Department of Anaesthesiology, School of Medicine, The University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand.
Department of Biological Sciences, The University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand.
Sci Rep. 2017 Jun 19;7(1):3780. doi: 10.1038/s41598-017-03245-3.
How animals precisely time behaviour over the lunar cycle is a decades-old mystery. Experiments on diverse species show this behaviour to be endogenous and under clock control but the mechanism has remained elusive. We present new experimental and analytical techniques to test the hypotheses for the semilunar clock and show that the rhythm of foraging behaviour in the intertidal isopod, Scyphax ornatus, can be precisely shifted by manipulating the lengths of the light/dark and tidal cycles. Using light T-cycles (T) the resultant semilunar beat period undergoes shifts from 14.79 days to 6.47 days under T = 23 hours (h), or to 23.29 days under T = 24.3 h. In tidal T-cycles (T) of natural length T = 12.42 h, the semilunar rhythm is shifted to 24.5 days under T = 12.25 h and to 9.7 days under T = 12.65 h. The implications of this finding go beyond our model species and illustrate that longer period rhythms can be generated by shorter period clocks. Our novel analysis, in which periodic spline models are embedded within randomization tests, creates a new methodology for assessing long-period rhythms in chronobiology. Applications are far-reaching and extend to other species and rhythms, potentially including the human-ovarian cycle.
动物如何精确地在月相周期中计时是一个几十年来的未解之谜。对不同物种的实验表明，这种行为是内源性的，受生物钟控制，但机制仍难以捉摸。我们提出了新的实验和分析技术来检验半月球钟假说，并表明潮间带等足类 Scyphax ornatus 的觅食行为节律可以通过操纵光/暗和潮汐周期的长度来精确地移位。使用光 T 周期（T），当 T=23 小时（h）时，半月球的拍频周期从 14.79 天变为 6.47 天，当 T=24.3 h 时变为 23.29 天。在自然长度为 T=12.42 h 的潮汐 T 周期（T）中，当 T=12.25 h 时，半月球节律被移至 24.5 天，当 T=12.65 h 时移至 9.7 天。这一发现的意义超出了我们的模式物种，并说明了更长周期的节律可以由更短周期的时钟产生。我们的新分析方法，将周期性样条模型嵌入随机化检验中，为节律生物学中的长周期节律评估创造了一种新的方法。应用范围广泛，可扩展到其他物种和节律，包括人类卵巢周期。
