Experimental Population Genetics of Drosophila Mitochondrial DNA

本研究的主要目的是检验这一假设 不同的线粒体基因组会影响繁殖率 或者说果蝇的“适应性”。 的 研究将使用实验种群笼， 携带不同的线粒体DNA（mtDNA）的细胞之间相互竞争 以确定某些线粒体 基因型与其他基因型相比具有一致的生殖优势， 基因型 这些实验将涉及基因杂交， 构建具有相同核染色体的果蝇品系， 但仅在线粒体DNA上不同 的几个成对检验 竞争力将在品系间进行 来自不同的人群。 人口是经过挑选的， 成对测试将涉及果蝇品系， 少量、中等量和大量的DNA序列差异 竞争的线粒体基因组之间。 这将提供 DNA序列差异对强度影响的试验 不同菌株之间的适应性差异。 该研究还涉及一套补充的 实验来测试不同mtDNA的“适应性”， 细胞 使用显微注射技术将完整的 果蝇品系之间的线粒体，人们可以创造一个 微型“人口笼”内的生殖细胞， 雌性苍蝇 通过创造生殖细胞， 不同的mtDNA，我们可以测试不同的假设， 线粒体基因组在遗传上具有优势， 母亲对子女 这种方法将用于 与种群笼实验中使用的果蝇品系相同 上面描述 这种研究线粒体DNA的“两级”方法 变异将提供有关功能意义的信息 自然发生的线粒体DNA变异，并作为一个模型 系统来研究细胞核和线粒体的共同进化 基因组 此外，这项研究将测试关键的 许多关于种群动态的研究假设， 变化是中性的。

The general focus of this research is to test the hypothesis that different mitochondrial genomes affect the reproductive rate or "fitness" of the fruit fly Drosophila melanogaster. The research will employ experimental population cages where flies carrying different mitochondrial DNAs (mtDNAs) are competed against one another to determine whether certain mitochondrial genotypes have consistent reproductive advantages over other genotypes. The experiments will involve genetic crosses to construct strains of flies that have the same nuclear chromosomes but differ only in their mtDNAs. Several pairwise tests of competitive ability will be conducted between strains of flies from different populations. The populations have been chosen so that the pairwise tests will involve strains of flies with little, moderate and large amounts of DNA sequence difference between the competing mitochondrial genomes. This should provide a test of the effect of DNA sequence difference on the strength of the fitness different between strains. The research also involves a complementary set of experiments to test the "fitness" of different mtDNAs inside cells. Using a microinjection technique to transplant intact mitochondria between strains of fruit flies, one can create a miniature "population cage" inside the reproductive cells of female flies. By creating reproductive cells with mixtures of different mtDNAs, one can test the hypothesis that different mitochondrial genomes have an advantage in inheritance from mother to offspring. This approach will be employed with the same strains of flies used in the population cage experiments described above. This "two-level" approach to the study of mtDNA variation will provide information on the functional significance of naturally occurring variation in mtDNA and serve as a model system to study the coevolution of nuclear and mitochondrial genomes. Furthermore, this research will test the critical assumption for many studies of population dynamics that mtDNA variation is neutral.