Characterization of muscle actin genes in Drosophila virilis reveals significant molecular complexity in skeletal muscle types

Actin is a ubiquitous and highly conserved eukaryotic protein required for cell motility and locomotion. In this manuscript, we characterize the four muscle actin genes of the insect Drosophila virilis and demonstrate strong similarities between the D. virilis genes and their homologues in Drosophil a melanogaster; intron locations are conserved, and there are few amino aci d differences between homologues. We also found strong conservation in temp oral expression patterns of the muscle actin genes - the homologues of the D. melanogaster genes Act57B and Act87E are expressed throughout the life c ycle, whereas the other two D. virilis genes, homologous to Act79B and Act8 8F are specific to pupal and adult stages. In situ hybridization revealed t hat each D. virilis gene is expressed in a unique pattern in the muscles of the thorax and abdomen. These muscle-specific patterns of actin isoforms s uggest a greater physiological diversity for the adult muscles of insects t han has been appreciated to date from their categorization into fibrillar, tubular (non-fibrillar) and supercontractile muscle types.