Application of the comet assay, micronucleus test and global DNA methylation analysis in Darevskia lizards as a sentinel organism for genotoxic monitoring of soil pollution.

Widely distributed in Armenia bisexual and parthenogenetic species of Darevskia rock lizards have the potential to be considered as bioindicators of the effects of environmental pollutants. Juvenile and adult bisexual D. raddei and parthenogenetic D. armeniaca lizards were sampled from four locations with different levels of soil contamination. The comet assay, micronucleus (MN) test and global DNA methylation detection were applied in peripheral blood erythrocytes to assess genotoxic and epigenetic effects of pollutants. The concentrations of heavy metals were analyzed in the corresponding soil samples. In polluted areas levels of DNA damage were significantly higher and levels of global DNA methylation were significantly lower in both species than in reference sites. The levels of comets and global DNA methylation decreased with age but did not depend on sex. MN test did not show significant differences among localities or between sexes and age groups. The positive correlation between DNA damage and contents of Cr, Cu, As and Mo and negative correlation between global DNA methylation and contents of Cr, Cu, Zn, Mo and Pb were shown for D. raddei. The positive correlations between DNA damage and contents of Cr, Zn and Pb and negative correlations between global DNA methylation and contents of Cr, Zn, Mo, Cd and Pb were revealed for D. armeniaca. The correlation results for some metals are different in juveniles and adults. D. armeniaca showed higher sensitivity toward environmental pollution than D. raddei in their common habitat. Genetic homogeneity of parthenogenetic lizards permits to evaluate the effects of environmental pollutants independently from inter-individual genetic variation. In conclusion, the current study suggests that DNA damage and global DNA methylation may be applied to Darevskia lizards as a sentinel organism for assessing the effects of environmental pollutants.