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

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

Nuclear Abnormalities in LMNA p.(Glu2Lys) Variant Segregating with LMNA-Associated Cardiocutaneous Progeria Syndrome

The LMNA gene encodes lamin A and lamin C, which play important roles in nuclear organization. Pathogenic variants in LMNA cause laminopathies, a group of disorders with diverse phenotypes. There are two main groups of disease-causing variants: missense variants affecting dimerization and intermolecular interactions, and heterozygous substitutions activating cryptic splice sites. These variants lead to different disorders, such as dilated cardiomyopathy and Hutchinson-Gilford progeria (HGP). Among these, the phenotypic terms for LMNA-associated cardiocutaneous progeria syndrome (LCPS), which does not alter lamin A processing and has an older age of onset, have been described. Here, we present the workup of an LMNA variant of uncertain significance, NM_170707.2 c. 4G>A, p.(Glu2Lys), in a 36-year-old female with severe calcific aortic stenosis, a calcified mitral valve, premature aging, and a family history of similar symptoms. Due to the uncertainty of in silico predictions for this variant, an assessment of nuclear morphology was performed using the immunocytochemistry of stable cell lines to indicate whether the p.(Glu2Lys) had a similar pathogenic mechanism as a previously described pathogenic variant associated with LCPS, p.Asp300Gly. Indirect immunofluorescence analysis of nuclei from stable cell lines showed abnormal morphology, including lobulation and occasional ringed nuclei. Relative to the controls, p.Glu2Lys and p.Asp300Gly nuclei had significantly (p < 0.001) smaller average nuclear areas than controls (mean = 0.10 units, SD = 0.06 for p.Glu2Lys; and mean = 0.09 units, SD = 0.05 for p.Asp300Gly versus mean = 0.12, SD = 0.05 for WT). After functional studies and segregation studies, this variant was upgraded to likely pathogenic. In summary, our findings suggest that p.Glu2Lys impacts nuclear morphology in a manner comparable to what was observed in p.Asp300Gly cells, indicating that the variant is the likely cause of the LCPS segregating within this family.

Ecotoxicological effects of conventional herbicides and a natural herbicide on freshwater fish (Danio rerio)

The contamination of aquatic environments has increased over time, affecting environmental integrity and human health. Herbicides represent a source of this contamination, and among the most commercialized are the triazines and glyphosate. In contrast, there are natural herbicides, which are less harmful to the environment. The aim of this study was to verify the ecotoxicological effects of the conventional herbicides (Atrazine and Glyphosate) and a natural herbicide on Zebrafish (Danio rerio). Fish were exposed for 72 h to different concentrations of conventional herbicides (1, 65, and 5,000 µg L^-1) and the natural herbicide (0.62, 1.25, and 2.5 µg L^-1) in aquaria (20 L). At end of the experiment, blood was collected from the fish, and slides were prepared to verify the frequency of nuclear abnormalities and micronuclei. A greater number of morphological nuclear alterations were recorded in the conventional herbicide treatments. In addition, significant differences were observed in the composition of abnormalities between treatments. Atrazine and Glyphosate can cause greater damage in D. rerio, demonstrating potential toxicity at all concentrations applied. The natural herbicide showed less mutagenic potential and was less harmful to fish. Thus, natural herbicides can be a better option for the preservation of the environment.

In vivo assessment of genotoxic effects in Cyprinus carpio L., 1758 (Teleostei: Cyprinidae) exposed to selected metal(oid)s

Heavy metals and metalloids originating from industrial, agricultural, and urban wastes and increasing in aquatic ecosystems cause genotoxic damage to fish species. This study aimed to determine the potential genotoxic effects of mixtures of aluminum, arsenic, and manganese in Cyprinus carpio. The effects of the mixtures on erythrocyte cells of C. carpio were examined using the comet assay, micronucleus test, and erythrocytic nuclear abnormalities in two groups after exposure to three doses of the mixtures (Group A; Dose 1: 0.3 + 0.1 + 0.02 mg/L, Dose 2: 0.6 + 0.2 + 0.04 mg/L, Dose 3: 0.9 + 0.3 + 0.06 mg/L and Group B; Dose 1: 1 + 3 +0.1 mg/L, Dose 2: 2 + 6 + 0.2 mg/L, Dose 3: 3 + 9 + 0.3 mg/L). Experimental groups were formed according to the permissible limits specified in the Turkish Surface Water Quality Regulation (TSWQR). The results of comet assay parameters such as tail DNA %, tail moment, and olive tail moment confirmed the genotoxic effect of metal(oid)s mixtures on erythrocyte cells compared with control groups and showed that DNA damage increased with increasing the concentrations. The micronucleus and other nuclear abnormalities such as blebbed nuclei, notched nuclei, eightshaped nuclei, lobed nuclei, and binucleated cells were detected in the erythrocyte cells exposed to the mixtures. Consequently, it was found that the frequency of micronucleus and erythrocytic nuclear abnormalities significantly increased in the erythrocyte cells exposed to metal(oid) concentrations compared to control groups. These results show the existence of potential genotoxicity in C. carpio even at the minimum values specified in the TSWQR after exposure to the mixtures.

A Systematic Review of Studies on Genotoxicity and Related Biomarkers in Populations Exposed to Pesticides in Mexico

In agricultural activities, pest control is essential, and the most effective method is the use of chemical agents that also represent an important source of exposure to potentially toxic compounds. Pesticides constitute a heterogeneous group of compounds designed specifically to control different pests. Besides measuring their levels or that of their metabolites in air, plasma, serum, blood, urine, etc., some studies reported increased DNA damage levels after occupational or environmental pesticides exposure, evidenced by several cytogenetic biomarkers such as chromosomal aberrations (CA), sister chromatid exchanges (SCE), micronuclei frequency (MN) together with other nuclear abnormalities (NA), alkaline comet assay, but also changes in oxidative stress parameters and miRNA levels. Single or combined, these techniques have also been used in genotoxic biomonitoring studies of workers occupationally exposed to pesticides in Mexico. Despite being a country with great agricultural activity and reported excessive pesticide use, genotoxic studies have been relatively few and, in some cases, contradictory. A review was made of the studies available (published until the end of 2020 on PubMed, Web of Science, Redalyc and Scielo, both in English and Spanish) in the scientific literature that evaluated occupational exposure of human samples to pesticides assessed with DNA damage and related biomarkers in Mexico.

Genotoxic effects of urban pollution in the Iguaçu River on two fish populations

Environmental impacts on water resources and discharges of pollutants are some of the main problems of aquatic ecosystems. Currently, the Iguaçu River is considered the second most polluted river in Brazil, therefore, given the importance of understanding the effects of water pollution on living organisms, this study aimed to analyze the possible genotoxic effects in Astyanax bifasciatus (Characiformes; Characidae) and Geophagus brasiliensis (Perciformes: Cichlidae) in response to the water quality of the Iguaçu River. Four sampling points were determined on the Iguaçu River, with different levels of environmental impact. The micronuclei and nuclear abnormalities were quantified by counting 2000 erythrocytes from each specimen. There was a statistical difference in the frequency of nuclear abnormalities both for A. bifasciatus (Kruskal-Wallis _3;30 = 10.9; p = 0.01) and for G. brasiliensis (Kruskal-Wallis _3;26 = 12.27; p = 0.006), with point 1 (critically degraded) showing a higher frequency of nuclear abnormalities and point 4 (moderately degraded) showing a lower frequency of nuclear abnormalities for both species, showing genotoxic potential in fish erythrocytes. This result demonstrates the need for further discussion on the conservation of the Iguaçu River as well as broadening the discussion on its potability.

Directly converted astrocytes retain the ageing features of the donor fibroblasts and elucidate the astrocytic contribution to human CNS health and disease

Astrocytes are highly specialised cells, responsible for CNS homeostasis and neuronal activity. Lack of human in vitro systems able to recapitulate the functional changes affecting astrocytes during ageing represents a major limitation to studying mechanisms and potential therapies aiming to preserve neuronal health. Here, we show that induced astrocytes from fibroblasts donors in their childhood or adulthood display age‐related transcriptional differences and functionally diverge in a spectrum of age‐associated features, such as altered nuclear compartmentalisation, nucleocytoplasmic shuttling properties, oxidative stress response and DNA damage response. Remarkably, we also show an age‐related differential response of induced neural progenitor cells derived astrocytes (iNPC‐As) in their ability to support neurons in co‐culture upon pro‐inflammatory stimuli. These results show that iNPC‐As are a renewable, readily available resource of human glia that retain the age‐related features of the donor fibroblasts, making them a unique and valuable model to interrogate human astrocyte function over time in human CNS health and disease.

MnTE-2-PyP Suppresses Prostate Cancer Cell Growth via H2O2 Production

Prostate cancer patients are often treated with radiotherapy. MnTE-2-PyP, a superoxide dismutase (SOD) mimic, is a known radioprotector of normal tissues. Our recent work demonstrated that MnTE-2-PyP also inhibits prostate cancer progression with radiotherapy; however, the mechanisms remain unclear. In this study, we identified that MnTE-2-PyP-induced intracellular H₂O₂ levels are critical in inhibiting the growth of PC3 and LNCaP cells, but the increased H₂O₂ levels affected the two cancer cells differently. In PC3 cells, many proteins were thiol oxidized with MnTE-2-PyP treatment, including Ser/Thr protein phosphatase 1 beta catalytic subunit (PP1CB). This resulted in reduced PP1CB activity; however, overall cell cycle progression was not altered, so this is not the main mechanism of PC3 cell growth inhibition. High H₂O₂ levels by MnTE-2-PyP treatment induced nuclear fragmentation, which could be synergistically enhanced with radiotherapy. In LNCaP cells, thiol oxidation by MnTE-2-PyP treatment was not observed previously and, similarly to PC3 cells, there was no effect of MnTE-2-PyP treatment on cell cycle progression. However, in LNCaP cells, MnTE-2-PyP caused an increase in low RNA population and sub-G₁ population of cells, which indicates that MnTE-2-PyP treatment may cause cellular quiescence or direct cancer cell death. The protein oxidative modifications and mitotic catastrophes caused by MnTE-2-PyP may be the major contributors to cell growth inhibition in PC3 cells, while in LNCaP cells, tumor cell quiescence or cell death appears to be major factors in MnTE-2-PyP-induced growth inhibition.

Genomic Instability Decreases in HIV Patient by Complementary Therapy with Rosmarinus officinalis Extracts

Genomic instability is associated with increased oxidative stress in patients with human immunodeficiency virus (HIV). The aim of this study was to determine the effect of intake of methanolic and aqueous extracts of Rosmarinus officinalis on genomic instability in HIV patients. We studied 67 HIV patients under pharmacological treatment with ATRIPLA who were divided into three groups: group 1, patients under ATRIPLA antiretroviral therapy; group 2, patients with ATRIPLA and rosemary aqueous extract (4 g/L per day); and group 3, patients with ATRIPLA and rosemary methanolic extract (400 mg/day). The genomic instability was evaluated through the buccal micronucleus cytome assay. Oral epithelial cells were taken at the beginning and 1 and 4 months later. The groups that received the pharmacological therapy with ATRIPLA and the complementary therapy with R. officinalis extracts showed a decrease in the number of cells with micronuclei and nuclear abnormalities compared with the group that only received ATRIPLA. The complementary therapy with R. officinalis decreased the genomic instability in HIV patients.

Chronic exposure to quinalphos shows biochemical changes and genotoxicty in erythrocytes of silver barb, Barbonymus gonionotus

An in vivo study was carried out on the freshwater fish Barbonymus gonionotus to evaluate the genotoxic effects of the organophosphate quinalphos. The fish were exposed to sub-lethal doses of quinalphos (0%, 10%, 25%, and 50% of LC₅₀) for a period of 30 days. Analysis of biochemical characteristics (protein and lipid contents of different organs), nuclear abnormalities of erythrocytes (NAE) and morphological abnormalities of erythrocytes (MAE) were performed on peripheral erythrocytes sampled at post-treatment intervals of 0 and 30 days. The biochemical results revealed a significant dose-dependent decline in protein and lipid contents and increase in the frequencies of NAE as well as MAE. Our findings also confirmed that the morphological deformations of erythrocytes in addition to NAE on fish erythrocytes in vivo are effective tools in determining the potential genotoxicity of organophosphates.

Effect of staining procedures on the results of micronucleus assay in the exfoliated buccal mucosal cells of smokers and nonsmokers: A pilot study

Background

Tobacco consumption in smoke form causes severe health problems such as cancer. Micronuclei are structures that present after genomic damage in buccal mucosal cells which could be a good indicator of chromosomal alterations in cytological samples. The nuclear anomalies that are consequences of cell injury are also found in these cells.

Aim

The present study was aimed at evaluating the effectiveness of deoxyribonucleic acid (DNA)-specific stain over DNA-nonspecific stain in exfoliated buccal mucosa cells in smokers and nonsmokers for assessment of micronuclei and nuclear anomalies.

Materials and Methods

Thirty subjects were divided into three groups; Group 1 (control) nonsmokers (n = 10), Group 2 individuals with history of smoking for less than 10 years (n = 10), and Group 3 individuals with history of smoking for more than 10 years (n = 10). The exfoliated buccal mucosal cells were scrapped using wooden spatula, smeared over the glass slide, and stained with DNA-nonspecific stain, Giemsa; and DNA-specific stains, Feulgen and acridine orange.

Results

We found that the mean micronuclei score with DNA-nonspecific stain, Giemsa, was significantly higher in smokers group when compared to nonsmokers group. No such significant differences were observed with DNA-specific stains. Also, in the smokers groups, mean micronuclei were higher in Group 3 when compared to Group 2.

Conclusion

The score of MN assay and nuclear anomalies in exfoliated buccal mucosal cells of smokers and nonsmokers strongly depended on staining procedures and duration of smoking. Hence, these should be interpreted with caution to avoid false-positive results.

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

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

Genotoxicity of non-alcoholic mouth rinses: A micronucleus and nuclear abnormalities study with fluorescent microscopy

AIM

The aim of the present study was to evaluate the genotoxicity of non-alcoholic mouth rinses on buccal epithelial cells using a micronucleus test.

METHODS

A total of 105 patients were selected and randomly divided into five groups. Four different mouth rinses and normal saline were given for 2 weeks' duration, and cytological smears were collected before and after exposure. These smears were subjected to micronucleus (MN) and other nuclear abnormalities (ONA) tests using acridine orange stain, and their frequencies were obtained in 500 buccal epithelial cells. The statistical analysis included mean, χ² -test, analysis of variance, and post-hoc analysis by Bonferroni test.

RESULTS

Micronucleated cells (P < .00) and MN (P < .00) were higher in individuals exposed to chlorhexidine (CHX), followed by chlorine dioxide (ClO₂ ), potassium nitrate (KNO₃ ), and sodium fluoride (NaF), amine fluoride (AmF), and normal saline. ONA were greater (P < .00) in individuals exposed to CHX, followed by ClO₂ , AmF, KNO₃ , and NaF and normal saline. Overall, the results showed that genotoxic damage was greater in the case of CHX, followed by ClO₂ , KNO₃ , and NaF, AmF, and normal saline.

CONCLUSION

Chronic exposure to mouth rinses can cause genotoxic damage to buccal epithelial cells. Long-term injudicious and inadvertent use of mouth rinses should be discouraged.

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

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

Proliferating fibroblasts and HeLa cells co-cultured in vitro reciprocally influence growth patterns, protein expression, chromatin features and cell survival

AIM

to identify biological interactions between proliferating fibroblasts and HeLa cells in vitro.

MATERIALS AND METHODS

Fibroblasts were isolated from both normal and tumour human tissues. Coverslip co-cultures of HeLa and fibroblasts in various ratios with medium replacement every 48 h were studied using fixed cell staining with dyes such as Giemsa and silver staining, with immunochemistry for Ki-67 and E-cadherin, with dihydrofolate reductase (DHFR) enzyme reaction, as well as live cell staining for non-specific esterases and lipids. Other techniques included carmine cell labeling, autoradiography and apoptosis assessment.

RESULTS

Under conditions of feeding and cell: cell ratios allowing parallel growth of human fibroblasts and HeLa cells, co-cultured for up to 20 days, a series of phenomena occur consecutively: profound affinity between the two cell types and exchange of small molecules; encircling of the HeLa colonies by the fibroblasts and enhanced growth of both cell types at their contact areas; expression of carbonic anhydrase in both cell types and high expression of non-specific esterases and cytoplasmic argyrophilia in the surrounding fibroblasts; intense production and secretion of lipid droplets by the surrounding fibroblasts; development of a complex net of argyrophilic projections of the fibroblasts; E-cadherin expression in the HeLa cells; from the 10th day onwards, an increasing detachment of batches of HeLa cells at the peripheries of colonies and appearance of areas with many multi-nucleated and apoptotic HeLa cells, and small HeLa fragments; from the 17th day, appearance of fibroblasts blocked at the G2-M phase. Co-cultures at approximately 17-20 days display a cell-cell fight with foci of (a) sparse growth of both cell types, (b) overgrowth of the fibroblasts and (c) regrowth of HeLa in small colonies. These results indicate that during their interaction with HeLa cells in vitro, proliferating fibroblasts can be activated against HeLa. This type of activation is not observed if fibroblast proliferation is blocked by contact inhibition of growth at confluency, or by omitting replacement of the nutrient medium.

CONCLUSION

The present observations show that: (a) interaction between proliferating fibroblasts and HeLa cells in vitro drastically influences each other's protein expression, growth pattern, chromatin features and survival; (b) these functions depend on the fibroblast/HeLa ratio, cell topology (cell-cell contact and the architectural pattern developed during co-culture) and frequent medium change, as prerequisites for fibroblast proliferation; (c) this co-culture model is useful in the study of the complex processes within the tumour microenvironment, as well as the in vitro reproduction and display of several phenomena conventionally seen in tumour cytological sections, such as desmoplasia, apoptosis, nuclear abnormalities; and (d) overgrown fibroblasts adhering to the boundaries of HeLa colonies produce and secrete lipid droplets.

Karyopathological traits of thyrocytes and exposure to radioiodines in Belarusian children and adolescents following the accident at the Chernobyl nuclear power plant

The Belarus-American (BelAm) thyroid study cohort consists of persons who were 0-18 years of age at the time of exposure to radioactive iodine fallout from the 1986 Chernobyl nuclear power plant accident and who have undergone serial thyroid screenings with referral for fine-needle aspiration biopsy (FNAB) using standardized criteria. We investigated thyrocyte nuclear abnormalities in cytological samples from FNABs in 75 BelAm subjects with single and multiple thyroid nodules and 47 nodular goiter patients from Leningrad, Russia, unexposed to Chernobyl fallout. Nuclear abnormalities examined included internuclear chromosome bridges and derivative nuclei with broken bridges (i.e., "tailed" nuclei), which are formed from dicentric and ring chromosomes and thus may be cellular markers of radiation exposure. Among subjects with single-nodular goiter, thyrocytes with bridges were present in 86.8% of the exposed BelAm cohort compared with 27.0% of unexposed controls. The average frequency of thyrocytes with bridges and with tailed nuclei was also significantly higher in the BelAm subjects than in controls. Among subjects with multinodular goiters, thyrocytes with bridges were present in 75.7% of exposed BelAm patients compared with 16.7% of unexposed controls; thyrocytes with tailed nuclei were observed in all of the BelAm subjects but in only 40% of controls, and the mean frequencies of bridges and tailed nuclei were significantly higher in the exposed group. Unusually, long bridges were detected in 29% of BelAm patients with single-nodular goiters and 35% of those with multinodular goiters, while no such abnormalities were observed among patients from the Leningrad region. In the exposed subjects from BelAm, we also found positive correlations between their estimated dose of Iodine-131 from Chernobyl fallout and the frequency of tailed nuclei (p = 0.008) and bridges (p = 0.09). Further study is needed to confirm that these phenomena represent consequences of radiation exposure in the human organism.

Cytogenotoxicity biomarkers in fat snook Centropomus parallelus from Cananéia and São Vicente estuaries, SP, Brazil

The aquatic environment receives many contaminants that can induce damages at the molecular, biochemical, cellular and physiological levels. Centropomus parallelus, an important food resource for local populations, is a predator fish that feeds on small fishes and benthic invertebrates, thus being vulnerable to the bioconcentration and biomagnification processes. This study aimed to evaluate cytogenotoxic responses in erythrocytes from C. parallelus juveniles collected in the Cananéia and São Vicente estuaries, both in winter and in summer. After anesthesia, blood samples were collected by caudal puncture. Blood smears were prepared on glass slides and stained with May-Grünwald-Giemsa dye. Two thousand cells were analyzed per slide (1000x), and nuclear abnormalities (NA) and micronuclei (MN) were scored. The São Vicente sample showed MN and NA frequencies (%/1000 cells) of 0.325 and 3.575, in winter, and of 0.125 and 2.935 in summer respectively; the Cananéia sample showed frequencies of 0.0325 and 0.03, in winter, and of 0.065 and 0.355 in summer, respectively. The rates found in São Vicente were significantly higher than those found in Cananéia, evidencing that the levels of pollution in that estuary were high enough to induce genetic damages.