University of Edinburgh, Edinburgh EH8 9YL, United Kingdom; email:
Annu Rev Entomol. 2020 Jan 7;65:373-389. doi: 10.1146/annurev-ento-011019-025116. Epub 2019 Oct 8.
Whole-animal experiments devised to investigate possible association between photoperiodic time measurement and the circadian system (Bünning's hypothesis) are compared with more recent molecular investigations of circadian clock genes. In and some other species, experimental cycles of light and darkness revealed a photoperiodic oscillator, set to constant phase at dusk and measuring night length repeatedly during extended periods of darkness. In some species, however, extreme dampening revealed an unrepetitive (i.e., hourglass-like) response. Rhythms of clock gene transcript abundance may also show similar phase relationships to the light cycle, and gene silencing of important clock genes indicates that they play a crucial role in photoperiodism either alone or in concert. However, the multiplicity of peripheral oscillators in the insect circadian system indicates that more complex mechanisms might also be important.
将旨在研究光周期时间测量与生物钟系统之间可能存在的联系的整体动物实验（Bünning 假说）与最近对生物钟基因的分子研究进行了比较。在 和其他一些物种中，光暗实验周期揭示了一个光周期振荡器，在黄昏时设定为恒定相位，并在长时间的黑暗中反复测量黑夜长度。然而，在某些物种中，极端的衰减显示出非重复性（即沙漏状）的反应。生物钟基因转录丰度的节律也可能与光周期呈现相似的相位关系，重要生物钟基因的基因沉默表明它们单独或协同在光周期中起着至关重要的作用。然而，昆虫生物钟系统中众多的外周振荡器表明，更复杂的机制也可能很重要。
