The Subchronic Toxic Effects On Mussel (Perna Viridis) With Its Exposure To Bromobisphenol A (TBBPA)

Tetrabromobisphenol A (TBBPA) is widely used throughout the world as flame retardant for electronic equipment or building materials, and is detected in air at the dismantling plant, sewage sludge, sediment or human serum samples. Therefore, this study was performed to evaluate the possible toxic effects of TBBPA on marine bivalves. In present study, we examined the effects of TBBPA on digestive gland when administrated to mussel (Perna Viridis) for 28 consecutive days. The integral relationships were analyzed between the induction of Phase I cytochrome P450 monooxygenase (CYP) enzymes (e.g., CYP450, Cyt b5, and EROD) and Phase II conjugation enzymes (e.g., glutathione-S-transferases), and their involvement in perturbing oxyradical metabolism (Total Oxyradical Scavenging Capacity, TOSC) and cell DNA strand breakage. The results showed as following:1. In mussels exposed to TBBPA, CYP450 level and EROD activity in digestive glands were inhibited in different degree with the increasing concentrations of the test compound and exposure time (the data of Cytb5 showed no statistics different).2. Different concentrations of TBBPA showed different influence models on GST activity in digestive glands: Low concentration (or initial exposure stage) can induce GST activity, while 250μg/L groups (or late exposure stage) showed an inhibiting effect.3. The results of TOSC showed a significant decreasing trend of TOSC in mussels exposed to different concentrations of TBBPA, especially to 100μg/L,250μg/L groups. Sensitivity of three oxyradicals to mussel digestive glands: HO->HOONO->ROO-.4. Comet Assay showed TBBPA would cause DNA strand breakage in cell from mussel digestive glands, which indicated TBBPA might have genotoxicity. Furthermore, the fact that TBBPA caused DNA damage exists both time and dose-effect might indicate that it is feasible to apply DNA damage into TBBPA water pollution monitoring as well as take DNA damage as a comparatively sensitive biomarker to TBBPA water pollution. 5. The relationships between the induction of Phase I cytochrome P450 monooxygenase (CYP) enzymes and Phase II conjugation enzymes: (1) In 40μg/L group, the inhibition of Phase I and the induction of Phase II enzymes is synchronous; (2) In 100μg/L group, Phase I and Phase II enzymes perform a perfect rule of activation and inactivation. (2) In 250μg/L group, metabolic balance was broken, as a result, Phase I and Phase II enzymes do not function any more.6. The relationships between efficiency of antioxidant defenses and cell DNA damage: (1)TOSC and DNA damage degree:①Totally, DNA damage increased while TOSC decreased;②In 40 and 100μg/L groups, DNA damage may be mainly caused by the attack of HO-and HOONO-, while it might be ROO-and HO-caused DNA damage in 250μg/L group; (2) DNA damage has a certain relevance with the level of GST activity; (3) TOSC is a more effective indicator to oxidative stress compared with some single antioxidant parameter.