Identification of differentially expressed genes from contaminant and thermal exposed goldfish Carassius auratus in Gaobeidian Lake in Beijing, China.

Gaobeidian Lake, located in Beijing, China, derives its water mainly from the effluent of the Gaobeidian Wastewater Treatment Plant, which is moderately polluted. Additionally, as this water is used as a coolant in the nearby thermal power plant, the water of this lake has an elevated temperature. To screen differential gene expression in Gaobeidian Lake, suppressive subtractive hybridization (SSH) methodology was performed on RNA in goldfish Carassius auratus hepatic tissues from the lake, using Huairou Reservoir as reference site. A total of 768 candidate clones were selected to perform differential screening. Of these, 264 clones were differentially expressed between the two sites, 124 of which were then subjected to DNA sequencing. Consequently, 36 different genes with known functions were obtained, and some of these differential genes were further confirmed by semiquantitative RT-PCR experiments. Many genes related to detoxification, stress and immune response, and metabolism, such as glutathione S-transferase (GST), cytochrome P450, family 2, subfamily b, polypeptide 10 (CYP2B10), CYP2X10, alpha-1-antitrypsin, and apolipoprotein A-I (Apo-AI), had higher expression levels in goldfish hepatic tissue from Gaobeidian Lake than those from the reference site. A set of nine genes with known functions were downregulated in Gaobeidian Lake compared to the reference site. The results provided evidence that organisms inhabiting Gaobeidian Lake were suffering a complex stress process and showing metabolism changes and disturbance of homeostasis.