A Role for the Adult Fat Body in Drosophila Male Courtship Behavior

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Abstract
Mating behavior in Drosophila depends critically on the sexual identity of specific regions in the brain, but several studies have identified courtship genes that express products only outside the nervous system. Although these genes are each active in a variety of non-neuronal cell types, they are all prominently expressed in the adult fat body, suggesting an important role for this tissue in behavior. To test its role in male courtship, fat body was feminized using the highly specific Larval serum protein promoter. We report here that the specific feminization of this tissue strongly reduces the competence of males to perform courtship. This effect is limited to the fat body of sexually mature adults as the feminization of larval fat body that normally persists in young adults does not affect mating. We propose that feminization of fat body affects the synthesis of male-specific secreted circulating proteins that influence the central nervous system. In support of this idea, we demonstrate that Takeout, a protein known to influence mating, is present in the hemolymph of adult males but not females and acts as a secreted protein. Many animal species have developed elaborate courtship rituals. Male courtship behavior in fruit flies, Drosophila melanogaster, consists of a well-defined series of behaviors. Specific regions of the male brain are required for successful courtship, and these neuronal cells require expression of male-specific proteins for normal function. We show here that male factors produced by a secretory tissue that surrounds the brain are also required for successful courtship. When these factors were eliminated, the frequency of several aspects of courtship was reduced, leading to fewer successful matings. At least one of these factors is secreted into the circulatory system of the fly and acts as a secreted protein. Male courtship may therefore require the interaction of endocrine factors with specific parts of the nervous system.