Targeting sex-specific gene expression to the dipteran fat body

The insect fat body is the primary organ of intermediary metabolism for all insects and in this capacity is highly dependent on hormonal signaling for regulation of gene expression.  Expression of fat body-specific genes is not only critical during metamorphosis of both sexes and at specific stages of egg production in females, but also essential for immune competence throughout the insect life cycle.  Certain transcription factors, conserved even between vertebrates and invertebrates, are responsible for fat body-specific gene activity. In holometabolous insects, such as the Diptera, fat body gene expression may vary significantly from one life stage to another and especially between males and females.  The transcription factor Doublesex (DSX) exhibits sexually dimorphic expression and controls the development of many sex-specific traits in both Diptera and other holometabolous insects.  We have used transgenesis in both the fruit fly, Drosophila melanogaster, and the culicine mosquito, Aedes aegypti, to identify specific DNA sequences, including DSX-binding sites, that dictate sex-specific gene expression in the fat body.