Effects of temperature changes on the generation of reactive oxygen species and the expression and activity of glutathione-S transferases in two congeneric copepods Tigriopus japonicus and Tigriopus kingsejongensis

We measured the generation of intracellular reactive oxygen species (ROS) and the enzymatic activity and expression of glutathione-S transferase (GST) in response to temperature changes in the temperate copepod Tigriopus japonicus and the Antarctic copepod Tigriopus kingsejongensis. The levels of ROS and GST enzymatic activity were slightly elevated (P < 0.05) in T. japonicus in response to temperature changes but not in T. kingsejongensis. Furthermore, transcriptional regulation of all the GST genes in T. japonicus was significantly downregulated (P < 0.05) in response to temperature elevation to 35 degrees C, whereas messenger RNA expression of GST genes in T. kingsejongensis showed a significant increase (P < 0.05) at 24 degrees C, indicating that these two related but geographically distinct Tigriopus species have different molecular responses to temperature elevation. Overall, these findings indicate that temperature changes modulate oxidative damage through different modes of action, leading to different types of antioxidant defense in two congeneric copepods.