Using the nucleolar biomarker and the micronucleus test on in vivo fish fin cells

Toxicogenetic, biochemical, and anatomical effects of the herbicide Clethodim on Allium cepa L

Pesticides are compounds with several chemical or biological agents developed to potentiate the biocide action. Their use is associated with increased economic and agricultural productivity worldwide but can harm health and the environment, damaging existing biota. Clethodim is a systemic post-emergent herbicide for grasses, highly selective for cotton, coffee, onions, carrots, soybeans, etc. Therefore, this work aimed to evaluate the harmful effect of the herbicide Clethodim with the model plant Allium cepa. A series of tests were conducted to evaluate the effects of the herbicide under study. Germination tests, root growth, cell, and nucleolar cycle analysis, as well as oxidative stress assessment and histological analysis of the roots, were performed. The results indicated that the herbicide demonstrated phytotoxicity, inhibiting germination at C1 (1.92 g/L) and C3 (0.84 g/L), and root growth at all concentrations, presenting mutagenicity at C1 (1.92 g/L) and C4 (0.24 g/L), evidenced by the increased frequency of micronuclei. In addition, changes were observed in the enzymatic activity of the enzymes catalase at concentrations C1 (1.92 g/L) and C2 (0.96 g/L) and ascorbate peroxidase at concentrations C1 (1.92 g/L), C2 (0. 96 g/L), and C3 (0.48 g/L) and in cell elongation at concentrations C1 (1.92 g/L) and C3 (0.48 g/L), demonstrated in histological analyses of the root apex.

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.

Comparative analyses of hypothalamus transcriptomes reveal fertility-, growth-, and immune-related genes and signal pathways in different ploidy cyprinid fish

Triploid crucian carp (TCC) is obtained by hybridization of female diploid red crucian carp (Carassius auratus red var., RCC) and male allotetraploid hybrids. In this study, high-throughput sequencing was used to conduct the transcriptome analysis of the female hypothalamus of diploid RCC, diploid common carp (Cyprinus carpio L., CC) and TCC. The key functional expression genes of the hypothalamus were obtained through functional gene annotation and differential gene expression screening. A total of 71.56 G data and 47,572 genes were obtained through sequencing and genome mapping, respectively. The Fuzzy Analysis Clustering assigned the differentially expressed genes (DEGs) into eight groups, two of which, overdominance expression (6005, 12.62%) and underdominance expression (3849, 8.09%) in TCC were further studied. KEGG enrichment analysis showed that the DEGs in overdominance were mainly enriched in four pathways. The expression of several fertility-related genes was lower levels in TCC, whereas the expression of several growth-related genes and immune-related genes was higher levels in TCC. Besides, 15 DEGs were verified by quantitative real-time PCR (qPCR). The present study can provide a reference for breeding sterility, fast-growth, and disease-resistant varieties by distant hybridization.

Comparative assessment of the acute toxicity, haematological and genotoxic effects of ten commonly used pesticides on the African Catfish, Clarias gariepinus Burchell 1822

Freshwater fishes are faced with increasing threats due to intensification of agriculture. This study evaluated the haematological and genotoxic effects of exposure of the African Catfish, Clarias gariepinus to sublethal concentrations of commonly used pesticides in agricultural settings. The evaluated pesticides were abamectin, carbofuran, chlorpyrifos, cypermethrin, deltamethrin, dichlorvos, dimethoate, fipronil, lambda-cyhalothrin and paraquat. The fishes were initially exposed singly to the pesticides for 96 h periods to determine their LC₅₀, followed by exposure to sublethal concentrations (1/100^th 96 h LC₅₀) over a 21 d period. In all cases, a control experiment with catfishes kept in dechlorinated municipal water was monitored simultaneously. The 96 h LC₅₀ values was found to vary widely from 2.043 μgL^-1 (Lambda-cyhalothrin) to 10284.288 μgL^-1(Paraquat). Significant differences (P < 0.05) were observed between mean haematological parameters-WBC, RBC, HGB, HCT, MCH and MCHC in the exposed and control catfishes. More so, micronucleus and nuclear abnormalities occurred at significantly higher proportions in pesticide exposed catfishes. Holistic cradle to grave approach as well as fate analysis is required to mitigate the potential harmful effects of pesticides to fresh water fishes.

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.

Expression Profile Analysis of the Cell Cycle in Diploid and Tetraploid Carassius auratus red var

Polyploidization often leads to “transcriptome shock,” and is considered an important factor in evolution of species. Analysis of the cell cycle, which is associated with survival in polyploidy, has proved useful in investigating polyploidization. Here, we used mRNA sequencing to investigate global expression in vitro (in cultured cells) and in vivo (in fin and liver tissues) in both the diploid and tetraploid Carassius auratus red var.. Differential expression (DE) of genes in diploid (7482, 36.0%) and tetraploid (3787, 18.2%) states suggested that in vitro and in vivo conditions dramatically change mRNA expression levels. However, of the 20,771 total shared expressed genes, 18,050 (87.0%), including 17,905 (86.2%) non-differentially expressed genes (DEGs) and 145 (0.7%) DEGs between diploids and tetraploids, showed the same expression trends in both cultured cells and liver tissues. Of the DEGs, four of seven genes in the cell cycle pathway had the same expression trends (upregulated in diploids and tetraploids) in both cultured cells and liver tissues. Quantitative PCR analysis confirmed the same expression trends in the nine DEGs associated with regulation of the cell cycle. This research on common characteristics between diploids and tetraploids provides insights into the potential molecular regulatory mechanisms of polyploidization. The steady changes that occur between diploids and tetraploids in vitro and in vivo show the potential value of studying polyploidy processes using cultured cell lines, especially with respect to cell cycle regulation.

Cytogenotoxic effects of fullerene C60 in the freshwater teleostean fish, Anabas testudineus (Bloch, 1792)

In recent years, carbon nanomaterials, including fullerene C₆₀ is regarded as the building block in nanotechnology because of its widespread use in medicine, industry, cosmetics and commercial products. Despite the special properties, several reports have raised public health concerns due to the unknown and practically unexplored toxic effects of nanomaterials. However, there have been relatively few studies regarding the genotoxic responses of fullerene C₆₀in vivo. Genotoxic effects of DMSO-solublized C₆₀ nanomaterial suspension at sublethal concentrations (5 and 10 mg/L) were investigated on adult freshwater fish, Anabas testudineus using micronucleus and comet assays. An assessment of micronucleus induction showed severe cytoplasmic and nuclear abnormalities in erythrocytes, gill and liver cells. Abnormalities in cytoplasm were identified as formation of sticky cells, vacuolated cytoplasm, cytoplasmic degeneration, echinocyte, acanthocyte, anisochromatic cells and abnormal erythrocyte membrane. The nuclear abnormalities included micronucleus, binucleated cells, nuclear buds, irregular nucleus, vacuolated, notched and serrated nucleus in the erythrocytes compared to the control groups. Similarly, significant increase (P < 0.05) in micronucleus frequencies were observed in gill and liver cells. The high frequency of micronucleus was observed in the gill cells followed by liver and erythrocytes, respectively, at both sublethal concentrations, and the severity was duration and concentration-dependent. In comet assay, significant increase (P < 0.05) in DNA damage was observed using the comet parameter, percent tail DNA. The highest level of comet damage with grade 3 was observed in blood, gill and liver cells on increase in duration and concentration when compared to the respective control groups. Thus the results revealed that fullerene C₆₀ nanomaterials may pose risk to aquatic organisms, especially fish, by the induction of genotoxicity. Further studies are warranted to provide new insights on the mechanisms and consequences of C₆₀ nanomaterials interactions with biological membranes.

Nucleolar alterations are reliable parameters to determine the cytogenotoxicity of environmental pollutants

Pollution generated by deposition of industrial activity waste in the environment without due care can lead to serious environmental consequences. Bioassays in higher plants are means of understanding the cytogenotoxic effects of these substances. In the present work, Allium cepa L. was used as a model species to assess nucleolar changes induced by environmental pollutants. The substances used were Methyl Methane Sulfonate (MMS), cadmium (Cd), Spent Potliner (SPL) and the herbicide Atrazine. Water was used as a negative control. The silver-stained nucleolar organizer region (AgNOR) assay was used making it possible to evaluate how nucleolar parameters (number of nucleoli per nucleus and nucleoli area) behave when facing stress caused by such pollutants. The results obtained showed a variation in the observed parameters: an increase in the number of nucleoli in the treated cells and tendency to a reduction in nucleolar area, indicating that the tested pollutants may have impaired nucleolar activity. In addition, it was possible to establish a relationship between the behavior of the nucleolus with other changes as plantlet growth, cell proliferation, and DNA damage.

Borax Supplementation Alleviates Hematotoxicity and DNA Damage in Rainbow Trout (Oncorhynchus mykiss) Exposed to Copper

Heavy metals have harmful effects on health of both ecosystems and organisms to their accumulation ability. Copper (Cu) is an essential element for organism survival, but EPA considers Cu as a priority pollutant. On the other hand, boron has well-defined biological effects in living organisms including cytoprotection and genoprotection, although borax (BX) metabolism is poorly described in fish. Moreover, the effects of boron supplementation against Cu-induced hematotoxicity and DNA damage in aquatic organisms are still undetermined. Therefore, the main aim of this study was to provide an overview of the strategy for therapeutic potential of BX against Cu exposure in rainbow trout, Oncorhynchus mykiss. For this aim, fish were fed with different doses of BX and/or copper (1.25, 2.5, and 5 mg/kg of BX; 500 and 1000 mg/kg of Cu) for 21 days in pretreatment and combined treatment options. At the end of the treatments (pre and combined), the hematological index (total erythrocytes count (RBC), total leucocytes count (WBC), hemoglobin (Hb), hematocrit (Hct), total platelet count (PLT), mean cell hemoglobin concentration (MCHC), mean cell hemoglobin (MCH), mean cell volume (MCV)), oxidative DNA damage (8-hydroxy-2-deoxyguanosine (8-OHdG)), and nuclear abnormalities in blood samples of treated and untreated fish were investigated. The statistically significant (p < 0.05) and dose-dependent increases in hematological indices, 8-OH-dG level, and rates of nuclear abnormalities were observed after exposure to Cu in both treatment group fish as compared to untreated group. On the contrary, treatments with BX doses alone did not alter these hematological and DNA damage endpoints. Moreover, both pretreatment and combined treatments with BX significantly alleviated Cu-induced hematotoxicity and genotoxicity. In a conclusion, the obtained data firstly revealed that borax exhibited hematoprotective and genoprotective effects against copper-induced toxicity in fish.

A study on the impact of water quality on the murrel fish Channa striata and Channa punctata from three major Southern Tamilnadu rivers, India

Rivers are one of the natural fresh water resources that satisfy the domestic, agricultural and industrial needs of people. The Cauvery, Vaigai and Thamirabarani are the three major rivers flowing through the Southern Tamil Nadu region of India. In this study, the Water Quality Index (WQI) and heavy metal concentrations of river water during the pre- and post-monsoon periods in 2015 were recorded and the impact of heavy metal accumulation in two important murrel fish species, Channa striata and Channa punctata, was analysed using micronuclei and histology assays. The results revealed that the WQI was greater than 50 in most sites, indicating poor water quality for the sustainability of living organisms. The Heavy metal Pollution Index (HPI) was critical with values >100 in a few sites along the Cauvery and the Vaigai. The bioaccumulation of heavy metals was higher in the C. punctata than in the C. striata in most instances. Cd, Cu and Pb showed higher bioaccumulation in the pre-monsoon samples whereas As, Cr and Zn exhibited higher bioaccumulation during the post monsoon period. The Ni bioconcentration was consistent in both of the periods. The accumulation of heavy metals in the fish organs was as follows: gills > liver > kidney > muscle. The muscles exhibited Hazard Quotient (HQ) values 0.05–3.3 × 10⁻⁶ times lower than the Reference Dose (RfD) level, indicating no significant health risk from the intake of these metals through the consumption of their muscle tissues. The MN% was 0.19–0.22% in the C. striata, 0.15–0.25% in the C. punctata from heavily polluted sites and less polluted sites showed 0.05% and 0.07% MN in the C. striata and C. punctata, respectively. The MN% in the pre-monsoon samples was higher than that of the post-monsoon samples and the C. punctata had a higher MN% than the C. striata. The gills of the fish with high bioaccumulation showed severe lamellar fusion, hyperplasia, hypertrophy and epithelial lifting, their liver hepatocytes showed necrosis of the parenchymal cells and vacuolation, their Kidney tubules were dilated and vacuolated glomeruli with no Bowman's space were observed. Their muscles had normal myotomes with equally spaced muscle bundles. The C. punctata showed more severe histopathological changes than the C. striata. Thus, the present study defines a warning alarm for the proper remediation steps to be taken to safeguard the natural water resources as well as the aquatic ecosystem.

The impact of heavy metal accumulation in two important murrel fish species, Channa striata and Channa punctata, was analysed using micronuclei and histology assays.

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.

Genotoxicity and cytotoxicity response to environmentally relevant complex metal mixture (Zn, Cu, Ni, Cr, Pb, Cd) accumulated in Atlantic salmon (Salmo salar). Part I: importance of exposure time and tissue dependence

Health impact of metal mixture at environment realistic concentrations are difficult to predict especially for long-term effects where cause-and-effect relationships may not be directly obvious. This study was aimed to evaluate metal mixture (Zn-0.1, Cu-0.01, Ni-0.01, Cr-0.01, Pb-0.005 and Cd-0.005 mg/L, respectively for 1, 2, 4, 7, 14 and 28 days at concentrations accepted for the inland waters in EU) genotoxicity (micronuclei, nuclear buds, nuclear buds on filament), cytotoxicity (8-shaped nuclei, fragmented-apoptotic erythrocytes), bioaccumulation, steady-state and the reference level of geno-cytotoxicity in hatchery-reared Atlantic salmon tissues. Metals accumulated mostly in gills and kidneys, to the lesser extent in the muscle. Uptake of metals from an entire mixture in the fish for 14 days is sufficient to reach steady-state Cr, Pb concentrations in all tissues; Zn, Cu-in kidneys and muscle, Ni-in liver, kidneys, muscle and Cd-in muscle. Treatment with metal mixture significantly increased summed genotoxicity levels at 7 days of exposure in peripheral blood and liver erythrocytes, at 14 days of exposure in gills and kidney erythrocytes. Significant elevation of cytotoxicity was detected after 2 and 14 days of exposure in gills erythrocytes and after 28 days-in peripheral blood erythrocytes. The amount of Cu, Cr, Pb and Cd accumulated in tissues was dependent upon duration of exposure; nuclear buds, 8-shaped nuclei frequencies also were dependent upon duration of exposure. This study indicates that metals at low levels when existing in mixture causes significant geno-cytotoxicity responses and metals bioaccumulation in salmon.

Buccal micronucleus cytome assay of populations under chronic heavy metal and other metal exposure along the Santiago River, Mexico

The Santiago River is one of the most contaminated rivers in Mexico, with heavy metal levels above the allowed limits. Scientific evidence indicates that chronic heavy metal exposure leads to cytogenotoxic effects. The aims of this study were to evaluate the genotoxic and cytotoxic effects of such exposure in buccal mucosa cells by micronucleus (MN) assay and to identify other nuclear abnormalities (NAs), such as nuclear buds (NBUDs), binucleated cells (BNs), pyknotic nuclei (PNs), karyorrhexis (KX), karyolysis (KL), and abnormally condensed chromatin (CC). Assays were performed on samples from four populations located alongside the Santiago River that are under chronic exposure to heavy metals and other metals (HMMs), and the results were compared with those of a population without exposure to HMMs. The exposed group showed increased frequencies of NAs (KX, CC, and KL), which are associated with cytotoxic damage, and NBUDs, which are associated with genotoxic damage. Increased frequencies of NBUDs and CC were observed in subjects from El Salto/Juanacatlán, Ocotlán, and Paso de Guadalupe, and an increase in KX frequency was observed in subjects from El Salto/Juanacatlán. Significant differences in KL frequency were observed in subjects from La Barca, El Salto/Juanacatlán, Paso de Guadalupe, and Ocotlán. Predictors for increased development of MNs and NBUDs were high concentrations of Al, Zn, and Cu. In conclusion, chronic exposure to HMMs, especially Al, Cu, and Zn, in the studied population could be related to increased frequencies of NAs, such as NBUDs, KX, CC, and KL, in the buccal mucosa cells.

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.

Multibiomarker response in ten spotted live-bearer fish Cnesterodon decemmaculatus (Jenyns, 1842) exposed to Reconquista river water

The aim of this paper is to assess the water quality to chemical pollution at Roggero Dam, the headwater of the Reconquista river, and to perform a Cadmium (Cd) contamination pulse simulation through a wide battery of biomarkers which included: genotoxicity and enzymatic biomarker parameters on a neotropical teleost fish namely Cnesterodon decemmaculatus. Water samples were taken in order to determine the river's physicochemical profile. An integrative approach was applied using a biomarker index. The bioassay involved the use of laboratory culture adult animals, acclimatized in moderately hard water (MHW) and fed ad libitum. A semi-static 96h bioassay was conducted and the experimental groups were as follows: [1] river water (Rg); [2] river water + 2mg/L Cd (RgCd); [3] MHW + 2mg/L Cadmium (Cd), positive metal control; [4] MHW + 5mg/L Cyclophosphamide (positive genotoxicity control -CP); [5] MWH, negative control (NC). At the end of the exposure time fishes were sectioned and the following biomarkers were determined: 1) condition factor rate (CF); 2) for the anterior section (A) (head): glutathione (GSH) and protein (Pr) content; 3) for the body midsection (M) (viscera): Pr, GSH, Glutathione-S-transferase (GST), catalase (CAT) and superoxide dismutase (SOD). Blood samples were also taken from the fish specimens to estimate the frequency of micronuclei (MN) as well as other nuclear abnormalities (NA). The physicochemical profile of the river water sample indicated high Copper concentrations. CAT and SOD activity and total Pr content did not show any significant changes. GST activity decreased in fish exposed to Rg, while GSH content decreased significantly for all treatments compared to controls in MHW. These results would seem to point to a reduction in cell defense capability as a result of the depletion antioxidants such as GSH. The NA frequency increased significantly in all treated groups while MN frequency was increased only in Cd and CP groups. Using some the biomarkers measured, a biomarker index was estimated which revealed that fish exposed to Rg were 90% affected or highly affected, while those exposed to RgCd were 80% and Cd 68% affected or highly affected. The obtained results indicate the usefulness of the use of a battery of variables by means of the biomarker index to analyze water quality.

Genotoxic Effects Induced by Cd(+2), Cr(+6), Cu(+2) in the Gill and Liver of Odontesthes bonariensis (Piscies, Atherinopsidae)

Genotoxic effects of Cd(+2), Cr(+6), and Cu(+2) on the gill and liver of the Argentinean Silverside (Odontesthes bonariensis) were studied using the comet assay and in relation with the metal tissue accumulation. Fish were exposed to three waterborne concentrations of each metal for 2 and 16 days. Genotoxicity was assessed by the single cell gel electrophoresis (comet assay). After 2 days, significant increase of the genetic damage index (GDI) was only observed in the gill of fish exposed to Cr(+6) and Cu(+2), and the LOECs were 2160 nM and 921.1 nM, respectively. The gill LOEC for Cd(+2) by 16 days was 9.4 nM. In the liver, LOECs were obtained only for Cd(+2) and Cr(+6) and were 9.4 and 2160 nM, respectively. The three metals were able to induce genotoxic effects at environmentally relevant concentrations and the gill was the most sensitive organ.

Genotoxicity Effects in Freshwater Fish from a Brazilian Impacted River

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

Evaluation of drinking water treatment combined filter backwash water recycling technology based on comet and micronucleus assay

Based on the fact that recycling of combined filter backwash water (CFBW) directly to drinking water treatment plants (WTP) is considered to be a feasible method to enhance pollutant removal efficiency, we were motivated to evaluate the genotoxicity of water samples from two pilot-scale drinking water treatment systems, one with recycling of combined backwash water, the other one with a conventional process. An integrated approach of the comet and micronucleus (MN) assays was used with zebrafish (Danio rerio) to investigate the water genotoxicity in this study. The total organic carbon (TOC), dissolved organic carbon (DOC), and trihalomethane formation potential (THMFP), of the recycling process were lower than that of the conventional process. All the results showed that there was no statistically significant difference (P>0.05) between the conventional and recycling processes, and indicated that the genotoxicity of water samples from the recycling process did not accumulate in 15 day continuous recycling trial. It was worth noting that there was correlation between the concentrations of TOC, DOC, UV254, and THMFPs in water and the DNA damage score, with corresponding R(2) values of 0.68, 0.63, 0.28, and 0.64. Nevertheless, both DNA strand breaks and MN frequency of all water samples after disinfection were higher than that of water samples from the two treatment units, which meant that the disinfection by-products (DBPs) formed by disinfection could increase the DNA damage. Both the comet and MN tests suggest that the recycling process did not increase the genotoxicity risk, compared to the traditional process.

Genotoxicity evaluation of environmental pollutants using analysis of nucleolar alterations

Nucleolar alterations resulting from the action of either chemical or physical agents can serve as important genotoxicity biomarkers. In this study, the efficiency of AgNOR banding technique to identify the presence of nucleoli in micronucleus and assess nucleolar alterations in aberrant cells of Allium cepa was evaluated. Seeds of this plant were exposed to both water samples from a river that receives untreated urban effluent and to the trifluralin herbicide (0.84 mg/L concentration), both analyzed in two different seasons (summer and winter seasons). Samples induced significant frequencies of chromosomal and nuclear aberrations and micronuclei, as observed in cells submitted to conventional chromosomal staining. The herbicide caused a significant increase in the number of nucleoli and micronuclei, interpreted as due to the elimination of excessive nucleolar material resulting from polyploidization. The use of the AgNOR technique enabled the identification of both the presence of the nucleolus in some micronuclei and the nucleolar organizer region (NOR) behavior of aberrant cells. The NOR-banding technique showed to be an efficient tool for studying the genotoxic effects caused by a xenobiotics and a complex environmental sample.

Assessment of micronuclei induction in peripheral blood and gill cells of some fish species from Aliağa Bay Turkey

The aim of this paper was to assess the biological damages in fish caused by various mutagenic agents present in polluted waters of Aliağa Bay. For this purpose, micronuclei (MN) test was performed using peripheral erythrocytes and gill cells of different fish specimens caught from both polluted and relatively clean sites from Aliağa Bay (Turkey). Micronuclei tests is a system of mutagenicity testing used for determining changes in DNA fragments such as micronuclei in the cytoplasm of interphase cells caused by the pollution and chemicals in the environment. Thus, it was attempted to determine whether pollution affected the erythrocytes and gills of fish living in Aliağa Bay at the level of DNA by the means of micronuclei (MN) test. According to the results of present study, frequency of MN was found at high level in polluted site. In conclusion, this study indicates that the micronuclei test gives sensitive results in monitoring the pollution, especially the pollution of harbor, and thus it might be used as standard method in regularly monitoring pollution of coastal ecosystem.

DNA damage in haemocytes and midgut gland cells of Steatoda grossa (Theridiidae) spiders exposed to food contaminated with cadmium

The aim of this study was to assess the genotoxic effects of Cd on haemocytes and midgut gland cells of web-building spiders, Steatoda grossa (Theridiidae), exposed to the metal under laboratory conditions. Analyzes were conducted on adult females and males, fed for four weeks with cadmium-contaminated Drosophila hydei flies, grown on a medium suplemented with 0.25 mM CdCl2. The comet assay, providing a quantitative measure of DNA strand breaks, was used to evaluate the DNA damage caused by the metal. Cadmium content was measured in whole spider bodies by the AAS method. Metal body burden was significantly lower in females (0.25 µgg(-1) dry weight) than in males (3.03 µgg(-1) dry weight), suggesting that females may have more effective mechanisms controlling the uptake of metal, via the digestive tract, or its elimination from the body. Irrespectively of sex, spiders fed prey contaminated with cadmium showed significantly higher values of comet parameters: tail DNA (TDNA), tail length (TL) and olive tail moment (OTM), in comparison with the control. In midgut gland cells, the level of DNA damage was higher for males than females, while in haemocytes the genotoxic effect of cadmium was greater in females. The obtained results indicate that in spiders cadmium displays strong genotoxic effects and may cause DNA damage even at low concentrations, however the severity of damage seems to be sex- and internal organ-dependent. The comet assay can be considered a sensitive tool for measuring the deleterious effect of cadmium on DNA integrity in spiders.

Genotoxic effects of water pollution on two fish species living in Karasu River, Erzurum, Turkey

Karasu River, which is the only river in the Erzurum plain, is the source of the Euphrates River (Eastern Anatolia of Turkey). The river is in a serious environmental situation as a result of pollution by agricultural and industrial sewage and domestic discharges. The present study aims to evaluate genotoxic effects of toxic metals in chub, Leuciscus cephalus, and transcaucasian barb, Capoeta capoeta, collected from contaminated site of the Karasu River, in comparison with fish from an unpolluted reference site. Heavy metal concentrations in surface water of the river were determined. The condition factor (CF) was taken as a general biomarker of the health of the fish, and genotoxicity assays such as micronucleus (MN) and other nuclear abnormalities (NA) were carried out on the fish species studied. MN and NA such as kidney-shaped nucleus, notched nucleus, binucleated, lobed nucleus, and blebbed nucleus were assessed in peripheral blood erythrocytes, gill epithelial cells, and liver cells of the fish. A significant decrease in CF values associated with a significant elevation in MN and NA frequencies was observed in fish collected from the polluted sites compared with those from the reference site. Results of the current study show the significance of integrating a set of biomarkers to identify the effects of anthropogenic pollution. High concentrations of heavy metals have a potential genotoxic effects, and the toxicity is possibly related to industrial, agricultural, and domestic activities.

The relationship of cytotoxic and genotoxic damage with blood aluminum levels and oxidative stress induced by this metal in common carp (Cyprinus carpio) erythrocytes

Aluminum is one of the most abundant elements in nature and is used in diverse industrial processes. As a result, it contaminates aquatic ecosystems, inducing damage on associated biota. In fish, it has been observed to induce hypoxia, hypercapnia, metabolic acidosis and respiratory arrest. Although there is little information on Al-induced cytotoxicity and DNA damage, this type of studies are essential in order to identify the mechanisms of action of this metal. The cytotoxic and genotoxic effects induced by Al on common carp (Cyprinus carpio) erythrocytes were determined in specimens exposed to 0.05, 120 and 239mgAlL(-1) in static exposure systems. Blood samples were taken at 12, 24, 48, 72 and 96h, erythrocytes were separated, and the following were evaluated: frequency of micronuclei and frequency of terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL)-positive cells, blood Al levels, lipid peroxidation, protein carbonyl content, and activity of the antioxidant enzymes superoxide dismutase, catalase and glutathione peroxidase. The results show that tested aluminum concentrations produces oxidative stress (increase in lipid peroxidation degree and oxidized proteins content, as well as decrease in antioxidant enzymes activity) and induced higher frequencies of micronuclei and TUNEL-positive cells, so this metal can be considered as a cytotoxic and genotoxic agent for erythrocytes of common carp.

Genotoxic evaluation of different doses of methylmercury (CH₃Hg⁺) in Hoplias malabaricus

The survey of the effects of toxic metals and its organic compounds are of critical importance because these compounds tend to accumulate in aquatic environments. In the present work, the genotoxic potential of methylmercury, an organomercurial compound with high toxicity and present in large amounts in fish of the Amazon due to the mining process, was evaluated using the piscine micronucleus test and comet assay in fish. Specimens of Hoplias malabaricus (popularly known as traira), a neotropical specie, was exposed to methylmercury via food web, over 70 days, in two different concentrations: two groups of fifteen fish were tested with 0.075 μg CH(3)Hg(+)/g and 0.75 μg CH(3)Hg(+)/g of methylmercury per gram of fish, at 5-day intervals and over 14 successive intervals whereas control group, composed by nine fish, was fed by uncontaminated prey fish (Astyanax sp). One of the aims of this study was to reproduce the contamination found in nature in an attempt to increase our biological knowledge on the neotropical species. Hoplias malabaricus specimens were then anesthetized for removal of blood samples and dissected, for cephalic kidney removal. As a result, it was observed that the piscine micronucleus test showed no significant differences between exposed groups and control group. The comet assay performed on erythrocyte system cells, showed a significant difference between controls and contaminated, but there was no difference between doses. In contrast, the kidney cells comet assay showed no significant difference between groups, probably due to the type of damage caused by xenobiotics to be related to the tissues of most contact with it, as well as its mode of action and the chain of bioaccumulation within bodies.

Potential risks of natural mercury levels to wild predator fish in an Amazon reservoir

Mercury (Hg) is a toxic metal that bioaccumulates in aquatic organisms and along food chain. Many studies have reported the problem of mercury exposure in aquatic systems from Amazon basin, but very few have focused on the potential risks to wild fish. The present study reports the bioaccumulation of mercury and alterations in target organs of the predator fish Hoplias malabaricus (traíra) from Samuel reservoir, Amazon basin, Northern Brazil. About 18% of fish had mercury levels in muscle exceeding the safe limit for ingestion through food, established by WHO (0.5 μg Hg g(-1)). Fish were separated in two groups according to mercury bioaccumulation in liver (<0.2 μg Hg g(-1)-group I and >0.2 μg Hg g(-1)-group II) for biomarker comparisons. Catalase activity and number of macrophage centers were statistically higher in group II, confirming the potential of Hg to interfere with redox balance and to recruit defense cells to the liver. Conversely, erythrocyte nuclear alterations were less frequent in group II, indicating a more rigorous selection of erythrocytes or hormesis pattern of response. Glutathione S-transferase activity, lipid peroxidation, and histopathological analyses were not statistically different in the liver and gills of both groups. Comparison of lipid peroxidation levels of these fish with others captured in Southern Brazil during another study and the high incidence of morphological alterations in the liver and gills suggest that the bioaccumulation of mercury during continuous exposure is posing potential risks to the species.

Genotoxicity and oxidative stress biomarkers in Carassius gibelio as endpoints for toxicity testing of Ukrainian polluted river waters

This study aimed to assess oxidative stress and genotoxicity biomarkers in Prussian carp Carassius gibelio laboratory-exposed to water from polluted Ukrainian rivers in order to evaluate their usefulness as endpoints in a short-term bioassay for toxicity testing of freshwaters. The micronucleus (MN) test and the frequency of cells with double nuclei (DN) in erythrocytes and gill cells were used as indicators of chromosome aberrations and abnormalities in cell divisions, respectively. Cellular antioxidant defenses i.e. antioxidant enzyme activities (catalase, Se-dependent glutathione peroxidase, total glutathione peroxidase and glutathione-S-transferase) and oxidative damage, i.e. lipid peroxidation (measured as thiobarbituric acid reactive substances) in the fish liver were used as biomarkers of oxidative stress. Exposure to the polluted river water samples for 96 h resulted in significantly increased MN and DN frequencies, limited increases in antioxidant enzyme activities and no changes in lipid peroxidation. Results suggest that MN and DN frequencies in C gibelio are useful endpoints in a short-term bioassay for genotoxicity testing of environmental water samples in contrast to the oxidative stress biomarkers applied that showed low potential for assessing sublethal effects after a 96 h exposure.

Oxidative stress and genotoxicity biomarker responses in grey mullet (Mugil cephalus) from a polluted environment in Saronikos Gulf, Greece

This study aimed to assess oxidative stress and genotoxicity biomarkers in grey mullet Mugil cephalus from a site receiving discharges from industrial and harbor activities and a reference site in Saronikos Gulf, Greece. Cellular antioxidant defenses, i.e., antioxidant enzyme activities (catalase, selenium [Se]-dependent glutathione peroxidase, glutathione-S-transferase) and oxidative damage, i.e., lipid peroxidation (measured as thiobarbituric acid reactive substances) were used as biomarkers of oxidative stress. The micronucleus test was used for evaluation of chromosome damage, and the frequency of cells with double nuclei was used as an indication of damage to cell divisions. Antioxidant enzyme activities were lower in fish from the polluted site compared with fish from the reference site, suggesting deficiency of the antioxidant system to compensate for oxidative stress. This is further supported by the higher lipid peroxidation levels in fish from the polluted site, which represent oxidative damage. Micronuclei and double-nuclei frequencies were higher in fish from the polluted site compared with fish from the reference site, indicating genotoxic effects. Correlations between biomarkers suggest that observed effects were due to contaminants exhibiting oxidative stress potential that can also induce genotoxicity. Results suggest that the selected biomarkers in M. cephalus are useful for the assessment of pollution impacts in coastal environments influenced by multiple pollution sources.

Giemsa versus acridine orange staining in the fish micronucleus assay and validation for use in water quality monitoring

This study concerns a comparative analysis of the acridine orange and Giemsa staining procedures for the fish erythrocyte micronucleus assay. The goal was to optimize the assay in the context of field water monitoring. Fish (Carassius carassius) were exposed to a reference genotoxic agent, cyclophosphamide monohydrate 5 mg l(-1) for 2, 4, and 6 days before testing. Slides from each individual were scored using the two procedures. The results show that the assay was more sensitive when acridine orange was used. When slides were Giemsa stained, the presence of ambiguous artefacts, leading to false positives and increasing random variance, reduced the contrast between exposed and control samples. Acridine Orange staining was then applied in the context of water quality monitoring. Fish were exposed for 4 days to water sampled in two hydrological contexts: basal flow and spring flood. The results show that exposure to spring flood water in an agricultural stream can induce mutagenicity.

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.

Multimarker approach analysis in common carp Cyprinus carpio sampled from three freshwater sites

The aim of this study is to assess the response of a multimarker approach in common carp Cyprinus carpio sampled from three Tunisian dam lakes selected according to different environmental and ecological characteristics. Glutathione-S-transferase (GST) activity was analyzed in carp liver and used as a phase II detoxification enzyme, hepatic metallothionein content (MTs) was used as a metallic stress indicator, and cholinesterase activities were analyzed in muscle and brain and used as neurotoxicity biomarker. Micronucleus frequency test (MN) as a genotoxicity marker. GST and MT levels showed an increase in fish from the Bir Mcherga site and a decrease in Sidi Saâd site with respect to fish from Nebhana site. Results showed a strong inhibition of cholinesterase activities in fish from Bir Mcherga and Sidi Saâd sites compared to Nebhana site. Relatively high level of MN is reported specially in fish blood from the Bir Mcherga site.

In vivo genotoxicity and stress defences in three flatfish species exposed to CuSO4

We have used the comet assay to analyse, after 3h, 24h and 6 days, the genotoxic effect in vivo of applying a single intraperitoneal injection of CuSO4, at a concentration of 2mg/kg, to adult specimens of Solea senegalensis, Dicologlossa cuneata and Scophthalmus rhombus. Metals content (Cu, Zn and Cd) in liver was also measured. The activity of key stress defences was evaluated by analysing antioxidant enzyme activity (catalase (CAT), superoxide dismutase (SOD), total glutathione peroxidase (t-GPX), glutathione reductase (GR), glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH)), metallothionein (MT) and heat shock proteins (HSP70 and HSP60). The results show that CuSO4 intake generates high and cumulative levels of genotoxicity throughout the 6 days in all 3 species. After 6 days, metals content detected in specimens showed significant differences from controls. Inter-species differences were detected in enzyme activity (P<0.05). A clear response to CuSO4 was detected only in S. rhombus, with an increase of MT and a decrease of HSPs. Variations in antioxidant defence levels and their comparative responses to the stress-inducing agent are discussed.

Detecting micronuclei frequency in some aquatic organisms for monitoring pollution of Izmir Bay (Western Turkey)

Micronuclei tests is a system of mutagenicity testing used for determining the pollution and chemicals causing changes in DNA fragments such as micronuclei in the cytoplasm of interphase cells. Damage caused on the DNA by genotoxic pollutants is the first consequence occurring in the aquatic organisms. Thus, it was attempted to determine whether pollution affected the erythrocytes and gills of fish Gobius niger and haemolymph and gills of mussels Mytilus galloprovincialis living in Izmir Bay at the level of DNA by the means of micronuclei (MN) test. Organisms used in the MN test were collected from seven locations (Alsancak, Alaybey Shipyard, Karsiyaka, Bostanli, Göztepe, Konak and Pasaport) which are known as the most polluted part of inner Bay of Izmir (Western Coast of Turkey). According to the results of the present study, frequency of MN was found at high level in Alaybey Shipyard and Pasaport where wastes from existing dockyard contributed to high level of pollution. In conclusion, this study indicates that the micronuclei test gives sensitive results in monitoring the pollution, especially the pollution of harbor, and thus it might be used as standard method in regular monitoring of pollution of coastal ecosystem.

Long-term toxicity of hexabromocyclododecane (HBCDD) to the benthic clam Macoma balthica (L.) from the Baltic Sea

The world's largest brackish water sea area, the Baltic Sea, is considered to be one of the most polluted seas of the world. Many new pollutants are constantly entering the environment, such as brominated flame-retardants (BFRs). BFRs represent a group of compounds that structurally resemble hydrophobic organic contaminants, but only scarce data about their toxicity to marine organism exist. Thus, the purpose of this study was to analyze long-term in vivo cytotoxicity and genotoxicity of hexabromocyclodododecane (HBCDD) to exposed marine invertebrates using a suite of cytogenetic biomarkers. This included a set of nuclear and nucleolar characteristics and the micronucleus test. The use of those parameters reflects different mechanisms of nuclear activity regulation in cells (as a parameter of cytotoxicity) and measures subcellular processes. The induction of nuclear abnormalities (like the formation of micronuclei) was also employed here as a parameter of genotoxicity. In order to reflect the proliferative and metabolic activity of the cells the number of argylophillic nucleolar organiser regions (NORs) in interphase cells was scored. Over a period of 50 days an in vivo exposure experiment with a clam Macoma balthica and different concentrations of HBCDD (nominal concentrations of 0, 100 and 250microg/l) with three replicates each was performed. Gill cells were used as "sentinel systems" considering specificity in metabolism, repair mechanisms, adaptative response and cell proliferation. A significant increase in nuclear and nucleolar abnormalities and in the frequency of dead cells was observed during the duration of the experiment with the highest peak occurring 10 days after exposure for nuclear abnormalities and 20-30 days after exposure for malfunction of ribosomal genes (NORs) (GLM analyses and Spearman correlation, p<0.05). Thus, the induction of micronuclei and other nuclear abnormalities reflected the toxic potential of HBCDD to marine invertebrates while an increase in the number of NOR may also reflect adaptive responses of the system as enhanced induction of proliferative regeneration of the gill tissue.

Biomarker responses in flounder Platichthys flesus from the Polish coastal area of the Baltic Sea and applications in biomonitoring

The objective of this study was to investigate the pattern of enzymatic activities, environmental genotoxicity and cytotoxicity in flounder, Platichthys flesus, from the Polish coastal area of the Baltic Sea. Fish were sampled in different contaminated sites in the Gulf of Gdansk and in a reference area outside the gulf. The activities of acetylcholinesterase (AChE), glutathione S: -transferase (GST), catalase (CAT), alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatine kinase (CK), lactate dehydrogenase (LDH), were studied, as well as the frequency of micronuclei, nuclear buds and fragmented-apoptotic cells. A higher mean activity level of muscular AChE and a lower activity level of hepatic GST were evident in samples taken from the reference site, relative to those found in the gulf. Modeled CAT activity (in both liver and gill tissue), blood plasma LDH and CK activities were all significantly higher in flounder collected at locations within the Gulf of Gdansk than at the reference site. No statistically significant alterations were observed in the activities of ALT and AST in the blood plasma of flounder in this study. Fish collected from a location at the mouth of the Vistula River showed the highest hepatic GST and CAT, the highest gill CAT activity, and the highest frequency of blood micronuclei, nuclear buds and fragmented-apoptotic cell inductions, as well as the lowest level of blood plasma CK. The present study confirms that compared to fish from the reference area, flounder from the Gulf of Gdansk clearly demonstrate a different enzyme activity, genotoxicity and cytotoxicity biomarker response pattern.

Genotoxic and oxidative stress-inducing effects of deltamethrin in the erythrocytes of a freshwater biomarker fish species, Channa punctata Bloch

Deltamethrin, an alpha-cyano class of pyrethroid insecticide is used in insect pest control and antimalaria programs in several countries including India. Although various toxic manifestations of deltamethrin are reported in mammals, its ecotoxicologic dimensions are not adequately researched in ecologically and commercially important fishes. In this study, we report genotoxic effect of deltamethrin in a biomarker fish Channa punctata (Bloch). Adult fish were exposed to three concentrations of technical grade deltamethrin (0.4, 0.8, and 1.2 microg/L) for 48 and 72 h. Ethyl methane sulfonate was used as a positive control. Fish were analyzed for induction of micronucleus (MN), nuclear abnormalities (NAs), and oxidative stress biomarkers in erythrocytes. Deltamethrin significantly induced MN and NAs accompanied by increased lipid peroxidation. Activity of antioxidant enzyme superoxide dismutase was significantly decreased but an increase was observed in reduced glutathione level after 72 h of exposure. The NAs in exposed fish included blebbed, lobed and notched nuclei, and binucleated erythrocytes. Our findings suggest that oxidative stress may, in part, be contributing to deltamethrin-induced genotoxic damage to erythrocytes. Although MN induction is a nonspecific biomarker, it may provide an indication of pollution load of deltamethrin in the affected fish population when used as part of suite of other biomarkers.

Evaluation of genotoxicity using the micronucleus assay and nuclear abnormalities in the tropical sea fish Bathygobius soporator (Valenciennes, 1837) (Teleostei, Gobiidae)

The micronucleus and nuclear abnormalities assays have been used increasingly to evaluate genotoxicity of many compounds in polluted aquatic ecossystems. The aim of this study is to verify the efficiency of the micronucleus assay and nuclear abnormality assay in field and laboratory work, when using erythrocytes of the tropical marine fish Bathygobius soporator as genotoxicity biomarkers. Gill peripheral blood samples were obtained from specimens of Bathygobius soporator. In order to investigate the frequencies of micronuclei and to assess the sensitivity of species, the results were compared with samples taken at the reference site and maintained in the laboratory, and fish treated with cyclophosphamide. The micronucleus assay was efficient in demonstrating field pollution and reproducing results in the labotatory. There were significant higher frequencies of micronuclei in two sites subject to discharge of urban and industrial effluents. The nuclear abnormality assay did not appear to be an efficient tool for genotoxicity evaluation when compared with field samples taken at a reference site in laboratory, with a positive control.

The long amplicon quantitative PCR for DNA damage assay as a sensitive method of assessing DNA damage in the environmental model, Atlantic killifish (Fundulus heteroclitus)

DNA damage is an important mechanism of toxicity for a variety of pollutants, and therefore, is often used as an indicator of pollutant effects in ecotoxicological studies. Here, we adapted a PCR-based assay for nuclear and mitochondrial DNA damage for use in an important environmental model, the Atlantic killifish (Fundulus heteroclitus). We refer to this assay as the long amplicon quantitative PCR (LA-QPCR) assay. To validate this method in killifish, DNA damage was measured in liver, brain, and muscle of fish dosed with 10 mg/kg benzo[a]pyrene. This exposure caused 0.4-0.8 lesions/10 kb. We also measured DNA damage in liver and muscle tissues from killifish inhabiting a Superfund site, confirming the utility of this method for biomonitoring. In both cases, damage levels were comparable in nuclear DNA (nDNA) and mitochondrial DNA (mtDNA). Since extensive nDNA sequence data are not readily available for many environmentally relevant species, but mitochondrial genomes are frequently fully sequenced, this assay can be adapted to examine mtDNA damage in virtually any species with little development. Therefore, we argue that this assay will be a valuable tool in assessing DNA damage in ecotoxicological studies.

Modulatory role of copper on β-naphthoflavone-induced DNA damage in European eel (Anguilla anguilla L.)

Gill and kidney DNA integrity (alkaline unwinding assay) was assessed in Anguilla anguilla exposed for 24-h to copper (Cu: 1 or 2.5 μM), with or without 24-h pre-exposure to a polycyclic aromatic hydrocarbon (PAH)-like compound--β-naphthoflavone (BNF: 2.7 μM). Gill showed DNA integrity loss in all the exposure conditions, reflecting a dual mode of BNF-Cu interaction depending on the metal concentration. Thus, antagonistic or additive effects were observed for BNF+Cu 1 μM or BNF+Cu 2.5 μM, respectively. Kidney showed decreased DNA integrity for single exposures (BNF, Cu 1 μM), whereas sequential exposures displayed higher DNA integrity than BNF alone, revealing a Cu antagonistic effect at both the concentrations. The results also demonstrated that (i) both organs are receptive for Cu inhibitory role against BNF genotoxicity; (ii) kidney is more resistant to Cu individual exposures; and (iii) under multi-pollution conditions genotoxicity cannot be predicted on the basis of individual chemicals responses.

Genotoxic effects and LC50 value of NaOCl on Orthrias angorae (Steindachner 1897)

Studies show that different organisms used as bio-indicators have indicated several genotoxic and mutagenic effects of disinfected waters. In this study, the 96 h LC(50 )mean value of NaOCl for Orthrias angorae was calculated to be 0.5509 mg/L. The results showed that NaOCl is highly toxic to O. angorae specimens. Statistical analysis demonstrated a significant increase in micronuclei after the induction of 0.5 mg/L NaOCl concentration after 36 h. The same increase has been reported for 0.37 and 0.5 mg/L NaOCl concentrations after 72 h. Even though the MN frequency of 0.37 mg/L was similar after 36 and 72 h, only 72 h micronuclei frequency was statistically significant. The 72 h MN frequency of the negative control group was smaller than 36 h MN frequency of the negative control group. This discrepancy has led to 72 h MN frequency being statistically significant. MN frequency of 0.25 mg/L NaOCl concentration was insignificant when compared to negative test groups. The benzene treatment also caused a significant increase (p < 0.01) in the frequency of micronucleated erythrocytes.

The use of biomarkers in biomonitoring: a 2-tier approach assessing the level of pollutant-induced stress syndrome in sentinel organisms

The paper outlines a 2-tier approach for wide-scale biomonitoring programmes. To obtain a high level of standardization, we suggest the use of caged organisms (mussels or fish). An "early warning", highly sensitive, low-cost biomarker is employed in tier 1 (i.e. lysosomal membrane stability (LMS) and survival rate, a marker for highly polluted sites). Tier 2 is used only for animals sampled at sites in which LMS changes are evident and there is no mortality, with a complete battery of biomarkers assessing the levels of pollutant-induced stress syndrome. Possible approaches for integrating biomarker data in a synthetic index are discussed, along with our proposal to use a recently developed Expert System. The latter system allows a correct selection of biomarkers at different levels of biological organisation (molecular/cellular/tissue/organism) taking into account trends in pollutant-induced biomarker changes (increasing, decreasing, bell-shape). A selection of biomarkers of stress, genotoxicity and exposure usually employed in biomonitoring programmes is presented, together with a brief overview of new biomolecular approaches.