Profile of micronucleus frequencies and DNA damage in different species of fish in a eutrophic tropical lake

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.

Comet Assay and Micronucleus Test in Circulating Erythrocytes of Ctenopharyngodon idella Exposed to Nickel Oxide Nanoparticles

The number of pollutants released into freshwater and marine environments has increased due to the widespread use of nanoparticles. Nickel oxide nanoparticles (NiO-NPs) were tested for genotoxicity in fish fingerlings of the species Ctenopharyngodon idella. For 7, 14, and 21 days, fingerlings were exposed to NiO-NPs with each increasing concentrations of 2.25 mg/L, 4.50 mg/L, and 6.75 mg/L, respectively. The micronuclei assay and comet assay were used to evaluate the DNA damage. The experiment revealed that with the increase in nanoparticle concentration and exposure duration, the level of DNA damage also increased. The experiment resulted to be time and dose dependent, and the damage was found as follows: 6.75 mg/L > 4.50 mg/L > 2.25 mg/L against each exposure period. In terms of comet assay, the results showed that after 7 days, the level of DNA damage in all the concentrations was highly significant (P < 0.001). Increased DNA damage was calculated at the higher administered dose of 6.75 mg/L for 21 days of exposition, followed by 14 and 7 days, respectively. The second high toxic effect was observed in the fish blood at the exposure concentration of 4.50 mg/L for 21 days, followed by 14 and 7 days, respectively. The micronuclei induction in the nanoparticle's administered blood could be detected only for a 7-day exposition period. Whereas for the exposed duration of 14 and 21 days, the entire red blood cells of the grass carp were completely destroyed demonstrating the ability of the nanoparticles to cause anomalies in aquatic life.

Study of the frequencies of erythrocyte abnormalities as in situ biomarkers of genotoxic risk of chemicals in special fish stock in water supply reservoirs

In three water-supply reservoirs in the catchment area of the Odra River (Czech Republic), a special fish stock was monitored for control of health to estimate the mutagenic effect of chemicals. The results contribute to obtaining initial information about the morphology of erythrocyte abnormalities classified in 21 categories in 16 fish species in reservoirs with abundant salmonids (the Morávka Reservoir) or with the prevalence of cyprinids (the Kružberk and Šance Reservoirs), not directly exposed to the adverse environmental effects such as industrial, urban, agricultural and intensive farming activities. The different intensities and prevalence of nuclear abnormalities (NA) and cytoplasmic abnormalities (CA) in fish from the same reservoir habitat show that to be able to obtain an objective view of the genotoxic risk of chemicals, it is necessary to respect the different requirements of the fish for the exploitation of the food available in the biotope and to subject all representatives of piscivorous, omnivorous and benthophagous fishes in the reservoir to cytogenetic analysis. The occurrence of certain categories of erythrocyte abnormalities in diseased fish draws attention to the need to know the state of health of the fish and to employ this knowledge to exclude parasitological, viral and other infectious agents. These results are the first report of the frequencies of erythrocyte abnormalities in native fish. They should serve to check which of the categories examined could be of use in assessing the genotoxic risk in other stagnant and running aquatic ecosystems affected by anthropogenic activities.

Comparative genomic damage among three shark species with different habits: Sublethal impacts of human origin in a protected island environment in the South Atlantic

Elasmobranchs can bioaccumulate and biomagnify pollutants. However, few studies are directed to the effects of pollutants on the health of these animals, and in most cases, are limited to the analysis of biochemical markers. Thus, the incidence of genomic damage among shark species inhabiting a protected ocean island in the South Atlantic was investigated in association with the analysis of pollutants in seawater sample. High levels of genomic damage were identified, especially in Negaprion brevirostris and Galeocerdo cuvier, in addition to interspecific variations that may be related to characteristics such as animal size, metabolism and habits. High concentrations of Surfactants were observed in seawater sample, in addition to low concentrations of Cadmium, Lead, Copper, Chromium, Zinc, Manganese, and Mercury. The results evidenced the potential of shark species as a bioindicator of environmental quality and allowed assessing the anthropic impact on the archipelago, which currently drives its economy through tourism.

Combined use of biomarkers to assess the impact of untreated wastewater from the Danube River, Serbia

In this study a battery of bioassays, both in vivo (metals and metalloids concentrations, erythrocyte morphometry, comet assay, micronucleus assay, and histopathological analyses) on vimba bream Vimba vimba (L., 1758) and white bream Blicca bjoerkna (L., 1758), and in vitro (treatment of HepG2 cells with native water samples) was applied to assess the harmful potential of untreated wastewater. Faecal indicator bacteria were quantified to assess the microbiological water quality. Vimba bream had significantly higher Fe concentrations in both liver and muscle, while white bream had higher Ca and Cu concentrations in liver. Vimba bream had a significantly higher level of DNA damage in both liver and blood cells, in comparison to white bream. Low levels of micronucleus and nuclear abnormalities were observed in both species. Erythrocytes morphometry did not show significant interspecific differences. Histopathological analyses revealed a similar response of the studied species, with a significantly higher presence of ceroid pigments in the liver of vimba bream. Treatment of HepG2 cells revealed the high genotoxic potential of water downstream of the discharge point. The results of this study clearly demonstrate the importance of effect-based monitoring, in order to enforce more efficient management of natural resources and implementation of wastewater treatment systems.

Genotoxicity of surface waters in Brazil

Brazil has abundant surface water resources, huge aquatic biodiversity and is home to 213 million people. Genotoxicity assays are sensitive tools to detect the effects of contaminants in surface waters and wastewaters, as well as to determine potential risks of contaminated waters to aquatic organisms and human health. This work aimed to survey the articles published in 2000-2021 that evaluated the genotoxicity of surface waters within Brazilian territory to unveil the profile and trends of this topic over time. In our searches, we considered articles focused on assessing aquatic biota, articles that conducted experiments with caged organisms or standardized tests in the aquatic sites, as well as articles that transported water or sediment samples from aquatic sites to the laboratory, where exposures were performed with organisms or standardized tests. We retrieved geographical information on the aquatic sites evaluated, the genotoxicity assays used, the percentage of genotoxicity detected, and, when possible, the causative agent of aquatic pollution. A total of 248 articles were identified. There was a trend of increase in the number of publications and annual diversity of hydrographic regions evaluated over time. Most articles focused on rivers from large metropolises. A very low number of articles were conducted on coastal and marine ecosystems. Water genotoxicity was detected in most articles, regardless of methodological approach, even in little-studied hydrographic regions. The micronucleus test and the alkaline comet assay were widely applied with blood samples, mainly derived from fish. Allium and Salmonella tests were the most frequently used standard protocols. Despite most articles did not confirm polluting sources and genotoxic agents, the detection of genotoxicity provides useful information for the management of water pollution. We discuss key points to be assessed to reach a more complete picture of the genotoxicity of surface waters in Brazil.

Genotoxicity and cytotoxicity of textile production effluents, before and after Bacillus subitilis bioremediation, in Astyanax lacustris (Pisces, Characidae)

Textile effluents may be highly toxic and mutagenic. Monitoring studies are important for sustaining the aquatic ecosystems contaminated by these materials, which can cause damage to organisms and loss of biodiversity. We have evaluated the cyto- and genotoxicity of textile effluents on erythrocytes of Astyanax lacustris, before and after bioremediation by Bacillus subitilis treatment. We tested 60 fish (five treatment conditions, four fish per condition, in triplicate). Fish were exposed to contaminants for 7 days. The assays used were biomarker analysis, the micronucleus (MN) test, analysis of cellular morphological changes (CMC), and the comet assay. All concentrations of effluent tested, and the bioremediated effluent, showed damage significantly different from the controls. We conclude that water pollution assessment can be accomplished with these biomarkers. Biodegradation of the textile effluent was only partial, indicating the need for more thorough bioremediation to effect complete neutralization of toxicity.

DNA damage as indicator of the environmental vulnerability of bats in Brazil's Caatinga drylands

Brazil's Caatinga drylands is under extensive environmental deterioration, with 38% of its natural cover already lost. There is a need for a better understanding of the effects of such degradation on Caatinga's rich and singular biota. Bats form a large part of this biota, and are pointed as good bioindicators. Here, we used the micronucleus test -an easy-to-use, accessible and cost-effective in vivo approach- to detect DNA damage in cells from bats of different species and feeding habits in three protected areas in the Caatinga, comparing them with samples from an industrial sugarcane plantation. We hypothesized that environmental disturbance would reflect in DNA damage, with lower levels of damage in the less disturbed protected areas. The frequency of micronucleated cells differed significantly between sites and feeding habits (carnivores > insectivores > frugivores > nectarivores > hematophagous) but did not differ between sexes. Alarmingly, the highest levels of DNA damage were in two strictly protected areas (Seridó and Raso da Catarina Ecological Stations). Glossophaga and Anoura were the genera with more damaged cells, and had, respectively, 1.48 and 3.53 times more micronucleated cells (average of 19.33 and 22.67 cells, respectively) than individuals from the same genera from the area with least damaged cells (average of 7.80 and 5.00 cells, respectively). Our analysis is a warning call for an in-depth investigation on the effects of both genotoxic contamination and environmental stressors on bats and other species in Brazil's Caatinga, including the role that historical human-induced processes -like the intense use of agrochemicals- may have had in the region.

Temporal and spatial toxicogenetic damage in estuarine catfish Cathorops spixii from a marine protected area with evidence of anthropogenic influences

Taking action to contribute to the preservation of the natural coastal environment, which maintains a diversity of life, is important in today's world. In estuarine ecosystems that are included in marine protected areas (MPA), it is important to conduct biomonitoring over time to monitor the effects of xenobiotics on bioindicator species such as the catfish Cathorops spixii. This study aims to evaluate the toxicogenetic signals in C. spixii from a MPA (Cananéia-Iguape region, Brazilian coast). These genotoxic signals are demonstrated by the presence of micronuclei (MN) and abnormalities in erythrocytes (AE). This study also takes into account the environmental differences signaled by the water's properties (temperature, salinity, pH, DO, dissolved nutrients, and particulate material) over time (2009, 2014, 2017, and 2018). The results show that in the northern region of the estuary, and mainly in 2009, the water properties reveal the influence of the river in the form of the lowest levels of salinity and pH and the highest levels of nutrients. The most significant levels of suspended particulate material and chlorophyll-a are found in the southern region of the estuary, mainly in 2017 and 2018. In general, the C. spixii from the northern region had better well-being than catfish from the more preserved (southern) region. The data on MN and AE show evidence of toxicogenetic damage occurring over time and clastogenic/aneugenic effects mainly in fish sampled in 2018. The presence of a new AE, first recorded in C. spixii sampled in 2018, and named here as double bubbled, is another indicator of toxicogenetic effects. Finally, although the southern region of the estuary has better abiotic properties and conditions for primary production, the obtained toxicogenetic data for C. spixii reinforces the need for - and encourages the implementation of - monitoring actions in this marine protected area using bioindicator species of contamination.

Effect of heat stress on the antioxidant defense system and erythrocyte morphology of Antarctic fishes

This study analyzed the effect of thermal stress on erythrocytes of Notothenia rossii and Notothenia coriiceps, abundant notothenioids in Admiralty Bay, Antarctic Peninsula. In both species, the antioxidant defense system enzymes, superoxide dismutase, catalase, glutathione peroxidase, glutathione-S transferase, glutathione reductase were punctually altered (8°C for 1, 3 and 6 days) in erythrocytes, indicating that these markers are not ideal for termal stress. However, under the influence of thermal stress, morphological changes in Notothenia coriiceps erythrocytes were observed at all exposure times (1, 3 and 6 days at 8°C), and in Notothenia rossii occurred in 6 days. These results suggest that Notothenia corriceps presents a lower tolerance to thermal stress at 8°C for up to 6 days, since the cellular and nuclear alterations recorded are pathological and may be deleterious to the cells. Among the morphological markers analyzed in this work, we believe that the shape change and nuclear bubble formation may be good stress biomarkers in erythrocytes of Notothenia rossii and Notothenia coriiceps.

DNA damage in an estuarine fish inhabiting the vicinity of a major Brazilian port

The Itaqui Port Complex (northeastern Brazil) is one of the largest Brazilian port facilities, whose effluents and waste are dumped directly into the estuarine waters. Although environmental monitoring has been a concern around this site, there has been no toxicogenetics study on organisms living in this environment. Thus, we assessed the toxicogenetics potential of the estuarine waters surrounding Itaqui, using the native catfish Sciades herzbergii as a biomonitor. We found a significantly higher frequency of genetic damage and mutations in the animals collected near to Itaqui in both seasons compared to the reference site (distant from Itaqui with no port activities). We also quantified chemical elements in the surface water and sediments near the port and found that clorine, phosphorus, zinc, and boron were above the limits set by the Brazilian legislation. We suggest that such contaminants are involved in the origin of DNA damage. Moreover, we recommend including toxicogenetics assays in the environmental monitoring of pollutants, as well as in the definition of their allowable limits, as they could be used as law enforcement tools and help to predict large-scale contamination events associated with port activities.

Metal bioaccumulation and its genotoxic effects on eggs and hatchlings of giant Amazon river turtle (Podocnemis expansa)

The aim of this study was to assess whether possible metal contamination in the sediment of the nests of giant Amazon river turtle, Podocnemis expansa, could contaminate eggs and hatchlings, triggering genotoxic damage. Therefore, sediments of P. expansa nests from two sites in the Brazilian Amazon were evaluated, with the first being collected at Araguaia River and the second at Crixás-Açu River. Newly hatched offspring, eggs, and sediments were collected from the beaches of these two rivers and the quantification of metals (Al, Cd, Co, Cr, Cu, Fe, Mn, Pb, and Zn) was carried out by atomic absorption spectroscopy. All targeted metals were found in both sediment and P. expansa biological samples collected on the beaches presenting higher concentrations in the sediment of Crixás-Açu River. Metals found in the eggshells before nesting and in the egg contents were maternally transferred. Moreover, augmented concentration of metals led by metal transfer from the nests sediments were detected in the eggshells after nesting (ENH) and in the newly hatched offspring (H). Probably this metal relocation to the newly hatchlings augmented the frequency of micronuclei in their blood, presenting 15.25‰ in hatchling found in Crixás-Açu River beaches and 10‰ in newly hatched animals from Araguaia River beaches. These results indicate the occurrence of maternal transfer of metals (essential or not) to the eggs in testudines as well as a transference from the sediments to the nesting eggs, triggering genotoxic effects on the hatchlings.

A multibiomarker approach in the caged neotropical fish to assess the environment health in a river of central Brazilian Cerrado

Water safety is a world-wide concern and several efforts have been made in order to ensure the conservation of aquatic ecosystems. Water quality monitoring must be performed with an integrated approach using biomonitor organisms allied to water parameters. Nonetheless, very few studies have focused on biomarker responses in neotropical fish, especially in the freshwater ecosystem of Brazilian Cerrado savanna. In present study, the active biomonitoring of the João Leite river (central Brazilian Cerrado river) was performed through the evaluation of biomarker responses in caged Astyanax lacustris in combination with land use classification and analysis of water parameters. Caged fish were exposed for seven days at four sites along the river and two control groups were kept in a tank under controlled conditions. Results showed that pasture was the predominant land use in the João Leite river basin (54.07%), followed by natural vegetation (34.92%) and other kind of land use (11.01%). Water analyses showed metal concentrations (Mn and Fe) above the maximum allowed by Brazilian regulation, with particularly higher concentrations at Site 2 (near to pasture area). Biomarker responses did not show significant differences for somatic and mutagenic biomarkers between sites. However, the comet assay showed high DNA damage at Sites 2 and 3, indicating genotoxic effects in caged fish at pasture areas. Histopathological analysis showed highest frequency of leukocyte infiltration in liver of fish from Site 2, confirming the ecotoxic effects on A. lacustris in streams impacted by grazing activities. DNA damage and leukocyte infiltration in fish hepatic tissues were sensitive biomarkers in the neotropical fish A. lacustris to assess the environment health of the Cerrado river. These results showed the importance of using a multibiomarker approach in environmental risk assessment, especially in areas more at risk from anthropogenic pollution.

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.

Accumulation of trace metals in eggs and hatchlings of Chelonia mydas

BACKGROUND

The objective of this study was to verify the accumulation of trace metals in eggs and hatchlings of Chelonia mydas, evaluating if metal accumulation is originated from maternal transfer and/or from the incubation environment. Other assessments were also performed, as metal distribution in different tissues (blood, kidney, liver, muscle, and turtle shells) of newly hatched turtles, and genotoxic analysis, to verify possible damages caused by the presence of metals.

METHODS

The assessments were carried out by quantifying Cd, Ni, Pb, Mn and Fe in egg sample collected during laying time (eggshells (ELT) and egg content (EC)), eggshells from newly hatched turtles (ENH), hatchlings tissues (H - blood, kidney, liver, muscle, and shell)) (n = 18 for each biological sample - 3 of each nest) and nest sediments (n = 6, one of each nest). Comparative analysis were made between ELT and ENH, as well as between egg content (EC) and the sum of tissue samples from hatchlings, using Mann-Whitney hypothesis test (p < 0,05). The amount of metals in different hatchling was quantified and followed by the Dunn post-test. A principal component analysis (PCA) was also employed.

RESULTS

Metals studied were found in all investigated samples. The concentration of a great amount of investigated metals was significantly higher (P=<0.001) in eggshells from ENH than in ELT. An increase in Cd (2.16-fold), Pb (3.47-fold), Fe (6.83-fold) and Mn (195.57-fold) concentration was noticed in ENH. We also observed an increase in Fe (1.59-fold), Mn (1.74-fold) and Ni (1.59-fold) concentration in hatchling, when compared with EC, due to transfer from nest sediments. In relation to the hatchling's tissues, blood was shown to accumulate higher concentrations of Ni and Pb, while shells accumulated more Cd and Fe, and Mn is more associated with liver and kidney. Fe was the highest accumulated metal in both tissues, and muscles presented discrete concentrations of Ni, Mn, and Pb. A mean concentration of 1.25‰ MN was obtained in C. mydas hatchlings, indicating that the accumulation of metals in hatchlings didn't cause toxicology effects.

CONCLUSION

Hatchlings accumulate metals through the maternal and sediment transfer, although the levels of metal accumulation were not enough to cause genotoxic damage.

Steroid androgen 17 alpha methyltestosterone used in fish farming induces biochemical alterations in zebrafish adults

The 17 alpha methyltestosterone (MT) hormone is fed to Oreochromis niloticus larvae in fish farms with the purpose of inducing sex reversal. The aim of this study was to evaluate the toxicity and sub-lethality of MT (99.9% purity) and cMT (a commercial MT with 90% purity) in zebrafish (Danio rerio) adults, where the animals were exposed to concentrations of 0, 4, 23, 139, 833 and 5000 µg/L for 96 hours. Genotoxicity was evaluated by micronucleus test (MN), nuclear abnormalities (NA) and comet assay. A low genotoxic potential of MT was showed, inducing micronucleus, nuclear abnormalities and DNA damage in Danio rerio, depending on the use of MT or cMT, gender and tested concentrations. In the sub-lethality trials, there was a basal difference in the activity of the enzymatic biochemical markers for males and females, while the Glutatione S transferase (GST) activity decreased in all analyzed tissues, and for males the enzymatic activity decreased only in the intestine. Results suggest that MT has a toxic potential to fish because it alters enzymatic metabolic pathways and may pose a risk to the ecosystems.

Comparative metal accumulation and toxicogenetic damage induction in three neotropical fish species with distinct foraging habits and feeding preferences

Environmental pollutants affect fish species differently because their routes of exposure make them more critical to a specific group regarding foraging habits or food preferences. However, the association between local problems and environmental conditions makes a particular species more suitable for use in monitoring programs. Thus, this study compared muscle accumulation of metals (Al, Ba, Cr, Cu, Fe, Mn, Ti and Zn) and toxicogenetic damage to three neotropical species from the Itapemirim River Basin (Brazil) with distinct foraging habits and feeding preferences: Geophagus brasiliensis (benthopelagic - omnivorous); Harttia sp. (benthic - detritivorous); and Leporinus copellandii (pelagic - omnivorous). There was seasonal influence on muscle metal concentrations: Ba and Mn concentrations in G. brasiliensis, Cr in Harttia sp. and Zn, Al and Fe in L. copellandii increased during the rainy season. G. brasiliensis was the most sensitive species, since it had a statistically higher prevalence of erythrocytic nuclear abnormalities, which was influenced by seasonality. This result might be an effect of its benthopelagic habits, which favors contact with a larger group of contaminants due to its interaction with both water column and sediment. The present study showed the differential sensitivity of fish species and that the combination of chemical analysis of pollutants with evaluation of toxicogenetic responses helps to choose the best species for field studies.

Benefits of Adding Virginiamycin to Arapaima gigas (Schinz, 1822) Diet Cultivated in the Brazilian Amazon

The aim of this study was to evaluate the physiological, zootechnical, and environmental benefits of the use of growth-promoting virginiamycin in the pirarucu diet. The research was conducted at the Carlos Eduardo Matiazze Fish Center, Federal University of Rondônia. In this study, 96 pirarucu fish were distributed in excavated nursery, divided into two treatment groups, control (0.0 mg kg^-1) and treatment (75.0 mg kg^-1) of feed with virginiamycin, with 8 replications in a completely randomized design. With virginiamycin being incorporated into commercial feed, for 107 days of cultivation, the fish were slaughtered with an average weight of 9.18 kg. Carcass weight, flesh, residues, and internal organs/guts were evaluated to calculate slaughter yields, Spearman's correlation, and subsequently regression. For the quantification of micronuclei, a count of 1,000 cells per blade was determined. The means of the results obtained were contrasted by the Student's t-test (α = 0.05). Virginiamycin did not cause oscillations in the limnological variables of the nursery but could reduce micronucleated erythrocytes. The average yields in carcass, flesh, and waste were 67.43, 53.4, and 43.14%, respectively. Virginiamycin provided strong correlations (ρ ²) for better productive yields and lower slaughter residue. The hepatosomatic index indicated a strong relationship between liver weight and fat. Virginiamycin may be recommended for fish farming in pirarucu fattening because it contributes to the productive efficiency and sustainability of the fish farm system.

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.

Assessing the seasonal and intrinsic variability of neurotoxic and cyto-genotoxic biomarkers in blood of free-living Eleonoras' falcons

In the present study we investigated seasonal and intrinsic variability of neurotoxic and cyto-genotoxic biomarkers in blood plasma and erythrocytes of free-living Eleonoras' falcons, captured during the pre-breeding (May of 2017 and 2018) and breeding period (September of 2017) on the Antikythira Island (Greece). Specifically, blood samples of captured birds were prepared for the determination of cholinesterase (ChEs, i.e. acetylcholinesterase/AChE and butyrylcholinesterase/ BChE) activity, as well as the formation of nuclear (i.e. the formation of micronuclei into the cells/MN, binucleated cells/BN and others), and cellular/cytoplasmic (i.e. echinocytes/EC, acanthocytes/AC and notched cells/NC) abnormalities in blood plasma and erythrocytes, respectively. Our results indicated that birds sampled in late May had higher ChE and BChE activity levels, as well as higher frequency of total nuclear abnormalities. The latter were also higher in second calendar year (2cy) birds. Cellular/cytoplasmic abnormalities were less frequent in falcons having better body condition, sampled in late May, as well as in light-morph falcons. The observed ChEs activities, as well as nuclear and cellular/cytoplasmic abnormalities revealed that Eleonora's falcons are likely to be exposed to chemical agents with neurotoxic and cyto-genotoxic potential year round, while different aspects of their biology and ecology, such as their reproductive and nutritional status, could mediate their levels. Although we encourage more sampling campaigns to verify the identified seasonal and intrinsic sources of variation in biomarkers tested, the current study enriches the existing knowledge about their usefulness in the environmental monitoring and risk assessment of migratory birds, like Eleonoras' falcon.

Assessment of DNA integrity through MN bioassay of erythrocytes and histopathological changes in Wallago attu and Cirrhinus mirigala in response to freshwater pollution

The aim of this study was to determine the level of contamination and genotoxic impact through micronucleus assay and histopathology in Wallago attu and Cirrhinus mrigala procured from the polluted site of the River Chenab at industrial and sewage waste disposal. The water sample was found viciously contaminated with heavy metals i.e. Ni, Cr, Mn, Co, Pb, Hg, Zn, Sn, Cu while all other physio-chemical variables crossed the suggested limits of WHO. The heavy metals load induced histopathological alterations were correlated to environmental degradation and the productivity of this biological system. W. attu and C. mrigala harvested from contaminated sites of the river indicated higher intensity of DNA damage through micronucleus induction and nuclear abnormalities with 5.46 ± 0.17, 1.23 ± 0.08 and 4.2 ± 0.11, 0.4 ± 0.04‰ respectively. Muscle sections of W. attu and C. mrigala harvested from the polluted section of river demonstrated the necrosis, degeneration of muscle fibers, intra-fibular edema and release of the blood into the tissues due to the bursting of blocked of the blood vessels. Dermal layers showed degeneration of the collagen bundles those were found loose or collapsed in some regions. Photomicrography also revealed vacuolar degeneration in muscle tissues and atrophy of muscle bundles. Intra fibular edema and splitting of muscle fibers were also seen along with bioaccumulation of toxicants. W. attu showed maximum incidence of alterations with highest histopathological alteration index related to environmental degradation. Control fish samples showed normal muscle tissues with normal equally spaced muscle bundles and myotomes.

Distinctive fingerprints of genotoxicity induced by As, Cr, Cd, and Ni in a freshwater fish

Genotoxicity of three toxic elements (chromium, cadmium, nickel) and a metalloid (arsenic) has been studied in a freshwater fish, Channa punctatus using micronuclei (MN) test, comet assay, and erythrocyte nuclear alterations (ENAs) as fingerprints of genotoxicity. These tests yielded different results suggesting involvement of different mechanisms for their genotoxicity. While highest frequency of blebbed nuclei was observed in chromium-treated fish (6.5 ± 0.76), lowest was observed in cadmium-treated fish (4.0 ± 1.0). Maximum number of notched nuclei was recorded in arsenic-treated fish (5.5 ± 1.15) whereas highest numbers of lobed nuclei were found in cadmium-treated fish (4.5 ± 0.13). These differences might be attributed to selective bioaccumulation and chemodynamics of each element. Other parameters used to determine genotoxicity viz.: lipid peroxidation and DNA damage also suggested different mechanisms of their genotoxicity. It is suggested that an integrative approach, using a battery of tests for determining genotoxicity, should be made while making environmental health risk assessment and ecotoxicological studies of these toxic elements.

The Response of Neotropical Fish Species (Brazil) on the Water Pollution: Metal Bioaccumulation and Genotoxicity

The streams and rivers of the Upper Paraná River Basin have been seriously affected by impacts of high population density around the basin area. Fishes are widely used as models to assess the health of aquatic ecosystems, being considered as bioindicators of environmental pollution. In this context, our objective was to assess the potential genotoxic and mutagenic effects of the polluted water in three native fish species (Astyanax lacustris, Hypostomus ancistroides, and Rhamdia quelen) from Tarumã Microbasin, Upper Paraná River, Brazil. We also investigated the concentration of metals in water and in fish muscle to verify bioavailability and bioaccumulation of metals. For both less impacted sites (LI) and impacted sites (IMP) of the microbasin, the concentrations of metals were above the maximum limit allowed by Brazilian legislation (Resolution CONAMA 357/2005), except for Pb, total Cr, and Cu at LI sites and total Cr at IMP sites. A. lacustris showed a higher frequency of micronuclei (MN) at IMP sites compared with LI sites (p < 0.0001). We found no significant differences in MN frequency between site classes for H. ancistroides and R. quelen (p > 0.05). There were no significant differences between site classes regarding to nuclear abnormalities in erythrocytes frequencies (p > 0.05). A. lacustris from IMP sites had higher concentrations of Pb, Cu, Fe, Zn, and Ni in muscle tissue (p < 0.05), whereas H. ancistroides from IMP sites had higher concentration of Cr, Cu, and Ni (p < 0.0001) and R. quelen showed higher concentration of Cd, Fe, and Ni at these sites (p < 0.0001). So, the chosen biomarkers are able to identify the environmental risk of the water pollution.

Baseline levels of environmental genotoxicity and potential confounding factors using common sole (Solea solea) as sentinel organism

Micronuclei (MN) and nuclear buds (NB) frequency was assessed monthly over a one-year period in erythrocytes of common soles (Solea solea) from the Basque continental shelf, a minor disturbed area, in order to determine baseline levels and potential biotic and abiotic confounding factors within biomonitoring purposes. Both genotoxic parameters presented seasonal variations, although only NB frequency was positively correlated with environmental variables (i.e. water temperature and salinity). On the contrary, MN and NB were not affected by age and gender. Therefore, samples of combined age and gender can be used for biomonitoring genotoxic effects, although sampling period together with water temperature and salinity should be thoroughly considered for NB. Overall, these findings are the first attempt to establish baseline MN (0.10-0.78‰) and NB (0.13-0.82‰) frequencies in common sole from Basque marine waters, which are useful for upcoming data comparisons and integration within genotoxicity evaluation procedures of similar marine environments under biomonitoring scopes.

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.

Multivariate and integrative approach to analyze multiple biomarkers in ecotoxicology: A field study in Neotropical region

Aquatic pollution has dramatically worsened in developing countries, due to the discharge of a mixture of pollutants into water bodies, to the lack of stringent laws, and the inadequate treatment of effluents. In this study, the Neotropical fish Astyanax aff. paranae was sampled from three sites with different pollution levels: 1) a Biological Reserve (Rebio), protected by the Brazilian government; 2) an agricultural area in one of the most productive regions of Brazil, upstream of an urban zone; and 3) a site downstream from urban zone, characterized by the influx of different effluents, including wastes from industry, a sewer treatment plant, and agricultural areas. We assess biomarkers at multiple levels, such as the comet assay, hepatic histopathological analysis, brain and muscle acetylcholinesterase (AChE) and the hepatic enzymes glutathione-S-transferase (GST), catalase (CAT), and lipoperoxidation (LPO), during winter and summer. The interpretation of field results is always a very complex operation, since many factors can influence the variables analyzed in uncontrollable conditions. For this reason, we apply an integrative multivariate analysis. The results showed that the environmental risk of the three sites was significantly different. We can see a gradient in data distribution in discriminant analysis: separating, from one side, the fish of Rebio; in the middle are the fish from agricultural area and, in the other side are the animals from downstream site. Overall, the biomarkers responses were more greatly altered in the downstream site, whereas fish from the agricultural area showed an intermediate level of damage. The greatest changes were likely caused by agriculture, industrial chemical effluents and ineffective sewage treatments, in a synergic interaction in downstream site. In conclusion, the use of multiple biomarkers at different response levels to assess the toxic effects of mixed pollutants in a natural aquatic environment is an important tool for monitoring polluted regions.

Water quality parameters, biomarkers and metal bioaccumulation in native fish captured in the Ilha River, southern Brazil

The Ilha River is one of the main tributaries of the Sinos River, southern Brazil, and it is located in an area characterized by low population density and presence of agricultural activities. Thus, this study aimed to assess the water quality of two sites of the Ilha River (source and mouth, S1 and S2 respectively) in five sampling periods using water physicochemical and microbiological analyses, biomarkers, such as condition factor, micronucleus test, gill histopathological analysis, and metal bioaccumulation in the native fish Bryconamericus iheringii. Mean values of BOD₅, thermotolerant coliforms, aluminum, iron and lead exceeded the limits established by the Brazilian legislation for surface waters at both sampling sites. Significant higher micronucleus, nuclear abnormalities and mucous cells frequencies were found at S2 in, at least, one sampling period, whereas fish from S1 presented significant lower condition factor, higher frequencies of lamellar alterations and higher concentrations of chromium and nickel in muscle. Additionally, concentrations of cadmium, chromium and lead in fish muscle exceeded the limits considered safe for human consumption at both sites in at least one sampling period. Data from our study evidenced the mouth of the Ilha River suffers from point genotoxic effects, whereas the source is also contaminated by metals, despite being located in an area under minor anthropic activities.

Micronuclei and other erythrocyte nuclear abnormalities in fishes from the Great Lakes Basin, USA

Biological markers (biomarkers) sensitive to genotoxic and mutagenic contamination in fishes are widely used to identify exposure effects in aquatic environments. The micronucleus assay was incorporated into a suite of indicators to assess exposure to genotoxic and mutagenic contamination at five Great Lakes Areas of Concern (AOCs), as well as one non-AOC (reference) site. The assay allowed enumeration of micronuclei as well as other nuclear abnormalities for both site and species comparisons. Erythrocyte abnormality data was also compared to skin and liver tumor prevalence and hepatic transcript abundance. Erythrocyte abnormalities were observed at all sites with variable occurrence and severity among sites and species. Benthic-oriented brown bullhead (Ameiurus nebulosus) and white sucker (Catostomus commersonii) expressed lower rates of erythrocyte abnormalities, but higher rates of skin and liver neoplasms, when compared to pelagic-oriented largemouth bass (Micropterus salmoides) or smallmouth bass (Micropterus dolomieu) at the same site. The reduced erythrocyte abnormalities, increased transcript abundance associated with Phase I and II toxicant responsive pathways, and increased neoplastic lesions among benthic-oriented taxa may indicate the development of contaminant resistance of these species to more acute effects. Environ. Mol. Mutagen. 58:570-581, 2017. © 2017 This article is a U.S. Government work and is in the public domain in the USA. Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society.

Activity of the endophytic fungi Phlebia sp. and Paecilomyces formosus in decolourisation and the reduction of reactive dyes' cytotoxicity in fish erythrocytes

The current study investigates the potential for discolouration and degradation of Reactive Blue 19 and Reactive Black 5 textile dyes by endophytic fungi Phlebia sp. and Paecilomyces formosus as well as the potential cytotoxicity of products or by-products generated by the treatments in fish erythrocytes. It was observed at 30 days that both endophytes showed biodegradation activity with 0.1 g mL^-1 of dyes. P. formosus showed highest extracellular and intracellular protein content levels after the 15th day, and Phlebia sp. stands out for production of extracellular laccase, indicating that this enzyme may be associated with the decolouration capacity. The dyes showed toxic effects in fishes at 0.01 g mL^-1 concentration, resulting in the appearance of micronuclei in erythrocyte cells. When degraded dyes treated by endophytes were tested, the frequency of micronuclei reduced approximately 20%, indicating the effectiveness of these endophytic in the treatment of textile dyes with less environmental impact, thus indicating a potential for application of these fungi in bioremediation process.

Application of the micronucleus test and comet assay in Trachemys callirostris erythrocytes as a model for in situ genotoxic monitoring

Trachemys callirostris is a turtle species endemic to northern South America. In northern Colombia it occurs in the middle and lower Magdalena River drainage and its principal tributaries (lower Cauca and San Jorge rivers) and in other minor drainages such as the lower Sinú River. In recent years, industrial, agricultural, and mining activities have altered natural habitats in Colombia where this species occurs, and many of the pollutants released there are known to induce genetic alterations in wildlife species. The micronucleus test and comet assay are two of the most widely used methods to characterize DNA damage induced by physical and chemical agents in wildlife species, but have not been employed previously for genotoxic evaluations in T. callirostris. The goal of this study was to optimize these genotoxic biomarkers for T. callirostris erythrocytes in order to establish levels of DNA damage in this species and thereby evaluate its potential as a sentinel species for monitoring genotoxic effects in freshwater environments in northern Colombia. Both genotoxic techniques were applied on peripheral blood erythrocytes from 20 captive-reared T. callirostris individuals as a negative control, as well as from samples obtained from 49 individuals collected in Magangué (Magdalena River drainage) and 24 individuals collected in Lorica (Sinú River drainage) in northern Colombia. Negative control individuals exhibited a baseline frequency of micronuclei of 0.78±0.58 and baseline values for comet tail length and tail moment of 3.34±0.24µm and 10.70±5.5, respectively. In contrast, samples from both field sites exhibited significantly greater evidence of genotoxic effects for both tests. The mean MN frequencies in the samples from Magangué and Lorica were 8.04±7.08 and 12.19±12.94, respectively. The mean tail length for samples from Magangué and Lorica were 5.78±3.18 and 15.46±7.39, respectively. Finally, the mean tail moment for samples from Magangué and Lorica were 23.59±18.22 and 297.94±242.18, respectively. The frequency of micronuclei in the samples was positively related to comet tail length and tail moment. Thus, this study showed that both genotoxicity biomarkers may be applied to T. callirostris erythrocytes as a sentinel organism for assessing the effects of environmental pollutants in freshwater ecosystems in northern South America.

Genotoxicity Effects in Freshwater Fish from a Brazilian Impacted River

This study evaluated the incidence of nuclear abnormalities (NA) in four fish species from an impacted river in Northeastern Brazil, characterized by accumulation of heavy metals and organic sewage. Two carnivores (Serrasalmus brandtii and Hoplias malabaricus) and two omnivore species (Oreochromis niloticus and Geophagus brasiliensis), used as food sources by local populations, were collected during the dry and the rainy season along Contas River basin. Nuclear abnormalities (bulbs, binuclei, lobes, micronuclei, notches, and vacuoles) were reported in all fish samples, with high occurrence in S. brandtii and H. malabaricus, species commonly found in local fish markets. This result agrees with previous analyses of accumulation of trace metals in both species, suggesting an association of genotoxic effects and biomagnification. Moreover, native specimens collected near urban areas presented higher frequencies of NA while O. niloticus seems to be more tolerant to environmental contamination. Therefore, effective policies are required to reduce the contamination of Contas River, since pollution by xenobiotics are potential threats to both local biodiversity and human population.

What the Erythrocytic Nuclear Alteration Frequencies Could Tell Us about Genotoxicity and Macrophage Iron Storage?

Erythrocytic nuclear alterations have been considered as an indicative of organism’s exposure to genotoxic agents. Due to their close relationship among their frequencies and DNA damages, they are considered excellent markers of exposure in eukaryotes. However, poor data has been found in literature concerning their genesis, differential occurrence and their life span. In this study, we use markers of cell viability; genotoxicity and cellular turn over in order to shed light to these events. Tilapia and their blood were exposed to cadmium in acute exposure and in vitro assays. They were analyzed using flow cytometry for oxidative stress and membrane disruption, optical microscopy for erythrocytic nuclear alteration, graphite furnace atomic absorption spectrometry for cadmium content in aquaria water, blood and cytochemical and analytical electron microscopy techniques for the hemocateretic aspects. The results showed a close relationship among the total nuclear alterations and cadmium content in the total blood and melanomacrophage centres area, mismatching reactive oxygen species and membrane damages. Moreover, nuclear alterations frequencies (vacuolated, condensed and blebbed) showed to be associated to cadmium exposure whereas others (lobed and bud) were associated to depuration period. Decrease on nuclear alterations frequencies was also associated with hemosiderin increase inside spleen and head kidney macrophages mainly during depurative processes. These data disclosure in temporal fashion the main processes that drive the nuclear alterations frequencies and their relationship with some cellular and systemic biomarkers.

The Comet Assay and its applications in the field of ecotoxicology: a mature tool that continues to expand its perspectives

Since Singh and colleagues, in 1988, launched to the scientific community the alkaline Single Cell Gel Electrophoresis (SCGE) protocol, or Comet Assay, its uses and applications has been increasing. The thematic areas of its current employment in the evaluation of genetic toxicity are vast, either in vitro or in vivo, both in the laboratory and in the environment, terrestrial or aquatic. It has been applied to a wide range of experimental models: bacteria, fungi, cells culture, arthropods, fishes, amphibians, reptiles, mammals, and humans. This document is intended to be a comprehensive review of what has been published to date on the field of ecotoxicology, aiming at the following main aspects: (i) to show the most relevant experimental models used as bioindicators both in the laboratory and in the field. Fishes are clearly the most adopted group, reflecting their popularity as bioindicator models, as well as a primary concern over the aquatic environment health. Amphibians are among the most sensitive organisms to environmental changes, mainly due to an early aquatic-dependent development stage and a highly permeable skin. Moreover, in the terrestrial approach, earthworms, plants or mammalians are excellent organisms to be used as experimental models for genotoxic evaluation of pollutants, complex mix of pollutants and chemicals, in both laboratory and natural environment. (ii) To review the development and modifications of the protocols used and the cell types (or tissues) used. The most recent developments concern the adoption of the enzyme linked assay (digestion with lesion-specific repair endonucleases) and prediction of the ability to repair of oxidative DNA damage, which is becoming a widespread approach, albeit challenging. For practical/technical reasons, blood is the most common choice but tissues/cells like gills, sperm cells, early larval stages, coelomocytes, liver or kidney have been also used. (iii) To highlight correlations with other biomarkers. (iv) To build a constructive criticism and summarize the needs for protocol improvements for future test applications within the field of ecotoxicology. The Comet Assay is still developing and its potential is yet underexploited in experimental models, mesocosmos or natural ecosystems.

Oxidative stress and hypermethylation induced by exposure of Oreochromis niloticus to complex environmental mixtures of river water from Cubatão do Sul, Brazil

In this study, we investigated the effects of oxidative stress and hypermethylation through lipid peroxidation and DNA methylation, respectively, in erythrocytes of Oreochromis niloticus exposed to environmental complex mixture of water from Cubatão do Sul River throughout the year. This river is the source of drinking water for the region of Florianópolis, the capital of Santa Catarina State, Brazil. Lipid peroxidation was quantified by the rate of malondialdehyde (MDA) formation, and DNA methylation was quantified by the rate of 5-methyldeoxycytosine (m(5)dC) formation. In all studied sites, the river water samples caused metabolic changes in O. niloticus. MDA formation rates were significantly different when compared to the negative control (except for samples from Site 1 during spring 2010, summer 2011 and fall 2011). All samples (except Site 1, spring 2010) induced increases in the m(5)dC formation rates, and at the end of the study, the values were near the values found in the positive control (potassium dichromate 2.5mg/L). The results showed that samples of environmental complex mixtures of water from Cubatão do Sul River are capable of inducing high levels of oxidative damage and hypermethylation in O. niloticus.

Micronucleus test in fishes as indicators of environmental quality in subestuaries of the Río de la Plata (Uruguay)

Genotoxic agents may exert damage that may be active through following generations. Micronuclei are cytoplasmic chromatin masses outside the main cell nucleus, indicators of chromosomal damage. This study applied micronuclei test to evaluate genetic damage of fish in three breeding and nursery areas of commercially important fishes exposed to differing degrees of anthropogenic impact: Pando, Solís Chico and Solís Grande sub-estuaries. The micronuclei test revealed differences in the presence and concentrations of genotoxic components in these sub-estuaries. Fish in the urban and industrialized Pando sub-estuary presented the highest percentages of micronuclei. The absence of seasonal changes in micronuclei in Pando fish could be explained by physical characteristics of the sub-estuary and by regional weather conditions. Odontesthes argentinensis (Valenciennes, 1835) was the species most susceptible to genotoxic components. It is recommended the use of a battery of biomarkers to better explain the health of organisms in that important nursery area.

Toxicity and genotoxicity of water and sediment from streams on dotted duckweed (Landoltia punctata)

Most rivers are used as a source to supply entire cities; the quality of water is directly related to the quality of tributaries. Unfortunately men have neglected the importance of streams, which receive domestic and industrial effluents and transport nutrients and pesticides from rural areas. Given the complexity of the mixtures discharged into these water bodies, this study aimed to evaluate the quality of water and sediment of ten tributaries of Pirapó River, in Maringá, Paraná State, Brazil. To this end, the free-floating macrophyte Landoltia punctata (G. Meyer) Les & D.J.Crawford was used as test organism in microcosm, and the toxicity of water and sediment samples was evaluated by the relative growth rate, dry/fresh biomass ratio, and genotoxic effects (comet assay). Samples of water and sediment of each stream were arranged in microcosms with L. punctata. Seven days later, plants were collected for analysis. Nutrient levels were higher than the reference location, indicating eutrophication, but the results indicated a toxic effect for only three streams, and a genotoxic effect for all streams.

Genotoxicological response of the common carp (Cyprinus carpio) exposed to spring water in Tlaxcala, México

This study evaluated the genotoxic impact of anthropic activities in Huactzinco Spring, using Cyprinus carpio as a biomonitor. In situ and in vivo experimental designs were compared by means of simultaneous 2-week exposures. The water from the spring generated mean micronuclei frequency values (108.6 ± 32 MN/1,000) and DNA fragmentation values (143.4 ± 35 au) which were statistically higher than those for the negative control (10.9 ± 6 MN/1,000 and 67.6 ± 23 au). The in situ and in vivo experiments supported one another. The comet assay proved to be the most sensitive test, with an EC50 value (11.4 % ± 3.4 %) being less than that determined for the micronuclei test (54.8 % ± 3.2 %). The results of this study confirm the usefulness of C. carpio as an environmental contamination biomonitor, and suggest that Huactzinco Spring water constitutes a latent risk to human health and the environment.

First application of comet assay in blood cells of Mediterranean loggerhead sea turtle (Caretta caretta)

The aim of this study was to validate the comet assay in erythrocytes of Caretta caretta, a species never investigated for genotoxicity. We studied 31 loggerhead sea turtles from three Italian marine rescue centres. Peripheral blood samples were collected from all the animals and the comet assay applied. All comet cells were analysed using two methods: visual scoring and computer image analysis. The % DNA in tail mean value ± SD and Damage Index were 21.56 ± 15.41 and 134.83 ± 94.12, respectively. A strong and statistically significant statistically correlation between the two analytical methods was observed (r = 0.95; p < 0.05). These results demonstrate that the comet assay is a useful method to detect the possible effects of genotoxic agents in loggerhead sea turtle and to increase the knowledge about the ecotoxicological health status of this threatened species.

Genotoxicity in Astyanax bimaculatus (Twospot Astyanax) exposed to the waters of Engano River (Brazil) as determined by micronucleus tests in erythrocytes

Changes in aquatic environments are potentially large, and effects on biota are highly variable. In Santa Catarina State, Brazil, the main sources of pollution in headwaters are wastewater, pesticides, and animal waste, which contain chemical and organic additives, and there is little knowledge about their effects on aquatic organisms. This study was aimed at investigating the possible genotoxic effects of the waters of the Engano River through the micronucleus (MN) test in Astyanax bimaculatus erythrocytes. Samplings were performed at two sites on the river, and there were six temporal repetitions with collection of blood from six individuals per site/repetition. For the negative-control treatment, we used fish from organic culture; cyclophosphamide was inoculated to constitute the positive-control treatment. MN was obtained in 3,000 erythrocytes/individual. Kruskal-Wallis analysis of variance, Scott-Knott test, and Spearman correlation were employed for data analysis. We found 124 MN in fish from the river, with 70 and 54 MN, respectively, for each site and 16 and 59 MN in negative and positive controls, respectively. The results showed a statistical difference for the formation of MN between river fish and fish in the positive-control treatment. Considering the average MN, we found the formation of three distinct groups: (1) fish from site no. 1 and those in the negative-control group, (2) fish from site no. 2, and (3) fish in the positive-control group. The greater values of chromosomal damage were found during periods of lower rainfall. The test used indicated the presence in the water of substances likely to cause clastogenic and aneugenic effects.

Baseline micronuclei and nuclear abnormalities frequencies in native fishes from the Paraná River (Argentina)

This work aims to establish baseline frequencies of micronuclei (MN) and nuclear abnormalities (NA) in native fish species collected in situ from the Paraná River. For this purpose, the micronucleus test was applied in peripheral blood erythrocytes from specimens obtained from samplings collected at two localities (Posadas and Candelaria, Misiones, Argentina) during the period 2007-2010. The results were statistically analyzed using the Kruskal Wallis test. Data from nine fish species were obtained, among which Steindachnerina brevipinna(Characiformes) revealed the highest baseline frequency of MN and NA, showing statistically significant differences with regard to the other analyzed species. These results are the first report of baseline MN and NA frequencies for native fish species studied and could be useful for future comparisons with data of fishes belonging to other environments.

Induction of micronucleus of Oreochromis niloticus exposed to waters from the Cubatão do Sul River, southern Brazil

In an effort to characterize the pollution of surface waters by potentially genotoxic agents, this study aimed at assessing the frequency of micronucleated (MN) erythrocytes of the fish species, Oreochromis niloticus, from the Cubatão do Sul River. This river is the source of drinking water for the region of Florianópolis, capital of Santa Catarina State, Brazil. Negative control fish showed low frequency of MN, ranging between 0.49‰ and 0.90‰. Positive control (potassium dichromate 2.5 mg/L) organisms showed high MN frequency (16.82-17.25‰). The MN frequency increased along the river (Site 1--1.24‰ winter 2011; Site 4--9.76‰ summer 2011). Based on the observation of elevated MN erythrocytes frequency in O. niloticus exposed to water samples from along the river course, we conclude that the complex environmental mixtures of water from the Cubatão do Sul River have genotoxic potential. This genotoxicity most likely originated from agricultural runoff and domestic effluents released without treatment, based on the evidence from literature data and a survey in the region. This study provides a scientific basis for future studies regarding the genotoxicity of complex environmental mixtures in natural environments.

Profile of micronucleus frequencies and nuclear abnormalities in different species of electric fishes (Gymnotiformes) from the Eastern Amazon

The frequency of spontaneous micronucleus (MN) formation in fish species needs to be determined to evaluate their usefulness for genotoxic biomonitoring. The definition of a good bioindicator takes into account the current knowledge of its metabolic traits as well as other factors including its feeding behavior and relationship to the environment. In this study, we compared the basal frequencies of micronucleated erythrocytes and nuclear abnormalities (NA) among different species of the fish Order Gymnotiformes (Rhamphichthys marmoratus, Steatogenys elegans, Sternopygus macrurus, Parapteronotus hasemani, Gymnotus mamiraua, Gymnotus arapaima, Brachyhypopomus beebei, Brachyhypopomus n. sp. BENN) sampled in several localities of the Eastern Amazon. A baseline of MN and NA frequency in these fish was determined, enabling the identification of potentially useful species as models for genotoxicity studies. Only one impacted sample collected at a site in the River Caripetuba showed a significant number of NAs, which may be due to the release of wastewater by neighbouring mining industries and by the burnt fuel released by the small boats used by a local community. Our results may provide support for further studies in areas of the Eastern Amazon affected by mining, deforestation and other anthropogenic activities.

Biomarker responses in mudskipper (Periophthalmus waltoni) from the coastal areas of the Persian Gulf with oil pollution

A suite of 5 different biomarker responses were selected and measured in 3 different phases of detoxification process in mudskipper Periophthalmus waltoni from 3 different stations including Soltani Inlet, Shif Island and Ameri Port in Bushehr coastal area of the Persian Gulf. The selected biomarkers were 7-ethoxyresorufin O-deethylase (EROD), glutathione S-transferase (GST), biliary fluorescent aromatic compounds (FACs), DNA damage using the Comet assay and micronucleus (MN). Spatial variations in biomarker responses were observed in different sites. EROD, GST, FACs, DNA damage and MN were significantly elevated in mudskippers in the most oil impacted site (Soltani inlet). Based on the assessments, bile metabolites, EROD and GST induction appear to be sensitive to polycyclic aromatic hydrocarbons (PAHs) and can be considered as complementary biomarkers; therefore P. waltoni has the potential to be used as a bioindicator in these types of ecosystems.

Effects of exposure to soluble fraction of industrial solid waste on lipid peroxidation and DNA methylation in erythrocytes of Oreochromis niloticus, as assessed by quantification of MDA and m⁵dC rates

In this study, lipid peroxidation and DNA methylation were observed in erythrocytes of Oreochromis niloticus exposed to soluble fractions of textile, metal-mechanic and pulp and paper industrial waste, after a period of 48 h. Lipid peroxidation was quantified by the rate of malondialdehyde (MDA) and DNA methylation was quantified by the rate of 5-methyldeoxycytosine (m⁵dC). Soluble fractions of textile industrial waste caused metabolic changes for all studied samples. In organisms exposed to samples TX1 and TX2 (textile waste) MDA rates were 132.36 and 140.28 nM MDA/mg protein, respectively, while in control organism the MDA rates were 27.5 nM MDA/mg protein. All samples from soluble fractions of textile industrial waste induced increases in m⁵dC rates, increases varied between 300 percent and 700 percent when compared to the control organism. All the organisms exposed to soluble fractions of metal-mechanic industrial waste presented increases between 360 percent and 600 percent in the rates of MDA, and one of them (sample MM3) induced an increase of 180 percent in the rate of m⁵dC, when compared to control. Although a significant increase was not observed in the MDA rate of fish exposed to the soluble fractions of pulp and paper industrial waste, there was an increase of 460 percent in the rate of m⁵dC in one of the samples (sample PP2), when compared to control. The results showed that the soluble fractions of these industrial wastes are capable of inducing oxidative damage and altering the DNA methylation of O. niloticus. Thus, the MDA and m⁵dC rates demonstrated to be effective biomarkers of exposure, which could be used to evaluate the toxicity of soluble fractions of industrial solid waste.

Studies of micronuclei and other nuclear abnormalities in red blood cells of Colossoma macropomum exposed to methylmercury

The frequencies of micronuclei (MN) and morphological nuclear abnormalities (NA) in erythrocytes in the peripheral blood of tambaqui (Colossoma macropomum), treated with 2 mg.L(-1) methylmercury (MeHg), were analyzed. Two groups (nine specimens in each) were exposed to MeHg for different periods (group A - 24 h; group B - 120 h). A third group served as negative control (group C, untreated; n = 9). Although, when compared to the control group there were no significant differences in MN frequency in the treated groups, for NA, the differences between the frequencies of group B (treated for 120 h) and the control group were extremely significant (p < 0.02), thus demonstrating the potentially adverse effects of MeHg on C. macropomum erythrocytes after prolonged exposure.