Biology Letters ( IF 3.3 ) Pub Date : 2020-07-15 , DOI: 10.1098/rsbl.2020.0257 Lukas Hüppe 1, 2, 3 , Laura Payton 1, 3 , Kim Last 4 , David Wilcockson 5 , Elizaveta Ershova 6, 7 , Bettina Meyer 1, 2, 3
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 Calanus finmarchicus, a key zooplankter in the north Atlantic, to determine in situ 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 C. finmarchicus, 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.
中文翻译:
北极夏至期间the足类Calaus finmarchicus的昼夜节律基因振荡的证据。
昼夜节律时钟提供了一种预测环境周期的机制,并通过时间提示(例如每日亮/暗周期或光周期)同步。但是,北极环境的特征是连续数月的午夜太阳,这时太阳一直在地平线上方,海冰进一步减弱了光周期。为了测试昼夜节律时钟基因的振荡是否与微妙的环境变化保持同步,我们采样了co足类Calanus finmarchicus(北大西洋的主要游动动物),以就地测定夏至临近南(74.5°N)无冰和北(82.5°N)北冰覆盖站附近的昼夜生物钟基因表达。结果显示两个站的基因均发生明显振荡,表明此时时钟持续存在。来自南部站的co足类动物在日范围内表现出振荡,而来自北部站的co足类动物的超弧度振荡则有所增加。我们建议在C. finmarchicus中,即使太阳高度的每日微小变化似乎也足以夹带生物钟,并建议在非常高的纬度下,在冰层以下的生态系统中,可以将潮汐线索用作附加的夹带线索。