The case of the perplexing phenotypes: Juvenile hormone signaling in Drosophila melanogaster

In the case of the perplexing phenotypes, a novel salivary gland phenotype linked to juvenile hormone (JH) signaling in the fruit fly, Drosophila melanogaster has been discovered. Prior to this discovery, the only known phenotypes associated with the loss of JH signaling in fruit flies include irregular pupal size, pupal lethality, and changes in gene expression. In other insects, application of JH or a JH analog to a last instar nymph causes an additional immature stage, while the elimination of the hormone, either by allatectomy or gene knockdown of the receptors, causes precocious metamorphosis, producing miniature adults. Although this “status quo” action of JH best describes the most extreme function of the hormone, this exciting observation is not seen in Drosophila. It has been suggested that a minimum number of immature stages is required to observe this status quo action and three larval stages in Drosophila simply do not fulfill this minimum. Join us as we investigate a unique salivary gland phenotype observed in JH-deficient fruit flies that can be used to study JH signaling in future fly research.