A biomarker model of sublethal genotoxicity (DNA single-strand breaks and adducts) using the sentinel organism Aporrectodea longa in spiked soil.

Abstract

There is a need to develop risk biomarkers during the remediation of contaminated land. We employed the earthworm, Aporrectodea longa (Ude), to determine whether genotoxicity measures could be applied to this organism's intestinal tissues. Earthworms were added, for 24 h or 7 days, to soil samples spiked with benzoapyrene (BaP) and/or lindane. After exposure, intestinal tissues (crop/gizzard or intestine) were removed prior to the measurement in disaggregated cells of DNA single-strand breaks (SSBs) by the alkaline comet assay. Damage was quantified by comet tail length (CTL, {\ensuremath{\mu}}m). BaP 24-h exposure induced dose-related increases (P{\ensuremath{<}}0.0001) in SSBs. Earthworm intestine was significantly (P{\ensuremath{<}}0.0001) more susceptible than crop/gizzard to BaP and/or lindane. However, both tissues appeared to acquire resistance following 7-day exposure. BaP-DNA adducts, measured by 32P-postlabelling, showed a two-adduct-spot pattern. This preliminary investigation suggests that earthworm tissues may be incorporated into genotoxicity assays to facilitate hazard identification within terrestrial ecosystems.