Transcriptome dynamics in benzo[a]pyrene exposed Hydra

Abstract

Backgrounds Benzo[a]pyrene (BaP) is a well-known ecotoxicant that induces a wide spectrum of toxic effects in organisms, including carcinogenicity, teratogenicity, genotoxicity, and immunotoxicity. Thus, re-evaluation of its acute toxic effects in gene expression at sublethal concentration in experimental animal is essential to understand and/or predict metabolic and physiological changes in an organism after exposure. Objectives To understand the changes in acute toxicity by exposure time, differential gene expression profiling of Hydra magnipapillata was performed by DNA microarray after exposure to BaP. Results The median lethal concentrations of the animals (LC50) were determined to be 78.5, 53.6, and 28.9 mg/L after exposure to BaP for 24, 48, and 72 h, respectively. Morphological responses of hydra polyps to 50 mg/L of BaP by exposure time were observed. The gene expression levels of molecular chaperones, antioxidative enzymes were altered at the early phase of the exposure. Transcription of the genes related to development and differentiation; apoptosis and necrosis were affected by the 4 h BaP exposure group. After 12 h exposure, developmental processes, immune responses, and ion transport in hydra polyp seemed to be affected, since the transcriptions of the genes that related to those biological processes were induced or repressed by BaP exposure. Neurotransmission might be suppressed, but tumorigenesis and carcinogenesis, the DNA repair process might be induced in the 24 h BaP-exposed hydra group. Finally, tumorigenesis and carcinogenesis, and the DNA repair process seemed to be induced after 48 h exposure. Conclusion We successfully demonstrated the dynamic response of Hydra to BaP by exposure time at transcription level. The results could extend our knowledge on acute toxic effect of BaP at sublethal conditions.