Transcriptional responses of male fathead minnows exposed to oil sands process-affected water

Oil sands process-affected water (OSPW) is produced by the oil sands industry in Alberta, Canada. OSPW has acute and chronic effects on aquatic organisms, but the suite of effects of OSPW, and mechanisms of effects, are not understood. The goal of this study was to use RNA sequencing (RNAseq) to quantify abundances of transcripts in livers of male fathead minnows exposed to untreated OSPW and ozone-treated OSPW to investigate sublethal effects of untreated OSPW and to determine whether ozonation imparts toxicity upon OSPW. A reference transcriptome of 25,342 contigs was constructed from RNA from livers of fathead minnows exposed to various experimental conditions. Exposure to untreated OSPW resulted in greater abundances of 104 transcripts and lesser abundances of 91 transcripts. Oxidative metabolism, oxidative stress, apoptosis, and immune function were identified as processes affected by OSPW. Exposure to ozone-treated OSPW resulted in greater abundances of 57 transcripts and lesser abundances of 75 transcripts. However, in general, putative pathways for effects of OSPW in fathead minnows exposed to untreated OSPW were not identified in minnows exposed to ozone-treated OSPW, and pathways by which ozone-treated OSPW might have effects were not identified.