Fujisawa Koichi, Takami Taro, Kimoto Yoshitaka, Matsumoto Toshihiko, Yamamoto Naoki, Terai Shuji, Sakaida Isao
Center for Regenerative Medicine, Yamaguchi University School of Medicine, Minami Kogushi 1-1-1, Ube Yamaguchi 755-8505, Japan.
Department of Gastroenterology and Hepatology, Yamaguchi University Graduate School of Medicine, Minami Kogushi 1-1-1, Ube Yamaguchi 755-8505, Japan.
Sci Rep. 2016 Feb 10;6:20916. doi: 10.1038/srep20916.
Circadian rhythms are biological rhythms with a period of around 24 hours. In this study, we compared the metabolome of the liver of medaka during the day and night. To comprehensively analyze the circadian variations in the levels of metabolites in the liver, livers were isolated from Zeitgeber time (ZT)4 and ZT16, and the variations in metabolite levels were evaluated. Inosinemonophosphate (IMP) and uridinemonophosphate (UMP) were found to be increased at night, indicating that nucleotide synthesis is most active during the night. Furthermore, the levels of metabolites of the tricarboxylic acid cycle were also reduced at night. In addition, the levels of many amino acids were reduced during the night, suggesting that the amino acids had been degraded. Moreover, the citrulline/ornithine ratio, which is related to arginine consumption, was lower during the day than at night. This pattern suggests that the urea cycle is activated during the day, whereas large amounts of nitric oxide and citrulline may be produced from arginine via nitric oxide synthase during the night. The results of this metabolomic analysis may be useful in future fundamental research to provide insight into chronobiology as well as applied research on drug evaluations using medaka as a model species.
昼夜节律是一种周期约为24小时的生物节律。在本研究中，我们比较了青鳉肝脏在白天和夜晚的代谢组。为了全面分析肝脏中代谢物水平的昼夜变化，在授时时间（ZT）4和ZT16分离肝脏，并评估代谢物水平的变化。发现单磷酸肌苷（IMP）和单磷酸尿苷（UMP）在夜间增加，表明核苷酸合成在夜间最为活跃。此外，三羧酸循环的代谢物水平在夜间也降低。此外，许多氨基酸的水平在夜间降低，表明氨基酸已被降解。而且，与精氨酸消耗相关的瓜氨酸/鸟氨酸比值在白天低于夜间。这种模式表明尿素循环在白天被激活，而在夜间精氨酸可能通过一氧化氮合酶产生大量一氧化氮和瓜氨酸。这种代谢组学分析的结果可能在未来的基础研究中有用，可以为时间生物学提供见解，以及在以青鳉作为模式物种的药物评估应用研究中发挥作用。
