Abstract: The expression of locomotor circadian rhythm in female German cockroach is masked by the development of ovaries. Since the masking effect is mediated through the regulation of hormone, we propose the ecdysone, the major hormone secreted from ovaries, is the masking factor. Firstly, by monitoring the ecdysone titer in different aged females, we can establish the base line of ecdysone along with its reproductive cycles. This result can be correlated with the masking effect on the locomotor circadian rhythm. In addition, we will employ immunostain method against ecdysone receptor to reveal the action sites. These sites may shine light on the interference of circadian signals with masking factor-ecdysone. In order to prove the masking role of ecdysone, ovariectomized females who showed unmasked locomotor circadian rhythm will be treated with ecdysone analog to regain the masked rhythm. Since the sibling species of the Germany cockroach, the double-striped cockroach is a feral species and expresses locomotor circadian rhythm in virgin females, it is a great advantage to use this species as a comparative study to further demonstrate the function of ecdysone on the locomotor circadian rhythm. The same experimental procedures, therefore, will be repeated on the double-striped cockroach. The main focus of this proposal is to investigate the physiological mechanism of masking effect on the locomotor circadian rhythm by ecdysone. Furthermore, the molecular mechanism of masking effect by ecdysone will be also demonstrated by abolishing ecdysone production at the mRNA level with RNA interference technique.
locomotor circadian rhythm