Transposition of the Gnome MITE Family and its Development Toward a Gene Driver for Genetic Control of Mosquito-Borne Diseases

黄热病蚊子是黄热病、登革热和基孔肯雅热等疾病的重要病原体传播媒介。大规模灭蚊是一项具有挑战性的任务。基因控制蚊子的前景看好，而且比化学应用更环保。一种有吸引力的方法是种群置换，即少数对病原体具有抵抗力的蚊子可以在种群中传播耐药性，将防线推到疾病媒介之外。这种方法的成功依赖于基因驱动系统来传播抗药性。转座元件(TES)，被称为跳跃基因，可以迅速增加它们在种群中的频率，被认为是基因驱动系统的优秀候选者。然而，目前用于蚊子研究的TES来自其他物种，一旦整合到蚊子的染色体中，它们的再动员效率通常很低。蚊子中高效转座和扩增的成分是非常可取的。植物和动物中的一组TES，称为微型反向重复序列转座元件(MITE)，具有这些理想的特征。对我实验室的黄热病蚊子中的蠕虫进行了全基因组分析，确定了它最年轻、最有可能活跃的蠕虫家族，我们将其命名为侏儒。然而，这种成分并不携带产生负责动员的蛋白质的基因。通过对我之前开发的名为Mite分析工具包的计算工具的重大改进，发现了一个难以捉摸的单一拷贝元素，我们将其命名为Ozma，它是Gnome的祖先元素。利用我之前为大米元素建立的实验系统，初步研究表明，Ozma转座酶，即移动TES的蛋白质，能够动员酵母中的Gnome。在这里，我建议对这些元件进行详细的研究，以加深我们对Gnome和相关元件转座机制的了解，了解它们在蚊子中的当前活动，并将它们用作遗传工具。为了实现这些目标，我们将进行以下研究：(1)Gnome转座和Ozma转座酶的特性以揭示重要特征；(2)分析蚊体中螨类家族的活动及其自主元件；(3)基于螨类的货运基因载体和可再动员系统的开发。在这些研究中，我们将使用分子生物学和计算生物学相结合的方法。拟议中的研究将揭示蚊子基因组中最年轻的蠕虫家族转位和扩增背后的机制的秘密。它将为我们对基因组进化的认识做出重要贡献。我们将在这些研究中分析的元素是潜在的有效的新型遗传工具，可用于科学研究和实际应用，如转基因、基因治疗和害虫的遗传控制。在研究期间，包括博士后研究员、研究生和本科生在内的高素质人才将在我的实验室进行培训。因此，拟议的研究不仅将为研究界创造新的知识，还将在教育、医学和环境保护领域为加拿大经济做出贡献。

Yellow fever mosquito is an important vector for pathogens of diseases such as Yellow Fever, Dengue Fever and Chikungunya. Large scale mosquito control is a challenging task. Genetic control of mosquitoes is promising and more environmentally friendly than chemical applications. One attractive approach is population replacement where a small number of mosquitoes resistant to pathogens can spread the resistance in a population, pushing the defense line beyond the disease vectors. The success of this approach relies on a gene drive system to spread the resistance. Transposable elements (TEs), known as jumping genes, can increase their frequency in a population rapidly and are considered excellent candidates for a gene drive system. However, currently used TEs in the studies on the mosquito are from other species and typically remobilize inefficiently once they integrate into the chromosomes of the mosquito. Elements in mosquito that transpose and amplify efficiently are highly desirable. A group of TEs in plants and animals named miniature inverted repeat transposable elements (MITEs) bear these desirable features. Genome wide analyses of MITEs in the yellow fever mosquito in my lab identified its youngest and most likely active MITE family we named Gnome. However, this element does not carry the gene that produces the protein responsible for its mobilization. With major improvements of a computational tool name MITE Analysis Kit that I previously developed, an elusive single copy element we named Ozma was discovered to be the ancestral element of Gnome. Using an experimental system I previously established for rice elements, preliminary studies suggest that the Ozma transposase, protein that moves TEs, is capable of mobilizing Gnome in yeast. Here I propose detailed studies on these elements to deepen our knowledge on the transposition mechanisms of Gnome and related elements, understand their current activity in mosquito and use them as genetic tools. To achieve these goals, we will perform the following studies: (1) Characterization of Gnome transposition and Ozma transposase to reveal important features; (2) Analyses of the activities of MITE families and their autonomous element in mosquito; (3) Development of MITE based cargo gene vectors and remobilization systems. We will use a combined approach of molecular biology and computational biology in these studies. The proposed studies will reveal the secrets of the mechanisms underlying the transposition and amplification of the youngest MITE family in the mosquito genome. It will make important contributions to our knowledge on genome evolution. The elements we will analyze in these studies are potentially efficient novel genetic tools for scientific research and practical applications such as transgenesis, gene therapy and genetic control of pest insects. During the studies, highly qualified personnel including postdoctoral fellows, graduate students and undergraduate students will be trained in my lab. Therefore, the proposed research will not only generate new knowledge for the research community, but will also contribute to the Canadian economy in the areas of education, medicine and environment protection.