Abstract: The proteins from the brain tissue of the fish Paralichtys olivaceus (PO) were separated by the optimized two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). Approximately 650 protein spots in each gel were detected from the brain sample when applying 200 mg protein to a 2D-PAGE gel in the pH range of 3.0-10.0. The differential proteins from the PO brain were separated and identified by proteomic technologies and they were further selected as the potential protein markers to monitor the contamination levels of methyl parathion (MP). Compared with the control group, 17 differential proteins were obtained from the PO brain under the stress of MP at 3 mg/L. Among these spots, fourteen were up-regulated and three were down-regulated. Then these differential proteins were further identified by peptide mass fingerprint (PMF) and database search. The results showed that heat shock protein 70, glutathione S-transferase and cytochrome P450 were significantly found in those differential proteins. These proteins might have strong potential for monitoring the contamination levels of MP and searching for the toxicological mechanism, as well as to evaluate the degree of risk of human fatalities under the condition of MP pollution. The results indicated that the application of the multiple biomarkers has the advantages over that of the single biomarker for monitoring the levels of MP contamination in the flowing seawater.

Key words: methyl parathion, Paralichthys olivaceus brain , protein marker, two-dimensional electrophoresis, proteomics