Study of the biological impact of organic contaminants on mussels (Mytilusgalloprovincialis L.) from the Venice Lagoon, Italy: responses of CYPIA-immunopositive protein and benzo(a)pyrene hydroxylase activity

A survey to evaluate the impact of organic contaminants on the mussel Mytil us galloprovincialis in the Venice Lagoon, Italy was carried out in May 199 3. M. galloprovincialis were sampled from putative moderately contaminated (Alberoni, Lio Grande, Crevan), urban (Salute) and industrial (CVE) sites i n the Venice Lagoon, and from a clean reference site (Plataforma) in the ad jacent Adriatic Sea. Measurements comprised (i) whole-tissue body burdens o f aliphatic hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), polychlo rinated biphenyls (PCBs) and other organochlorines (DDTs, hexachlorocyclohe xanes and hexachlorobenzene); and (ii) digestive gland microsomal cytochrom e P450 (CYP)-dependent monooxygenase system (i.e. total CYP and cytochrome P4501A (CYP1A)-immunopositive protein levels, benzo(a)pyrene hydroxylase (B PH) activity) as a specific biomarker of impact by organic contaminants. Ch emical analysis identified a contaminant gradient with Plataforma as the cl eanest and CVE followed by Salute as the most contaminated extremes. No ele vation of total CYP content or CYP1A-immunopositive protein level was seen at any of the lagoon sires compared with Plataforma. In contrast, BPH activ ity and BPH turnover (i.e. BPH activity per amount total CYP) were respecti vely 1- and 2.5-fold higher at CVE than Plataforma (P < 0.05), and indicate d to be higher (up to 1-fold) at all the other lagoon sites compared with P lataforma. Correlation was seen between BPH activity and tissue levels of t otal aliphatic hydrocarbons (r = 0.94-0.98), but not between the former and total PAHs or PCBs. The results are consistent with other studies in the a rea and indicate greatest biological impact of contaminants was at CVE foll owed by the other lagoon sites, with a possible genotoxic role for the elev ated BPH activity in the formation of bulky DNA-ad ducts.