细菌DNA序列中的长程相关性

为了深入研究基因组序列的长程相关性质，将一些估计序列长程相关因数的参数化方法引入脱氧核糖核酸（ Ｄ Ｎ Ａ）序列自相似结构的研究之中。与 Ｆｏｕｒｉｅｒ 分析方法比较，这些参数化方法的结果更加稳定可靠。应用这些方法，该文对 ８ 种细菌 Ｄ Ｎ Ａ 全序列进行了统计分析，发现在细菌 Ｄ Ｎ Ａ 序列中存在着长程相关结构，其存在范围可以延伸到整个 Ｄ Ｎ Ａ 分子。粗粒化过程的高阶累积量检验表明 Ｄ Ｎ Ａ序列中存在的是单分形结构，在较大尺度下可以渐近地用分数高斯噪声过程来建模。这为进一步分析和理解 Ｄ Ｎ Ａ 序列的组织形式和功能行使方式提供了新的思路。

Long-range correlation properties in bacteria DNA sequence

In order to explore the long range correlation properties of DNA sequences in a further step, some parametric methods are introduced to characterize the self similarity of DNA sequences. Compared with Fourier analysis, these methods perform statistically more stable and yield more reliable results. Using these methods, eight whole genomes of bacteria are analyzed. Long range correlation properties in the nucleotide density distribution along these DNA sequences are explored. Estimation results show that the long range correlation structure prevails through the entire molecule of DNA. Higher order statistics through coarse grain reveal that rather than multi fractal, there are only mono fractal phenomena presented in the sequences. Hence, the nucleotide density distribution can be modeled asymptotically as fractional Gaussian noise. This result brings about a new direction for analyzing and understanding the intrinsic structures of DNA sequences.