Sumová Alena, Kováciková Zuzana, Illnerová Helena
Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
J Biol Rhythms. 2007 Jun;22(3):259-67. doi: 10.1177/0748730407301052.
The molecular clockwork of the rat suprachiasmatic nucleus, the site of the circadian clock, is affected by the photoperiod (Sumová et al., 2003). The aim of the present study was to partly elucidate the dynamics of the adjustment of the clockwork to a change from a long to a short photoperiod accomplished by an asymmetrical prolongation of the dark period into the morning hours. Rats maintained under a regime with 16 h of light and 8 h of darkness per day (LD 16:8) were transferred to LD 8:16, and after 2, 3, and 13 days, daily profiles of Per1, Per2, Bmal1, and Cry1 mRNA were assessed by in situ hybridization. The rhythms of Per1, Per2, and Bmal1 expression adjusted to the change from a long to a short photoperiod with larger phase delays of the morning Per mRNA rise and Bmal1 mRNA decline than of the evening and nighttime Per mRNA decline and Bmal1 mRNA rise. The rhythm of Cry1 expression adjusted to the change by parallel delays of the Cry1 mRNA rise and decline. Adjustment of the Cry1 mRNA rhythm to short days was almost accomplished within 13 days, whereas adjustment of the Per1 and Bmal1 mRNA rhythms took longer. Different dynamics of the adjustment of rhythms in clock gene expression to a change from a long to a short photoperiod suggests complex resetting effects of the photoperiod change.
大鼠视交叉上核（昼夜节律钟的所在部位）的分子生物钟机制受光周期影响（苏莫娃等人，2003年）。本研究的目的是部分阐明生物钟机制在由长光周期转变为短光周期过程中的调节动态，这种转变是通过将黑暗期不对称地延长至上午时段来实现的。将每天处于16小时光照和8小时黑暗（LD 16:8）条件下的大鼠转移至LD 8:16条件下，并在2天、3天和13天后，通过原位杂交评估Per1、Per2、Bmal1和Cry1 mRNA的每日表达谱。Per1、Per2和Bmal1的表达节律适应了从长光周期到短光周期的变化，与傍晚和夜间Per mRNA下降及Bmal1 mRNA上升相比，上午Per mRNA上升和Bmal1 mRNA下降的相位延迟更大。Cry1的表达节律通过Cry1 mRNA上升和下降的平行延迟来适应这种变化。Cry1 mRNA节律在13天内几乎完成了对短日照的适应，而Per1和Bmal1 mRNA节律的适应则需要更长时间。生物钟基因表达节律对从长光周期到短光周期变化的不同调节动态表明光周期变化具有复杂的重置效应。
