The seminal vesicle is a juvenile hormone-responsive tissue in adult male <i>Drosophila melanogaster</i>

Juvenile hormone (JH) is one of the most essential hormones controlling insect metamorphosis and physiology. While it is well known that JH affects many tissues throughout the insect life cycle, the difference in JH responsiveness and the repertoire of JH-inducible genes among different tissues has not been fully investigated. In this study, we monitored JH responsiveness <i>in vivo</i> using transgenic <i>Drosophila melanogaster</i> flies carrying a <i>JH response element-GFP</i> (<i>JHRE-GFP</i>) construct. Our data highlight the high responsiveness of the epithelial cells within the seminal vesicle, a component of the male reproductive tract, to JH. Specifically, we observe an elevation in the JHRE-GFP signal within the seminal vesicle epithelium upon JH analogue administration, while suppression occurs upon knockdown of a gene encoding the intracellular JH receptor, <i>germ cell-expressed</i>. Starting from published transcriptomic and proteomics datasets, we next identified <i>Lactate dehydrogenase</i> as a JH-response gene expressed in the seminal vesicle epithelium, suggesting insect seminal vesicles undergo metabolic regulation by JH. Together, this study sheds new light on the biology of the insect reproductive regulatory system.