Organization of a β and α Globin Gene Set in the Teleost Atlantic Cod, Gadus morhua

Developmental globin gene expression and gene switching in vertebrates have been extensively studied. Globin gene regions have been characterized in some fish species and show linked alpha and beta loci. Understanding coordinated expression between alpha and beta globin genes in fish is of importance for further insights into globin gene regulation in teleosts and higher vertebrates. We characterize linked beta and alpha globin genes in Atlantic cod, pulled from the Atlantic cod genome with a PCR research strategy, by screening a genomic lambda library and primer walking. The genes are oriented tail-to-head (5'aEuro3'), differing from the head-to-head orientation in transcriptional polarity characteristic of teleostean globin genes. Four tandem repeats are found in an intergenic region of 1500 base pairs. One microsatellite, which consists primarily of atg tandem repeats, has an open reading frame. The globin genes and open reading frame have a CCAAT promoter element and TATA boxes. The promoters of the open reading frame and the beta gene share an 89-bp block (with 100% identity) that probably regulates transcription.