The redox status of cells is involved in the regulation of several cellular stress-response pathways. It is frequently altered by xenobiotics, as well as by environmental stressors. As such, there is an increasing interest in understanding the redox status of proteins in different scenarios. Recent advances in proteomics enable researchers to measure oxidative lesions in a wide range of proteins. This opens the door to the sensitive detection of toxicity targets and helps decipher the molecular impact of pollutants and environmental stressors. The present study applies the measurement of protein carbonyls, the most common oxidative lesion of proteins, to gel-based proteomics in Daphnia magna. Daphnids were exposed to copper and paraquat, 2 well-known pro-oxidants. Catalase activity was decreased by paraquat, whereas global measurement of protein carbonyls and thiols indicated no change with treatment. Despite the absence of observed oxidative stress, 2-dimensional electrophoresis of the daphnid proteins and measurement of their carbonylation status revealed that 32 features were significantly affected by the treatments, showing higher sensitivity than single measurements. Identified proteins affected by copper indicated a decrease in the heat-shock response, whereas paraquat affected glycolysis. The present study demonstrates the applicability of redox-proteomics in daphnids, and indicates that the heat-shock response plays a counterintuitive role in metal resistance in daphnids.
- Daphnia magna
- Heat-shock response