GENOMIC ORGANIZATION OF THE BOVINE AROMATASE ENCODING GENE AND A HOMOLOGOUS PSEUDOGENE AS REVEALED BY DNA FIBER FISH

In cattle, the CYP19 locus comprises the aromatase cytochrome P450-enc oding gene (CYP19) and a homologous pseudogene (CYP19P1). It has been assigned to chromosome region 10q26. Cloning of genomic DNA revealed t hat the CYP19 gene covers more than 56 kb. Its precise extent is still unknown because the DNA spanning the untranslated first exon 1.1 and the coding region (exons 2 to 10) have not been isolated. Furthermore, the chromosome arrangement of closely linked CYP19 and CYP19P1 was al so not clear. To establish a high resolution physical map of the entir e CYP19 locus, fluorescence in situ hybridization to extended bovine g enomic DNA fibers (fiber FISH) was performed. The results demonstrate (1) that the clone containing exon 1.1 is located about 19 kb upstream from the CYP19 coding region. (2) Within the chromosome region 10q26 CYP19 and CYP19P1 are arranged ''tail-to-head'', being separated by a distance of about 24 kb between the labeled clones. (3) The physical s ize of the bovine CYP19 locus amounts to a minimum of 130 kb.