Changes in gene expression profile of medaka with acute toxicity of Arochlor 1260, a polychlorinated biphenyl mixture

Differential gene expression profiling was performed with a cDNA microarray in the liver tissue of the medaka fish, Oryzias latipes, after exposure to Arochlor 1260, a polychlorinated biphenyl (PCB) mixture, which is used as a coolant and insulating fluid for transformers and capacitors and is classified as a persistent organic pollutant. Twenty-six differentially expressed candidate genes were identified. The expression of 12 genes was up-regulated and that of 14 genes was down-regulated. These genes are associated with the cytoskeleton, development, endocrine/reproduction, immunity, metabolism, nucleic acid/protein binding, and signal transduction, or are uncategorized. The transcription of molecular biomarkers known to be involved in endocrine disruption (e.g., vitellogenins, choriogenins, and estrogen receptor α) was highly up-regulated. The same tendencies in gene expression changes were observed with real-time quantitative PCR (qRT–PCR) analysis, which was conducted to examine 12 selected candidate genes. These genes could be used as molecular biomarkers for biological responses to toxic chemicals, especially endocrine disrupting and carcinogenic chemical contamination in aquatic environments.