Modulation of Expression of Oxidative Stress Genes of the Intertidal Copepod Tigriopus japonicus after Exposure to Environmental Chemicals

The intertidal copepod Tigriopus japonicus has been recognized as a potential model species for toxicity testing of marine pollutants. In last five years or so sequence information and expression pattern of several genes critical in detoxification, stress, growth and reproduction have been described from T. japonicus. A number of genes, especially those representing antioxidant and detoxification pathways, have potential application as biomarkers in biomonitoring and risk assessment. Many of the environmental chemicals such as trace metals induce oxidative stress. Therefore, biomarkers of oxidative stress have been used in risk assessment and biomonitoring. The expression of over a dozen of genes encoding for antioxidant enzymes have been studied in T. japonicus exposed to prooxidant such hydrogen peroxide, redox cyclinginducing trace metals and endocrine disrupting chemicals (EDCs). Finally, we identified GST-sigma (GSTS) as a potential biomarker gene of oxidative stress. Most of the metals caused upregulation of GSTS. Therefore, GSTS appears to be a potential biomarker of trace metal exposure in T. japonicus. Currently, we are standardizing a 12k oligochip for T. japonicus for study of gene expression profile after exposure to trace metals and EDCs. T. japonicus has already been shown to be a good model for acute toxicity and two generation toxicity testing. Using this microchip we intend to test it for trace metals and endocrine disrupting chemicals (EDCs) and finally use it in the field applications. Additionally, our recent research is also focused on study of mechanism of action of toxic chemicals at molecular level. We have successfully demonstrated utility of T. japonicus in study of chemically-induced cytotoxicity and apoptosis. This brief review highlights the significance of T. japonicus in marine pollution monitoring and risk assessment.