Effect of Dibutyl phthalate on antioxidant parameters and related gene expression in Daphnia magna

Abstract

Dibutyl phthalate (DBP) is a widespread environmental pollutant that poses a major threat to aquatic organisms and humans. However, the toxicological influences of DBP on zooplankton have not been completely researched. To determine the effect of DBP on antioxidant parameters and mRNA levels of antioxidant enzyme gene in Daphnia magna, D. magna were cultured with the sublethal concentrations of 0.5 or 2 mg/L DBP. We measured hydroxyl radicals (·OH) scavenging and peroxidase (POD) activities of D. magna exposed to DBP. The expression levels of the two antioxidant enzyme genes glutathione S-transferases (GST) and catalase (CAT) in Daphnia magna were also analysed using quantitative real-time polymerase chain reaction. The results showed that the ·OH scavenging activity in D. magna exposed to DBP were increased at 24 h and decreased at 48 h. The POD activities in D. magna showed no obvious change under 0.5 mg/L DBP treatment, but were increased significantly at 2 mg/L DBP exposure. We observed significant increase in gst and cat mRNA levels in D. magna exposed to 0.5 mg /L DBP for 24 h, while the mRNA levels of the two genes in D. magna were reduced after 48 h DBP exposure. These data indicated that DBP-induced antioxidant defence systems were involved at the transcriptional level in D. magna.