DNA SEQUENCE COMPLEXITY AND MUTATIONAL DYNAMICS

DNA序列在其局部显示出大量的统计异质性 构成特征。该项目正在调查 序列复杂性中镶嵌的可能原因，特别是 突变偏向在中长期组合中的作用 特定功能类和结构类的约束和关联 顺序性。 A.局部复杂性的分布：使用局部复杂性的正式定义 DNA子序列的组成复杂性、健壮性 探讨了Salamon/Konopka的最大熵关系：给定一个 功能等价的DNA序列集，其分布 这个集合的所有子序列之间的复杂性似乎是随机的 可能与这些子序列的平均复杂性一致。它 现在已经证明，这种最大熵效应遵循如下公式 几乎任何突变机制的动力学后果 偏向于低复杂性，例如邻居- 在人类基因组中观察到的替代突变中的依赖偏见 突变。 B.中程复杂性分布的羽毛结构：DNA 长度范围为40到200个核苷酸的片段具有以下分布 具有新的结构规律性的成分复杂性 (“羽化”)。这是数学特性的结果 局部成分复杂性度量在应用于相对 很长的序列。在基因组序列中观察到的模式，但在 随机序列反映了不同的 自然DNA序列中的复杂性类别。项目的意义： Project正在开始为一些 从DNA序列的统计分析中发现的令人费解的特征， 包括所谓的“长程关联”的各个方面。 其他课题组来自光谱分析。

DNA sequences show enourmous statistical heterogeneity in their local compositional characteristics. This project is investigating the possible causes of the mosaicism in sequence complexity, particularly the roles of mutational biases, medium and long range combinatorial constraints, and correlates of specific functional and structural classes of sequence. A. Distributions of local complexity: Using formal definitions of local compositional complexity of DNA subsequences, the robustness of the Salamon/Konopka maximum entropy relationship has been explored: Given a functionally equivalent set of DNA sequences, the distribution of complexity among all subsequences of this set appears to be as random as possible consistent with the mean complexity of these subsequences. It has now been shown that this maximum entropy effect follows as a consequence of the dynamics of almost any mutational mechanism that incorporates a bias toward low-complexity, for example the neighbor- dependent biases in substitution mutations observed in human genomic mutations. B. Feathered structure of medium range complexity distributions: DNA segments of length range 40 to 200 nucleotides have distributions of compositional complexity with a novel regularity of structure ("feathering"). This is a consequence of the mathematical properties of the local compositional complexity measures when applied to relatively long sequences. The pattern observed in genomic sequences but not in random sequences reflects the nonuniform representation of different complexity classes in natural DNA sequences. Significance of project: The project is beginning to provide detailed explanations for some of the puzzling features found from statistical analyses of DNA sequences, including aspects of the so-called "long range correlations" inferred by other research groups from spectral analysis.