THE SKELETAL MUSCLE ALPHA ACTIN GENE OF CHANNEL CATFISH (Ictalurus punctatus) IS ASSOCIATED WITH TWO CLASSES OF SINE ELEMENTS

Department of Fisheries and Allied Aquacultures, and Program of Cell and Molecular Biosciences, 203 Swingle Hall, Auburn University, Auburn, AL 36849

The 4.4-kb channel catfish genomic DNA containing the alpha actin gene was cloned and sequenced. The channel catfish alpha actin gene has a very similar organization, with six exons and five introns, to alpha actin genes from other species. The promoter region contains one TATA box, one CAAT box, one CArG box, one GATA box, and four E boxes. Nested deletion clones containing various segments of the promoter have been linked to the reporter gene chloramphenicol acetyl transferase (CAT) and tested in C2C12 myotube cells. The functional importance of the regulatory elements will be discussed. The alpha actin gene is associated with Mermaid and Merman short interspersed repetitive elements (SINE) at its 3' end. The Mermaid and Merman sequences are intermediately repetitive with 9,000 and 1,200 copies, respectively. They are distributed throughout the genome in an interspersed manner. The Mermaid and Merman elements were found to be associated with various genes from aquatic animals, but were not found from genes of land animals as revealed by database searches, suggesting their specific association with aquatic animals. These elements may be important in shaping the genomes of catfish and other aquatic animals. Along with several classes of repetitive elements identified in channel catfish, such as the Xba elements and the Tc1-like transposable elements, the present work contributes to the understanding of genomic composition and organization in catfish. The alpha actin promoter should be important for biotechnology applications.