Gene expression profile changes induced by acute toxicity of [C₁₆ mim]Cl in loach (Paramisgurnus dabryanus)

Ionic liquids (ILs) are widely used as reaction media in various commercial applications. Many reports have indicated that most ILs are poorly decomposed by microorganisms and are toxic to aquatic organisms. In this study, differential gene expression profiling was conducted using a suppression subtraction hybridization cDNA library from hepatic tissue of the loach (Paramisgurnus dabryanus) after exposure to 1-hexadecyl-3-methylimidazolium chloride ([C₁₆ mim]Cl), a representative IL. Two hundred and fifty-nine differentially expressed candidate genes, whose expression was altered by >2.0-fold by the [C₁₆ mim]Cl treatment, were identified, including 127 upregulated genes and 132 downregulated genes. A gene ontology analysis of the known genes isolated in this study showed that [C₁₆ mim]Cl-responsive genes were involved in cell cycle, stimulus response, defense response, DNA damage response, oxidative stress responses, and other biological responses. To identify candidate genes that may be involved in [C₁₆ mim]Cl-induced toxicity, 259 clones were examined by Southern blot macroarray hybridization, and 20 genes were further characterized using quantitative real-time polymerase chain reaction. Finally, six candidate genes were selected, including three DNA damage response genes, two toxic substance metabolic genes, and one stress protein gene. Our results indicate that these changes in gene expression are associated with [C₁₆ mim]Cl-induced toxicity, and that these six candidate genes can be promising biomarkers for detecting [C₁₆ mim]Cl-induced toxicity. Therefore, this study demonstrates the use of a powerful assay to identify genes potentially involved in [C₁₆ mim]Cl toxicity, and it provides a foundation for the further study of related genes and the molecular mechanism of [C₁₆ mim]Cl toxicity. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 404-416, 2017.