[Antioxidant enzyme gene expression as molecular biomarkers of exposure to polycyclic musks]

The objective of this study was to investigate the molecular toxicological effects of low level synthetic musks exposure on the earthworm Eisenia fetida. The method of Sybr Green I real time quantitative PCR (RT-qPCR) for detecting gene expression level was established. SOD (superoxide dismutase) and CAT (catalase) mRNA expression levels were measured after 28 days. of AHTN and HHCB exposure. The analysis results of both sequence alignment and melting curve demonstrated that the selected primers were suitable for mRNA quantification. The liner correlation coefficients of SOD and CAT standard curves were 0.997 and 0.994, respectively, and the PCR amplification efficiencies were both close to 100%. Therefore, relative quantification method could be applied to analyze the gene expression levels. The significant elevation of malondialdehyde (MDA) levels indicated that the reactive oxygen species-induced cellular oxidative injury might be one of the main toxic effects of AHTN and HHCB. Besides, a significant positive correlation was observed between the up-regulation of SOD, CAT mRNA and the MDA levels, suggesting that possible changes in the transcript expression of antioxidant enzyme genes were associated with the oxidative stress. Furthermore, the dose-response correlation between SOD, CAT mRNA levels and the exposure concentrations was also found. The overall results indicated that SOD and CAT genes might be potential molecular biomarkers for the evaluation of the pollution stress and toxicological effects of synthetic musks in the environment.