Micronucleus test in fish cells: a bioassay for in situ monitoring of genotoxic pollution in the marine environment

Inter- and intraspecific blood-related biomarkers and chemical exposure in confined and free-living sea turtles

The relevance of recovery centers and head-starting programs for rescue, rehabilitation, rearing, and conservation of sea turtles is recognized worldwide. In addition, these centers contribute to generating biochemical and physiological data needed to identify health markers and provide baseline values. Because of the marine ecosystems' deterioration, biomarker identification is a global priority for sea turtle conservation; nevertheless, information on specific endpoints, such as neurotoxicity and mutagenesis, is still limited in sea turtles. This study aimed to contrast a set of non-invasive blood biomarkers with ecotoxicological and clinical applications in confined green sea turtles (Chelonia mydas) compared with free-living ones from the Mexican Caribbean. Additionally, interspecific (green, hawksbill (Eretmochelys imbricata), loggerhead (Caretta caretta) turtles) differences were also evaluated. Plasmatic organochlorine pesticides (OCs) and polychlorinated biphenyl (PCBs) were also determined. The concentration ranges of uric acid, total proteins, lipids (cholesterol and triglycerides), and thyroxine of both confined and free-living green turtles fell outside the reference intervals for the species. Additionally, confined green turtles had the highest number of erythrocytic nuclear abnormalities (ENA) and elevated levels of hemoglobin, lipid peroxidation, and activity of glutathione S-transferase, glutathione peroxidase, and carboxylesterase (CE). Contrasts among confined species identified hawksbill turtles with the lowest glutathione reductase activity, green turtles with the lowest ENA frequency and CE activity, and loggerhead turtles with the highest plasmatic concentrations of PCBs and OCs. The information here provided can be used as information in health monitoring programs and for conservation and management policies at regional, national, and international level.

Parasitological investigation and potential effects of parasitism on hematological, genotoxic and immune parameters in free ranging sea turtles rescued along the Southern Adriatic coast (Eastern Mediterranean Sea)

Sea turtles can host a wide range of parasitic taxa, some of which may lead to severe diseases, weakening and endangering their health. Assessing free-ranging sea turtles' responses to these potential pathogens using biomarkers can provide valuable insights into the cellular and molecular impacts of parasites. This information can serve as a crucial tool for conservation efforts. During rehabilitation, hematological, genotoxic and innate immune parameters were evaluated in 70 free-ranging sea turtles rescued along the Southern Adriatic coast (Eastern Mediterranean Sea) from 2021 to 2023, 24 of which were found to have parasitic infections. Hapalotrema mistroides, Sulcascaris sulcata and Neospirorchis sp. were identified by coprological and molecular techniques. Some significant differences for biomarkers were associated with these parasites. These findings highlight the importance of considering the infection status of free-ranging sea turtles when evaluating biomarker results, as major pathogens like parasites can influence certain parameters.

Effects of blood metal(loid) concentrations on genomic damages in sharks

The use of effect biomarkers has contributed to the understanding of the sublethal effects of contaminants on different organisms. However, the analysis of genotoxic markers as an indicator of organism and environmental health in sharks is underexplored. Thus, the present study investigated the relationship between the genomic damage frequency in erythrocytes and metal(loid) concentrations in whole blood of three shark species (Galeocerdo cuvier, Negaprion brevirostris and Ginglymostoma cirratum), taking into account climatic seasonality. The results showed that G. cuvier, an apex predator, presented the highest total erythrocyte genomic damage frequencies together with the highest mean whole blood concentrations of Al, Cd, Cr, Fe, Mn, Ni, Pb and Zn. The shark N. brevirostris also presented high levels of metal(loid), indicating a greater susceptibility to these contaminants in species that preferentially feed on fish. In contrast, G. cirratum, a mesopredator, presented the lowest erythrocyte damage frequencies and whole blood metal(loid) concentrations. The presence of micronuclei was the most responsive biomarker, and Al, As and Zn had an important effect on the genomic damage frequencies for all species evaluated. Zn concentration influenced the binucleated cells frequencies and Al concentration had an effect on the total damage and micronuclei frequencies in G. cuvier and N. brevirostris. Binucleated cells and blebbed nuclei frequencies were affected by As concentration, especially in G. cirratum, while showing a strong and positive correlation with most of the metals analyzed. Nonetheless, baseline levels of metal(loid) blood concentrations and erythrocyte genomic damage frequencies in sharks have not yet been established. Therefore, minimum risk levels of blood contaminants concentrations on the health of these animals have also not been determined. However, the high genomic instability observed in sharks is of concern considering the current health status of these animals, as well as the quality of the environment studied.

Toxicity evaluation of water-accommodated fraction of heavy and light oils on the rainbow trout fish cell line RTL-W1

Fish are currently used models for the toxicity assessment of chemicals, including polycyclic aromatic hydrocarbons (PAHs). Alternative methods including fish cell lines are currently used to provide fast and reliable results on the toxic properties of chemicals while respecting ethical concerns about animal testing. The Rainbow trout liver cell line RTLW1 was used to analyze the effects of two water-accommodated fractions from two crude oils: Arabian Light crude oil (LO) and refined oil from Erika (HO). Several toxicity endpoints were assessed in this study, including cytotoxicity, EROD activity, DNA damage (comet and micronucleus assays), and ROS production. RTL-W1 cells were exposed for 24 h at two or three dilutions of WAF at 1000 µg/L (0.1% (1 μg/L), 1% (10 μg/L), and 10% (100 μg/L)) for cytotoxicity and EROD activity and 1% and 10% for ROS production and genotoxicity). Exposure of RTL-W1 cells to LO WAF induced a significant increase of EROD activity and ROS production and altered DNA integrity as revealed by both the comet assay and the micronucleus test for 10 µg/L of LO. On the other hand, HO WAF exhibited limited toxic effects except for an EROD induction for 1% WAF dilution. These results confirmed the usefulness of RTL-W1 cells for in vitro toxicological assessment of chemical mixtures.

Hormonal and haematological biomarkers as indicators of stress induced by Diuron herbicide toxicity on Clarias gariepinus (Burchell, 1822) sub-adults

Diuron is a globally used herbicide for weed control but has anti-androgenic effects on androgens (testosterone and androstenedione), antagonist effects on thyroid hormone signaling, and haematological effects due to their biotransformation in fish. Endocrine-disrupting biomarkers such as thyroid hormones, sex hormones, and haematological indices of Clarias gariepinus sub-adults exposed to sub-lethal diuron concentrations were studied over a 28-day period. C. gariepinus (n = 200) sub-adults were exposed to sub-lethal concentrations (0.00, 0.09, 0.18, 0.26, and 0.35 mg/L) of diuron. Changes in the hormonal and haematological profiles of the exposed fish were concentration and exposure duration-dependent. The thyroxine (T4), tri-iodothyronine (T3), and 17β-estradiol (E2) profiles decreased with an increase in concentration and exposure duration. The haemoglobin, pack cell volume, red blood cell, white blood cell, mean cell volume, and mean corpuscular haemoglobin cell decreased, while the mean corpuscular haemoglobin increased with an increase in concentration and exposure duration. Diuron induced stress and altered the physiological mechanisms of fish, and its application in farmlands should be regulated so as to enable a sustainable aquatic eco-system and fishery resources.

Erythrocyte Recovery in Oreochromis niloticus Fish Exposed to Urban Effluents

Urban activities pollute aquatic ecosystems, and the integrity of organisms such as fish. The use of cytological techniques, such as the analysis of blood cellular integrity using the Micronucleus test, can help detect mutagenic damage as a result to urban effluents exposure. In this context, this study aimed to evaluate the frequency of micronucleus and other nuclear abnormalities in Oreochromis niloticus fish environmentally exposed to urban effluents in relation to their erythrocyte recovery capacity when exposed to clean water (30 and 45 days). The results indicated high copper, dissolved iron, nickel, and thermotolerant coliform levels in the urban stream. There was no difference in the frequency of micronuclei. In contrast, cells with nuclear nuclei, binucleates, kidney-shaped nuclei, notched nuclei, lobed nuclei, and segmented nuclei decreased according to the time the fish were exposed to clean water. When exposed to clean water, we conclude that urban fish recover from genotoxic and cytotoxic damage.

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.

Using native fish in eco-genotoxic assessment of heavy metal contamination pollution arising from nearby large Brazilian rivers

Worldwide water quality has declined progressively due to continuous pollution of aquatic resources by agrochemicals in particular heavy metals. Fish genotoxicity biomarkers are vital to identify and complement chemical parameters for determining environmental risk of adverse effects. Therefore, it was of interest to examine the eco-genotoxicity attributed to water pollution over different stream sections of Brazilian rivers by using Cichlasoma paranaense (Teleostei: Cichlidae), a neotropical freshwater cichlid fish, as a biological model. Chemical analysis of water and sediments collected from different Brazilian rivers sites demonstrated contamination by metals. Cichlasoma paranaense were collected at a reference location (a permanent water preservation area), maintained in the lab under standard conditions (controlled temperature, lighting, daily feeding, and constant aeration) and exposed to environmental samples of water and sediments. Subsequently, micronucleus (MN) and nuclear abnormalities (NA) frequencies were assessed in erythrocytes obtained from the caudal and gill regions. The highest concentrations of Cu were found in samples from river sites with forest fragmentation attributed to intensive agriculture practices. Similarly, exposure of fish to samples from agricultural areas induced significantly higher number of genotoxic effects. There was no marked difference between the tissues (tail and gill) regarding the observed frequencies of MN and NA. Thus C. paranaense fish served as a reliable model for detecting genotoxic effects, especially when water samples were collected near the discharge of agrochemicals. Evidence indicates that this method be considered for other global river sites which are also exposed to agrochemicals discharges containing Cu.

Description and quantification of micronucleus and nuclear abnormalities in erythrocytes of the sentinel green turtle (Chelonia mydas) with fluorescence microscopy

Contamination in marine ecosystems is of the most critical threats to marine turtles. The identification of useful biomarkers to detect and monitor the physiological and clinical effects of pollutants on these populations will allow early detection of alterations (e.g., mutagenic damages) that could risk their viability or favor the development of diseases, thus threatening the biodiversity of these ecosystems and human population. This study is aimed at describing and quantifying nuclear anomalies in peripheral blood erythrocytes of green turtles (Chelonia mydas) from three distinct foraging areas in Mexico (Akumal, Xcalak, and Punta Herrero). We developed a novel morphological index that could be used as a biomarker to identify abnormal nuclei in peripheral blood erythrocytes. Here we describe for the first time in C. mydas, with a species-specific staining protocol, distinct nuclear abnormalities such as blebbed, lobed, notched, eight shape nuclei, and binucleated cells. These nuclear abnormalities were present in > 90 % of the subjects (n = 30). Moreover, 50 % of the organisms presented erythrocytes with micronuclei. The number of nuclear abnormalities did not correlate with size of the green turtles or differ between sites, or health status. We found a higher frequency of green turtles with nuclear abnormalities in the southern region (Punta Herrero and Xcalak) with the highest frequency of micronucleus and buds. The former could be associated to the constant exposure to chemical pollutants of oceanographic origin in the southern coast of Quintana Roo. Furthermore, the increasing anthropogenic pollution in Akumal could also explain the highest variability in the number of nuclear abnormalities presented in resident individuals. We propose that a long-term monitoring programs of green turtle populations in the Mexican Caribbean that include a micronucleus test could be a useful to determine possible mutagenic damage in these animals.

Pesticide contamination in agro-ecosystems: toxicity, impacts, and bio-based management strategies

Continuous rise in application of pesticides in the agro-ecosystems in order to ensure food supply to the ever-growing population is of greater concern to the human health and the environment. Once entered into the agro-ecosystem, the fate and transport of pesticides is determined largely by the nature of pesticides and the soil attributes, in addition to the soil-inhabiting microbes, fauna, and flora. Changes in the soil microbiological actions, soil properties, and enzymatic activities resulting from pesticide applications are the important factors substantially affecting the soil productivity. Disturbances in the microbial community composition may lead to the considerable perturbations in cycling of major nutrients, metals, and subsequent uptake by plants. Indiscriminate applications are linked with the accumulation of pesticides in plant-based foods, feeds, and animal products. Furthermore, rapid increase in the application of pesticides having long half-life has also been reported to contaminate the nearby aquatic environments and accumulation in the plants, animals, and microbes surviving there. To circumvent the negative consequences of pesticide application, multitude of techniques falling in physical, chemical, and biological categories are presented by different investigators. In the present study, important findings pertaining to the pesticide contamination in cultivated agricultural soils; toxicity on soil microbes, plants, invertebrates, and vertebrates; effects on soil characteristics; and alleviation of toxicity by bio-based management approaches have been thoroughly reviewed. With the help of bibliometric analysis, thematic evolution and research trends on the bioremediation of pesticides in the agro-ecosystems have also been highlighted.

Genotoxicity assessment in two Amazonian estuaries using the Plagioscion squamosissimus as a biomonitor

Genotoxicity studies in coastal ecosystems have been a priority in Environmental Risk Assessment (ERA). This research aimed to study the genotoxicity by the micronucleus test and comet assay in two Brazilian Amazon estuaries (anthropized and control) using Plagioscion squamosissimus as a biomonitor. Blood samples were collected from 54 specimens. No significant genotoxic effects were detected in the cells analyzed, although the highest occurrence (MN and DNA damages) was observed in anthropized site. The percentage of genomic damage differed between the sites studied, being always higher in anthropizes site as well. Of the nucleoids analyzed in this site, on average, 28 ± 14.42% of the cells were classified in the highest damage class. The fish analyzed in the present study are direct influenced of xenobiont agents capable of producing damage to the genetic material of aquatic organisms in both sites and, consequently, may bring consequences still little reported in studies of morphophysiological alterations in humans.

Seasonal effect on biomarker responses in sentinel species: innovation in mangrove conservation status assessment

We evaluated the environmental quality in mangrove areas of the Western Atlantic with different levels and history of contamination, considering biomarkers for the crab Ucides cordatus. For this purpose, specimens were collected in two climatic seasons (rainy and dry seasons) and assays of genotoxicity (MN, micronucleus), cytotoxicity (NRRT, neutral red retention time) and biochemical (MT, metallothionein; and LPO, lipoperoxidation) were conducted. In the most impacted mangroves, there was an increase in the mean of micronucleus (frequency of MN/1000), which was associated with a shorter retention time (minutes of NRRT). In contrast, the most pristine areas showed MN < 3 and NRRT < 100 min, with no seasonal effect, indicating a lower effect of degenerative processes by xenobiotics. The rainy season was more harmful, especially regarding cytogenotoxicity. The use of bioindicator species for environmental monitoring should be guided by an analysis of biomarkers considering the season, because during the period of highest rainfall, biomarkers values can change.

Genotoxicity and Trace Elements Contents Analysis in Nile Tilapia (Oreochromis niloticus) Indicated the Levels of Aquatic Contamination at Three Egyptian Areas

The toxic waste and pollutants of heavy metals continuously pollute freshwater aquatic reservoirs, which have severe implications on aquatic life and human health. The present work aims to evaluate trace elements (Zn, Mn, Cu, Cd, and Pb) along with three sites, Mariout Lake, Abbassa, and River Nile Aswan in Egypt, using Nile tilapia (Oreochromis niloticus) as bioindicator. The quality assurance, health-risk assessment, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), quantitative polymerase chain reaction (qPCR), and micronucleus test were performed to investigate the effect of different trace elements on Hsp70 gene level and micronuclei formation. We observed the highest expression of Hsp70 protein band of 70 KD and stress-responsive Hsp70 gene in the liver followed by gills of Nile tilapia caught from Mariout and Abbassa, but the lowest expression was in Nile tilapia caught from Aswan. Obvious micronuclei were observed under the microscope in erythrocytes, and their number was gradually decreased in the following manner: Mariout > Abbassa > Aswan. Noticeably, Cu, Zn, and Mn contents were low. Still, Pb and Cd contents were higher than the toxicity level recommended by the Food and Agriculture Organization (FAO), The World Health Organization (WHO), and the European Commission (EC). These results showed that Hsp70's appearance at the two levels of mRNA and protein is an effective indicator for aquatic pollution besides the aberration at the chromosome level represented in the micronucleus test. Furthermore, these results showed that Nile tilapia of the Aswan region had comparatively low trace elements contamination and were suitable for consumption.

Acute and subchronic effects of petroleum on the freshwater fish Hoplias aff. malabaricus

Abstract Petroleum water soluble fraction (WSF) impairs organisms, but damages may vary among cell and tissue levels. The aim of the present study was to evaluate the acute (24 h, 48 h, 72 h) and subchronic effects (36 days) of WSF (0%, 25% and 100%) in juveniles of the Neotropical top predator fish Hoplias aff. malabaricus. The effects of WSF were evaluated at a molecular level using the comet assay and micronucleus test for genome damage; and at a morphological level through histological identification of liver pathologic lesions. In both acute and subchronic exposure we found low levels of DNA damage (< 10% of comet tail) and non-significant frequency of micronucleus in WSF exposed fish. The most significant liver lesions in WSF exposed fish were fatty vacuolization, hypertrophy and focal necrosis. Since these tissue injuries were progressive and persistent, their irreversibility may negatively affect fish recruitment, even in a such resistant top predator.

Assessing sub-lethal effects of the dinitroaniline herbicide pendimethalin in zebrafish embryos/larvae (Danio rerio)

Pendimethalin is a dinitroaniline herbicide used to control broadleaf weeds by inhibiting the formation of microtubules during cell division. Its use on a variety of crops leads to its potential entry into aquatic environments, but little is known about its sub-lethal toxicity to early developmental stages of aquatic vertebrates. To address this knowledge gap, we assessed the toxicity of pendimethalin to zebrafish embryos and larvae by measuring mortality, developmental abnormalities, oxidative respiration, reactive oxygen species, gene expression, and locomotor activity following exposure to the herbicide throughout early development. Embryos at ~6 h post-fertilization (hpf) were exposed to either a solvent control (0.1% DMSO, v/v), embryo rearing medium (ERM), or one dose of either 1, 2.5, 5, or 25 μM pendimethalin for up to 7-days post fertilization depending on the bioassay. Exposure to 25 μM pendimethalin resulted in high prevalence of spinal curvature, tail malformations, pericardial edema, and yolk sac edema at 4 dpf, while exposure to 5 μM pendimethalin induced pericardial edema and lordosis in the fish exposed over 7 dpf. Exposure to pendimethalin up to 5 μM did not negatively impact oxidative respiration (e.g., basal respiration, oligomycin-induced ATP production) in embryos following a 24-h exposure. Pendimethalin did not induce reactive oxygen species at concentrations of 1-5 μM. Levels of transcripts associated with oxidative respiration and damage response were altered in 7d-larvae; cox1 mRNA was increased in larvae fish exposed to 1 μM while cox5a1 and sod2 mRNA were decreased with 2.5 μM exposure. The Visual Motor Response (VMR) test for light-dark response revealed that larval activity in the dark period was reduced for zebrafish exposed to >1 μM pendimethalin compared to ERM and DMSO solvent control groups. These data inform on the sub-lethal toxicity of pendimethalin to early stages of fish embryos and larvae.

Assessment of cytotoxicity in gills of fish Labeo rohita reared in untreated and treated sewage water

The unregulated discharge of untreated municipal sewage water to the natural water bodies is a major threat to the aquatic ecosystems. In the present study, the fingerlings of Labeo rohita were exposed to treated sewage water and 1/10^th of LC₅₀ and 1/20^th of LC₅₀ of untreated sewage water (UT) obtained from sewage water treatment plant, Ludhiana, India. After determining 96-h LC₅₀ value of UT, fingerlings were divided into four groups: control, treated, 1/10^th of LC₅₀ UT and 1/20^th of LC₅₀ UT and exposed for a period of 2 months. Our study revealed that 1/10^th LC₅₀ UT and 1/20^th LC₅₀ UT groups had significant reduction in body weight, total body length, standard body length and gills somatic index in comparison with the control and treated groups. Histopathological alterations in cellular structure of gills such as ruptured primary lamellae, broken secondary lamellae, distorted chloride cells and goblet cells, missing lamellae and disintegrated lamellar epithelium were also observed in 1/10^th LC₅₀ UT and 1/20^th LC₅₀ UT groups. A significantly high frequency of micronucleated (MN) cells was observed in 1/10^th LC₅₀ UT and 1/20^th LC₅₀ UT groups along with the presence of binucleated cells (BN), elongated nuclei (EN) and nuclear buds in gill cells. Genotoxic nature of UT was further confirmed from significantly high values of genetic damage index (GDI) and percentage (%) DNA damage in gill cells of fingerlings exposed to sub-lethal concentrations of UT. The study concluded that untreated sewage water has potential to induce anatomical and physiological defects in gills cells and the severity of toxicity increases with the increase in duration of exposure.

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.

Water assessment of the Itapemirim River/Espírito Santo (Brazil): abiotic and toxicogenetic aspects

The Itapemirim River is considered one of the most important water resources in the state of Espírito Santo, Brazil. However, environmental problems due to continuous anthropogenic contamination are threatening its potential use. This study assessed water quality by analyzing abiotic and toxicogenetic aspects of the water from four stations along the river. Samples were collected in both dry and rainy seasons. Most of the abiotic variables were below the threshold established by CONAMA Resolution No. 357/2005, and so were most of the metals. However, Al and Cu contents were above those allowed by legislation, ranging from 0.2 to 0.9 mg/L. Regarding toxicogenetic aspects, genotoxic effects were observed in meristematic cells of Allium cepa, in micronucleus test and comet assay of Oreochromis niloticus, and CHO-K1 cells. Mutagenic effects were significant at RI 02 (0.34), RI 03 (0.46), and RI 04 (0.12) stations on the first campaign in A. cepa F1 cells, compared to the negative control (0.0). The second campaign revealed the same results, but with the addition of samples from RI 01 (0.17) and RI 03 (0.18) showing mutagenicity in the micronucleus test with fish erythrocytes when compared to the negative control (0.3). Essentially, all the samples evaluated in both campaigns showed damage in A. cepa, O. niloticus, and CHO-K1 cells, thus demonstrating that the water quality of the Itapemirim River is compromised and requires action plans for its recovery.

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.

Impact of herbicide pretilachlor on reproductive physiology of walking catfish, Clarias batrachus (Linnaeus)

Herbicide pretilachlor is widely used in paddy fields to control annual weeds. The present study has been carried out in walking catfish, Clarias batrachus, to evaluate the impact of herbicide pretilachlor on reproductive physiology after chronic exposure. Based on the median lethal concentration value (96 h), fish were exposed to three nominal test concentrations of pretilachlor ((SL-I (1/20th LC₅₀), SLII (1/15th LC₅₀), and SL-III (1/10th LC₅₀)) for 30, 45, and 60 days after which plasma sex steroid profile, plasma vitellogenin concentration, and gonadal aromatase activity were analyzed in both sexes. Plasma concentration of testosterone decreases in herbicide-exposed male fish. Significant increase in plasma 17β-estradiol, plasma vitellogenin concentration, and gonadal aromatase activity were observed in herbicide-exposed male fish. All these alterations in reproductive parameters in male fish are dependent on concentration and exposure duration of herbicide. On the other hand, significant decrease in plasma concentration of testosterone was observed in female fish which was also dependent on concentration and exposure duration of herbicide. No significant changes in plasma 17β-estradiol concentrations, plasma vitellogenin concentration, and gonadal aromatase activity were observed in female fish. Above findings clearly suggested that herbicide pretilachlor acts as endocrine disruptor in fish and affects overall reproductive physiology of fish, but its ability to induce reproductive toxicity in male and female differs considerably.

Genotoxicity in the rivers from the Brantas catchment (East Java, Indonesia): occurrence in sediments and effects in Oreochromis niloticus (Linnæus 1758)

This paper reports the first data from an integrated study investigating genotoxicity in the Brantas River, Java, Indonesia. Results showed that organic sediment extracts from the sites in the Brantas Delta retained genotoxic compounds identified using the SOS Chromotest and that the Aloo River and, to a lesser extent, the Surabaya River were the most contaminated studied sites. This genotoxicity was attributable to compounds that did not require any bioactivation under the test conditions. Occurrence of genotoxic effects was further investigated in erythrocytes from Nile tilapia, Oreochromis niloticus. High numbers of micronuclei were counted, especially in fish sampled in the rivers of the Brantas Delta. Moreover, cytoplasmic alterations which could be indicative of the presence of lipofuscin were found in the cytoplasm of the fish blood cells, especially in fish from the Aloo, Surabaya and Kalimas rivers. Altogether, our data showed that genotoxicity is occurring in fish living in rivers of the delta of the Brantas River and suggest that sediments from these sites may constitute a major source of pollution and hazard for species living or feeding in the area.

Impacts of herbicide pendimethalin on sex steroid level, plasma vitellogenin concentration and aromatase activity in teleost Clarias batrachus (Linnaeus)

Pendimethalin (PM) is a selective herbicide, widely present in aquatic environment. It causes detrimental effects in fishes, but little is known regarding its reproductive toxicity. The present study was carried out in Clarias batrachus exposed to sub lethal concentrations of PM for 30, 45 and 60 days. Male fish showed a significant increase in plasma 17β-estradiol (E2) however plasma E2 in females was not affected. Plasma testosterone levels were significantly decreased in both sexes. In male plasma vitellogenin (VTG) and gonadal aromatase activity was increased irrespective of herbicide concentration and exposure duration. In females concentration and time dependent reduction in plasma VTG but no significant change in the gonadal aromatase activity were observed. Results indicated that PM act as endocrine disruptor but act differentially in male and female fishes and plasma E2, T and VTG levels and aromatase activity can be considered as reliable biomarkers for PM toxicity in fishes.

Contamination and genotoxicity biomarker responses in bivalve mussels from the major Lithuanian rivers

European inland waters are under continuous threat of anthropogenic pollution. Determination of background level of biomarker response and subsequent classification of the impact increases the applicability of results. In the current study, we evaluate the range of chemical contamination by measuring the concentrations of metals, polycyclic aromatic hydrocarbons and polychlorinated biphenyls, and the levels of environmental genotoxicity by using the micronuclei and nuclear bud tests in bivalve mussels of the major Lithuanian rivers. Second, we aimed to evaluate the association between chemical contamination and genotoxicity biomarker responses. Finally, we set to determine the background level of genotoxic effects. Such value (summed frequency of MN and NB) was assessed-6‰. On that basis, we develop a scale of potential genotoxic impact and perform ranging sites into five categories. The results clearly indicate the existence of significant differences in the levels of chemical pollution and genotoxicity in different sites. Increased levels of studied parameters were assessed at the areas affected by municipal and industrial effluents, road runoff, combustion products, and in the area contaminated by accidental spillage. On the other hand, downstream decrease of contamination level, presumably associated with biological degradation and photochemical oxidation, were also observed. Genotoxicity parameters were associated with PAH and metal concentrations measured in mussel tissues as well as in sediments. Results also indicate that in situ genotoxicity assessment performed in the areas affected by long-term contamination of municipal origin might be not sufficiently precise. Study highlights the necessity to combine genotoxicity assessment with chemical analysis. Environ. Mol. Mutagen. 61:338-354, 2020. © 2019 Wiley Periodicals, Inc.

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.

Genotoxicity assessment of polluted urban streams using a native fish Astyanax altiparanae

Water quality has declined globally due to increased contamination of aquatic ecosystems. The use of fish genotoxicity biomarkers may improve and complement parameters for environmental risk assessment. The aim of this study was to assess the genotoxicity of samples collected from streams of the Jordão River, a tributary of the Paranaíba River, Brazil with different levels of metal contamination, utilizing a native fish species to determine the sensitivity and viability of implementing a useful, reliable technique for routine biomonitoring programs. Chemical analysis of water and sediments collected from different sites indicated that a gradient of contamination existed as evidenced by different concentrations of metals detected. After chronic exposure to contaminated samples, micronucleus (MN) frequencies in fish erythrocytes were measured and correlation with environmental parameters determined. Sites where the water concentrations of the metals aluminum (Al), iron (Fe), manganese (Mn), zinc (Zn) and copper (Cu) were high indicating a greater genotoxic potential of these elements. At the samples collected from the urban zone, a gradual increase was found for chromium (Cr), cadmium (Cd) and nickel (Ni) indicative of adverse impacts of discharge of urban effluents. Data demonstrated that Astyanax altiparanae, used in the test, exhibited a reliable sensitivity for detection of genotoxic consequences attributed to exposure to water samples collected near the discharge of industrial and domestic waste.

Genomic damage in Mugil curema (Actinopterygii: Mugilidae) reveals the effects of intense urbanization on estuaries in northeastern Brazil

The largest metropolitan centers in northeastern region of Brazil are all located near the coast, and industrial, tourist, and agro-industrial activities are the principal causes of water contamination due to discharges of untreated sewage. Adverse environmental conditions can often be detected by analyzing the genetic material of organisms exposed to pollutants, and furnish an overview of environmental quality. We evaluated possible damage to the DNA of one of the fish resources most widely consumed and commercialized by coastal communities in northeastern Brazil, Mugil curema ("tainha"). Erythrocytes from M. curema were analyzed by the presence of micronuclei and by comet assay (single cell gel electrophoresis, SCGE). Statistical comparisons to both tests revealed considerably greater genomic damage in polluted estuaries than in the control site (p < 0.05), suggesting strong genotoxic impacts on the specimens evaluated, principally among those taken near localities with dense demographic and industrial development.

WaterSpy: A High Sensitivity, Portable Photonic Device for Pervasive Water Quality Analysis

In this paper, we present WaterSpy, a project developing an innovative, compact, cost-effective photonic device for pervasive water quality sensing, operating in the mid-IR spectral range. The approach combines the use of advanced Quantum Cascade Lasers (QCLs) employing the Vernier effect, used as light source, with novel, fibre-coupled, fast and sensitive Higher Operation Temperature (HOT) photodetectors, used as sensors. These will be complemented by optimised laser driving and detector electronics, laser modulation and signal conditioning technologies. The paper presents the WaterSpy concept, the requirements elicited, the preliminary architecture design of the device, the use cases in which it will be validated, while highlighting the innovative technologies that contribute to the advancement of the current state of the art.

Genotoxicity assessment of pesticide profenofos in freshwater fish Channa punctatus (Bloch) using comet assay and random amplified polymorphic DNA (RAPD)

The present study explored the induced genotoxicity (DNA damage) due to organophosphate pesticide profenofos (PFF) after in vivo exposure in freshwater fish Channa punctatus by the use of Comet assay and Random amplified polymorphic DNA (RAPD). The fish specimens were exposed to sub-lethal concentration of 1.16 ppb (50% of LC₅₀) in a semi-static system and the DNA damage was assessed in exposed and control fish. The DNA damage was measured in erythrocytes as the percentage of DNA damage in Comet tails and RAPD technique using oligonucleotide primers of fish specimens exposed to the sublethal concentrations of PFF. The most informative primers in terms of variation in RAPD profile were found to be OPA-01, OPA-03, OPB-02, OPB-01 and OPA-13. Appearance/disappearance of bands and increase/decrease in the band intensity were evident in the RAPD profile of fish specimens exposed to PFF as compared to the control. Findings from the present study suggest that the potential impacts of assessment of the genotoxic impact of pesticide on fish.

Evaluation of chromosomal instability in somatic cells of farmed foxes

The micronucleus (MN) test is a common tool used to evaluate cellular genetic instability at the chromosomal level. It determines the effect of physical, chemical and environmental factors on DNA, and thus the body's individual resistance to harmful substances. The karyotypes of blue and silver foxes and their interspecific hybrids are characterized by morphological and structural variation. This variation is partly attributable to the presence of chromosomal polymorphism, which may significantly influence the stability of genetic material in the cells of these species. The objective of the study was to evaluate genetic material stability in selected Canidae species. To this end, analyses using the MN test were performed. Binucleated cells (BNCs) were analysed in microscopic preparations, and the number of micronuclei was determined within these cells. For the proportions of both MN and BNCs, highly significant differences were observed between the fox species. The interspecific hybrids differed from the other fox species in MN percentage. The lowest average was noted in blue foxes (3.33) and the highest in interspecific hybrids (15.21).

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.

Zn2+ induced molecular responses associated with oxidative stress, DNA damage and histopathological lesions in liver and kidney of the fish, Channa punctatus (Bloch, 1793)

Zn²⁺ is essential for normal physiological functioning of all organisms in small quantities, but when its concentration enhances in surrounding environment it acts as a toxicant to organisms. Common sources of Zn²⁺ pollution are electroplating, alloying, mining, and allied industrial operations. The present study aims to assess the biochemical, histopathological and genotoxicological implications under Zn²⁺ intoxication along with its accumulation patterns in prime biotransformation sites-liver and kidney, of a bottom feeder fish, Channa punctatus. Fish were chronically exposed to two different concentrations of Zn²⁺i.e., 5mg/L (permissible limit, T1) and 10mg/L (twice the permissible limit, T2). Simultaneous control was maintained. A significant (p<0.05) increment in Zn²⁺ bioaccumulation, antioxidant enzymes activities of SOD, CAT and GR and induction in micronuclei frequencies along with the significant (p<0.05) decrement in total protein and GSH were observed in all the exposed groups after 28 d. Altered biochemical parameters coupled with enhanced induction in micronuclei and accumulation of Zn²⁺ in liver and kidney of fish can be regarded as sensitive biomarkers of Zn²⁺ induced toxicological manifestations and thus, they may be effectively utilized for reliable ecotoxicological biomonitoring of aquatic regimes polluted with Zn²⁺.

Evaluation of genotoxic potential in the Velika Morava River Basin in vitro and in situ

The Velika Morava River is the greatest national Serbian river and the significant tributary of the Danube River. The major problems in the Velika Morava River Basin (VMRB) represent untreated industrial and municipal wastewaters. In this study, the level of genotoxic potential at the sites along the VMRB was evaluated by parallel in vitro and in situ approach. Within in vitro testing, genotoxicity of native water samples collected from the sites in VMRB was evaluated by SOS/umuC test on Salmonella typhimurium TA1535/pSK1002 and by the comet assay on HepG2 cells. DNA damage in situ was assessed in bleak (Alburnus alburnus) erythrocytes by the comet (alkaline and Fpg-modified comet) and micronucleus assays. Additionally, the concentration of heavy metals in fish tissue was measured and this data, compiled with the data of the physico-chemical parameters measured in water, was used as a measure of the pollution pressure at the sites. Results showed that applied in vitro tests with native water samples are less sensitive in comparison with in situ tests and should be taken with precaution when making predictions on the status of the ecosystem. Within applied battery of in situ assays differential sensitivity of assays was observed where alkaline comet assay showed the highest potential in differentiation of the sites based on genotoxic potential. Integrated biomarker response showed that usage of the battery of bioassays provides better insight in a genotoxic effects in animals, and consequently, that the holistic approach is more suitable for this type of study.

In situ assessment of Karaj River genotoxic impact with the alkaline comet assay and micronucleus test, on feral brown trout (Salmo trutta fario)

The in situ evaluation of the genotoxic impact of the Karaj River was performed using the comet and micronucleus (MN) assays in erythrocytes, liver, gill and kidney of indigenous brown trout, Salmo trutta fario from three different stations, including Varangerud, Asara and Purkan. The results showed that DNA damage significantly increased in sampled fish erythrocytes, liver and gill from low levels in the upstream river (Varangerud) via intermediate levels in downstream (Purkan) to high levels in the middle of the river (Asara), correlating with the river increasing pollution gradient. Gill was the most sensitive tissue followed by blood and liver. Kidney did not respond to the genotoxic gradient of the river. MN test (as a complementary assay) of liver cells of fish was a sensitive biomarker of genotoxic exposure. MN test in blood, gill and kidney did not reflect the genotoxic condition of the river.

Mucociliary transport, differential white blood cells, and cyto-genotoxicity in peripheral erythrocytes in fish from a polluted urban pond

The present study evaluated the water quality of a polluted pond through the analysis of in vitro mucociliary transport, hematological parameters, and biomarkers of cyto-genotoxicity in the Nile tilapia (Oreochromis niloticus). Blood and mucus samples were collected from ten specimens from the polluted pond and from ten specimens from a control area. The fish were anesthetized with 3% benzocaine, mucus was collected directly from the gills, and blood was drawn from the caudal artery. Blood smears were stained using the May-Grünwald Giemsa process for the differential leukocyte counts and to determine the frequency of leukocytes, thrombocytes, erythroblasts, micronuclei, and nuclear abnormalities. The results revealed low transportability in vitro, a high percentage of monocytes and eosinophils, and increased frequency of leukocytes and nuclear abnormalities in fish from the polluted pond. However, the frequency of thrombocytes and erythroblasts and the percentage of lymphocytes and neutrophils were significantly lower. It is possible to conclude that changes in fish are due to poor water quality and that these non-destructive biomarkers can be used for the biomonitoring of aquatic environments vulnerable to contamination.

Effects of triclosan on acute toxicity, genetic toxicity and oxidative stress in goldfish (Carassius auratus)

Triclosan (TCS) is used as an antimicrobial agent and has been widely dispersed and detected in the aquatic environment. However, it remains uncertain whether TCS is genotoxic or not. In this study, the acute toxicity of TCS in goldfish (Carassius auratus) was studied. Then, based on the results for acute toxicity, other goldfish were exposed to various concentrations of TCS (control, DMSO control, and 1/4, 1/2, and 1/8 LC₅₀) for 14 days, and the effects on genetic toxicity were evaluated using micronucleus (MN) and nuclear abnormalities (NA) frequencies in peripheral blood and the comet assay in the liver of the goldfish. In addition, malondialdehyde (MDA), reduced glutathione (GSH), catalase (CAT), and total antioxidant capacity (T-AOC) in the liver were assayed to evaluate oxidative stress and the possible mechanism of genotoxicity. The 96 h median lethal concentration of TCS was 1111.9 µg/l. After 14 days of exposure, the MN and NA frequencies were significantly increased in peripheral blood of the TCS-treated groups compared with the solvent control, and the comet tail moment and MDA in the liver in the highest dose of TCS groups were also significantly high. Meanwhile, an evident change in GSH, CAT, and T-AOC of the liver was found as the TCS exposure concentration increased. The results showed that TCS caused oxidative stress and a genotoxic response in goldfish, suggesting that it presents a potential ecotoxicological risk to aquatic ecosystems.

Oxidative stress and genotoxicity biomarker responses in tilapia (Oreochromis niloticus) exposed to environmental concentration of 1-nitropyrene

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

Biomarkers and bioindicators of the environmental condition using a fish species (Pimelodus maculatus Lacepède, 1803) in a tropical reservoir in Southeastern Brazil

Abstract The Funil Reservoir receives a large amount of xenobiotics from the Paraíba do Sul River (PSR) from large number of industries and municipalities in the watershed. This study aimed to assess environmental quality along the longitudinal profile of the Paraíba do Sul River–Funil Reservoir system, by using biomarkers and bioindicators in a selected fish species. The raised hypothesis is that Funil Reservoir acts as a filter for the xenobiotics of the PSR waters, improving river water quality downstream the dam. Two biomarkers, the ethoxyresorufin–O–deethylase activity (EROD), measured as fluorimetricly in S9 hepatic fraction, and the micronuclei frequency (MN), observed in erythrocytes of the cytoplasm, and three bioindicators, the hepatosomatic index (HSI), gonadosomatic index (GSI) and condition factor (CF) were used in Pimelodus maculatus, a fish species widely distributed in the system. Four zones were searched through a longitudinal gradient: 1, river upstream from the reservoir; 2, upper reservoir; 3, lower reservoir; 4, river downstream of the reservoir. EROD activity and HSI and GSI had significant differences among the zones (P<0.05). The upper reservoir had the lowest EROD activity and HSI, whereas the river downstream of the reservoir had the highest EROD and lowest GSI. The river upstream from the reservoir showed the highest HSI and GSI. It is suggested that the lowest environmental condition occur at the river downstream of the reservoir, where it seems to occur more influence of xenobiotics, which could be associated with hydroelectric plant operation. The hypothesis that Funil reservoir acts as a filter decanting pollution from the Paraíba do Sul River waters was rejected. These results are novel information on this subject for a native fish species and could be useful for future comparisons with other environments.

Bioaccumulation of trace metals and total petroleum and genotoxicity responses in an edible fish population as indicators of marine pollution

The present study reports the genetic damage and the concentrations of trace metals and total petroleum hydrocarbons prevailing in natural populations of an edible fish, Arius arius in different seasons along the coast of Goa, India as an indicator of the pollution status of coastal water. Fish were collected from a suspected polluted site and a reference site in the pre-monsoon, monsoon and post-monsoon seasons. Physico-chemical parameters as well as the concentrations of total petroleum hydrocarbons (TPH) and trace metals in the water and sediment as well as the tissues of fish collected from these sites were recorded. The genotoxicity status of the fish was assessed employing the micronucleus test and comet assay. A positive correlation (p<0.001) was observed between the tail DNA and micronuclei in all the fish collected. Multiple regression analysis revealed that tissue and environmental pollutant concentrations and genotoxicity were positively associated and higher in the tissues of the fish collected from the polluted site. Pollution indicators and genotoxicity tests, combined with other physiological or biochemical parameters represent an essential integrated approach for efficient monitoring of aquatic ecosystems in Goa.

Aneugenicity and clastogenicity in freshwater fish Oreochromis niloticus exposed to incipient safe concentration of tannery effluent

Conventional effluent bioassays mostly rely on overt responses or endpoints such as apical and Darwinian fitness. Beyond the empirical observation, laboratory toxicity testing needs to rely on effective detection of prognostic biomarkers such as genotoxicity. Indeed, characterization of tannery effluent requires slotting in of genotoxic responses in whole effluent toxicity testing procedures. Hence, the prime objective of the present experimental investigation is to apply the technique of biological assay as a tool of toxicity testing to evaluate the induction of micronuclei (MN) in peripheral erythrocytes, and exfoliated cells of gill and kidney of O.niloticus exposed to Maximum tolerable concentrations (MTCs) of composite Modjo tannery effluent (CMTE) and to compare the sensitivity of each cells origin to the induction of MN. After 72h of exposure, cellular aberrations were detected using MN and nuclear abnormality (NA) tests. The induction of MN was significantly higher in exposed groups (P<0.05) when compared to the control group; moreover the tissue specific MN response was in the order, gill cells>peripheral erythrocyte>kidney. Total NA was found to increase significantly (P<0.05), when compared to the non-exposed group. NA was also further ramified as blebbed (BL), bi-nucleated (BN), lobbed (LB) and notched (NT) abnormalities. The result of each endpoint measured has demonstrated that at a concentration of total chromium (0.1, 0.73 and 1.27mg/L), a perceptible amount cellular aberration was measured, further implicating somber treat of genotoxicity to fishes, if exposed to water contaminated with tannery effluent. This further highlight that conventional effluent monitoring alone cannot reveal the effects expressed at cellular and genetic levels further demanding the incorporation of effluent bioassays in risk assessment and risk management/abatement programs.

Frequencies of erythrocyte nuclear abnormalities and of leucocytes in the fish Barbus peloponnesius correlate with a pollution gradient in the River Bregalnica (Macedonia)

Integrated chemical and biomarker approaches were performed to estimate if there is ongoing toxicity in the River Bregalnica, namely connected with the presence of metals. The study was performed in water, sediment, and barbel (Barbus peloponnesius), collected in two seasons, from two suspected polluted and one reference zones. The water analyses revealed higher mean values in polluted sites for most of the examined physicochemical parameters. Metal concentrations (Zn, Cu, Cd, Mn, Pb, and Fe) in water were more or less constant, whereas in sediment, they were higher at the two polluted locations. Condition factor (CF), as a general health indicator, revealed better overall condition in barbel from the reference site. In general, blood parameters revealed higher values in the polluted localities. Irrespective of sex and/or season, the frequency of micronuclei (MN) and vacuolated nuclei (VN) were with higher rates in polluted sites. Similarly, the frequencies of the leucocytes (Le), binuclei (BN), and irregularly shaped nuclei (ISN) were also significantly increased in the polluted localities, but they seemed prone to be influenced by sex and/or season. However, strong positive correlations between blood biomarkers and most water physicochemical parameters and metal in sediment were estimated. Our data support that the River Bregalnica's lower course receives significant genotoxic pollution, likely via metal industry effluents, agricultural runoff, and domestic sewage, and reinforced the utility of MN and other nuclear abnormalities as sensitive and suitable biomarkers for genotoxicity when used in monitoring studies.

Water quality assessment in the "German River of the years 2014/2015": how a case study on the impact of a storm water sedimentation basin displayed impairment of fish health in the Argen River (Southern Germany)

BACKGROUND

The present work investigates the impact of discharges from a storm water sedimentation basin (SSB) receiving runoff from a connected motorway in southern Germany. The study lasted for almost two years and was aimed at assessing the impact of the SSB on the fauna of the Argen River, which is a tributary of Lake Constance. Two sampling sites were examined up- and downstream of the SSB effluent. A combination of different diagnostic methods (fish embryo test with the zebrafish, histopathology, micronucleus test) was applied to investigate health impairment and genotoxic effects in indigenous fish as well as embryotoxic potentials in surface water and sediment samples of the Argen River, respectively, in samples of the SSB effluent. In addition, sediment samples from the Argen River and tissues of indigenous fish were used for chemical analyses of 33 frequently occurring pollutants by means of gas chromatography. Furthermore, the integrity of the macrozoobenthos community and the fish population were examined at both investigated sampling sites.

RESULTS

The chemical analyses revealed a toxic burden with trace substances (originating from traffic and waste water) in fish and sediments from both sampling sites. Fish embryo tests with native sediment and surface water samples resulted in various embryotoxic effects in exposed zebrafish embryos (Fig. 1). In addition, the health condition of the investigated fish species (e.g., severe alterations in the liver and kidney) provided clear evidence of water contamination at both Argen River sites (Fig. 2). At distinct points in time, some parameters (fish development, kidney and liver histopathology) indicated stronger effects at the sampling site downstream of the SSB effluent than at the upstream site.

CONCLUSIONS

Our results clearly showed that the SSB cannot be assigned as the main source of pollutants that are released into the investigated Argen River section. Moreover, we showed that there is moderate background pollution with substances originating from waste waters and traffic which still should be taken seriously, particularly with regard to the impairment of fish health at both investigated field sites. Since the Argen is a tributary of Lake Constance, our results call for a management plan to ensure and improve the river's ecological stability.

Microelectrophoretic study of environmentally induced DNA damage in fish and its use for early toxicity screening of freshwater bodies

This study investigates the potential of the comet and micronucleus assays of fish DNA as a means of screening the toxicity of aquatic environments. Catla catla and Cirrhinus mrigala collected from the River Chenab in Pakistan were used as a case study for the application of comet and micronucleus techniques. Comet and micronucleus assays were used to compare DNA damage in C. catla and C. mrigala collected from polluted areas of the River Chenab and farmed fish. Atomic absorption spectrophotometry showed an acute level of toxicity from Cd, Cu, Mn, Zn, Pb, Cr, Sn, and Hg in river water. Comet assay showed significant (p < 0.05) DNA damage in C. catla representing 17.33 ± 2.42, 11.53 ± 2.14, and 14.17% DNA in the comet tail, averaged from three sites of the polluted area of the river. Tail moment was observed as 10.06 ± 2.71, 3.11 ± 0.74, and 14.70 ± 1.89, while olive moment was 8.85 ± 1.84, 3.83 ± 0.76, and 7.11 ± 0.73, respectively. Highly significant (p < 0.01) damage was reported in C. mrigala as 37.29 ± 2.51, 34.96 ± 2.53, and 38.80 ± 2.42% DNA in comet tail, tail moment was 23.48 ± 3.90, 19.78 ± 4.26, and 14.30 ± 1.82, and olive moment was 16.22 ± 2.04, 13.83 ± 1.96, and10.99 ± 0.90. Significant (p < 0.05) differences were observed in genotoxicity between farmed and polluted area fish. Micronucleus assay showed a similar picture of significant difference in respect to single and double micronucleus induction: i.e., 23.20 ± 4.19 and 2.80 ± 1.07‰ in C. catla and 44.80 ± 3.73 and 06.20 ± 0.97‰, respectively, in C. mrigala. Nuclear abnormalities were found as 6.00 ± 0.84 and 09.60 ± 1.72/thousand cells, respectively, in both species. The results of this study suggest that these novel fish DNA damage assays can be used as an expedient toxicity screening for aquatic environments.

Erythrocyte micronucleus cytome assay of 17 wild bird species from the central Monte desert, Argentina

Birds have the potential to be considered valuable bioindicators of the quality of ecosystems and the environmental impact of pollutants. The aims of this study were to determine the micronuclei frequency and other nuclear abnormalities in erythrocytes by analyzing a wild bird community from central Monte desert (Argentina) and to clarify if there were any differences among certain species. Frequencies of nuclear abnormalities were determined in 73 wild birds belonging to 17 species and two orders (Passeriformes and Columbiformes). A high proportion of individuals, 90.4 and 80.9 %, had erythrocytes with micronuclei and nuclear buds, respectively. Notched nuclei, binucleated cells, nuclear tails, and nucleoplasmic bridges were also recorded. Certain species appeared to be more informative than others with regard to the possibility of being used as bioindicators of genetic damage. Saltator aurantiirostris and Columbina picui were the only species that showed significantly different frequencies of nuclear alterations, in comparison with the other species. The frequencies here presented are the first reported for these bird species from the orders Passeriformes and Columbiformes. This research supports the notion that the use of these biomarkers could be effectively applied to evaluate spontaneous or induced genetic instability in wild birds.

Evaluation of genotoxic potential throughout the upper and middle stretches of Adige river basin

In this study a comprehensive genotoxicological survey throughout the upper and middle stretches of Adige river basin is presented. The study was carried out at 7 sites located along the Adige main course and one the most significant tributaries, the Noce creek, both presenting different levels of pollution pressure. To give an insight into the nature of the genotoxic activity we employed the battery of prokaryotic and eukaryotic assays. Mutagenicity in water samples was evaluated by SOS/umuC test in Salmonella typhimurium TA1535/pSK1002. The level of DNA damage as a biomarker of exposure (comet assay) and biomarker of effect (micronucleus assay) and the level of oxidative stress as well (Fpg - modified comet assay) were studied in blood cells of Salmo cenerinus Nardo, 1847 and Salmo marmoratus Cuvier, 1829. Within the applied bioassays, comet assay showed the highest potential for discriminating the sampling sites which are under lesser extent of pressure (sampling sites 1-Barnes at Bresimo and 4-Noce downstream S. Giustina) from the sites under high pressure (sampling sites 5-Noce at Mezzolombardo and 6/7-Adige upstream and downstream municipality of Trento). Significant correlation between the standard and Fpg - modified comet assay indicated that oxidative stress could be a major contributor to observed DNA damage in collected specimens.

Comparing the genotoxicity of a potentially carcinogenic and a noncarcinogenic PAH, singly, and in binary combination, on peripheral blood cells of the European sea bass

Research on the toxicological mechanisms of polycyclic aromatic hydrocarbons (PAHs) deemed carcinogenic and noncarcinogenic has mostly been developed for individual compounds even though, in the environment, PAHs invariably occur in mixtures. The present work aimed at understanding the interaction effects of two model PAHs, the potentially carcinogenic benzo[b]fluoranthene (B[b]F) and the noncarcinogenic phenanthrene (Phe) to a marine fish (the sea bass Dicentrarchus labrax). The study endeavoured an ecologically-relevant scenario with respect to concentrations and contaminant matrix, sediments, which are the main reservoirs of these substances in the environment, due to their hydrophobic nature. For the purpose, 28-day laboratorial bioassays with spiked sediments (with individual and combined PAHs at equitoxic concentrations) were conducted. Genotoxicity was determined in peripheral blood through the "Comet" assay and by scoring erythrocytic nuclear abnormalities (ENA). The results showed that exposure to either PAHs induced similar levels of DNA strand breaks, although without a clear dose- or time-response, likely due to the low concentrations of exposure and potential shits in PAH bioavailability during the assays. However, clastogenic/aneugenic lesions were only observed in fish exposed to B[b]F-spiked sediments. Conversely, the combination assays revealed a supra-additive effect especially at chromosome level, linked to concentrations of PAHs in water. A decrease in DNA-strand breakage was observed over time during all assays, revealing some ability of fish to cope with this DNA lesion. Overall, the findings show that low-moderate concentrations of sediment-bound mixed PAHs may significantly increase the hazard of mutagenesis even when the individual concentrations indicate low risk, especially considering that chromosome-level damage is unlikely to be repaired, leading to the fixation of DNA lesions upon prolonged exposures. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1307-1318, 2016.

Genotoxicity assessment of the Danube River using tissues of freshwater bream (Abramis brama)

This study examines the use of freshwater bream (Abramis brama) as a sentinel organism for genotoxicity assessment of the Danube River using the comet assay. Sampling of bream was performed during February, April, August, and November in 2014 to assess seasonal variation of DNA damage level as a response to genotoxicity in annual cycle. Additionally, concentrations of fecal coliforms and enterococci were analyzed and they indicated a critical to strong level of fecal pollution on investigated locality during annual cycle. Comet assay was performed on blood, liver, and gill cells of bream. DNA damage level was expressed using tail intensity (TI %), Olive tail moment (OTM), and tail length (TL pix). According to TI and OTM, all three tissues had the highest level of DNA damage in August. The lowest level of DNA damage in liver was measured during February, in blood during November, and in gills during April. According to TL, gills had the highest level of DNA damage in February, and liver cells had the lowest level of damage during April. Multiple correspondence analysis (MCA) showed that DNA damage in blood cells is under the strong influence of variations in NO₂, NO₃^-, NH₄⁺ levels and also the variation in temperature and oxygen levels. DNA damage in liver cells is highly associated with the variations of Mn, Fe, Cu, Zn, and PO₄^3- levels. DNA damage in gill cells is strongly affected by the variations of As, Cd, Pb, Cr, and COD (Mn) levels. Freshwater bream is shown to be a potentially good indicator organism in genotoxic potential field studies.