Benzo(a)pyrene-induced DNA damage in Mytilus galloprovincialis: Measurement of bulky DNA adducts and DNA oxidative damage in terms of 8-oxo-7,8-dihydro-2'-deoxyguanosine formation.

Bulky DNA adducts and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) were measured in gill DNA of benzo[a]pyrene (B[a]P)-exposed mussels (50 mg kg(-1) dw day(-1)), respectively by the P-32-post-labelling technique and high performance liquid chromatography coupled to electrochemical detection assay. A time-course study was performed for both biomarkers and their potential use for marine biomonitoring discussed for the sentinel species studied. In gills, B[a]P-related DNA adducts were positively correlated with B[ a] P concentration in whole mussel, and were produced in a time-dependent manner relative to exposure. Comparison of adduct levels recorded in this paper in gills (0.149 +/- 0.079 (standard deviation) to 0.480 +/- 0.139 adduct per 10(8) normal nucleotides) with previous measures carried out in the digestive gland of the same animals (0.010 +/- 0.005 to 0.251 +/- 0.062 adduct per 10(8) normal nucleotides) (Akcha et al. in press) showed higher levels in the former tissue (p 0.05), whereas by the chaotropic method lower 8-oxodGuo levels (0.02 p < 0.05) were measured for both tissue (8.3 +/- 2.0 and 4.8 +/- 1.1 8-oxodGuo per 10(5) dGuo respectively). Contributory factors to the lack of observed increase in gill 8-oxodGuo level by B[ a] P exposure could be due to the selected way of exposure (via the feed supply) for which gills were not the target tissue of exposure and artifactual DNA oxidation during sample processing that could have masked the possible B[a]P oxidative DNA damage