IDENTIFYING UNIVERSAL TELEOST BIOMARKERS FOR ENVIRONMENTAL POLLUTANTS THROUGH COMPARATIVE TRANSCRIPTOMICS

Abstract

Cross-species toxicogenomic studies provide valuable information in identifying core mechanisms underlying chemical toxicity cross-species, and insights into the mechanistic basis of species-specific responses. Using RNA-Seq, we compared the transcriptomic response in medaka and zebrafish livers on acute exposure to seven water pollutants to identify cross-species conserved response. Cross-species toxicity response was conserved most in PCB-126, followed by TDCPP, triclosan, BPA and cadmium. Atrazine and progesterone caused high species-specific responses. Baseline liver transcriptome analysis showed that medaka liver had higher baseline oxidoreductase activity, CYP2 expression and immunity factors than zebrafish, providing insights into the species-specific response. Cross-species conserved candidate biomarkers identified for PCB-126, cadmium and BPA exposures were validated in tilapia, and tested using degenerate primers in guppies for PCB-126. We found that cyp1b1, cyp1c2 and cyp1a were robust candidate universal teleost biomarkers for PCB-126 toxicity. This study demonstrates a strategy to identify universal fish biomarkers for predicting environmental contaminants.