Genotoxic analysis in aquatic environment under influence of cyanobacteria, metal and radioactivity

Accessing the Health Risk of Ingestion of Surface Water from Lucrécia and Parelhas Dams in Northeast Brazil Using the Sentinel Organism Drosophila melanogaster

This study investigated the genotoxic risk of chronic exposure of hemolymph's cells of Drosophila melanogaster (Insecta, Diptera) to water samples from Boqueirão de Parelhas Dam and from Lucrécia Dam in the semiarid region of Brazil. The dams are located over the Pegmatite Province of Borborema, with rocks rich in uranium and thorium. Water samples hydrated a culture medium composed of mashed potatoes, where larvae of D. melanogaster fed for 24 h, before be underwent to the Comet assay. The same water was evaluated for the presence of dissolved Radon gas (222Rn) and concentrations of 11 toxic metals (Ag, Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn). The results indicated a genotoxic effect resulting from exposure to the waters of the Parelhas dam, in the samples of August 2018; and in Lucrécia dam, in January 2019. D. melanogaster stood out for its high sensitivity to monitor the genotoxic effects of compounds dissolved in public dams. And unlike to other essentially aquatic sentinel organisms, this species stood out as a model to concomitant studies of air and water possible contaminated, in a scenario of natural environmental radioactivity present in semiarid of Brazil.

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.

Bioaccumulation of trace metals and genotoxicity responses in Liza aurata as an indicator of industrial pollution

Heavy metal contamination in the coastal and marine ecosystems is becoming a serious risk to aquatic organisms and humans. This study reports the effects, including genetic damage, of accumulations of trace metals on Liza aurata, which is used as a bio-indicator species, in the Payas coast of Iskenderun Bay, north-eastern Mediterranean by COMET Assay. L. aurata were seasonally collected from a sampling site and a reference site for one year. Physicochemical parameters in water and trace metals in the tissues of fish collected from these sites were determined by electrochemical techniques. High DNA damage frequency in L. aurata was observed along the Payas coast of Iskenderun Bay compared to the reference site because of pollutants. The detected high levels of Cd, Pb, Fe and Cu accumulation in L. aurata exceed the maximum levels allowed by the national and international limit values. Significant positive correlations between Cd, Pb, Hg, Cr, Fe, Zn, and Cu accumulations and DNA damage parameters were observed in the present study. Additionally, we first reported the successful use of the electrochemical technique in the determination of trace metal concentrations in mullet. Moreover, L. aurata constitutes a key tool as a sentinel organism for biomonitoring of coastal ecosystems.

Combination of Water Quality Parameters and Bioassays for the Assessment of Two Rivers, Southern Brazil

In the present study, water physicochemical and microbiological parameters, as well as bioassays using Allium cepa L. seeds and the fish species Astyanax jacuhiensis were used to assess the water quality of two rivers - Ilha River and Paranhana River -, located in southern Brazil. Water samples were collected at the source and mouth of the rivers and then, laboratory experiments were performed. The results evidenced high levels of aluminum and iron in water samples collected at the four sampling sites. The micronucleus (MN) test in fish showed significant difference in the frequencies of nuclear abnormalities (NA) in the mouth of the Paranhana River in comparison to control group in one sampling period, whereas the A. cepa test evidenced significant spatial differences in cytotoxicity between the source and mouth of both rivers. Therefore, these data evidence the poor water quality of the rivers studied as well as the potential toxicity to the aquatic organisms.

Cytogenetic analysis of nuclear abnormalities in the erythrocytes of gecko lizards (Phyllopezus periosus) collected in a semi-arid region of northeast Brazil: Possible effects of natural background radioactivity

High natural-background radioactivity levels occur in the semi-arid region of the State of Rio Grande do Norte, northeastern Brazil. We have studied the lizard Phyllopezus periosus, an endemic species of the Brazilian caatinga with saxicolous habitat, as a bioindicator of environmental quality. Specimens were collected in three areas, an environmental protection area and two areas recognized as having high natural background radiation, one of these being a mining area. Level of metals and gamma radiation emitters present in the water sources potentially used by the lizards were measured. The biological endpoints assessed were micronuclei and nuclear abnormalities in blood samples. Significant differences in background radioactivity levels were found among the assessed areas. Statistically significant differences in micronuclei and nuclear abnormality frequencies were seen, among the study areas and a relationship between radioactivity level and genetic damage was observed.

Heavy metal bioaccumulation, oxidative stress and genotoxicity in African catfish Clarias gariepinus from Orontes river

One of the major problems affecting the ecosystem health is the exposure of heavy metals due to anthropogenic activities. These exposures may induce toxiogenetic damage and carcinogenesis in aquatic organism. DNA damage biomarkers for fish species detect genotoxic parameters for ecological risk assessment. In the present study, the effect of heavy metals (Cr, Cd, Cu, Fe and Mn) on DNA damage and oxidative stress of Clarias gariepinus was examined by Comet assay at Reference site and two different sampling sites of the Orontes River. Moreover, the relationship between DNA damage and physiological response to oxidative stress caused in C. gariepinus was investigated by sampling seasonal water and fish samples for one year. In this study, Cr, Cd and Cu in water column of Orontes River and the concentrations of Fe and Mn in liver tissue of C. gariepinus were highly exceed the maximum permissible limit set by EPA (1999, 2016) WHO (1989) and TEG (2012) that can cause adverse effects on environment health. SOD activities in liver tissues were significantly higher than those in muscle tissues. SOD, CAT activity and MDA levels of both Site 1 and Site 2 at Orontes River were higher than those of the Reference site. In result of the COMET analysis, the highest levels of DNA damage were found at gill and liver tissues in Site 2 (17.746 ± 1.072% T-DNA; 16.014 ± 0.710% T-DNA respectively) at Orontes river. A higher level of DNA damage in gill cells compared to liver cells was observed in all regions of the Orontes River. In Principal component analysis (PCA), the heavy metals Cd, Cr and Cu (in the water column) and MDA in liver and muscle revealed strong contribution to the observed DNA damage that were scattered opposite to each other's along the principal components. Moreover, correlations between parameters revealed a positive significant relationship between Cd, Cr and Cu in water and DNA damage levels in C. gariepinus. Pearson correlation analysis detected a positive relationship between MDA, CAT and SOD and DNA damage levels in African catfish. Consequently, this study exposed genotoxic damage and oxidative stress of C. gariepinus due to metal pollution in Orontes River and lead to the better understanding of genotoxicty, oxidative stress and heavy metal relationships.

Phytotoxicity and cytogenotoxicity of composted tannery sludge

Tannery sludge (TS) contains high levels of organic matter and chemical elements, mainly chromium (Cr). This can increase its toxicity, rendering it unsuitable for application to soil. However, composting has been proposed as an alternative method for detoxifying TS before its addition to soil. Thus, the aim of this study was to evaluate the phytotoxic and cytogenotoxic potential of untreated (TS) and composted (CTS) tannery sludge in solid and solubilized samples. Seed germination and root growth bioassays were performed with Lactuca sativa, while chromosomal aberrations were assessed using the Allium cepa bioassay. In solid samples, the L. sativa bioassay showed that TS adversely affected germination and root growth, while CTS had a negative affect only on root growth. In solubilized samples, only TS showed significant adverse effects on seed germination and root growth. In both solid and solubilized samples, TS and CTS showed cytotoxic, genotoxic, and mutagenic effects on A. cepa. Thus, results demonstrated that the composting of TS does not result in its complete detoxification. For this reason, TS and CTS cannot be recommended for agricultural use, since they may increase the risk of environmental contamination and crop damage.

Lizards as model organisms to evaluate environmental contamination and biomonitoring

Environmental contamination is reaching ever higher levels and affecting several animal populations, including humans. In this context, studies are being developed to monitor and evaluate this environmental problem using bioindicators organisms, in addition to testing the toxicity of contaminants in the laboratory. In this perspective, reptiles are ideal animals for these types of studies, considering that they are ectothermic and have a slower metabolism directly influencing their recovery power, and therefore, they are more sensitive to xenobiotic effects. Among reptiles, lizards are animals that adapt to various environmental conditions, even being found in areas with arid characteristics. Therefore, a literature review was conducted in this study regarding the use of lizards as models for ecotoxicological studies, including biomonitoring, carried out in the last 10 years, with the aim of evaluating them as bioindicators in Brazilian semi-arid region. Studies were found involving ten lizard families, among which the most investigated was Lacertidae. The studies were classified into two categories: organic contaminants (pesticides, petroleum by-products, and explosives) and inorganic contaminants (metals such as zinc, lead and aluminum, and radionuclides). Contaminants directly contributed to DNA damage and to increasing the frequency of micronuclei in exposed animals, histopathological effects, and oxidative stress. The performed analysis highlights the usefulness of lizards as environmental biomonitors. However, the response profile is dependent on the exposure level and route, in addition to the environmental scenario analyzed. Therefore, future studies aimed at evaluating environmental contaminants are required under exposure conditions more related to the environmental reality to be studied.

Natural radioactivity in Brazil: a systematic review

Natural radioactivity is a public health concern worldwide. Its deleterious effects are largely associated with emitting ionizing particles which generate innumerable toxicological consequences to human being. The present study aimed to describe the research state of the art on natural radioactivity in Brazil through a systematic review limited to articles published in the twenty-first century in the PubMed, SciELO, Lilacs, and Google Scholar databases. A total of 55 research articles were considered for this purpose. Based on the collected sample types, the radiation analysis in most of the scientific reports was performed on solid samples (soil/sediment/rocks), followed by water and air. In fact, most of the available information came from geological studies. A wide range of concentrations and a variety of radionuclides have been assessed, with radium being the most cited. Most of the studies described radiation levels above the international guidelines, and consider the Brazilian territory as a high natural background radiation region (HNBR). In comparison with other HNBR areas, the scientific information about the related risks to human health is still scarce. There is uncertainty about the real impact of natural radioactivity on human health, as there is a lack of scientific information for most of the country about this issue. The analysis and comparison of the available information highlights the potential risks linked to natural radioactivity and the need to incorporate suitable environmental management policies about this issue.

Mutagenicity as a parameter in surface water monitoring programs-opportunity for water quality improvement

Effect-based analyses are being recognized as excellent tools to a comprehensive and reliable water quality evaluation to complement physical and chemical parameters. The Salmonella/microsome mutagenicity test was introduced in the São Paulo State water quality-monitoring program in 1999 and waters from 104 sites used to the production of drinking water were analyzed. Samples were tested after organic extraction, using the microsuspension version of the Salmonella/microsome assay with strains TA98 and TA100 with and without S9-mammalian metabolic system. Of the 1720 water samples analyzed in 20 years, 20% were positive; TA98 was the most sensitive strain, detecting alone 99%. Results were presented in hazard categories to facilitate water managers' understanding and general public communication. Hot spots of mutagenicity were identified, and pollution sources investigated. A flow scheme with instructions of how to proceed in case of mutagenic samples was developed and implemented in the monitoring program. Enforcement actions were taken to reduce exposure of humans and aquatic biota to mutagenic compounds. The results presented provide scientific basis for the incorporation of the Salmonella/microsome assay in a regulatory framework, and to guide water-quality managers. The inclusion of a mutagenicity assay using standardized conditions proved to be an opportunity to improve the quality of water, and the strategy presented here could be applied by any environmental agency around the world. Environ. Mol. Mutagen. 61:200-211, 2020. © 2019 Wiley Periodicals, Inc.

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.

Land Use and Seasonal Effects on the Soil Microbiome of a Brazilian Dry Forest

Drylands occupy approximately 41% of the Earth's terrestrial surface. Climate change and land use practices are expected to affect biogeochemical cycling by the soil microbiome in these ecosystems. Understanding how soil microbial community might respond to these drivers is extremely important to mitigate the processes of land degradation and desertification. The Caatinga, an exclusively Brazilian biome composed of an extensive seasonal tropical dry forest, is exposed to variable spatiotemporal rainfall patterns as well as strong human-driven pressures. Herein, an integrated analysis of shotgun metagenomics approach coupled to meteorological data was employed to unravel the impact of seasonality and land use change on soil microbiome from preserved and agriculture-affected experimental fields in Caatinga drylands. Multivariate analysis suggested that microbial communities of preserved soils under seasonal changes were shaped primarily by water deficit, with a strong increase of Actinobacteria and Proteobacteria members in the dry and rainy seasons, respectively. In contrast, nutrient availability notably played a critical role in driving the microbial community in agriculture-affected soils. The strong enrichment of bacterial genera belonging to the poorly-known phylum Acidobacteria ('Candidatus Solibacter' and 'Candidatus Koribacter') in soils from dry season affected by ferti-irrigation practices presupposes a contrasting copiotrophic lifestyle and ecological role in mitigating the impact of chemical fertilization. Functional analyses identify overrepresented genes related to osmotic stress response (synthesis of osmoprotectant compounds, accumulation of potassium ions) and preferential carbon and nitrogen utilization when comparing the microbiome of preserved soils under seasonal changes, reflecting differences in the genetic potential for nutrient cycling and C acquisition in the environment. However, the prevalence of nitrosative stress and denitrification functions in irrigation/fertilization-affected soils of the dry season clearly suggest that nutrient input and disruption of natural water regime may impact biogeochemical cycles linked to the microbial processes, with potential impacts on the ecosystem functionality. These findings help to better understand how natural seasonality and agricultural management differentially affect soil microbial ecology from dry forests, providing support for the development of more sustainable land management in dryland ecosystems.

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

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

The influence of heavy metals on toxicogenetic damage in a Brazilian tropical river

Anthropogenic activities in tropical rivers favor the eutrophication process, which causes increased concentration of heavy metals. The presence and bioaccumulation of metals are directly related to the presence of genotoxic damage in aquatic organisms. Thus, we evaluated the presence of heavy metals (Fe, Zn, Cr, Cu and Al) and performed toxicogenetic tests in surface (S) and bottom (B) of water samples of the Poti river (Piaui/Brazil). Cytotoxicity and genotoxicity tests were performed in Allium cepa, and micronucleus (MN) and comet assay were performed in Oreochromis niloticus. The chemical analysis showed concentrations above the limit for Cu, Cr, Fe and Al according to Brazilian laws, characterizing anthropogenic disturbance in this aquatic environment. Toxicogenetic analysis presented significant cytotoxic, mutagenic and genotoxic effects in different exposure times and water layers (S and B), especially alterations in mitotic spindle defects, MN formations, nuclear bud and DNA strand breaks. Correlations between Fe and cytotoxicity, and Al and mutagenicity were statistically significant and point out to the participation of heavy metals in genotoxic damage. Therefore, Poti river water samples presented toxicogenetic effects on all bioindicators analyzed, which are most likely related to heavy metals pollution.

Validation of Comet assay in Oregon-R and Wild type strains of Drosophila melanogaster exposed to a natural radioactive environment in Brazilian semiarid region

Natural radiation of geological origin is a common phenomenon in Brazil, a country where radioactive agents such as uranium may be often found. As an unstable atom, uranium undergoes radioactive decay with the generation of a series of decay by-products, including radon, which may be highly genotoxic and trigger several pathological processes, among which cancer. Because it is a gas, radon may move freely between cracks and gaps in the ground, seeping upwards into the buildings and in the environment. In this study, two Drosophila melanogaster Meigen (Diptera, Drosophilidae) strains called Oregon-R and Wild (collected in a non-radioactive environment) were exposed to atmospheric radiation in the Lajes Pintadas city, in the semiarid zone of northeastern Brazil. After six days of environmental exposure, the organisms presented genetic damage significantly higher than that of the negative control group. The genotoxic effects observed reinforce the findings of other studies carried out in the same region, which warn about the environmental risks related to natural radioactivity occurrence. The results also validate the use of the Comet assay in hemocytes of D. melanogaster as a sensitive test to detect genotoxicity caused by natural radiation, and the use of a recently collected D. melanogaster strain in the environmental of radon.

Cytotoxicity and genotoxicity of Guaribas river water (Piauí, Brazil), influenced by anthropogenic action

In general, tropical rivers have a great impact on human activities. Bioaccumulation of toxins is a worldwide problem nowadays and has been, historically, overlooked by the supervisory authorities. This study evaluated cytogenotoxic effects of Guaribas river (a Brazilian river) water during dry and rainy seasons of 2014 by using the Allium cepa test system. The toxicogenetic variables, including root growth, mitotic index, and chromosomal aberrations, were analyzed in meristematic cells of A. cepa exposed to water samples taken from the up-, within, and downstream of the city Picos (state: Piauí). The physical-chemical parameters were also analyzed to explain water quality and possible anthropogenic action. Additionally, the presence of heavy metals was also analyzed to explain water quality and possible damaging effects on eukaryotic cells. The results suggest that the river water exerted cytotoxic, mutagenic, and genotoxic effects, regardless of the seasons. In addition, Guaribas river presented physico-chemical values outside the Brazilian laws, which can be a characteristic of human pollution (domestic sewage, industrial, and local agriculture). The genetic damage was positively correlated with higher levels of heavy metals. The pollution of the Guaribas river water may link to the chemical contamination, including the action of heavy metals and their impacts on genetic instability in the aquatic ecosystem. In conclusion, necessary steps should be taken into account for further toxicogenetic studies of the Guaribas river water, as it has an influence in human health of the same region of Brazil.

Mutagenic potential assessment associated with human exposure to natural radioactivity

Lucrécia city, known to harbor a high cancer rate, is located in a semiarid region characterized by the presence of mineral reservoirs, facing a high exposure to metal and natural radioactivity. The present study aimed to assess the environmental scenario at a semiarid region located in Northeastern Brazil. Metal concentration, alpha and beta radiation, and cyanobacteria content in tap water along with indoor radon and gamma emitters (U, K and Th) concentrations were measured. In addition, mutagenic and nuclear instability effects were assessed using buccal micronucleus cytome assay. The study included five samplings corresponding to a period between 2007 and 2009. Drinking water from Lucrécia city presented levels of Mn, Ni and Cr along with cyanobacteria in concentrations one to four times higher than regulatory guidelines considered. Furthermore, high levels of all the tested radionuclides were found. A high percentage of the houses included in this study presented indoor radon concentrations over 100 Bq m^-3. The mean annual effective dose from Lucrécia houses was six times higher than observed in a control region. The levels of exposure in most of the Lucrécia houses were classified as middle to high. A significant mutagenic effect, represented as an increase of micronuclei (MN) frequency and nuclear abnormalities as nuclear buds (NB), binucleated cells (BN), and pyknotic cells (PYC) were found. The results obtained highlight the role of high background radioactivity on the observed mutagenic effect and could help to explain the exacerbated cancer rate reported in this locality.

Ecotoxicological water assessment of an estuarine river from the Brazilian Northeast, potentially affected by industrial wastewater discharge

Water pollution generated by industrial effluents discharge is a threat to the maintenance of aquatic ecosystems and human development. The Jundiai River estuarine, located in Northeast Brazil, receives an industrial pretreated effluent load from the city of Macaíba/RN/Brazil. The present study aimed to assess the water quality of this water reservoir through i) physicochemical characterization, ii) quantification of metal concentration and iii) by an ecotoxicological assessment carried out using Mysidopsis juniae and Pomacea lineata. The study was performed throughout the period comprising May to September 2014. Physicochemical variables such as chloride, total solids and electrical conductivity presented values in the waste discharge point, significantly different with those located out of the waste releasing point. Apart from that, metal concentration showed variable behavior throughout the monitored period. Levels of Al, Fe, Cu, Cd, Cr, Ni, Pb and Ag were over the considered guidelines. Both natural and anthropogenic sources seem to be involved in the resulting environmental scenario. A reduction in the fecundity rate (using Mysidopsis juniae) along with an increase in mortality rate (in both species) was observed ratifying the presence of toxic substances in this water reservoir. Moreover, a correlation analysis stated an association of the aforementioned toxicological effects with the delivery of industrial waste products. The ecotoxicological assessment performed highlighted the presence of toxic substance/s in water from the Jundiai River. Especially as a consequence of industrial activity, a fact that might threaten the bioma and, therefore, the human health of the population settled in the studied region.

Variation in genotoxic susceptibility and biomarker responses in Cirrhinus mrigala and Catla catla from different ecological niches of the Chenab River

A large number of methods have been applied to evaluate genotoxic damage in different aquatic species. Comet assay, as a method for detecting DNA alterations, and micronucleus test, as an index of chromosomal damage are the most widely used and authentic methods in laboratory and field studies. The primary objective of the study was to evaluate the genotoxic effects of heavy metals generated by toxic industrial effluents and various kinds of pollutants from urban and agricultural areas and domestic waste on Catla catla and Cirrhinus mrigala due to water pollution in the Chenab River, Pakistan. The heavy metals Cd, Cu, Mn. Zn, Pb, Cr, Sn, and Hg were detected by atomic absorption spectrophotometry from water samples collected from predetermined sampling sites. All the physicochemical parameters and heavy metals were found to exceed the upper limits recommended by various agencies. Comet assays showed significant (p < 0.05) DNA damage in C. mrigala compared to C. catla for tail length and olive tail moment from three different sites. Significant (p < 0.05) differences were reported between fish collected from polluted sites and farmed fish, but only non-significant (p > 0.05) findings were observed between fish collected from farmed and non-polluted upstream waters. Micronucleus assays showed similar findings for single and double micronucleus induction in C. catla and C. mrigala. A significantly (p < 0.05) higher micronuclei induction and percent tail DNA was observed in C. mrigala specimen collected from the polluted site. These findings infer that DNA damage could be used as a biomarker of pollution load and its early monitoring by using simple and reliable techniques such as the comet and micronucleus assays, expedient methods for toxicity screening of aquatic environments. Regular monitoring is necessary to assess eco-health of the Chenab River by choosing perhaps C. mrigala, being a bottom feeder, as a bioindicator that could provide more reliable information to determine the status of the environmental quality of the river.

Water mutagenic potential assessment on a semiarid aquatic ecosystem under influence of heavy metals and natural radioactivity using micronuclei test

The contamination of water bodies by heavy metals and ionizing radiation is a critical environmental issue, which can affect water quality and, thus, human health. This study aimed to evaluate the water quality of the Boqueirão de Parelhas Dam in the Brazilian semiarid region. A 1-year study (2013-2014) was performed through the assessment of physicochemical parameters, heavy metal content, and radioactivity along with the mutagenicity potential of water using micronuclei test in Orechromis niloticus (in vivo) and the cytokinesis-block micronucleus (CBMN) assay in human lymphocytes (in vitro). A deterioration of water organoleptics characteristics by the presence of high levels of sulfate and total solids was observed. High concentrations of aluminum, nickel, silver, and lead along with the alpha particle content were higher than the limits suggested by the World Health Organization and Brazilian legislation for drinking water. An increase in the frequency of micronuclei and nuclear abnormalities was observed in both experimental models. The results obtained confirmed the mutagenic potential present in water samples. This study highlights that geogenic agents affect water quality becoming a human health concern to be taken into account due to the relevance that this water reservoir has in the region.

Microbial Community Profile and Water Quality in a Protected Area of the Caatinga Biome

The Caatinga is a semi-arid biome in northeast Brazil. The Paraguaçú River is located in the Caatinga biome, and part of its course is protected by the National Park of Chapada Diamantina (PNCD). In this study we evaluated the effect of PNCD protection on the water quality and microbial community diversity of this river by analyzing water samples obtained from points located inside and outside the PNCD in both wet and dry seasons. Results of water quality analysis showed higher levels of silicate, ammonia, particulate organic carbon, and nitrite in samples from the unprotected area compared with those from protected areas. Pyrosequencing of the 16S rRNA genes revealed that Burkholderiales was abundant in samples from all three sites during both seasons and was represented primarily by the genus Polynucleobacter and members of the Comamonadaceae family (e.g., genus Limnohabitans). During the dry season, the unprotected area showed a higher abundance of Flavobacterium sp. and Arthrobacter sp., which are frequently associated with the presence and/or degradation of arsenic and pesticide compounds. In addition, genes that appear to be related to agricultural impacts on the environment, as well as those involved in arsenic and cadmium resistance, copper homeostasis, and propanediol utilization, were detected in the unprotected areas by metagenomic sequencing. Although PNCD protection improves water quality, agricultural activities around the park may affect water quality within the park and may account for the presence of bacteria capable of pesticide degradation and assimilation, evidencing possible anthropogenic impacts on the Caatinga.

Heavy metal accumulation and the genotoxicity in barbel (Barbus barbus) as indicators of the Danube river pollution

The aim of this study was to analyze 16 trace elements (Al, As, B, Ba, Cd, Co, Cr, Cu, Fe, Li, Mn, Mo, Ni, Pb, Sr, and Zn) in different barbel (Barbus barbus) tissues and to detect the presence of genotoxic effects in erythrocytes with the alkaline comet assay. Barbel specimens were collected in the Danube river near Belgrade, Serbia, where the discharge of untreated communal and industrial wastewaters is likely to produce negative effects on fish residing in this area. The highest concentrations of Sr, Mn, Fe, Ba, B, and Al were found in gills, Mo and Cu in liver, and As and Zn in gonads. Concentrations of Zn and Fe were above maximum acceptable concentrations (MACs) in a number of gonad, gill, and liver samples. Three-year-old barbel specimens had higher tail moment and Zn concentrations in gills (1.71 and 51.20 μg/g dw, resp.) than 5-year-old specimens (0.85 and 42.51 μg/g dw, resp.). Results indicate that the younger barbel specimens might be more suitable for the monitoring of environmental pollution.

Use of native species Crenicichla menezesi (Ariidae) as a model for in situ evaluation of genotoxicity in surface water

The aim of this work was to analyze the genotoxicity in surface water from the Pitimbú River (Natal, Brazil) using a neotropical species Crenicichla menezesi as bioindicator for in situ evaluation. The genotoxicity was analyzed using the micronucleus (MN) and comet assays in erythrocytes. The animals were collected from five sites of the river. A significant increase of MN frequency and comet class L1 to L4 were observed only in specimens collected from three sampling sites (SS3, SS4 and SS5) located into urban areas. These same sites also presented high metals concentration. Correlation of DNA damage and concentrations of Cu (Spearman r=0.8080), Cr (Spearman r=0.9772), and Ni (Spearman r=0.9909) were observed. These data indicate the presence of genotoxic agents. Moreover the C. menezesi species showed to be a good indicator for prompt analyses since this species presents sedentary and carnivore habits.