No abstract

We validated the alkaline comet assay in two species of land snail (Helix aspersa and Helix vermiculata) to test their suitability as sentinels for primary DNA damage in polluted environments. The study was conducted under the framework of a biomonitoring program for a power station in Central Italy that had recently been converted from oil to coal-fired plant. After optimizing test conditions, the comet assay was used to measure the % Tail DNA induced by in vitro exposure of hemocytes to different concentrations of a reactive oxygen species (H2 O2 ). The treatment induced significant increases in this parameter with a concentration effect, indicating the effectiveness of the assay in snail hemocytes. After evaluating possible differences between the two species, we sampled them in three field sites at different distances from the power station, and in two reference sites assumed to have low or no levels of pollution. No species differences emerged. Percent Tail DNA values in snails from the sites near the power station were higher than those from control sites. An inverse correlation emerged between % Tail DNA and distance from the power station, suggesting that the primary DNA damage decreased as distance increased away from the pollution source. Detection of a gradient of heavy metal concentration in snail tissues suggests that these pollutants are a potential cause of the observed pattern. The comet assay appears to be a suitable assay and Helix spp. populations suitable sentinels to detect the genotoxic impact of pollutants.

The choice of a suitable species to translate pollution signals into a quantitative monitor is a fundamental step in biomonitoring plans. Here we present the results of three years of biomonitoring at a new coal power plant in central Italy using three different aquatic and terrestrial wildlife species in order to compare their reliability as sentinel organisms for genotoxicity. The comet assay was applied to the common land snail Helix spp., the lagoon fish Aphanius fasciatus, and the green frog Rana esculenta sampled in the area potentially exposed to the impact of the power station. The tissue concentration of some expected pollutants (As, Cd, Ni, Pb, Cr) was analysed in parallel samples collected in the same sampling sites. The three species showed different values in the comet assay (Tail Intensity) and different accumulation profiles of heavy metals. Aphanius fasciatus showed an increasing genotoxic effect over time that paralleled the temporal increase of the heavy metals, especially arsenic, and the highest correlation between heavy metals and DNA damage. Helix spp. showed levels of damage inversely related to the distance from the source of pollution and in partial accordance with the total accumulation of trace elements. On the contrary, Rana esculenta showed a low capability to accumulate metals and had inconsistent results in the comet test. The fish appeared to be the most efficient and sensitive species in detecting chemical pollution. Overall, both the fish and the snail reflected a trend of increasing pollution in the area surrounding the power plant across time and space.

The release of contaminants as herbicides, fungicides and insecticides into the environment has been listed as one of the six major contributors to the global decline of reptiles. Although reptiles may face severe risk from contaminants due to their ecology and physiology, they are currently less studied than other vertebrate groups. In the present work, we investigated if and how different types of field treatment (conventional and organic) affected the health status of Italian wall lizard (Podarcis siculus) individuals in central Italy. We chose a multi-biomarker approach that evaluated the biological responses of lizards to the treatment by means of AChE activity in the nervous system, biotransformation enzymes activities and oxidative stress in the liver, micronuclei frequency measured in the erythrocytes, and rate of intestinal parasitic infection. Our findings showed evidence of effects of treatment in conventional areas and between sexes with significant oxidative stress due to hydroxyl radicals, that caused DNA damage. No difference of intestinal parasite infections was found among treatments. Podarcis siculus seems to be a good bioindicator in ecotoxicological studies and potentially in risk assessment of pesticides, although further analyses in laboratory and in the field are needed to achieve more accurate quantification of specific pesticide effects in relation to known exposure history and to understand if other mechanisms were involved in the toxicity and detoxification process of pesticides for this species.

Habitat choice is defined as a nonrandom distribution of genotypes in different microhabitats. Therefore, it could exert a great impact on the genetic variance of natural populations by promoting genetic divergence, local adaptation, and may even lead to sympatric speciation. Despite this potential role in micro‐ and macro‐evolutionary processes, there is little empirical evidence that the various genotypes within a population may differ in habitat choice‐related behaviors. Here, we tested whether habitat choice may have contributed to genetic divergence within a local population of the Mediterranean killifish Aphanius fasciatus, which emerged between groups inhabiting microhabitats with different oxygen concentrations during previous field studies. In a first experiment, we studied the distribution of individuals in conditions of hypoxia and normoxia to test whether they had a different ability to shy away from a hypoxic environment; in a second experiment, we analyzed the individual behavior of fish separately in the two conditions, to verify whether they showed peculiar behavioral responses linked to a possible differential distribution. We then analyzed the six allozyme loci, whose allelic and genotypic frequencies were significantly divergent in the previous studies. In the first test, we found that the distribution of the two homozygote genotypes of the glucose‐6‐phosphate isomerase‐1 locus (GPI‐1) was significantly different between the hypoxic and the normoxic conditions. During the second test, all individuals were more active in hypoxic conditions, but the two GPI‐1 homozygotes showed a significant difference in time spent performing surface breathing, which was consistent with their distribution observed in the first experiment. These results provide evidence that individual behavioral traits, related to genetic features, may lead to a nonrandom distribution of genotypes in heterogeneous although contiguous microhabitats and, consequently, that habitat choice can play a significant role in driving the micro‐evolutionary dynamics of this species.

No abstract