DNA damage and oxidative stress in digestive gland of Venerupis decussata collected from two contrasting habitats in the southern Tunisian coast: biochemical and histopathological studies

The present study aims to investigate the effects of pollution on the oxidative status of the natural species Venerupis decussata in the southern coast of Tunisia coast. Clams were collected each month during summer 2014 from two contrasting sites (Si: Zarrat coast region and S2: Boughrara lagoon). The concentration of copper (Cu), lead (Pb) and cadmium (Cd) in digestive gland of clams collected from the S2 was significantly higher from those of S1. We found an increase in malondialdehyde and advanced oxidation protein products levels in digestive gland homogenates of clams from S2 compared to Si. An increase in glutathione, non-protein thiol, metallothionein and vitamin C levels was also observed. Alteration of the antioxidant system in clams sampled from S2 was also confirmed by the significant increase of catalase and glutathione peroxidase activities. Further, a decrease of neurotoxicity biomarker, acetylcholinesterase activity, was also observed in clams collected from Boughrara lagoon. The principal component analysis of biomarker responses made a distinction between clams deployed in S2 and those from the reference site S1. These spatial differentiations were confirmed by histopathological observations and DNA damage variations. We can consider these parameters as the appropriate responses to evaluate the effects of pollutants on clams, in particular V decussata, which can be used for the bio-surveillance in the coastal and lagoon regions.