Abstract
Flow cytometry (FC) was used to determine effects of tetrabromobisphenol A (TBBPA) on the green alga Chlorella pyrenoidosa (C. pyrenoidosa) by evaluating esterase activity, membrane integrity, concentrations of intracellular reactive oxygen species (ROS) and chlorophyll a (Chl-a) auto-fluorescence. TBBPA can inhibit esterase activity. Esterase activity was inversely proportional with TBBPA with a 24 h EC50 value of 3.13 mg TBBPA/L. After 48 h of exposure to TBBPA intracellular ROS was significantly greater than in the unexposed cells. TBBPA inhibited Chl-a fluorescence after 168 h. Concentrations of ROS were directly proportional to both magnitude and duration of exposure and was inversely proportional to cellular Chl-a. FC was useful as an integrated, ecologically relevant, measure of a functional response of the algae. The possible action pathway of TBBPA in C. pyrenoidosa is that TBBPA can cause toxic effects on esterase activity. As concentrations and exposure time increased, TBBPA change the ROS level in the internal. The role of anti-oxidative action is marked and significant at the duration of 48 h exposure, compared to the control. This suggested there was a redox cycle. TBBPA changes physiological status of cells, further decreased Chl-a fluorescence indicating inhibition.
Acknowledgments
The work described in this paper was funded by an NSFC/RGC Joint Research Grant (project no. 20518002 & N_CityU110/05) and NSFC grant (project no. 20577020). This work was supported by the fund of National Natural Science, Grant No. 20737001, 20518002 and the fund of Talent Introduction and Cultivation Foundation of Nanjing University. Prof. Giesy was supported as an at large Chair Professorship from by Department of Biology and Chemistry and Research Centre for Coastal Pollution and Conservation, City University of Hong Kong and by an “Area of Excellence” Grant (AoE P-04/04) from the Hong Kong University Grants Committee. This study involving humans or experimental animals were conducted in accordance with national and institutional guidelines for the protection of human subjects and animal welfare.