Endosulfan-Induced Biomarkers in Japanese Rice Fish (Oryzias latipes) Analyzed by SELDI-TOF-MS

The objective of this study was to find and validate estrogen-related biomarkers from plasma proteins in Oryzias latipes after exposure to an estrogen disrupting compound, alpha-endosulfan. The acute toxicity of alpha-endosulfan on O. latipes after 96 h of exposure was 13.72, 16.18, and 22.18 mu g L-1 for the LC10, LC20, and LC50 values, respectively. To confirm estrogenic disturbance by alpha-endosulfan, the expression level of vitellogenin in the liver of male fishes was measured at the LC10 value, and it was found to be significantly different from the reference group, confirming the estrogenic effect of endosulfan in this concentration range. Proteinchip (R) array techniques using a weak cation exchange (CM10) and a strong anion exchange proteinchip (Q10) in conjunction with surface-enhanced laser desorption/ionization time of flight mass spectrometry (SELDI-TOF-MS) were used to determine plasma proteins of O. latipes differently expressed in response to endosulfan exposure at LC10 and LC20 concentrations. Analysis of protein profiling of the male fish exposed to alpha-endosulfan detected 48 significantly different protein peaks and the proteins at m/z 2819, 8462, 8860, and 9462 were significantly different (p<0.05). The protein peaks at m/z 2819, 8860, and 9462 were up-regulated and the peak at m/z 8462 was down-regulated. Therefore, these four differentially expressed proteins could be used as biomarkers to rapidly determine a possible risk of endosulfan on aquatic ecosystems, although these are not necessarily produced as a result of endocrine disruption.