Neurobiology and Genetics, Biocenter, University of Würzburg, Würzburg, Germany.
Animal Ecology and Tropical Biology, Biocenter, University of Würzburg, Würzburg, Germany.
Sci Rep. 2017 Nov 2;7(1):14906. doi: 10.1038/s41598-017-15014-3.
Timing seasonal events, like reproduction or diapause, is crucial for the survival of many species. Global change causes phenologies worldwide to shift, which requires a mechanistic explanation of seasonal time measurement. Day length (photoperiod) is a reliable indicator of winter arrival, but it remains unclear how exactly species measure day length. A reference for time of day could be provided by a circadian clock, by an hourglass clock, or, as some newer models suggest, by a damped circadian clock. However, damping of clock outputs has so far been rarely observed. To study putative clock outputs of Acyrthosiphon pisum aphids, we raised individual nymphs on coloured artificial diet, and measured rhythms in metabolic activity in light-dark illumination cycles of 16:08 hours (LD) and constant conditions (DD). In addition, we kept individuals in a novel monitoring setup and measured locomotor activity. We found that A. pisum is day-active in LD, potentially with a bimodal distribution. In constant darkness rhythmicity of locomotor behaviour persisted in some individuals, but patterns were mostly complex with several predominant periods. Metabolic activity, on the other hand, damped quickly. A damped circadian clock, potentially driven by multiple oscillator populations, is the most likely explanation of our results.
时间季节性事件，如繁殖或滞育，是许多物种生存的关键。全球变化导致世界各地的物候期发生变化，这需要对季节性时间测量进行机械解释。日照长度（光周期）是冬季到来的可靠指标，但物种如何准确测量日照长度仍不清楚。昼夜节律钟、沙漏钟或一些新模型所建议的阻尼昼夜节律钟都可以为一天中的时间提供参考。然而，到目前为止，时钟输出的阻尼现象很少被观察到。为了研究豌豆蚜 Acyrthosiphon pisum 的假定时钟输出，我们将单个若虫饲养在有色人工饲料上，并在 16:08 小时（LD）的明暗光照循环和恒定条件（DD）下测量代谢活动的节律。此外，我们将个体置于新的监测装置中，并测量其运动活动。我们发现 A. pisum 在 LD 中是白天活动的，可能具有双峰分布。在持续黑暗中，一些个体的运动行为节律性持续存在，但模式大多复杂，存在多个主要周期。另一方面，代谢活动很快就衰减了。一个由多个振荡器群体驱动的阻尼生物钟是我们结果最有可能的解释。
