DNA damage and micronuclei in parthenogenetic and bisexual Darevskia rock lizards from the areas with different levels of soil pollution

Application of land snail Helix lucorum for evaluation of genotoxicity of soil pollution

Application of native species as sentinels allows environmental scientists to determine real genotoxic impact of environmental pollutants. The present study aims at investigating the DNA damage in the land snail Helix lucorum as a biomarker of soil pollution. For this reason, the genotoxic impact of contaminated soil on H. lucorum, collected from different polluted areas, was investigated using the comet assay in haemocytes and digestive gland cells. An increase in DNA damage was found in the snails sampled from polluted sites compared with the reference one. Strong correlations between DNA damage in haemocytes and digestive gland cells with the level of contamination indicate pollution-induced genotoxic effects in both tissues. At the same time, the digestive gland was more sensitive towards pollutants compared with haemolymph. A direct relationship between concentrations of Cu, As and Mo in soil and the number of damaged cells for hаemolymph and digestive gland tissue was found. However, the data obtained reflect the total genotoxicity of all pollutants in the studied areas. Significant correlations between the DNA damage measured by the comet assay and metal contents in soil indicate that it is a suitable biomarker in ecotoxicological studies. Our results indicate the effectiveness of H. lucorum in biomonitoring of environmental pollution.

Micronucleus and different nuclear abnormalities in wild birds in the Cerrado, Brazil

Free-living birds play an important role as bioindicators in natural environments. In this study, we used the micronucleus test and nuclear erythrocyte abnormalities to investigate the difference in the genotoxic damage frequency between animals in agricultural areas (soybean planting) in relation to the conserved area. It was also discussed the bird's eating habits, which are important for ecotoxicological analysis. The results point to a difference between the insectivorous, granivorous, and omnivorous guilds. The omnivore Gnorimopsar chopi was the species that most exhibited micronucleus frequency in the protected area. In the agricultural area, the animals did not differ in the genotoxic damage frequency. In the comparison between common species in both environments, G. chopi from the agricultural area showed a micronuclei frequency almost three times higher in relation to specimens collected in the conserved area. Based on these results, this study adds to the efforts of using the micronucleus test as a simple and accessible tool for biomonitoring the wild fauna. It can be concluded that the passerine, G. chopi, due to its higher genotoxic damage frequency may be a strong candidate to indicate environmental health.

PLASMA BIOCHEMISTRY PROFILES OF WILD WESTERN TIGER SNAKES (NOTECHIS SCUTATUS OCCIDENTALIS) BEFORE AND AFTER SIX MONTHS OF CAPTIVITY

Urban wildlife often suffer poorer health than their counterparts living in more pristine environments due to exposure to anthropogenic stressors such as habitat degradation and environmental contamination. As a result, the health of urban versus nonurban snakes might be assessed by differences in their plasma biochemistries. We compared the plasma profiles of western tiger snakes (Notechis scutatus occidentalis) from a heavily urbanized wetland and a natural, nonurbanized wetland. Despite the urbanized snakes having lower body mass index, we found no significant difference between the plasma profiles of the two populations. We collected snakes from each population and kept them in captivity for 6 mo, providing them with stable conditions, uncontaminated (exempt from heavy metals and pesticides) food and water, and lowered parasite intensity in an attempt to promote better health through depuration. After captivity, snakes experienced a significant improvement in body mass index and significant changes in their plasma profiles. Snakes from the natural wetland initially had more variation of DNA damage; mean concentration of DNA damage in all snakes slightly decreased, but not significantly, after captivity. We present the plasma biochemistry profiles from western tiger snakes both before and after captivity and suggest a period of removal from natural stressors via captivity may offer a more reliable result of how plasma profiles of healthy animals might appear.

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

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

Lizards as model organisms to evaluate environmental contamination and biomonitoring

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

Cyto/genotoxicological evaluation of hot spots of soil pollution using Allium bioassays in relation to geochemistry

Soil from industrial and landfill sites affected by anthropogenic activity was screened for implicit negative effects in an Allium test-system in relation to geochemistry. The concentrations of 15 elements were compared to the ecotoxicologically-based soil guideline values. Admitted geoindices were used to classify test-soils according to risk/hazard categories. Test-soils were screened for the possible deleterious effects in common onion (Allium cepa L.) by employing a test battery of cytogenetic bioassays (root growth inhibition, mitotic activity, frequency of chromosome aberrations and micronuclei, and cell death rate) complemented with two assays of molecular DNA markers, random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR). Soil from industrial sites was more severely polluted and more cytotoxic for onions compared to soil from landfill sites. However, the cyto/genotoxic outcome of soil exposure in A. cepa was the same for all test-soils; the detrimental effects were observed in onions treated with every test-soil. Thus, test-soils could not be classified as non- and genotoxic, although certain of them had permissible contamination levels. The chromosome aberration frequency and cell death rates were consistent with the intensity of soil contamination, contrary to the micronuclei rate, which was independent of the soil risk/hazard level. Despite a relationship between risk (RI) and total soil contamination (Z) geoindices, both indices correlated with a different Allium cyto/genotoxicity endpoint, although the Z index was preferred over the RI index as being more informative in correlation analysis. Allium bioassays complemented each other by depicting different aspects of exposure to toxic substances, and determination of cyto/genotoxicity in a battery of different bioassays is important in the risk assessment of ecologically dangerous soils, and an application of a test battery is strongly advised.

The comet assay in animal models: From bugs to whales - (Part 2 Vertebrates)

The comet assay has become one of the methods of choice for the evaluation and measurement of DNA damage. It is sensitive, quick to perform and relatively affordable for the evaluation of DNA damage and repair at the level of individual cells. The comet assay can be applied to virtually any cell type derived from different organs and tissues. Even though the comet assay is predominantly used on human cells, the application of the assay for the evaluation of DNA damage in yeast, plant and animal cells is also quite high, especially in terms of biomonitoring. The present extensive overview on the usage of the comet assay in animal models will cover both terrestrial and water environments. The first part of the review was focused on studies describing the comet assay applied in invertebrates. The second part of the review, (Part 2) will discuss the application of the comet assay in vertebrates covering cyclostomata, fishes, amphibians, reptiles, birds and mammals, in addition to chordates that are regarded as a transitional form towards vertebrates. Besides numerous vertebrate species, the assay is also performed on a range of cells, which includes blood, liver, kidney, brain, gill, bone marrow and sperm cells. These cells are readily used for the evaluation of a wide spectrum of genotoxic agents both in vitro and in vivo. Moreover, the use of vertebrate models and their role in environmental biomonitoring will also be discussed as well as the comparison of the use of the comet assay in vertebrate and human models in line with ethical principles. Although the comet assay in vertebrates is most commonly used in laboratory animals such as mice, rats and lately zebrafish, this paper will only briefly review its use regarding laboratory animal models and rather give special emphasis to the increasing usage of the assay in domestic and wildlife animals as well as in various ecotoxicological studies.