Genetic, Phenotypic, and Quantitative Analysis of Myoblast Fusion in Drosophila Embryos

The fusion of mononucleated myoblasts into multinucleated syncytia is a fundamental process in skeletal muscle development. Drosophila melanogaster is a powerful, genetically tractable model for rapidly and efficiently assessing the function of candidate genes involved in this process. Here, we describe a comprehensive protocol with step-by-step instructions for analyzing the myoblast fusion phenotype in Drosophila embryos. This method includes mutant line selection for candidate gene, embryo collection and fixation, whole-mount immunostaining, developmental staging, confocal imaging, and phenotypic analysis. Myosin heavy chain (MHC) staining is used to visualize overall muscle morphology and to identify unfused mononucleated myoblasts. In parallel, Even-skipped (Eve) staining labels nuclei within a specific muscle fiber, enabling quantitative analysis of fusion extent by counting the nuclei incorporated into that fiber. Taken together, this protocol enables the readers to assess the mutant phenotypes of any genes of interest and evaluate their roles in myoblast fusion. This approach provides a robust framework for identifying and characterizing novel regulators of myoblast fusion.