Repeated sequence organization and RNA transcription map of the chicken adult beta-globin gene region.

We have used adaptations of the contact hybridization method to determine the repeated sequence map of a cloned fragment of chicken genomic DNA and to establish the map of RNA transcription in vivo from this same fragment. The cloned 6.2-kilobase pair (kbp) Eco RI fragment contains the adult beta-globin gene and a portion of the embryonic epsilon-globin gene. The technique of contact hybridization allows the rapid determination of DNA reiteration frequency or RNA abundance in a single experiment. The DNA sequence analysis reveals repeated sequence spanning about 1.5 kbp, located about 1 kbp to the 3'-side of the adult gene and immediately 5' of the embryonic gene. Examination of the in vivo RNA transcript by these methods reveals the presence of RNA homologous to both the adult beta-globin gene and to the repeated sequence region. In reticulocyte cytoplasm, these RNAs were of about equal abundance; in reticulocyte nuclei, adult globin RNA was found but the repeated sequence RNA was not detected. In erythrocyte cytoplasm, the abundance of the repeated sequence RNA was much greater than that of the globin RNA.