Increased temperatures affect oxidative stress markers and detoxification response to benzo[a]pyrene exposure in mussel Mytilus galloprovincialis.

The present research work was designed to study mussel's (Mytilus galloprovincialis) digestive gland biotransformation and detoxification responses to benzo[a]pyrene (B[a]P) exposure along with heat stress. Mussels were exposed to a sublethal dose of B[a]P [75 nM (19 μg/L/animal)] + temperature gradient (18, 20, 22, 24 and 26 °C) for 7 days. B[a]P hydroxylase (BPH) and glutathione-S-transferase (GST) activities were assessed in digestive gland tissues as phase I and phase II biotransformation parameters. Catalase (CAT) activity and malonedialdehyde (MDA) were measured as potential biomarkers of oxidative stress and lipid peroxidation. The cholinergic system was evaluated using acetylcholinesterase (AChE) activity. DNA damage was assessed using micronuclei (MN) test. BPH and GST activities showed a decreasing trend in B[a]P-exposed animals at 24 and 26 °C. CAT activity showed a bell-shaped response in B[a]P-exposed and in heat-stressed organisms at a maximum temperature of 22 °C. AChE activity was significantly inhibited in response to B[a]P being more pronounced at a temperature of 26 °C. MN in digestive gland cells suggest that B[a]P exposure induced significant DNA alteration with a maximum response in organisms coexposed to B[a]P and a temperature of 26 °C. Biomarker data are further discussed in relation B[a]P accumulation in mussels digestive gland. These data should be carefully considered in view of the biological effects of organic pollutants, particularly in organisms under the challenging effects of extreme temperature fluctuations.