Cytochrome P450 1 genes in birds: evolutionary relationships and transcription profiles in chicken and japanese quail embryos
2012 (English)In: The Toxicologist, 2012Conference paper (Other academic)
Cytochrome P450 1 (CYP1) genes are biomarkers for aryl hydrocarbon receptor (AHR) agonists and may be involved in their toxic effects. Susceptibility to AHR-mediated toxicity varies among species; e.g., Japanese quail is less sensitive than chicken to halogenated AHR agonists. CYP1s other than the CYP1As are poorly studied in birds. Here we characterize CYP1B and CYP1C genes in birds and examine mRNA expression of the complete CYP1 complement and AHR1, comparing basal and induced levels in chicken and quail embryos. We cloned cDNAs of chicken CYP1C1 and quail CYP1B1 and AHR1. CYP1Cs occur in several bird genomes, but we found no CYP1C gene in quail. The CYP1C genomic region was found to be highly conserved among many vertebrates. It also shared some synteny with the CYP1Bregion, suggesting CYP1B and CYP1C genes derive from duplication of a common ancestor gene. Quantitative PCR analysis revealed similar tissue distribution patterns for CYP1A4, CYP1A5, CYP1B1, and AHR1 mRNA in chicken and quail embryos, with the highest expression of CYP1As in liver, and of CYP1B1 in eye, brain, and heart. Our results suggest the basal transcript levels are considerably higher for CYP1A in quail than in chicken, but roughly similar for CYP1B1 and AHR1 in the two species. Chicken CYP1C1 was most highly expressed in eye and heart. Tissue distribution of CYP1B and CYP1C transcripts in birds resembles that previously found in zebrafish, which may imply that these genes serve similar functions in diverse vertebrates. 3,3’,4,5,5’-Pentachlorobiphenyl induced all four CYP1s in chicken; in quail a 1000-foldhigher dose induced the CYP1As, but not CYP1B1. The apparent absence of CYP1C1 in quail, and weak expression and induction of CYP1C1 in chicken suggest that CYP1Cs have diminishing roles in tetrapods, which may be met by CYP1B1. Determining catalytic functions of CYP1s in different species should indicate the evolving roles of these duplicated genes in physiological and toxicological processes.
Place, publisher, year, edition, pages
Evolutionary Biology Developmental Biology
IdentifiersURN: urn:nbn:se:uu:diva-191230OAI: oai:DiVA.org:uu-191230DiVA: diva2:585164
Society of Toxicology