MOLECULAR GENETICS OF MUTATIONAL VARIATION IN MITOCHONDRIAL DNA OF DROSOPHILA

真核生物中的线粒体是负责细胞内 呼吸，并且在动物细胞器中是独特的，因为它具有其 自己的DNA编码基因组。在果蝇属中，就像人类一样， 该基因组由一个大小约为16 Kb的环状分子组成， 母系遗传，不重组。有人指出， 人类疾病似乎与基因突变畸变有关， 线粒体DNA基因组，但是，我们对正常突变的理解 线粒体DNA中发生的过程知之甚少。因此，委员会认为， 关于模型系统中常见突变过程的知识，例如 会引起人们极大的兴趣。 为了了解果蝇中发现的突变变异， 在自然界中八种蛋白质编码线粒体基因的变异 种群和不同物种之间将进行检查，以确定 影响变异程度的因素。这将通过 通过两种不同的方式来测试证据：（1）通过检查是否 在果蝇种群中观察到的序列变异是由于 中性突变的积累，或突变的结果， 自然选择所维持的取代。这将是 使用基于中性理论的群体遗传模型进行测试， 聚结理论(2)通过检查影响序列的因素， 这些基因在不同种类的果蝇中的变异， 用比较系统发育树的方法进行测试。

The mitochondrion in eukaryotes is the organelle responsible for cellular respiration, and is unique among animal organelles in that it possess its own DNA coding genome. In the fruitfly genus Drosophila, as in humans, this genome consists of a circular molecule about 16 Kb in size, which is maternally inherited and non-recombining. It has been noted that several human diseases appear to be related to mutational aberrations in the mitochondrial DNA genome but, our understanding of the normal mutational processes occurring in mtDNA are poorly understood. Consequently, knowledge concerning the usual mutational process in a model system, such as Drosophila, would be of great interest. To understand the mutational variation found in Drosophila, sequence variation at eight protein coding mitochondrial genes within natural populations and among different species will be examined to determine the factors influencing the levels of variation. This will be accomplished by testing the evidence in two separate ways: (1) By examining whether sequence variation observed within populations of Drosophila is due to the accumulation of neutral mutations, or the result of mutational substitutions that are maintained by natural selection. This will be tested by using population genetic models based on neutral theory and coalescent theory. (2) By examining the factors affecting sequence variation in these genes among different species of Drosophila, which will be tested by using comparative phylogenetic tree methods.