Cloning and characterization of glutathione S-transferase gene in the intertidal copepod Tigriopus japonicus and its expression after exposure to endocrine-disrupting chemicals

To investigate the impacts of marine pollution on aquatic organisms, we tested the intertidal copepod Tigriopus japonicus as a model species. To analyze the copepods’ responses to endocrine-disrupting chemicals (EDCs), we exposed them to two different chemicals: 4,4′-octylphenol (4,4′-OP, 12.5–100 μg/L for 2 h) and polychlorinated biphenyl (PCB, 6.25–25 μg/L for two days). 4,4′-OP was toxic, although exposure time was limited to 2 h. After extracting total RNA from the exposed T. japonicus, we performed reverse transcriptase-polymerase chain reaction (RT-PCR) to determine gene expression patterns following chemical exposure. To analyze the gene expression of T. japonicus, we used glutathione S-transferase with GAPDH as an internal control. Of the genes tested using EDC-exposed samples, 4,4′-OP induced upregulation of the glutathione S-transferase (GST) gene, while PCB caused downregulation of the GST gene. These results suggest that the two EDCs act in different manners in T. japonicus.