Comparative proteomic analysis of ovary for Chinese rare minnow (Gobiocypris rarus) exposed to chlorophenol chemicals

Abstract

Pentachlorophenol (PCP) and 2,4,6-trichlorophenol (TCP) are suspected of disrupting the endocrine system and thus affecting human and wildlife reproduction, but the potential common mechanisms and biomarkers of chlorophenols (CPs) in the ovary are not fully elucidated. In the present study, the female rare minnow (Gobiocypris rarus) was exposed to PCP (0.5, 5.0, and 50 μg/L), TCP (1.0, 10, and 100 μg/L) and 17β-estradiol (as a positive control) for 28 days, and the matrix-assisted laser desorption/ionization (MALDI) tandem time-of-flight (TOF/TOF) mass spectrometry analysis was employed to investigate the alteration of protein expression in the ovary. After comparison of the protein profiles from treated and control groups, 22 protein spots were observed to be altered in abundance (>2-fold) from female treated groups, and 14 protein spots were identified successfully. These proteins were related to molecular response patterns, endocrine effects, metabolic pathways, and even the possible carcinogens in response to CP exposure. The seven differentially expressed mRNA encoding proteins were measured by quantitative real-time PCR (QRT-PCR) and histopathology was also measured. Our data demonstrate that alterations of multiple pathways may be associated with the toxic effects of CPs on ovaries. Although numerous studies have shown the affection of the endocrine system with exposure to chlorophenols (CPs), there is little report on the alterations of protein expression in the ovaries from rare minnows following exposure to PCP or TCP. In the present study, a comparative proteomic approach using two dimensional gel electrophoresis and mass spectrometry (MALDI-TOF/TOF MS) has been developed to identify certain proteins in the ovaries of Chinese rare minnow, whose abundance changes during exposure to CPs. After comparison of the protein profiles from treated and control groups, 22 protein spots were observed to be altered in abundance (>2-fold) from female treated groups, and 14 protein spots were identified successfully. These proteins were related to molecular response patterns, endocrine effects, metabolic pathways, and even the possible carcinogens in response to CP exposure. Because the mechanism often involves changes in the expression of multiple proteins rather than a single protein, a global analysis of the protein alterations can result in valuable information to understand the CP action mechanism. All the above results demonstrate that the Vtg, SUMO, Lec-3 and PIMT protein are potential biomarkers and involved in the toxicity pathway of CP exposure in aquatic animals, which should be the primary focus of studies on the CP ovary toxicity mechanism in the future.