Accessory Gland as a Site for Prothoracicotropic Hormone Controlled Ecdysone Synthesis in Adult Male Insects
Figure 5
A model for sex-specific synthesis and action of ecdysteroids in adults.
The ovaries of female Tribolium express spo and the genes for the terminal hydroxylases, including shd, required for synthesis of 20E. Male accessory glands also express a spo-like gene, spot, and the genes for the terminal hydroxylases required for synthesis of E, but not shd. However, shd expression was detected in the carcass without the reproductive system indicating that E synthesized by the accessory gland might be converted to 20E in peripheral tissues, like during the larval stages. Alternatively, E produced by the accessory gland may be involved in male-specific hormone signaling or be transferred to females during mating. Multiple arrows indicate several steps in the biosynthetic pathway.