生物钟基因调节网络随机涨落诱导的节律振荡研究

发布时间：2018-01-05 22:16

本文关键词：生物钟基因调节网络随机涨落诱导的节律振荡研究　出处：《华中师范大学》2005年硕士论文　论文类型：学位论文

【摘要】：Smolen等人于2002年提出了果蝇时钟蛋白节律振荡的基因调节网络两变量模型。作为节律振荡重要的控制因子,光通过提高磷酸化的TIM蛋白的衰减控制着时钟基因的表达和果蝇的昼夜节律振荡。我们把光噪声引入到该确定性模型里,得到了果蝇节律振荡的随机动力学模型。利用朗之万方程(Langevin Equation),我们首先研究了光噪声对于时钟蛋白昼夜节律振荡的影响。当光控参数超过分岔点略微远离振荡区域时,我们发现光的涨落可以诱导时钟蛋白昼夜节律振荡,并称之为超阈值的昼夜节律振荡:当光噪声的强度较大或者较小时,昼夜振荡的节律性并不明显;当光噪声强度取适当大小时,可以看到光噪声诱导的随机振荡具有明显的昼夜节律性。在某个噪声强度下出现了这种相干的昼夜节律振荡,由于它是一个被噪声优化的生物昼夜振荡,所以反映了生物系统的一种重要的相干共振现象,信噪比和特征关联时间的计算结果都确认了我们的结论。结论表明了光的涨落在果蝇的昼夜节律振荡中起着积极的作用。同时我们发现时间延迟可以控制相干共振的强度,在适当的时间延迟下,时钟蛋白昼夜节律振荡的相干性可以达到最大。其次,我们单独研究了分子噪声对于昼夜振荡子模型的影响。由于基因调节网络中的分子数目很少,所以分子数目的涨落对于昼夜节律振荡模型是重要的。为了估计分子噪声影响,我们把确定性模型分解为基本的反应项,通过Gillespie介绍的算法来进行分子噪声的随机模拟。我们发现分子噪声同样可以诱导超阈值的昼夜节律振荡,并且诱导的昼夜振荡非常稳固,表现为基因调节网络中时钟蛋白质分子数目只有数十个时,系统仍然产生了较明显的昼夜节律振荡。噪声诱导的时钟蛋白昼夜节律振荡显示了噪声可以引导一个非线性系统
[Abstract]:Smolen et al in 2002 proposed a network model with two variables of Drosophila circadian oscillations in clock protein gene regulation. As an important factor to control the circadian oscillations, light by increasing the phosphorylation of TIM protein expression and attenuation control of Drosophila clock gene in the circadian oscillation. We put the light noise into the deterministic model and the stochastic the dynamics model of Drosophila circadian oscillations. Using the Langevin equation (Langevin Equation), we first studied the influence of light noise on circadian oscillations. When the light control parameter exceeds the bifurcation point slightly away from the oscillation region, we found that the light fluctuation can induce the circadian oscillations, called circadian oscillation super threshold: when light and large noise intensities is small, rhythmic circadian oscillation is not obvious; when the light intensity of noise proper size, You can see the random oscillation light induced by noise has obvious circadian rhythm. In a noise intensity appeared under this circadian coherent oscillation, because it is a noise optimization of circadian oscillation, so the biological system reflects an important coherent resonance phenomenon, calculate the signal-to-noise ratio and characteristics the results of correlation time confirmed our conclusions. The conclusion shows that the light fluctuation plays a positive role in the Drosophila circadian oscillations. At the same time we find that the time delay can control the coherence resonance intensity, at the appropriate time delay, the coherence of the circadian oscillations can reach the maximum.
Secondly, we study the effect of molecular noise on circadian oscillator model. Because the number of molecules in the gene regulation network is very few, so the fluctuation of the number of molecules is important for circadian oscillator model. In order to estimate the effect of molecular noise, we put the deterministic model into elementary reaction steps, random simulation is introduced through Gillespie the algorithm for molecular noise. We found that molecular noise could induce the circadian oscillation threshold, and induced circadian oscillations are extremely stable, performance for the number of clock gene regulatory protein molecules in the network only dozens of, the system still has obvious circadian oscillation.
The noise induced clock protein circadian rhythm oscillations show that noise can guide a nonlinear system

【学位授予单位】：华中师范大学
【学位级别】：硕士
【学位授予年份】：2005
【分类号】：Q811.213

【引证文献】