EVALUATION OF BREED EFFECT ON GENE EXPRESSION OF ARYL HYDROCARBON RECEPTOR (AHR), CYTOCHROME P450 (CYP1A1) AND INTERLEUKINS (IL2) IN CHICKENS REARED IN A CRUDE OIL-POLLUTED ENVIRONMENT

Abstract

Hydrocarbon toxicity resulting from the disruption of homeostasis caused by exposure to hydrocarbon pollutants is a significant obstacle that could impede the expression of the full genetic potentials of chicken breeds in the Niger Delta. Depending on the population, the mechanism and severity of toxicity may vary with the level of expression of certain genes modulated by xenobiotics. This study investigated breed effects on expression of aryl hydrocarbon receptor (AhR), cytochrome p450 (CYP1A1) and interleukins (IL2) in chickens. For the investigation, two breeds of chicken: (Nigerian
native chickens and commercial line broiler chickens) raised under extensive system by rural smallholder farmers in Okrika and Nsukka Local government Areas, Rivers and Enugu States, Nigeria were utilized. Liver tissue was excised from individual bird (27 birds per breed) for RNA extraction and gene expression studies. Results revealed that there was significant breed effect in the response of chickens in Okrika where the expression of AhR, CYP1A1 and IL-2 genes was upregulated in the native chickens (p<0.05). Such disparities were not observed in chickens reared in Nsukka. This could
be an indication of increased metabolism and detoxification of hydrocarbon pollutants in the native chicken particularly in hydrocarbon polluted environment. We therefore propose studies on AhR, CYP1A1 and IL-2 as molecular markers for evaluating hydrocarbon toxicity in chickens and possible selection for genetic improvement.