Toxicogenomics of the Freshwater Oligochaete, Tubifex tubifex ( Annelida , Clitellata ), in Acute Water-Only Exposure to Arsenic.

A toxicogenomic approach was used for toxicity evaluation of arsenic in the aquatic environment, and differential gene expression was investigated from 24 h and 96 h water-only acute toxicity tests with the aquatic oligochaete, Tubifex tubifex ( Annelida , Clitellata ). Several toxicological endpoints (survival and autotomy) of the oligochaete and tissue residues were measured, and dose-response modelling of gene expression data was studied. A reference transcriptome of the aquatic oligochaete, T. tubifex , was reconstructed for the first time, and genes related to cell stress response ( Hsc70 , Hsp10 , Hsp60 , and Hsp83 ), energy metabolism ( COX1 ), oxidative stress ( Cat , GSR , and MnSOD ), and the genes involved in the homeostasis of organisms ( CaM , RpS13 , and UBE2 ) were identified and characterised. The potential use of the genes identified for risk assessment in freshwater ecosystems as early biomarkers of arsenic toxicity is discussed.