibians. In this study, a few contamination biomarkers, such as hepatic melanomacrophages (MMs), mast cells, erythrocyte micronuclei (MN) and white blood cells were used to determine how BaP acts in these cells in the anurans Physalaemus cuvieri and Leptodactylus fuscus. Animals of both species were divided into three treatment groups: 1 day, 7 days and 13 days, subcutaneously injected 2 mg/kg BaP diluted in mineral oil and control group with only mineral oil. After 7 days, BaP caused the frequency of MN to increase in both species while reducing melanin area. The micronucleus frequency increased due to the genotoxicity of BaP, while the decreasing melanin area may be related to the inhibition of tyrosinase activity, an enzyme responsible for regulating melanogenesis, decreasing the synthesis of melanin. The mast cell density increased in all groups and in both species as a response to the inflammatory action of BaP. These cells respond to nonspecific inflammatory effects leading, therefore, to this response in all treatments. The percentage of leukocytes remained unchanged probably due to great intraspecific variability. Additionally, the leukocyte profiles of both species were characterized and the differences were attributed to extrinsic factors. In short, BaP can affect the integrity of several organs and tissues, and cell functions leading to the conclusion that this compound is hepatotoxic, genotoxic and immunotoxic for anurans.

In situ monitoring of the Sinos River, southern Brazil: water quality parameters, biomarkers, and metal bioaccumulation in fish

The Sinos River is an important water supply in Southern Brazil and receives industrial, agricultural, and domestic effluents which may affect aquatic biota. Water physicochemical and microbiological analyses, biomarker responses (scaled mass index (SMI), gill histopathology, and micronucleus and nuclear abnormality (MN and NA) frequencies), and metal bioaccumulation in muscle were assessed in the fish species Bryconamericus iheringii (Characidae) captured at three sampling sites (S1, S2, and S3) in four sampling periods. The mean values of five parameters (total phosphorus, thermotolerant coliforms, aluminum, iron, and lead) exceeded the limits established by the Brazilian legislation at the three sampling sites. Although physicochemical analysis indicated higher impacts at S3, in some samples, significantly higher MN frequencies and bioaccumulation of manganese in fish muscle were observed at S1, whereas low SMI and higher concentrations of aluminum and zinc in fish muscle were found at S2. Histopathological alterations in gills were observed in fish collected at the three sampling sites; however, no spatial differences were observed, indicating similar environmental conditions with respect to this biomarker. Moreover, temporal variation of biomarker responses and metal bioaccumulation were found at all sampling sites. Furthermore, the consumption of fish from the Sinos River should be avoided given the concentrations of chromium (all samples), cadmium, and lead in fish muscle above the threshold for safe human consumption.

Protective effect of Uncaria tomentosa extract against oxidative stress and genotoxicity induced by glyphosate-Roundup® using zebrafish (Danio rerio) as a model

Oxidative stress and DNA damage are involved in the glyphosate-based herbicide toxicity. Uncaria tomentosa (UT; Rubiaceae) is a plant species from South America containing bioactive compounds with known beneficial properties. The objective of this work was to evaluate the antioxidant and antigenotoxic potential of UT extract in a model of acute exposure to glyphosate-Roundup® (GR) in zebrafish (Danio rerio). We showed that UT (1.0 mg/mL) prevented the decrease of brain total thiols, the increase of lipid peroxidation in both brain and liver, and the decrease of liver GPx activity caused after 96 h of GR (5.0 mg/L) exposure. In addition, UT partially protected against the increase of micronucleus frequency induced by GR exposure in fish brain. Overall, our results indicate that UT protects against damage induced by a glyphosate-based herbicide by providing antioxidant and antigenotoxic effects, which may be related to the phenolic compounds identified in the extract.

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.

Sensitivity of medaka (Oryzias latipes) to 4-nonylphenol subacute exposure; erythrocyte alterations and apoptosis

The present study was undertaken to assess the effects of the endocrine-disrupting compound; 4-nonylphenol (4-NP) in medaka (Oryzias latipes). The frequencies of erythrocyte alterations, apoptosis, and micronuclei were used as biological indicators of damage. Medaka were exposed 15 days to 4-NP at three sublethal concentrations (50, 80, and 100 μg/l 4-NP) and results compared with those of a previous study using catfish as an animal model. Exposure of medaka resulted in a dose-dependent increase in the frequency of erythrocyte alterations, apoptosis and micronucleus (MN). Many morphological alterations and nuclear abnormalities were observed, including acanthocytes, lobed nucleus, eccentric nucleus, fragmented nucleus, blebbed nucleus, binuclei, deformed nucleus, notched nucleus, hemolysed cells, crenated cells, teardrop-like cells, and schistocytes. Mortality was recorded after treatment with 80 and 100 μg/l 4-NP, indicating that medaka are more sensitive than catfish to 4-NP exposure. We concluded that, 4-NP causes several malformations in the shape and number of erythrocytes in medaka, indicating its genotoxicity.

Ecological risk assessment of a contaminated stream using multi-level integrated biomarker response in Carassius auratus

The goal of this study was to evaluate the adverse effects of wastewater effluents on freshwater crucian carp, Carassius auratus, inhabiting Sincheon stream using the integrated biomarker response (IBR) at the genotoxic (micronucleus [MN] test), oxidative stress (activity of catalase [CAT] and glutathione S-transferase [GST], and level of lipid peroxidation [LPO]), histopathological (degree of tissue changes [DTC]), and physiological (condition factor [CF] and liver somatic index [LSI]) levels. The CF and LSI were significantly (p < 0.05) enhanced in fish from downstream sites (DS1 and DS2) as compared to that of upstream (US) fish samples. Moreover, a significant increase in morphometric indices (DTC) was observed in C. auratus collected from downstream sites (p < 0.05) and histopathological responses showed the degree of pathogenicity in the order of liver > kidney > gills. The activities of CAT, GST, and LPO in fish from the DS1 and DS2 sites were notably increased in gills, liver, and kidney compared to that of fish from the US site. Additionally, the MN test level in C. auratus from the DS1 and DS2 were significantly increased (p < 0.05) when compared with that of the US site. Considering the higher bioaccumulation of Cd, Co, Cr, Mn, Ni, and Pb in gills, liver, and kidney of C. auratus collected from downstream sites compared to that of the upstream site (p < 0.05), the observed toxicity was likely attributable to metal accumulation. The multi-level IBR index was higher at the DS1 site (15.08) than at the DS2 (1.02) and the reference US (0.00) sites. Therefore, these findings demonstrated that wastewater effluent discharge induces significant DNA damage, oxidative stress, and tissue injuries in C. auratus and suggested that the multi-level IBR approach should be used to quantify these effects on fish in streams and rivers.

Addressing the impact of mercury estuarine contamination in the European eel (Anguilla anguilla L., 1758) - An early diagnosis in glass eel stage based on erythrocytic nuclear morphology

The decline of the European eel (Anguilla anguilla L., 1758) population throughout Europe has been partially attributed to pollution. As glass eel estuarine migration may represent a considerable threat, the impact of mercury (Hg) contamination at this stage was evaluated through an in situ experiment (7days). Total Hg (tHg) bioaccumulation was evaluated concomitantly with erythrocytic nuclear morphology alterations: erythrocytic nuclear abnormalities assay (ENA), frequency of immature erythrocytes (IE) and the erythrocytic maturity index (EMI). The ENA results suggested a genotoxic pressure at the most contaminated sites, in line with the tHg increase. The EMI data, together with IE frequency, showed that fish exposed to high levels of Hg exhibited alterations of haematological dynamics, translated into an erythropoiesis increment. Despite the presence of these compensatory mechanisms, the present findings suggest a harmful impact of Hg on genome integrity at this early development stage, potentially affecting eels' condition and ultimately the population sustainability.