Aromatase mRNA in the extragonadal tissues of chickens with the henny-feathering trait is derived from a distinctive promoter structure that contains a segment of a retroviral long terminal repeat. Functional organization of the Sebright, Leghorn, and Campine aromatase genes.

The henny-feathering trait is an autosomal dominant mutation that causes the expression of aromatase activity and accumulation of aromatase mRNA in extragonadal tissues of chickens. The current studies establish that the aromatase gene is not amplified and is organized similarly in control (Leghorn) and henny-feathered (Sebright and Campine) birds. Nucleotide sequence analysis of the nine coding exons of the aromatase gene reveals that the predicted amino acid sequence is identical in all three strains. We, therefore, characterized the genomic DNA segments flanking the coding segment of the Sebright, Leghorn, and Campine aromatase genes. The site of transcription initiation utilized in the ovary of all three strains is located approximately 147 nucleotides upstream of the initiator methionine. In addition to aromatase mRNA derived from this common ovarian promoter, another species of aromatase mRNA is present in Sebright and Campine ovary and is the only type detected in Sebright fibroblasts. cDNA copies of this second species of aromatase mRNA contain a unique 5' terminus, suggesting that a second promoter controls extragonadal aromatase expression in birds that carry the henny-feathering trait. Nucleotide sequence analysis of this 5' terminus indicates that this segment is derived from a retroviral long terminal repeat.