Characterization of the 5'-to-5'linked adult alpha- and beta-globin genes from three sciaenid fish species (Pseudosciaena crocea, Sciaenops ocellatus, Nibea miichthioides)

Recently, we cloned the adult alpha-globin genes from large yellow croaker Pseudosciaena crocea, cuneate drum Nibea miichthioides and red drum Sciaenops ocellatus. All these alpha-globins have a unique Gly insertion at the 47th residue. In this paper, the three sciaenid globin complexes were identified and compared in detail. Linkage analysis indicated that the sciaenid alpha- and beta-globin genes were oriented head-to-head relative to each other. The sciaenid intergenic regions between the linked alpha- and beta-globin genes were the smallest in reported fish globin gene complexes to date. Classical promoter elements were condensed and the CCAAT box unstable duplication was found in these regions. The promoter function of the intergenic region from large yellow croaker was tested by transient expression of EGFP in Vero cells. We also described a method for studying luciferase reporter gene transient expression in primary fish erythrocytes. We used the method to assess the promoter strength of the three intergenic regions between the sciaenid alpha- and beta-globin genes.