Horizontal gene transfer as a source of evolutionary innovation in metazoans

描述（由申请人提供）：水平基因转移作为后生动物进化创新的来源项目摘要蛭形目轮虫，微观淡水无脊椎动物，以其长期无性和对电离辐射的极端抵抗力而闻名，这可能是适应其自然短暂水生栖息地中频繁发生的干燥和再水化的结果。以前，我们发现蛭形轮虫也容易受到来自不同来源的大规模水平基因转移的影响，包括细菌，真菌，植物和原生生物。我们最近通过分析蛭形Adineta vaga的高质量序列草案，将这些发现扩展到全基因组范围，这表明多达8%，甚至可能更多，其蛋白质编码基因是外来的。我们现在建议调查的作用，选择外源基因可能发挥蛭基因组功能和进化适应不断变化的环境。水平转移基因的功能研究，这是罕见的后生动物，到目前为止，已被限制到研究的分离酶进行特定的反应，如色素的生物合成，或分解的化合物。在这里，我们计划将后生动物水平转移的功能研究提升到一个新的水平，并寻求调查可能导致重大进化创新的水平转移案例：获得不同于其他真核生物的非规范表观遗传修饰系统;获得和前所未有的抗生素抗性基因的扩增以及控制其表达的调控系统的出现;以及获得和多样化具有产生多种新的生物活性化合物的潜力的多功能次级代谢系统。除了显著增加我们对横向基因转移对后生动物进化的贡献的基础知识外，这些研究最终可能有助于理解抗生素耐药性进化的途径，并可能进一步导致发现以前未知的具有独特生物学或药用特性的次级代谢产物。

DESCRIPTION (provided by applicant): Horizontal gene transfer as a source of evolutionary innovation in metazoans Project summary Rotifers of the class Bdelloidea, microscopic freshwater invertebrates, are known for their long-term asexuality and extreme resistance to ionizing radiation, which may be a consequence of adaptation to frequent bouts of desiccation and rehydration in their natural ephemerally aquatic habitats. Previously, we discovered that bdelloids are also susceptible to massive horizontal gene transfer from diverse sources, including bacteria, fungi, plants, and protists. We have recently extended these findings to the genome-wide scale through analysis of the high-quality draft sequence of the bdelloid Adineta vaga, which revealed that as much as 8%, and likely even more, of its protein-coding genes are of foreign origin. We now propose to investigate the role that selected foreign genes might play in bdelloid genome function and evolutionary adaptation to changing environments. Functional studies of horizontally transferred genes, which are rare in metazoans, have so far been limited to studies of isolated enzymes performing a specific reaction, such as biosynthesis of a pigment, or decomposition of a compound. Here, we plan to take functional studies of metazoan horizontal transfers to a new level, and seek to investigate cases of horizontal transfer that may have resulted in major evolutionary innovations: acquisition of a non-canonical system of epigenetic modification differing from that in other eukaryotes; acquisition and unprecedented expansion of antibiotic resistance genes and emergence of regulatory systems controlling their expression; and acquisition and diversification of a versatile system of secondary metabolism that has the potential to yield a variety of novel bioactive compounds. Beyond adding significantly to our fundamental knowledge of the contribution of lateral gene transfer to metazoan evolution, these studies may eventually help in understanding the pathways to evolution of antibiotic resistance, and may further lead to discovery of previously unknown classes of secondary metabolites with unique biological or medicinal properties.