2023 Volume 40 Issue 2 Pages 88-96
In temperate regions, an external environment changes dramatically according to seasons. Many of organisms sense the seasonal change from photoperiod and adjust their physiological status and behaviors appropriately. It is suggested that the circadian clock that generates an internal rhythm of about 24 hours plays an important role in the photoperiodic time measurement. On the other hand, brain neural signals that transmit the circadian clock-based photoperiodic information and cellular photoperiodic responses caused by these signals were unclear. The authors’ research group uses field-collected insects that show clear photoperiodic responses, and analyzes the brain neural mechanism of circadian clock-based photoperiodism by a combination of physiological and RNA interference-mediated gene knockdown methods. In this paper, I first introduce the history of research on photoperiodic time measurement systems based on the circadian clock. Next, I introduce our recent researches of the neural signaling that transmits photoperiodic information and the cellular photoperiodic responses of reproductive control cells in the bean bug Riptortus pedestris that shows clear photoperiodism in reproduction.
