Identification of the Gene Responsible for the wings apart Phenotype in Drosophila melanogaster

Drosophila wings apart (wap) is a semi-lethal mutation which leads to the absence of the Tergal Depressor of Trochanter (TDT) muscle. wap has been mapped to the proximal X chromosome but it is unclear what gene is affected by this mutation. The aspect of muscle development disrupted in wap mutants leading to TDT loss is also unknown. To identify the wap gene, we performed complementation mapping of wap mutants with known X chromosome deletions. We sectioned thoraces of progeny from these crosses to observe if these flies exhibit the wap TDT phenotype. Results of mapping and phenotype analysis suggest the most likely candidate for the wap gene is DIP1. PCR of DIP1 in wild-type and wap mutants revealed an alanine to threonine amino acid substitution in the DIP1 coding region in wap mutants. Loss- and gain-of-function assays are underway to determine if loss of DIP1 reproduces the wap mutant phenotypes and if over-expression of DIP1 rescues the wild-type phenotype. The impact of the wap mutation will be analyzed by determining at which step in development TDT muscle formation is disrupted. Experiments indicate TDT specifying founder cells are lost in wap mutants, suggesting wap is necessary for early TDT specification. The broad goal of this research is to identify mechanisms of muscle formation in the Drosophila adult. Since similar developmental mechanisms are used in vertebrate and invertebrate muscle formation, this study can aid in understanding processes which may impact vertebrate muscle formation and whose mis-regulation may lead to muscular diseases.