Horizontal Gene Transfer in Multicellular Eukaryotes

描述（由申请人提供）：水平基因转移（HGT）现在被认为是驱动微生物世界基因组和表型变化的主要进化遗传力量-在整个原核生物和许多单细胞真核生物（所有噬菌体原生生物）中。我们和其他人最近发现了在任何多细胞真核生物群体中广泛存在HGT的第一个证据，发现植物中线粒体基因的水平转移是频繁和最近的。许多这些转移产生线粒体基因复制（垂直和水平传输的同源物），而其他人则导致惊人的嵌合基因（部分水平/部分垂直）或重新填充基因组与先前转移到细胞核的基因。一些转移的基因是完整的，表达，并可能功能。一个线粒体基因组已经被确定具有多个，也许是许多水平获得的基因。 这项研究的目标是建立在这些令人兴奋的发现，并在多细胞真核生物中进行第一次全面和严格的HGT研究。由于HGT是基因组进化中一个基本但知之甚少的过程，这些研究将为基因组结构和功能提供一个重要的新视角。维持一个完整的、功能正常的基因组对人类健康至关重要，了解基因交换的机制对基因治疗的发展至关重要。 该项目的重点是植物线粒体基因组，因为它们对HGT的特殊倾向和其他几个属性使它们成为研究真核生物HGT的模型系统。研究包括4000株植物的靶向宏阵列筛选，200株不同植物的全基因测序，15株具有非常广泛HGT的植物的全基因组测序，以及对上述高度感兴趣的特定病例的各种后续研究。结果将解决许多问题，有关率，模式，程度，嵌合的后果，供体/受体的关系，功能和机制的HGT在许多谱系的植物线粒体基因组。某些机制的研究遵循新出现的证据表明，某些植物和基因是不寻常的倾向于HGT和一个共同的机制，转移是寄生植物和它们的宿主植物之间的物理渗透。

DESCRIPTION (provided by applicant): Horizontal gene transfer (HGT) is now recognized as a major evolutionary genetic force driving genomic and phenotypic change in the microbial world -- throughout prokaryotes and in many unicellular eukaryotes (all phagotrophic protists). We and others recently discovered the first evidence for widespread HGT within any group of multicellular eukaryotes, finding that horizontal transfer of mitochondrial genes in plants is both frequent and recent. Many of these transfers yield mitochondrial gene duplications (of vertically and horizontally transmitted homologs), whereas others lead to strikingly chimeric genes (part horizontal/part vertical) or repopulate the genome with genes previously transferred to the nucleus. Some of the transferred genes are intact, expressed, and probably functional. One mitochondrial genome has already been identified with multiple, perhaps many horizontally acquired genes. The goal of this study is to build on these exciting findings and conduct the first comprehensive and rigorous study of HGT in multicellular eukaryotes. Because HGT is a fundamental but poorly understood process in genome evolution, these studies will provide an important new perspective on genome structure and function. The maintenance of an intact, functioning genome is critical for human health, and understanding mechanisms of gene exchange is important to the development of gene therapy. This project focuses on plant mitochondrial genomes because their exceptional propensity for HGT and several other attributes make them a model system for investigating HGT in eukaryotes. Studies include targeted macroarray screens of 4000 plants, all-gene sequencing in 200 diverse plants, whole-genome sequencing in 15 plants with exceptionally extensive HGT, and various follow-up studies on specific cases of high interest from the above. Results will address numerous questions concerning rates, patterns, extents, chimeric consequences, donor/recipient relationships, functionality, and mechanisms of HGT across many lineages of plant mitochondrial genomes. Certain of the mechanistic studies follow from emerging evidence suggesting that certain plants and genes are unusually prone to HGT and that a common mechanism of transfer is physical penetration between parasitic plants and their host plants.