a circadian clock in antarctic krill an endogenous timing system governs metabolic output rhythms in the euphausid species euphausia superba一个内源性生物钟在南极磷虾计时系统控制代谢产出节奏euphausid物种euphausia superba.pdfVIP

A Circadian Clock in Antarctic Krill: An Endogenous Timing System Governs Metabolic Output Rhythms in the Euphausid Species Euphausia superba 1 1 2,3 1 4 Mathias Teschke *, Sabrina Wendt , So Kawaguchi , Achim Kramer *, Bettina Meyer ´ ¨ 1 Laboratory of Chronobiology, Charite Universitatsmedizin Berlin, Berlin, Germany, 2 Department of Environment and Heritage, Australian Antarctic Division, Kingston, Australia, 3 Antarctic Climate and Ecosystems Co-operative Research Centre, Hobart, Australia, 4 Scientific Division Polar Biological Oceanography, Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany Abstract Antarctic krill, Euphausia superba, shapes the structure of the Southern Ocean ecosystem. Its central position in the food web, the ongoing environmental changes due to climatic warming, and increasing commercial interest on this species emphasize the urgency of understanding the adaptability of krill to its environment. Krill has evolved rhythmic physiological and behavioral functions which are synchronized with the daily and seasonal cycles of the complex Southern Ocean ecosystem. The mechanisms, however, leading to these rhythms are essentially unknown. Here, we show that krill possesses an endogenous circadian clock that governs metabolic and physiological output rhythms. We found that expression of the canonical clock gene cry2 was highly rhythmic both in a light-dark cycle and in constant darkness. We detected a remarkable short circadian period, which we interpret as a special feature of the krill’s circadian clock that helps to entrain the circadian system to the extr