Expression of Cyp1a and p53 Induced by Water-Soluble Fractions of Crude Oil in Juveniles of Clarias gariepinus (Burchell, 1822).

Abstract

Oil spills, like most other sources of pollutants, have been shown to disrupt biochemical pathways and cause the death of organisms. In this study, the relative expression of Cyp1a and p53 genes in juveniles of Clarias gariepinus was determined after exposure to sub-lethal concentrations of water-soluble fractions of crude oil. Fish (5.1 ± 0.3 g) were exposed to 4 sublethal concentrations (30, 45, 60, and 75% of the LC50 corresponding to 67, 101, 135, and 169 mg/L respectively) of the oil and a control. After 90 days of exposure, fish were sacrificed, tissue collected, and used for gene expression analysis. Total RNA was extracted using a modified CTAB extraction protocol. Gene quantification and amplification were carried out using standard methods. The B-actin gene was used as an internal control. The results revealed that the relative expression of Cyp1a mRNA increased in a dose-dependent manner, indicating the upregulation of Cyp1a. In contrast to Cyp1a, crude oil modulated the expression of p53, but the expression pattern did not vary in a dose dependent manner. The expression of the Cyp1a gene can therefore be used as an important factor for assessing the toxicity of crude oil, especially at sub-lethal concentrations in fish species.