Transcriptional regulation of the actin gene Act79B. P.W. Baker , N. Bancroft , R.M. Cripps. Biology, Univ New Mexico, Albuquerque, NM.

   We are characterizing the transcriptional regulation of the Act79B actin gene in order to elucidate the molecular events that result in the development of specific muscle types in the Drosophila adult. Act79B encodes a muscle actin expressed in adult leg muscles and direct flight muscles. As such Act79B expression labels a physiologically unique subset of the adult skeletal muscles. We have identified several elements located upstream of the transcriptional start site that show strong similarity with the D.virilis homologue of Act79B suggesting that they represent important regulatory sequences for Act79B transcription. We are currently searching for potential transcription factors that may regulate Act79B expression. Based on our observations we believe that a conserved MEF2 binding site may play a part in Act79B regulation and are in the process of determining its specific role. We anticipate that identifying regulators of Act79B will help define the molecular mechanisms which specify distinct muscle lineages in the adult.