In desert areas, mammals such as camel and goat are exposed to harsh environmental conditions. The ambient temperature (Ta) cycles have been shown to entrain the circadian clock in the camel. In the present work, we assumed that, in the goat living in a desert biotope, Ta cycles would have the same synchronizing effect on the central clock. Therefore, the effects of Ta cycles on body temperature (Tb), locomotor activity (LA) and melatonin (Mel) rhythms as outputs of the master circadian clock have been studied. The study was performed on bucks kept first under constant conditions of total darkness (DD) and constant Ta, then maintained under DD conditions but exposed to Ta cycles with heat period during subjective day and cold period during subjective night. Finally, the Ta cycles were reversed with highest temperatures during the subjective night and the lowest temperatures during the subjective day. Under constant conditions, the circadian rhythms of Tb and LA were free running with an endogenous period of 25.3 and 25.0 hours, respectively. Ta cycles entrained the rhythms of Tb and LA to a period of exactly 24.0 hours; while when reversed, the Ta cycles led to an inversion of Tb and LA rhythms. Similarly, Ta cycles were also able to entrain Mel rhythm, by adjusting its secretion to the cooling phase before and after Ta cycles inversion. All together, these results show that the Ta cycles entrain the master circadian clock in the goat.

中文翻译：

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每天在环境温度下循环会导致沙漠山羊（Capra hircus）的褪黑素节律和其他生物钟的其他输出。

在沙漠地区，骆驼和山羊等哺乳动物都处于恶劣的环境条件下。已证明环境温度（Ta）周期会在生物钟中夹带生物钟。在当前的工作中，我们假设，在生活在沙漠生物群落中的山羊中，Ta循环对中央时钟具有相同的同步作用。因此，已经研究了Ta周期对作为主生理时钟输出的体温（Tb），运动活动（LA）和褪黑激素（Mel）节律的影响。该研究是对雄鹿进行的，雄鹿首先保持在恒定的全黑（DD）和恒定的Ta条件下，然后保持在DD条件下，但在主观白天处于热期而在主观夜晚处于寒冷期而处于Ta循环。最后，在主观夜晚最高温度和主观白天最低温度时，Ta循环反转。在恒定条件下，Tb和LA的昼夜节律自由运行，内源周期分别为25.3和25.0小时。Ta周期将Tb和LA的节律带入正好为24.0小时。而当反转时，Ta循环导致Tb和LA节奏反转。类似地，Ta循环也可以通过在Ta循环反转之前和之后将其分泌物调节到冷却阶段来带动Mel节奏。总之，这些结果表明，Ta循环带动了山羊的主生物钟。分别为0小时。Ta周期将Tb和LA的节律带入正好为24.0小时。而当反转时，Ta循环导致Tb和LA节奏反转。类似地，Ta循环也可以通过在Ta循环反转之前和之后将其分泌物调节到冷却阶段来带动Mel节奏。总之，这些结果表明，Ta循环带动了山羊的主生物钟。分别为0小时。Ta周期将Tb和LA的节律带入正好为24.0小时。而当反转时，Ta循环导致Tb和LA节奏反转。类似地，Ta循环也可以通过在Ta循环反转之前和之后将其分泌物调节到冷却阶段来带动Mel节奏。总之，这些结果表明，Ta循环带动了山羊的主生物钟。