AI 中文总结
该研究提出基于曲率的谐波昼夜节律波形判定准则，证实蓝藻、哺乳动物SCN及Goodwin模型的振荡为谐波，为生物节律波形分析提供新视角。
AI 中文摘要
昼夜节律的实验与理论研究大多聚焦于周期、改变周期的突变体及相位偏移，这一研究重点推动了时钟基因的鉴定，并阐明了时钟如何对明暗周期同步。相比之下，振荡本身的波形作为潜在振荡器特性的指标，却很少受到关注。为直接评估波形，我们聚焦于变量及其时间导数构成的平面中的轨迹是否存在拐点，并定义不存在拐点的振荡为谐波。蓝藻和哺乳动物SCN（视交叉上核）的生物发光记录符合该定义下的谐波特征，昼夜节律时钟数学模型中的大多数核心时钟组件也如此。对核心昼夜节律振荡器的最小表示Goodwin模型的数值分析显示，其全程存在谐波振荡；我们采用分段线性化Goodwin模型半解析地证实了这一数值趋势。由于所提方法无需假设模型结构即可评估波形特性，它为生物节律（不仅限于昼夜节律）的波形分析提供了新视角。
英文摘要
Experimental and theoretical studies of circadian rhythms have focused largely on the period, on mutants that alter it and on phase shifts, and this focus has driven the identification of clock genes and clarified how clocks entrain to light--dark cycles. The waveform of the oscillation itself, by contrast, has attracted little attention as an indicator of the properties of the underlying oscillator. To assess the waveform directly, we focus on whether the trajectory in the plane spanned by a variable and its time derivative possesses an inflection point, and we define an oscillation to be harmonic when no inflection point is present. Bioluminescence recordings from cyanobacteria and from the mammalian SCN were harmonic in this sense, as were most of the core clock components in mathematical models of the circadian clock. Numerical analysis of the Goodwin model, a minimal representation of the core circadian oscillator, yielded harmonic oscillation throughout. We confirmed this numerical trend semi-analytically using a piecewise-linearized Goodwin model. Because it evaluates the properties of a waveform without assuming a model structure, the approach we propose offers a new perspective on the waveform analysis of biological rhythms in general, not only circadian ones.
