Effect of sodium dodecyl sulfate (SDS) on stress response in the Mediterranean mussel (Mytilus Galloprovincialis):Regulatory volume decrease (Rvd) and modulation of biochemical markers related to oxidative stress

In this study the effects of an anionic surfactant, sodium dodecyl sulfate (SDS), are assessed on theMediterranean mussel (Mytilus galloprovincialis), exposed for 18 days at a concentration ranging from0.1 mg/l to 1 mg/l. The effects are monitored using biomarkers related to stress response, such as regula-tory volume decrease (RVD), and to oxidative stress, such as reactive oxygen species (ROS), endogenousantioxidant systems and Hsp70 levels. The results demonstrate that cells from the digestive gland of M.galloprovincialis, exposed to SDS were not able to perform the RVD owing to osmotic stress. Further, SDScauses oxidative stress in treated organisms, as demonstrated by the increased ROS production, in com-parison to the controls (p < 0.05). Consequently, two enzymes involved in ROS scavenging, superoxidedismutase (SOD) and catalase (CAT) have higher activities and the proportion of oxidized glutathione(GSSG) is higher in hepatopancreas and mantle of treated animals, compared to untreated animals(p < 0.05). Furthermore Hsp70 demonstrates an up-regulation in all the analyzed tissues of exposed ani-mals, attesting the stress status induced by the surfactant with respect to the unexposed animals. Theresults highlight that SDS, under the tested concentrations, exerts a toxic effect in mussels in which thedisruption of the osmotic balance follows the induction of oxidative stress