A transcript at the flightless gene locus of Drosophila melanogaster exhibits significant homology with the cytoskeleton regulating protein factor gelsolin from vertebrates. When mutagenized, the gene causes either severe disruptions of the flight muscle structure or embryonic death. Gelsolin is implicated in a plethora of morphogenetic processes by either promoting the formation of actin filaments from monomeric subunits, or by restricting their length in a calcium dependent fashion. The molecular analysis of the Drosophila homologue of this family of actin-severing proteins will, for the first time, provide a way to correlate the molecular structure of a cytoskeleton-regulating factor with the cellular effects of a specific mutation. The project proposes to determine transcriptional patterns of the flightless gene by DNA sequence analysis and to study the developmental and tissue-specific expression by in situ hybridization and immunocytochemistry. Furthermore, it is intended to analyze mutant alleles by the polymerase chain reaction to obtain information about functional sites within the molecule, and to study the effects of over expression in situ by germ line transformation with a construct containing the gelsolin gene under the control of heterologous promoter. The results from this study are expected to provide a detailed understanding of functional domains of gelsolin its evolution, and of its role during embryonic development and myogenesis.
