engleski

Epigenetic signatures as sensitive tool in soil ecotoxicology: alterations and relation to biomarker response in heavy metal stressed earthworms

Emerging evidence suggests that soil heavy metal pollution can alter epigenetic marks in soil fauna, with DNA methylation as one of the underlying mechanisms - a process which can be persistent and even heritable. The aim of this study was to assess the consequences of chronic heavy metal exposure on genome wide DNA methylation in the earthworm Lumbricus terrestris. Earthworms were exposed to low (10 mg/kg) environmentally relevant concentration of cadmium (Cd) for a period of 3 months. Through the exposure period, the biomarker response and health status of the earthworms was monitored at the cellular (DNA damage, oxidative stress, lipid damage) and organismic level (fitness, reproductive success) and their detoxification capacity was assessed by monitoring the expression of metallothionein (MT) gene. Genome wide DNA methylation status was assessed by methylation sensitive amplification polymorphism (MSAP) at the beginning of the exposure and after 1 and 3 months of exposure. During the exposure, earthworm fitness remained unaffected by Cd. Cellular stress was evident in the first 2 weeks of the exposure but afterwards it returned to the control level which corresponded well with the MT expression results. On the epigenetic level, already after 1 month of exposure, Cd induced significant increase in DNA methylation, which remained increased until the end of the exposure. The results of this study demonstrate that low levels of environmental pollution can lead to the occurrence of subtle epigenetic modifications, even when no or very low impact on the cellular and organismic level can be observed. These findings reinforce the application of epigenetic tools as predictors of toxicological response and suggest their use in environmental toxicology assessment.

DNA methylation, earthworms, Cadmium, biomarkers

nije evidentirano