EVOLUTIONARY MOLECULAR GENETICS OF MITOCHONDRIAL DNA

动物的线粒体系统是一个很好的研究对象。 分子进化。它的DNA很容易提纯，含有13个 蛋白质，2个核糖体RNA和22个转移RNA，但足够小到 彻底分析。线粒体DNA(MtDNA)缺乏介导性、间隔区 和重复序列，使其分析变得简单。相同 所有动物都有基因，但基因排列可能会改变。 线粒体DNA是母系遗传的，因此不会出现由 双亲遗传。 脊椎动物线粒体DNA的序列变化很快，相对于核DNA， 由于碱基替换和删除/添加。最广泛的 变化发生在一个很小但很有趣的区域(D-loop区域)，它 包含复制和基因表达的调控元件。 这一区域的比对将使我们能够识别可能是 对这些功能很重要。脊椎动物线粒体DNA的变化可能是 通过化石记录，与时间相关。关于以下两个基本问题 脊椎动物线粒体DNA的进化将被讨论：(1)什么样的 发生顺序变化以及按什么比例发生变化，以及(2)如何才能高比率 在一个细胞器的基因组中是可以容忍的序列变化的 功能对细胞如此重要？要回答这些问题，线粒体DNA将是 从一系列物种中获得的，这些物种的分歧时间是众所周知的。 同样的线粒体基因将被克隆出来，并从每个基因中进行测序。这个 序列将被比较，并且种类和相对比例 已确定的变化。将分析与功能相关的更改 它们发生在哪些基因中。有关约束的有用信息 分子结构和功能以及限制条件如何受基因组影响 应获得大小。此外，序列重排的两个实例在 将对D环路进行分析，以深入了解 重新安排的基础。 对其他主要动物群体的线粒体DNA的长期研究将 被启动。这项研究的直接目标是确定 动物线粒体DNA存在的变异范围并测试其通用性 从脊椎动物线粒体DNA研究中获得的知识。 所选的基团分别包括 血吸虫病及其中间宿主。有关生物方面的知识 这些生物体可能最终会导致控制方法的出现。

The mitochondrial system of animals is an excellent one in which to study molecular evolution. Its DNA is easily purified, contains genes for 13 proteins, 2 ribosomal RNAs and 22 transfer RNAs, yet is small enough to analyze completely. Mitochondrial DNA (mtDNA) lacks intervening, spacer and repetitive sequences, making its analysis uncomplicated. The same genes are present in all animals, but the gene arrangement can change. MtDNA is inherited maternally and is thus free of complications caused by biparental inheritance. The sequence of vertebrate mtDNA changes rapidly, relative to nuclear DNA, due to both base substitutions and deletion/additions. The most extensive changes occur in one small but interesting region (the D-loop region) which contains the regulatory elements for replication and gene expression. Comparisons in this region will allow us to identify sequences that may be important to these functions. Changes in vertebrate mtDNA can be correlated with time, via the fossil record. Two basic questions regarding the evolution of vertebrate mtDNA will be addressed: (1) What kinds of sequence changes occur and in what proportions, and (2) how can a high rate of sequence change be tolerated in the genome of an organelle whose functions are so vital for the cell? To answer these, mtDNA will be obtained from a series of species whose divergence times are well known. The same mitochondrial genes will be cloned and sequenced from each. The sequences will be compared, and the kinds and relative proportions of the changes determined. Changes will be analyzed with respect to the functions of the genes in which they occur. Useful information about constraints on molecular structure and function and how constraints are affected by genome size should be obtained. Also, two instances of sequence rearrangement in the D-loop will be analyzed in order to gain insight into the mechanistic basis of rearrangements. A long-term study of mitochondrial DNA from other major animal groups will be initiated. The immediate goals of the study are to define the total range of variation present in animal mtDNA and to test the generality of the knowledge that has been obtained from studies of vertebrate mtDNAs. The groups chosen include, respectively, the causative agents of schistosomiasis and their intermediate hosts. Knowledge of the biology of these organisms may ultimately lead to methods of control.