Characterization of the differential expressed genes and transcriptomic pathway analysis in the liver of sub-adult red drum (Sciaenops ocellatus) exposed to Deepwater Horizon chemically dispersed oil.

Abstract

The Deepwater Horizon blowout resulted in the second-largest quantity of chemical dispersants used as a countermeasure for an open water oil spill in the Gulf of Mexico. Of which, the efficacy of dispersant as a mitigation strategy and its toxic effects on aquatic fauna remains controversial. To enhance our understanding of potential sub-lethal effects of exposure to chemically dispersed-oil, sub-adult red drum (Sciaenops ocellatus) were continuously exposed to a Corexit 9500: DWH crude oil chemically enhanced water accommodated fraction (CEWAF) for 3-days and transcriptomic responses were assessed in the liver. Differential expressed gene (DEG) analysis demonstrated that 63 genes were significantly impacted in the CEWAF exposed fish. Of these, 37 were upregulated and 26 downregulated. The upregulated genes were primarily involved in metabolism and oxidative stress, whereas several immune genes were downregulated. Quantitative real-time RT-PCR further confirmed upregulation of cytochrome P450 and glutathione S-transferase, along with downregulation of fucolectin 2 and chemokine C-C motif ligand 20. Ingenuity Pathway Analysis (IPA) predicted 120 pathways significantly altered in the CEWAF exposed red drum. The aryl hydrocarbon receptor pathway was significantly activated, while pathways associated with immune and cellular homeostasis were primarily suppressed. The results of this study indicate that CEWAF exposure significantly affects gene expression and alters signaling of biological pathways important in detoxification, immunity, and normal cellular physiology, which can have potential consequences on organismal fitness.