Universality of circadian behavior under low temperature conditions

昼夜节律是以24小时为周期的振荡现象。其突出特点之一是周期温度补偿。本文从分岔理论的角度出发，对目前尚不清楚分子机制的温度补偿进行了研究，观察了低温条件下生物体的昼夜节律，确定了生物体昼夜节律消失的分岔类型。研究表明，KaiC磷酸化、成纤维细胞拟南芥和果蝇的昼夜节律通过霍普夫分叉被取消。低温下的Hopf分岔可能与温度补偿有关，因为系统在Hopf分岔点附近对控制参数的敏感性较低。

Circadian rhythms are oscillatory phenomena with a 24 hours period. One of the prominent characteristics is temperature compensation of period. We focused on temperature compensation, of which molecular mechanism remain unclear, in terms of bifurcation theory.We had observed circadian rhythms of some organisms under low temperature conditions, and determined the type of bifurcation for the abolishment of circadian rhythms. It had been showed that circadian rhythms of KaiC phosphorylation, fibroblast Arabidopsis and fruits flies were nullified through Hopf bifurcation. Hopf bifurcation under low temperature might relate with temperature compensation because the system near Hopf bifurcation point have low sensitivity to the control parameter.