Control of Metamorphosis by PTTH and bombyxin in the silkworm Bombyx mori.

我们开发了一种时间分辨的荧光免疫法来检测家蚕促胸前激素（PTTH），并测定了家蚕血淋巴中从第三幼虫孵化到成虫羽化的整个发育过程中PTTH的滴度。在蜕皮周期的特定阶段观察到PTTH峰。在成人早期发育过程中，注意到甲状旁腺素滴度每日波动的节律。少量的甲状旁腺激素也存在于第五星的前半期的血淋巴中。接下来，我们在用于甲状旁腺激素滴度测定的相同血淋巴样本中测量了甲状旁腺激素滴度，以关联甲状旁腺激素和甲状旁腺激素滴度变化模式。甲状旁腺激素的释放与甲状旁腺激素的释放在时间和数量上均密切相关，提示甲状旁腺激素在控制前胸腺活性中起重要作用。从两种激素的动态变化来看，甲状旁腺激素对前胸腺的作用有急性和迟发性双重作用。通过延迟漫游来评估pth抗体注射的效果，提示5龄早期幼虫血淋巴中低滴度的pth也以某种方式作用于前胸腺。探讨了甲状旁腺激素分泌的调控机制。光-暗周期的相移导致PTTH峰值在时间上的移位，表明PTTH的释放被调节在光-暗周期的特定相位发生。第2 d 5龄幼虫饥饿时，血淋巴中甲状肾上腺素滴度下降，再摄食后，血淋巴中甲状肾上腺素滴度迅速升高，说明甲状肾上腺素在5龄早期释放受营养条件影响。

We have developed a time-resolved fluoroimmunoassay for Bombyx prothoracicotropic hormone (PTTH) and determined the PTTH titers in the Bombyx hemolymph throughout development from the third larval ecdysis to the adult emergence. PTTH peaks were observed at specific stages in the molting cycles. During the early adult-development, a daily rhythm of the PTTH titer fluctuation was noticed. A small amount of PTTH was also present in the hemolymph over the first half of the fifth instar. We next measured the ecdysteroid titer in the same hemolymph samples as used for PTTH titer determination, to correlate the titer change patterns for PTTH and ecdysteroids. The release of ecdysteroids was closely related to that of PTTH both in timing and in amount, strongly suggesting a crucial role of PTTH in the control of the prothoracic gland activity. From the dynamics of both hormones, dual actions of PTTH on the prothoracic glands, acute and delayd, were suggested. The effects of PTTH antibody injection as assessed by the delay of wandering suggested that PTTH present at low titers in the hemolymph of the early fifth instar larvae also acts somehow on the prothoracic glands.The control mechanisms of PTTH secretion were also investigated. The phase-shift of the light-dark cycles resulted in the shift of the PTTH peaks in timing, suggesting that the PTTH release is regulated to occur at a specific phase in the light-dark cycles. When day-2 fifth instar larvae were starved, the hemolymph PTTH titer was decreased and, on refeeding, increased rapidly, suggesting that the PTTH release in the early fifth instar is affected by the nutritional conditions.