Assessment of genotoxicity in Clarias gariepinus exposed to lethal and sub-lethal concentrations of oilfield chemicals: DNA concentration, purity, and genetic implications

Abstract

This study investigates the concentration and purity of DNA extracted from Clarias gariepinus after exposure to lethal concentrations (250 ml/l, 200 ml/l, 150 ml/l, 100 ml/l, 50 ml/l, 25 ml/l and 0.0 ml/l for the control) of Xylene: Diesel (X:D) and Oilfield-Based Emulsifiers (O-BE) over 96 hours using static bioassays and sub-lethal concentrations 0 ml/l (control), 12.8 ml/l, 25.6 ml/l, 38.4 ml/l, 51.2 ml/l and 64.0 ml/l) using renewal bioassay for 28 days. 210 juveniles were used for the experiment. The study used PCR and other methods to analyse DNA concentrations and purity in the fish samples. The results indicated variations in DNA concentration, purity, and the presence of micronuclei, suggesting genetic and cytogenetic responses to chemical exposures. The highest DNA concentration was recorded in the 25 ml/l group for both O-BE and X:D, while the lowest was in the 100 ml/l group. The genetic effects of Xylene: Diesel on the molecular level were also examined, with significant gaps in the alignments of experimental groups indicating notable differences in the sequences compared to the control group without chemical exposure. Through detailed analyses, including gel electrophoresis and sequence alignment, the study explores genetic variations and micronuclei frequencies in blood cells, shedding light on the ecotoxicological impacts and potential evolutionary implications of these oil-based substances on African catfish. Understanding the genetic variations induced by lethal concentrations of O-BE in Clarias gariepinus is crucial for assessing the broader environmental impact, as genetic changes in aquatic organisms can affect population health, adaptation, and ecosystem dynamics.