Use of Plant Bioassays for the Detection of Genotoxins in the Aquatic Environment

Antimitotic and toxicogenetic action of Stevia urticifolia aerial parts on proliferating vegetal and mammalian cells: in vitro and in vivo traditional and replacement methods

Stevia urticifolia Thunb. is an underexploited herb possessing bioactive flavonoids, saponins, and terpenoids. The aim of this study was to examine the antiproliferative and toxicogenetic properties of the ethyl acetate extract from Stevia urticifolia aerial parts (EtAcSur) upon Artemia salina, erythrocytes, Allium cepa and sarcoma 180 cells and fibroblasts, as well as in vivo studies on mice to determine systemic, macroscopic, and behavioral alterations and bone marrow chromosomal damage. The assessment using A. salina larvae and mouse blood cells revealed LC₅₀ and EC₅₀ values of 68.9 and 113.6 µg/ml, respectively. Root growth and mitosis were inhibited by EtAcSur, and chromosomal aberrations were detected only at 100 μg/ml. EtAcSur exhibited potent concentration-dependent viability reduction of S180 and L-929 cells and antioxidant capacity employing ABTS^• and DPPH^•. No previous in vivo studies were performed before with the EtAcSur. Signals of acute toxicity were not observed at 300 mg/kg. Physiological and toxicological investigations at 25 and 50 mg/mg/day i.p. for 8 days did not markedly change body or organ relative weights, nor patterns of spontaneous locomotor and exploratory activities. In contrast, clastogenic effects on bone marrow were found at 50 mg/mg/day. EtAcSur was found to (1) produce toxicity in microcrustaceans, (2) capacity as free radical scavenger, (3) antimitotic, cytotoxic and clastogenic activties upon vegetal and mammalian cells, and (4) lethality on both tumor and normal murine cells indistinctly. In vivo damage systemic effects were not remarkable and clinical signals of toxicity were not observed, suggesting the significant pharmacological potential of S. urticifolia for the development of antineoplastic agents.Abbreviations: ABTS: 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid); DMSO: dimethylsulfoxide; DPPH: 1,1-diphenyl-2-picrylhydrazyl; EC₅₀: effective concentration 50%; EtAcSur: ethyl acetate extract from Stevia urticifolia aerial parts; Hb, hemoglobin; IC₅₀: inhibitory concentration 50%; LC₅₀,: lethal concentration 50%; MI: mitotic index; RBC, red blood cells; Trolox: 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid.

Toxicological, chemopreventive, and cytotoxic potentialities of rare vegetal species and supporting findings for the Brazilian Unified Health System (SUS)

Caatinga flora which are found in a poor Brazilian region contain a substantial number of endemic taxa with biomedical and social importance for regional communities. This study examined the antioxidant and cytotoxic potential of 35 samples (extracts/fractions) from 12 Caatinga species and determined the antiproliferative and genotoxic action of dichloromethane fraction from Mimosa caesalpiniifolia stem bark (DC-Mca) on human and vegetal cells. Samples were assessed for chemopreventive ability, toxic effects on Artemia salina shrimp as well as cytotoxicity on tumor cell lines and erythrocytes. DC-Mca was also tested with respect to antiproliferative and genotoxic effects upon normal leukocytes and meristematic cells from A. cepa roots. Some extracts reduced free radical levels >95% and 7 samples exhibited a lethal concentration (LC) ₅₀ < 100 µg/ml upon Artemia salina larvae. Eight samples displayed in vitro antitumor effects and three produced hemolysis. Data also demonstrated the pharmacological significance of bioactive extracts from Brazilian semi-arid region. There was no significant relationship between antioxidant, toxic, and antiproliferative activities, and that these properties were dependent upon the extractant. DC-Mca contained betulinic acid as main compound (approximately 70%), which showed higher (1) cytotoxic activity on cancer cell lines and dividing leukocytes, (2) reduced mitotic index of Allium cepa roots, and (3) induced cell cycle arrest and chromosomal bridges, thereby providing native promising sources for phytotherapy development.

ABBREVIATIONS

ABTS: 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid); AcOH: ethyl acetate; ANOVA: analysis of variance; SUS: Brazilian Unified Health System; DC-Mca: dichloromethane fraction from Mimosa caesalpiniifolia stem bark; DMSO: dimethylsulfoxide; DPPH: 1,1-diphenyl-2-picrylhydrazyl; EC₅₀: effective concentration 50%; EtOAc: ethyl acetate; FDA: Food and Drug Administration; GC-Qms: gas chromatograph quadrupole mass spectrometer; GI: genotoxic index; HCT-116: colon carcinoma line; HL-60: promyelocytic leukemia line; HPLC: high-performance liquid chromatography; HRAPCIMS: high resolution atmospheric pressure chemical ionization mass spectrum; IC₅₀: inhibitory concentration 50%; LC₅₀: lethal concentration 50%; MeOH = methyl alcohol; MI: mitotic index; MTT: 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide; MutI: mutagenic index; OVCAR-8 = ovarian carcinoma line; PBMC: peripheral blood mononuclear cells; RPMI-1640: Roswell Park Memorial Institute medium; SF-295: glioblastoma line; TEAC: trolox equivalent antioxidant capacity; TLC: thin-layer chromatography; Trolox: 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid.

Micronucleus Assay with Tetrad Cells of Tradescantia

The Tradescantia micronucleus assay has been used since 50 years for the detection of genotoxins (including carcinogens) in the environment. A large database concerning the effects of individual chemicals and complex environmental mixtures (soil, air and waters) has accumulated. In contrast to other mutagenicity test systems, the effects of low concentrations of heavy metals, radionuclides, certain herbicides, pesticides and gaseous mutagens can be detected and it is also possible to conduct in situ biomonitoring studies with plant. The test system has been validated and standardized protocols have been developed for laboratory experiments and for field studies which are described in this chapter.

Far-reaching cytogenotoxic effects of mine waste from the Fundão dam disaster in Brazil

On November 2015, one of Brazil's most important watersheds was impacted by the mine waste from Fundão dam collapse in Mariana. The mine waste traveled over 600 km along the Doce River before reaching the sea, causing severe devastation along its way. Here we assessed trace element concentrations and cytogenotoxic effects of the released mine waste. Water samples were collected along the Doce River ten days after the disaster in two impacted sites and one non-impacted site. Sampling points were located hundreds of kilometers downstream of the collapsed dam. Water samples were used for trace element quantification and to run an experiment using Allium cepa to test cytogenotoxicity. We found extremely high concentrations of particulate Fe, Al, and Mn in the impacted sites. We observed cytogenotoxic effects such as alterations in mitotic and phase indexes, and enhanced frequency of chromosomal aberrations. Our results indicate interferences in the cell cycle in impacted sites located hundreds of kilometers downstream of the disaster. The environmental impacts of the dam collapse may not only be far-reaching but also very likely long-lasting, because the mine waste may persist in the Doce River sediment for decades.

Physicochemical and Genotoxic Evaluations of Singed Cowhide Meat (Ponmo) Wastewater

INTRODUCTION

In spite of doubts over the safety and nutritional benefits of singed cowhide meat, called ponmo in some parts of Nigeria, and its potential negative impact on the hide and leather industry, consumption in Nigeria and many parts of Africa has continued unabated.

OBJECTIVES

In the present study, physicochemical and genotoxic assessments of wastewater used to rinse ready-to-cook singed cowhide meat were carried out.

METHODS

Physicochemical analyses were carried out using the American Public Health Association procedures, while genotoxic assessment was carried out using Allium cepa chromosome assay.

RESULTS

The results of the physicochemical analyses indicated that some of the parameters, especially metals, were within the threshold of the limits set by the country's regulatory agencies, but some parameters like phosphate, chloride, nitrate, biological oxygen demand, and chemical oxygen demand were higher in concentration. The wastewater inhibited the growth of A. cepa roots and caused a decrease in its mitotic index relative to the control onions exposed to water only. The highest root growth inhibition of 72.14% was induced by a 10% wastewater concentration, while the lowest (53.57%) was induced by a 5% wastewater concentration. In addition, the wastewater induced bi-nucleated, attached, vagrant, C-mitosis, sticky and bridged chromosomal aberrations. Wastewater at a 5% concentration induced the highest significant (P < 0.05) percentage chromosome aberration of 36.62% at 48 hours of exposure. Sticky chromosomes had the highest significant frequency (P <0.01) at the end of the 72-hour exposure period. No chromosomal aberration was observed in the control.

CONCLUSIONS

These results indicate that singed cowhide meat wastewater is potentially genotoxic and environmentally harmful. Governments, public health practitioners, and relevant stakeholders should work in synergy to discourage the habit of processing cowhide into cowhide meat.

COMPETING INTERESTS

The authors declare no competing financial interests.

Clastogenecity evaluation of water of Lake Sevan (Armenia) using Tradescantia micronucleus assay

The clastogenic effects of water samples in seven locations of Lake Sevan (Armenia) with the application of Trad-MCN (micronuclei) bioassay using Tradescantia (clone 02) were investigated. A significant increase in the frequency of micronuclei in tetrads of pollen microspores and tetrads with micronuclei exposed to the test samples compared to the control has been revealed. A multivariate analysis indicated linkage between the frequencies of occurrence of micronuclei in the cells and Ni and Co ions. The results were compared with the endpoints of another Tradescantia-based test system (stamen hair mutation test) performed on the same water samples and generation of the plant: occurrences of micronuclei in sporogenic cells coincided with that of non-surviving stamen hair.

River pollution in the Kosovo: Cyto- and genotoxic effects of water samples in the primary rat hepatocyte assay

The actual stage of the development of Kosovo is characterized by the concerning levels of environmental pollution and the serious health problems attributed to the emission of pollutants into air, soil and water. In this context, river pollution is one of the main threats due to the discharge of untreated urban and industrial waste waters that affect the quality of surface and ground water. In addition, urban and agricultural discharges are affecting the river water quality. In this article, we are presenting data on the cyto- and genotoxic potential of water samples from three rivers (Sitnica, Drenica and Lepenci) in the Kosovo as determined in the cultures of primary rat hepatocytes. Sitnica and Drenica (as the most important Sitnica tributary) drain into the Black Sea, whereas the Lepenci river drains into the Aegean Sea. These rivers are polluted mainly by industry in the Kosovo together with municipal discharges. The results of this study show that the samples have primarily a cytotoxic potential by causing necrotic cell death that was not accompanied by any increase of the rate of micronucleated cells as an indicator for a genotoxic potential. The different effects in 2 consecutive years can be attributed to variations in physico-chemical parameters such as water levels, intake of pollutants, and so on, indicating the need for continuous monitoring and risk assessment.

Marinobufagin, a molecule from poisonous frogs, causes biochemical, morphological and cell cycle changes in human neoplasms and vegetal cells

Skin toad secretion present physiologically active molecules to protect them against microorganisms, predators and infections. This work detailed the antiproliferative action of marinobufagin on tumor and normal lines, investigate its mechanism on HL-60 leukemia cells and its toxic effects on Allium cepa meristematic cells. Initially, cytotoxic action was assessed by colorimetric assays. Next, HL-60 cells were analyzed by morphological and flow cytometry techniques and growing A. cepa roots were examined after 72 h exposure. Marinobufagin presented high antiproliferative action against all human tumor lines [IC₅₀ values ranging from 0.15 (leukemia) to 7.35 (larynx) μM] and it failed against human erythrocytes and murine lines. Human normal peripheral blood mononuclear cells (PBMC) were up to 72.5-fold less sensitive [IC_50: 10.88 μM] to marinobufagin than HL-60 line, but DNA strand breaks were no detected. Leukemia treaded cells exhibited cell viability reduction, DNA fragmentation, phosphatidylserine externalization, binucleation, nuclear condensation and cytoplasmic vacuoles. Marinobufagin also reduced the growth of A. cepa roots (EC₅₀: 7.5 μM) and mitotic index, caused cell cycle arrest and chromosomal alterations (micronuclei, delays and C-metaphases) in meristematic cells. So, to find out partially targeted natural molecules on human leukemia cells, like marinobufagin, is an amazing and stimulating way to continue the battle against cancer.

Genotoxic and mutagenic effects of polluted surface water in the midwestern region of Brazil using animal and plant bioassays

This study aimed to evaluate DNA damage in animal and plant cells exposed to water from the Água Boa stream (Dourados, Mato Grosso do Sul, Brazil) by using bioassays, and to identify the chemical compounds in the water to determine the water quality in the area. Through the cytotoxicity bioassay with Allium cepa, using micronucleus test, and comet assay, using Astyanax altiparanae fish, the results indicated that biological samples were genetically altered. Micronuclei were observed in erythrocytes of A. altiparanae after exposure to water from locations close to industrial waste discharge. The highest DNA damage observed with the comet assay in fish occurred with the exposure to water from locations where the presence of metals (Cu, Pb, Cd, Ni) was high, indicating the possibility of genotoxic effects of these compounds. Thus, these results reinforce the importance of conducting genotoxicity tests for developing management plans to improve water quality, and indicate the need for waste management before domestic and industrial effluents are released into the rivers and streams.

Detoxification and safety evaluation of aflatoxin B1 in peanut oil using alkali refining

BACKGROUND

Aflatoxin B1 (AFB1 ) is often detected in peanut oil, which comes from contaminated peanuts. AFB1 in peanut oil seriously threatens the health of consumers. However, there are few methods to effectively remove AFB1 in peanut oil. This study aimed to use an alkali-refining method to degrade AFB1 in peanut oil efficiently without increasing the equipment of oil and fat refining.

RESULTS

The optimum detoxifying conditions of AFB1 in peanut oil with alkali refining were established using response surface methodology (RSM), and the safety of peanut oil after being refined with alkali was evaluated based on the Ames tests and HepG2 cell viability. The results showed that AFB1 in peanut oil was decreased from 34.78 to 0.37 µg kg(-1) (98.94% reduction) under the optimum detoxifying conditions, i.e. when the initial temperature of alkali refining was 43.51 °C, the amount of excess alkali was 0.30%, the content of alkali solution was 23.42% and the end temperature of alkali refining was 77.07 °C. The acid value and color of peanut oil refined by alkali were improved significantly, while the peroxide value was increased within an acceptable level. The safety of peanut oil contaminated by AFB1 was improved significantly after being refined with alkali.

CONCLUSION

These results indicate that alkali refining is an effective method for removing AFB1 in peanut oil. The optimum detoxifying conditions of AFB1 in peanut oil with alkali refining could be used to guide the production of oil companies for ensuring food safety. © 2015 Society of Chemical Industry.

Analyses of combined effects of cytostatic drugs on micronucleus formation in the Tradescantia

Recent experiments showed that 5-fluorouracil (5FU), cisplatin (CDDP), etoposide (ET), and imatinib mesylate (IM), which are currently among the most widely used anticancer drugs, cause damage of the genetic material in higher plants. The aim of the present study was to determine whether mixtures of these drugs cause synergistic or antagonistic effects which may have an impact on their environmental safety. Therefore, the effects of binary mixtures of these anticancer drugs on the induction of micronuclei (MN) which reflect structural and numerical chromosomal aberrations were assessed in Tradescantia tetrads. Synergistic/antagonistic effects were determined by comparison with single exposures that would be equally effective in a reference model of independent action. This comparison was performed at two distinct effect sizes. We found clear evidence for synergisms in combination experiments with IM and antagonism in a high-dose experiment with ET and 5FU. Our findings indicate that IM increases the genotoxic effects of other anticancer drugs. The maximal effects which we found were in the range between 19 and 38 % in the excess of effect sizes predicted under independent action. These effects may have an impact on the overall genotoxic activities of untreated hospital waste waters but not on the environment in general as the predicted environmental concentrations of the studied drugs are several orders of magnitude lower as the levels which are required to cause induction of MN in higher plants.

Cytotoxic and genotoxic assessment of surface water from São Paulo State, Brazil, during the rainy and dry seasons

The aim of this study was to determine if the cytotoxic and genotoxic responses of Allium cepa are effective biomarkers of harmful effects caused by polluted river water and if changes in the responses reflect seasonality in the harmful effects. Samples were collected in the dry season (August 2011 and 2012) and rainy season (February 2012 and 2013) at sampling points on the Jaguari River and the Ribeirão Lavapés, in Brazil. Allium cepa bulbs were exposed to the samples, to positive controls (15 µg/L methyl methanesulfonate), and to negative controls (tap water). Three root tips from each bulb were then stained using the Feulgen reaction, then the micronucleus frequency, the mitotic index, and mitotic anomalies were measured. The total number of anomalies (stickiness, c-mitosis, multipolarity, chromosome bridges, and unidentified anomalies) in the rainy season (8.61 ± 3.65) and dry season (7.07 ± 2.96) were significantly different (U = 11.31, p = 0.04). Toxicity, indicated by the formation of micronuclei and the mitotic index, was higher in the February 2012 samples than in the August 2012 samples. The mean manganese concentration (0.13 mg/L) in the rainy season samples was higher than the maximum concentration permitted by the Brazilian National Environmental Council (<0.1 mg/L) and the manganese concentrations positively correlated with chromosomal aberration induction (p = 0.01, r = 0.69). In conclusion, the rainy season samples were more toxic than the dry season samples. This was probably related to rain water carrying compounds with potentially negative impacts into the rivers. These findings highlight the importance of biomonitoring studies and of treating wastewater in urban areas.

Biomonitoring of the environmental genotoxic potential of emissions from a complex of ceramic industries in Monte Carmelo, Minas Gerais, Brazil, using Tradescantia pallida

The micronucleus (MN) test and analysis of heavy metal biological accumulation in Tradescantia pallida (T. pallida) were bioassays used to assess the genotoxic potential of emissions from a complex of ceramic industries into the atmosphere in a city in Brazil that is considered a national reference source for roof tile production. The ceramic industry emission-exposed T. pallida plants were biomonitored during the dry season, in June, July, and August 2013. In addition to the contaminated monitoring site, a reference site in a peri-urban area was utilized, for comparative purposes. Genotoxicity assessments were determined monthly, while heavy metal bioaccumulation was measured at the end of the total exposure period. The MN frequency was significantly greater in T. pallida plants exposed in the ceramic industry emission monitored area compared to the reference site, and highest MN rates were observed in July and August. With respect to heavy metal bioaccumulation in T. pallida leaves, cadmium (Cd) and chromium (Cr) concentrations were significantly higher in plants at the ceramic industry emission monitoring site. Thus, in relation to the parameters assessed, T. pallida was found to be sensitive to atmospheric contamination by heavy metals attributed to ceramic products emissions generated by the ceramic industry, confirming that this plant species may be employed as a reference organism in biomonitoring studies.

Genotoxic evaluation of the River Paranaíba hydrographic basin in Monte Carmelo, MG, Brazil, by the Tradescantia micronucleus

Pollutants have adverse effects on human health and on other organisms that inhabit or use water resources. The aim of the present study was to assess the environmental quality of three watercourses in Monte Carmelo, MG, Brazil, using the micronucleus test on Tradescantia. For each treatment, 15 plants were exposed to water samples for 24 h. The control group was exposed to formaldehyde (0.2%) and the negative control to Hoagland solution. Subsequently the plants were placed in Hoagland solution for 24 h to recover. Cells were stained with 2% acetic carmine and examined by light microscopy. Three hundred tetrads were analyzed per slide. The frequency of genotoxic alterations was expressed as the number of micronuclei per 100 tetrads, and the groups were compared by ANOVA. At all sample sites for each watercourse significant genotoxicity indices were observed. The results suggest that in the Mumbuca creek, the current situation of effluent discharge should be reconsidered by the municipal environmental authorities. The increase in micronucleus frequency denoted for water samples of the Mumbuca creek, Lambari river and Perdizes river emphasizes the need to adopt environmental vigilance strategies, such as biological monitoring.

Potential cytotoxic effect of Anilofos by using Allium cepa assay

Cytogenetic effects of Anilofos which was widely used in agriculture, was evaluated in Allium cepa root meristematic cells. In the Allium root growth inhibition test EC50 value was determined 50 ppm and 1/2× EC50 (25 ppm), EC50 (50 ppm) and 2 × EC50 (100 ppm) concentrations of Anilofos were applied to onion roots. A negative and positive control were used in the experiment in parallel. According to results mitotic index decreased with increasing the Anilofos concentrations in all application groups and each exposure time, while disturbed anaphase-telophase, choromosome laggard(s), stickiness and anaphase bridge(s) were observed. In anaphase-telophase cells, c-metaphase, disturbed nucleus and binuclear cells were observed in other anomalies. The results were also analyzed statistically by using Dunnett t test (2-tailed) and all concentrations of Anilofos were found significant.

Evaluation of toxic, cytotoxic, mutagenic, and antimutagenic activities of natural and technical cashew nut shell liquids using the Allium cepa and Artemia salina bioassays

The cashew nut releases a substance that is known as cashew nut shell liquid (CNSL). There are both natural (iCNSL) and technical (tCNSL) cashew nut shell liquids. This study used an Artemia salina bioassay to evaluate the toxic effects of iCNSL and tCNSL cashew nut shell liquids. It also evaluated the toxicity, cytotoxicity, and mutagenicity of CNSL and its effects on the damage induced by copper sulfate (CuSO4·5H2O) on the meristems' root of Allium cepa. Effects of the damage induced by CuSO4·5H2O were evaluated before (pre-), during (co-), and after (post-) treatments. The iCNSL contained 94.5% anacardic acid, and the tCNSL contained 91.3% cardanol. The liquids were toxic to A. salina. Toxicity, cytotoxicity, and mutagenicity were observed with iCNSL compared with the negative control. Similarly, iCNSL failed to inhibit the toxicity and cytotoxicity of CuSO4·5H2O. The tCNSL was not toxic, cytotoxic, or mutagenic in any of the concentrations. However, the lowest iCNSL concentrations and all of the tCNSL concentrations had preventive, antimutagenic, and reparative effects on micronuclei and on chromosomal aberrations in the A. cepa. Therefore, protective, modulating, and reparative effects may be observed in the A. cepa, depending on the concentration and type of CNSL used.

Acute toxic and genotoxic activities of widely used cytostatic drugs in higher plants: Possible impact on the environment

Cytostatic drugs are highly toxic pharmaceuticals and it was repeatedly postulated that they may cause adverse effects in ecosystems. The acute toxic and genotoxic properties of these drugs have not been adequately investigated in higher plants so far; therefore, we studied the most widely used drugs (5-flurouracil, 5FU; etoposide, Et; cisplatin, CisPt; carboplatin, CaPt; vincristine sulfate, VinS and cyclophosphamide monohydrate, CP) in micronucleus (MN) assays with meiotic pollen tetrad cells of Tradescantia and with root cells from Allium cepa. MNi are formed as a consequence of chromosome breaks and aneuploidy. We monitored also the acute toxic properties of the drugs, i.e. inhibition of cell division (mitotic indices and retardation of root growth) in the latter species. All compounds caused in both indicator plants genotoxic effects. The order of genotoxic potencies expressed as NOELs in µM was CisPt (0.1)≥ Et (0.5)>CP (1.0)>CaPt (10)>5FU (30)>VinS (100) in Tradescantia. A similar order was seen in Allium MN but Et was less active (5.0µM). Four compounds caused alterations of the mitotic indices under the present conditions namely CisPt (0.5), Et (10.0), 5FU (10.0) and VinS (100). Inhibition of root growth decreased in the order CisPt (0.5)>Et (1.0)≥VinS (1.0)>5FU (5.0)>CaPt (33.0)>CP (>1000). Comparisons of the NOELs with the predicted environmental concentrations (PEC) show that the latter values are at least 5 orders of magnitude lower and indicate that it is unlikely that their release in the environment may cause adverse effects in higher plants. However, it is notable that the levels of both platinum compounds and of 5FU in hospital effluents may reach levels which may induce damage of the genetic material.

Allium cepa L. as a bioindicator to measure cytotoxicity of surface water of the Quatorze River, located in Francisco Beltrão, Paraná, Brazil

Due to an increase in water consumption in the industrial sector and within the Brazilian population, surface water that receives wastewater from industries, domestic sewage, agricultural industries, and sewage treatment stations can pollute water bodies when not properly treated. The water quality has been linked to catchment characteristics and intensity of agricultural activities. Thus, the aim of this study was to monitor the cytotoxic potential of the water of the Quatorze River, located in the town of Francisco Beltrão, Paraná, Brazil, along its route in the rural area, using the root meristematic cells of Allium cepa L. as a bioindicator. The results showed that the water at points 2, 3, and 4 were not cytotoxic because the rates of A. cepa cell division were unaltered. Point 1 had presented a mitotic index that was statistically larger than the negative control, indicating that this water contained substances with mitogenic capacity, as demonstrated by elevated values in chemical oxygen demand (COD) and biochemical oxygen demand (BOD). However, the mitotic index values decreased along the route of the river (point 1 to point 4), possibly indicating a mechanism of self-purification, despite having received other sources of pollution. Thus, the results of this study show that the water of the Quatorze River should undergo periodic environmental monitoring at different times of the year, including cytotoxicity analysis, to evaluate the principal sources of contamination to maintain the quality of the river water and, consequently, to maintain human health and equilibrium of the entire ecosystem.

DNA integrity of onion root cells under catechol influence

Catechol is a highly toxic organic pollutant, usually abundant in the waste effluents of industrial processes and agricultural activities. The environmental sources of catechol include pesticides, wood preservatives, tanning lotion, cosmetic creams, dyes, and synthetic intermediates. Genotoxicity of catechol at a concentration range 5 × 10(-1)-5 mM was evaluated by applying random amplified polymorphic DNA (RAPD) and time-lapse DNA laddering tests using onion (Allium cepa) root cells as the assay system. RAPD analysis revealed polymorphisms in the nucleotidic sequence of DNA that reflected the genotoxic potential of catechol to provoke point mutations, or deletions, or chromosomal rearrangements. Time-lapse DNA laddering test provided evidence that catechol provoked DNA necrosis and apoptosis. Acridine orange/ethidium bromide staining could distinguish apoptotic from necrotic cells in root cells of A. cepa.

Micronucleus assay with tetrad cells of Tradescantia

The Tradescantia micronucleus assay is being used since almost 50 years for the detection of genotoxins (including carcinogens) in the environment. A large database on the effects of individual compounds and of complex environmental mixtures (soil, air and water) has accumulated. In contrast to other mutagenicity test systems, the effects of low concentrations of heavy metals, radionuclides, certain herbicides and pesticides, and gaseous mutagens can be detected and it is also possible to use the test for in situ biomonitoring studies. The test system has been validated, and standardized protocols have been developed for laboratory experiments and for field studies, which are described in this chapter.

Plants as models for chromium and nickel risk assessment

The adverse effects of Cr(III), Cr(VI), and Ni(II) expressed as root and shoot growth inhibition, metal accumulation and translocation throughout plants, and genotoxicity study were examined. To examine phytoxicity and metal accumulation, Vicia sativa, Raphanus sativus, Zea mays and Sinapis alba plants were used. Except for S. alba root growth inhibition, Ni had the strongest inhibitory effect on root and shoot growth. The inhibitory rank order based on IC₅₀ values was Ni(II) > Cr(VI) > Cr(III). Z. mays was the least sensitive to all metals. While the accumulation of Cr was higher in the roots than the upper plant parts, Ni transport to shoots was at least two times higher than that of Cr. The highest accumulation of Cr was found in Z. mays and that of Ni in V. sativa and Z. mays roots. For all plants, the translocation factor was higher for Cr(VI) than for Cr(III). The translocation factor for Ni was several times higher than those of Cr. For mutagenicity assay, root tips of V. sativa, R. sativus and Z. mays were used. All metals exerted a significant increase of chromosomal aberrations and the rank order of aberrations was: Cr(VI) > Ni(II) > Cr(III). Genotoxic effects of metals were also determined by analysis of micronuclei frequency in the pollen tetrads of Tradescantia plants. None of metals significantly stimulated micronuclei frequency and the genotoxic effect decreased in the following order: Cr(VI) ≥ Ni(II) > Cr(III).

Biological activities of phenolic compounds and ethanolic extract of Halacsya sendtneri (Boiss) Dőrfler

The objective of this study was to evaluate the efficacy of the ethanolic extract of endemic plant Halacsya sendtneri in inhibiting the growing of the test fungi and bacteria as well as to determine its genotoxic potential and toxicity using the Allium anaphase-telophase assay. Minimum inhibitory concentrations (MIC) were determined for 15 indicator strains of pathogens, representing both bacteria and fungi. The highest susceptibility to the ethanolic extract of H.sendtneri was exhibited by Pseudomonas glycinea (FSB4), (MIC=0.09 mg/ml) among the bacteria, and by Phialophora fastigiata (FSB81), (MIC=1.95 mg/ml) among the fungi. The composition of H. sendtneri extracts was also determined using HPLC analysis. Rosmarinic acid was found to be the dominant phenolic compound. The Allium anaphase-telophase genotoxicity assay revealed that the ethanolic extract of H. sendtneri at concentrations of 31.5 mg/l and below does not produce toxic or genotoxic effects. This is the first report of chemical constituents, genotoxic and antimicrobial activities of the endemic species, H. sendtneri.

Impact of ozonation on the genotoxic activity of tertiary treated municipal wastewater

Ozonation is an emerging technology for the removal of micropollutants from treated wastewater. Aim of the present study was to investigate the impact of ozone treatment on genotoxic and acute toxic effects of tertiary treated municipal wastewater. It is known that DNA-damaging chemicals cause adverse effects in the environment and that exposure to humans leads to cancer and other diseases. Toxicity was tested in organisms from three trophic levels namely in bacteria (Salmonella/microsome assays) which enable the detection of gene mutations, in a plant bioassay (micronucleus assay with root tip cells of Allium cepa) which reflects clastogenic and aneugenic effects and in single cell gel electrophoresis (SCGE) tests with mammalian cells which detect DNA migration caused by single-, double strand breaks and alkali labile sites. In the bacterial tests negative results were obtained with untreated samples but after concentration with C(18) cartridges a positive result was found in strains TA1537 and TA98 which are sensitive to frameshift mutagens while no mutations were induced in other tester strains (TA100, TA102 and YG1024). Ozone treatment led to a decrease of the mutagenic activity of the samples. In the SCGE experiments, DNA migration was detected with the unconcentrated effluent of the treatment plant and ozonation led to a substantial decrease of this effect. In the plant bioassays, negative results were obtained with the effluent and ozone treatment did not cause an alteration of the micronucleus frequencies. Also acute toxic effects were monitored in the different indicator organisms under all experimental conditions. The bacteriocidal/bacteriostatic effects which were seen with the concentrated samples were reduced by ozonation. In the experiments with the eukaryotic (plant and animal) cells no acute toxicity was seen with the effluents and ozonation had no impact on their viability. In conclusion findings of this study indicate that ozonation of tertiary effluents of a municipal treatment plant reduces the adverse effects caused by release of mutagens in aquatic ecosystems and does not decrease the viability of bacteria and eukaryotic cells. However, future research is required to find out if, and to which extent these findings can be generalized and which mechanisms account for the detoxification of the wastewater.

Micronucleus assays with Tradescantia pollen tetrads: an update

Micronucleus (MN) assays with early pollen tetrad cells of Tradescantia (Trad-MN assays) are at present the most widely used bioassays with plants for the detection of genotoxins in the environment. So far, ∼ 160 chemicals have been tested and ∼ 100 articles that concern complex environmental mixtures were published. This article summarises the results of Trad-MN studies, which have been carried out during the last 15 years with individual compounds and investigations concerning the pollution of environmental compartments (soil, water and air). The evaluation shows that the effects of certain genotoxins such as heavy metals, radionuclides, pesticides and air pollutants can be easily detected with this test. Comparisons with results obtained in MN studies with mitotic (root tip) cells indicate that meiotic tetrad cells are in general more sensitive. Important issues for future research concern the evaluation of the suitability of wildlife Tradescantia species that are sometimes used instead of specific clones (such as #4430 for which standardised protocols have been developed) as well as the assessment of the predictive value of Trad-MN results in regard to the prediction of cancer hazards in humans and adverse effects at the ecosystem level. The fact that the genotoxic effects of certain compound such as metals, which can be detected with plant bioassays, in particular with the Trad-MN assay but not in other commonly used bioassays (e.g. in bacterial tests) makes them an essential element in the batteries for environmental monitoring.

Assessment of detoxification of microcystin extracts using electrochemical oxidation

Microcystins, cyclic heptapeptide toxins produced by cyanobacteria, possess tumor-promoting activity, which act through inhibition of protein phosphatases 1 and 2A. In this study, the variation in toxicity of microcystins from Microcystis aeruginosa during electrooxidation was assessed using bioassays. The microcystin-LR samples (MCLR) were prepared by crude extracts dissolved in electrolytes, e.g., 0.02 mol L(-1) Na(2)SO(4), 0.02 mol L(-1) Na(2)SO(4) containing 0.5 mmol L(-1) NaCl, and tap water. Electrooxidation was conducted at a current density of 4 mA cm(-2) at room temperature (20-26°C), using Ti/RuO(2) anodes. Toxicological profiles for acute toxic effects (Vibrio fischeri) and genotoxic effects (Vicia faba micronucleus assay and single cell gel electrophoresis assay of mice lymphocytes) were determined for both untreated and treated MCLR samples. Results showed that acute toxicity during treatment was caused mainly by residual oxidants from electrooxidation. The by-products from the degradation of MCLR samples showed very weak acute toxicity to V. fischeri. Before electrooxidation, MCLR samples could induce obvious cell damage to V. faba root tips and mice lymphocytes. Electrooxidation degradation significantly decreased the genotoxicity of MCLR samples until the final by-products showed no toxicity. Thus, electrooxidation can detoxify MCLR samples via degradation processes.

Sensitivity of Bidens laevis L. to mutagenic compounds. Use of chromosomal aberrations as biomarkers of genotoxicity

The wetland macrophyte Bidens laevis possesses suitable cytological characteristics for genotoxicity testing. To test its sensitivity as compared to terrestrial plants species currently in use in standardized assays, Methyl Methanesulfonate (MMS), N-ethyl-N-nitrosourea (ENU) and Maleic Hydrazide (HM) were used. On the other hand, the insecticide Endosulfan (ES)--an environmentally relevant contaminant--was assayed in seeds and two-month old plants. Mitotic Index (MI), frequency of Chromosome Aberrations in Anaphase-Telophase (CAAT) and frequency of Abnormal Metaphases (AM) were analyzed. MH, MMS and ENU caused a significant decrease of the MI. MMS was aneugenic whereas MH and ENU were both aneugenic and clastogenic. ES caused a significant concentration-dependent increase of total- and aneugenic-CAAT in roots and a significant high frequency of AM at high concentrations. Because of its sensitivity to mutagenic substances, B. laevis can be regarded as a reliable and convenient species for genotoxicity assays especially if aquatic contaminants are evaluated.

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.

Evaluation of the cytotoxic and genotoxic potential of water from the River Paraíba do Sul, in Brazil, with the Allium cepa L. test

This work investigated the cytotoxic and genotoxic potential of water from the River Paraíba do Sul (Brazil) using Allium cepa roots. An anatomo-morphological parameter (root length), mitotic indices, and frequency of micronuclei were analysed. Eight bulbs were chosen at random for treatment for 24 to 120 hours with the River water collected in the years of 2005 and 2006 from sites in the cities of Tremembé and Aparecida (São Paulo state, Brazil). Daily measurements of the length of the roots grown from each bulb were carried out throughout the experiment. Mitotic index (MI) and frequency of micronuclei (MN) were determined for 2000 cells per root, using 3-5 root tips from other bulbs (7-10). Only in the roots treated with samples of the River water collected in 2005 in Tremembé city was there a decrease in the root length growth compared to the respective control. However, a reduction in MI values was verified for both sites analysed for that year. Considering the data involving root length growth and especially MI values, a cytotoxic potential is suggested for the water of the River Paraíba do Sul at Tremembé and Aparecida, in the year of 2005. On the other hand, since in this year the MN frequency was not affected with the river water treatments, genotoxicity is not assumed for the river water sampled at the aforementioned places.

Genotoxicity assessment in aquatic environment impacted by the presence of heavy metals

The aim of this study was to access the genotoxic potential of Extremoz Lake waters in Northeastern Brazilian coast, using the Allium cepa system, piscine micronucleus test and comet assay. In addition, heavy metal levels were quantified by atomic absorption flame spectrometry. The results of the A. cepa system showed significant changes in the frequency of chromosome aberrations and in the mitotic index compared to negative control. No significant changes were observed in micronuclei frequency in the erythrocytes of Oreochromis niloticus. The comet assay showed a statistically significant alteration in the level of DNA breaks of O. niloticus. Chemical analysis detected an increase in heavy metal levels in different sampling periods. These results point out a state of deterioration of water quality at Extremoz Lake, caused by heavy metal contamination and genotoxic activity. It is recommended to establish a monitoring program for the presence of genotoxic agents in this water lake.

Genotoxic evaluation of an industrial effluent from an oil refinery using plant and animal bioassays

Polycyclic aromatic hydrocarbons (PAHs) are genotoxic chemicals commonly found in effluents from oil refineries. Bioassays using plants and cells cultures can be employed for assessing environmental safety and potential genotoxicity. In this study, the genotoxic potential of an oil refinery effluent was analyzed by means of micronucleus (MN) testing of Alium cepa, which revealed no effect after 24 h of treatment. On the other hand, primary lesions in the DNA of rat (Rattus norvegicus) hepatoma cells (HTC) were observed through comet assaying after only 2 h of exposure. On considering the capacity to detect DNA damage of a different nature and of these cells to metabolize xenobiotics, we suggest the association of the two bioassays with these cell types, plant (Allium cepa) and mammal (HTC) cells, for more accurately assessing genotoxicity in environmental samples.

Potential genotoxic effects of melted snow from an urban area revealed by the Allium cepa test

The presence of well-known atmospheric pollutants is regularly screened for in large towns but knowledge about the effects of mixtures of different pollutants and especially their genotoxic potential is largely missing. Since falling snow collects pollutants from the air, melted snow samples could be suitable for evaluating potential genotoxicity. For this purpose the Allium cepa anaphase-telophase test was used to analyse melted snow samples from Belgrade, the capital city of Serbia. Samples of snow were taken at two sites, characterized by differences in pollution intensity, in three successive years. At the more polluted site the analyses showed a very high degree of both toxicity and genotoxicity in the first year of the study corresponding to the effects of the known mutagen used as the positive control. At the other site the situation was much better but not without warning signals. The results showed that standard analyses for the presence of certain contaminants in the air do not give an accurate picture of the possible consequences of urban air pollution because the genotoxic potential remains hidden. The A. cepa test has been demonstrated to be very convenient for evaluation of air pollution through analyses of melted snow samples.

Comparison of the sensitivity of different toxicity test endpoints in a microalga exposed to the herbicide paraquat

The use of herbicides constitutes the principal method of weed control but the introduction of these compounds into the aquatic environment can provoke severe consequences for non-target organisms such as microalgae. Toxic effects of these pollutants on microalgae are generally evaluated using phytotoxicity tests based on growth inhibition, a population-based parameter. However, physiological cellular endpoints could allow early detection of cell stress and elucidate underlying toxicity mechanisms. Effects of the herbicide paraquat on the freshwater microalga Chlamydomonas moewusii were studied to evaluate growth rate and cellular parameters such as cellular viability and metabolic activity assayed by flow cytometry and DNA damage assayed by the comet assay. Sensitivity of growth and parameters assayed by flow cytometry were similar, showing a significant effect in cultures exposed to a paraquat concentration of 0.1 microM or higher, although in cultures exposed during 48 h to 0.05 microM, a significant stimulation of cellular fluorescein fluorescence was observed, related to cellular metabolic activity. After only 24 h of herbicide exposure significant DNA damage was observed in microalgal cells exposed to all paraquat concentrations assayed, with a 23.67% of comets in cultures exposed to 0.05 microM, revealing the genotoxicity of this herbicide. Taking into account the results obtained, comet assay provides a sensitive and rapid system for measuring primary DNA damage in Chlamydomonas moewusii, which could be an important aspect of environmental genotoxicity monitoring in surface waters.

Genotoxicity screening of the river Rasina in Serbia using the Allium anaphase-telophase test

Evaluation of the presence of genotoxic substances is especially important in rivers that serve as a source of drinking water. Nine water samples collected along the river Rasina in Serbia were analyzed for potential toxic and genotoxic effects using the Allium anaphase-telophase test. Inhibition of root growth relative to the negative control (synthetic water) was observed in all samples. Analysis of the genotoxic potential, through scoring anaphase and telophase aberrations, showed that in seven of the nine samples the level of aberrations was significantly increased relative to the negative control but was lower than that obtained for the positive control (methyl methanesulfonate). Changes in the relation between spindle and chromosome types of aberrations were found in some samples, indicating differences in the potential genotoxic substances present at the analyzed sites. The data, which were obtained from samples collected at the highest level of river water, warn that during periods of low flow the values could reach genotoxic activity. The Allium anaphase-telophase test can be recommended as an monitoring system, that can serve as the first alert for the presence of genotoxic environmental pollutants.

Evaluation of DNA damage in the root cells of Allium cepa seeds growing in soil of high background radiation areas of Ramsar-Iran

Plants are unique in their ability to serve as in situ monitors for environmental genotoxins. We have used the alkaline comet assay for detecting induced DNA damage in Allium cepa to estimate the impact of high levels of natural radiation in the soils of inhabited zones of Ramsar. The average specific activity of natural radionuclides measured in the soil samples for 226Ra was 12,766 Bq kg(-1) whereas in the control soils was in the range of 34-60 Bq kg(-1). A positive strong significant correlation of the DNA damage in nuclei of the root cells of A. cepa seeds germinated in the soil of high background radiation areas with 226Ra specific activity of the soil samples was observed. The results showed high genotoxicity of radioactively contaminated soils. Also the linear increase in the DNA damage indicates that activation of repair enzymes is not triggered by exposure to radiation in HBRA.