Scheiber Isabella B R, de Jong Margje E, Komdeur Jan, Pschernig Elisabeth, Loonen Maarten J J E, Millesi Eva, Weiß Brigitte M
Behavioural and Physiological Ecology, Groningen Institute for Evolutionary Life Sciences, The University of Groningen, Groningen, The Netherlands.
Arctic Centre, The University of Groningen, Groningen, The Netherlands.
PLoS One. 2017 Aug 7;12(8):e0182861. doi: 10.1371/journal.pone.0182861. eCollection 2017.
Here we describe the excretion pattern of corticosterone metabolites collected from droppings in barnacle goslings (Branta leucopsis) raised under 24 hours of continuous natural light in the Arctic. In lower latitudes, circulating corticosterone peaks around waking and shows a nadir between midnight and 4:00, whereas the peak and nadir are time-delayed slightly when measuring corticosterone metabolites from droppings. Photoperiod, along with other environmental factors, helps to entrain an animal's endogenous rhythm to that of the natural world. North of the Arctic Circle, photoperiod may not be a reliable cue as light is continuously absent during the winter and continuously present during the summer. Here, for the first time, we used droppings to describe a 24-hour excretion pattern of corticosterone metabolites (CORTm). By applying circular statistics for dependent data, we found a diel rhythmic pattern even under continuous natural light. We discuss potential alternative 'Zeitgeber' that may function even in the polar regions, focusing on melatonin. We propose a line of research to measure melatonin non-invasively from droppings. We also provide a validation of the adopted enzyme immunoassay (EIA) that was originally developed for greylag geese.
在此，我们描述了在北极持续24小时自然光下饲养的白颊黑雁（Branta leucopsis）粪便中皮质酮代谢物的排泄模式。在低纬度地区，循环皮质酮在醒来时达到峰值，并在午夜至4点之间处于最低点，而从粪便中测量皮质酮代谢物时，峰值和最低点会稍有延迟。光周期与其他环境因素一起，有助于使动物的内源性节律与自然世界的节律同步。在北极圈以北，光周期可能不是一个可靠的线索，因为冬季持续无光照，夏季持续有光照。在此，我们首次使用粪便来描述皮质酮代谢物（CORTm）的24小时排泄模式。通过对相关数据应用圆形统计分析，我们发现即使在持续自然光下也存在昼夜节律模式。我们讨论了即使在极地地区也可能起作用的潜在替代“授时因子”，重点是褪黑素。我们提出了一条从粪便中无创测量褪黑素的研究路线。我们还对最初为灰雁开发的采用的酶免疫测定法（EIA）进行了验证。
