Narrow Results

Current model for circadian rhythms is wrong both theoretically and practically. A new model, called yin yang model, is proposed to explain the mechanism of circadian rhythms. The yin yang model separate circadian activities in a circadian system into yin (night activities) and yang (day activities) and a circadian clock into a day clock and a night clock. The day clock is the product of night activities, but it promotes day activities; the night clock is the product of day activities, but it promotes night activities. The clock maintains redox or energy homeostasis of the internal environment and allows temporal separations between biological processes with opposite impacts on the internal environment of a circadian system.

Fractal geometry can adequately represent many complex and irregular objects in nature. The fractal dimension is typically computed by the box-counting procedure. Here I compute the box-counting and the Kaplan-Yorke dimensions of the 14-dimensional models of the Drosophila circadian clock. Clockwork Orange (CWO) is transcriptional repressor of direct target genes that appears to play a key role in controlling the dynamics of the clock. The findings identify these models as strange attractors and highlight the complexity of the time-keeping actions of CWO in light-day cycles. These fractals are high-dimensional counterexamples of the Kaplan-Yorke conjecture that uses the spectrum of the Lyapunov exponents.