Institute for Chemistry and Biology of the Marine Environment, Carl von Ossietzky University of Oldenburg, 26111 Oldenburg, Germany.
Helmholtz Institute for Functional Marine Biodiversity (HIFMB) at the University of Oldenburg, 26111 Oldenburg, Germany.
Biol Lett. 2020 Jul;16(7):20200257. doi: 10.1098/rsbl.2020.0257. Epub 2020 Jul 15.
The circadian clock provides a mechanism for anticipating environmental cycles and is synchronized by temporal cues such as daily light/dark cycle or photoperiod. However, the Arctic environment is characterized by several months of Midnight Sun when the sun is continuously above the horizon and where sea ice further attenuates photoperiod. To test if the oscillations of circadian clock genes remain in synchrony with subtle environmental changes, we sampled the copepod a key zooplankter in the north Atlantic, to determine daily circadian clock gene expression near the summer solstice at a southern (74.5° N) sea ice-free and a northern (82.5° N) sea ice-covered station. Results revealed significant oscillation of genes at both stations, indicating the persistence of the clock at this time. While copepods from the southern station showed oscillations in the daily range, those from the northern station exhibited an increase in ultradian oscillations. We suggest that in , even small daily changes of solar altitude seem to be sufficient to entrain the circadian clock and propose that at very high latitudes, in under-ice ecosystems, tidal cues may be used as an additional entrainment cue.
生物钟为预测环境周期提供了一种机制，并通过时间线索（如每日光/暗周期或光周期）进行同步。然而，北极环境的特点是几个月的午夜太阳，当太阳持续在地平线上方，海冰进一步衰减光周期时。为了测试生物钟基因的振荡是否仍然与微妙的环境变化同步，我们采集了桡足类动物——北大西洋的关键浮游动物——以确定在夏至附近，在没有海冰的南部（74.5°N）和有海冰的北部（82.5°N）站的每日生物钟基因表达。结果表明，两个站的基因都有明显的振荡，表明此时钟仍然存在。尽管来自南部站的桡足类动物显示出每日范围内的振荡，但来自北部站的桡足类动物表现出超昼夜振荡的增加。我们认为，即使太阳高度的微小日常变化似乎足以使生物钟同步，并提出在极北纬地区，在冰下生态系统中，潮汐线索可能被用作额外的同步线索。
