Glutathione peroxidase 1 expression, malondialdehyde levels and histological alterations in the liver of Acrossocheilus fasciatus exposed to cadmium chloride.

Cadmium (Cd) is known as a widespread pollutant in aquatic environment. The accumulation of reactive oxygen species (ROS) is attributed to Cd exposure, which may affect the growth, development and physiological metabolism of aquatic organisms. In response to these unfavorable damages, antioxidant systems have been developed to protect against oxidative stress. In this study, we investigated the expression pattern of glutathione peroxidase 1 genes (GPx-1a and GPx-1b) in the liver of Acrossocheilus fasciatus after Cd administration. Total RNA extraction, reverse-transcription polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) were performed in order to clone the A. fasciatus GPx-1a and GPx-1b full-length cDNA sequences and partial fragment of β-actin cDNA from the liver for the first time. Tissue-specific expression analysis proved that GPx-1 genes were widely expressed in the liver, kidney, gill, testis, muscle, spleen, heart and brain. The changes of GPx-1 mRNA and malondialdehyde (MDA) levels in the liver treated with Cd were measured. In addition, the acute toxic effects of Cd on the microstructure of the liver were studied using light microscopy. These results suggest that GPx-1, MDA and liver histology which represent molecular, biochemical and histological levels, can be used as potential biomarkers to monitor Cd pollution. The overall findings also highlight the potential use of those three bio-indicators combined together as a multi-level tool (molecular, biochemical and histological levels) when monitoring Cd contamination and other possible exogenetic pollutants in aquatic environment.