TRYPTOPHAN METABOLISM IN MOSQUITOES

蚊子是重要的疾病媒介，负责传播许多病毒、细菌和寄生虫病，如疟疾、登革热、黄热病和丝虫病。疟疾是一种毁灭性的疾病，由疟原虫感染引起，在全世界影响多达5亿人，每年造成多达200万人死亡。 抗药性寄生虫和杀虫剂抗性蚊子媒介的发展迫切要求开发新的和创新的蚊子或寄生虫控制策略。 阻断蚊子或疟原虫正常发育所必需的生理生化过程是控制疟疾的一种方法。 在埃及伊蚊中鉴定了一种新的转氨酶，其特异于色氨酸氧化过程中形成的化学反应性和潜在毒性的3-羟基犬尿氨酸转氨为稳定的黄尿酸，并且该酶在血餐后的幼虫和成年雌性中以高活性受到严格调节。 我们最近的数据表明，黄尿酸也刺激疟原虫的配子发生，这表明这一途径可能在启动疟原虫发育的蚊子载体中发挥关键作用。 本研究的长期目标是充分了解蚊子媒介中这种酶的调控途径和机制。 所提出的研究的具体目的是（I）通过各种生物化学技术从蚊子中纯化和表征3-羟基犬尿氨酸转氨酶，（II）用各种分子技术启动关于蚊子发育期间这种转氨酶的遗传调控的研究，其包括从蚊子幼虫制备cDNA文库，从文库中分离3-羟基犬尿氨酸转氨酶cDNA，并研究了3-羟基犬尿氨酸转氨酶在蚊子发育过程中的基因表达;（III）研究了3-羟基犬尿氨酸在按蚊体内转氨生成黄尿酸的途径。我们的假设是，这种转氨途径是至关重要的正常发育的蚊子，也可能发挥关键作用，刺激疟原虫的发展;因此，在本发明中，了解控制其调节的机制可能对未来通过创新的蚊子控制策略来负面干扰媒介发展的努力产生重大影响，也可能为开发控制疟疾的新工具提供见解通过中断蚊子载体中疟原虫的配子发生来消灭寄生虫。

Mosquitoes are important disease vectors, responsible for transmission of numerous viral, bacterial and parasitic diseases, such as malaria, dengue fever, yellow fever, and filariasis. Malaria, caused by infection with species of Plasmodium, is a devastating, disease which affects up to 500 million people world-wide, killing as many as 2 million a year. The development of drug resistant parasites, and insecticide resistant mosquito vectors urgently demands that new and innovative mosquito or parasite control strategies be developed. Disruption of the required physio-biochemical processes that are necessary for the normal development of either mosquitoes or malaria parasites is one approach for malaria control. A novel transaminase that is specific for the transamination of a chemically reactive and potentially toxic 3-hydroxykynurenine, formed during tryptophan oxidation, to stable xanthurenic acid is identified in Aedes aegypti mosquitoes, and this enzyme is tightly regulated with high activity in larvae and adult females after a bloodmeal. Our recent data show that xanthurenic acid also stimulates gametogenesis of Plasmodium parasites, suggesting this pathway may play critical role in initiating Plasmodium development in mosquito vectors. The long term goal of this research is to achieve a full understanding of the pathways and mechanisms governing the regulation of this enzyme in mosquito vectors. The specific aims of the proposed research are (I) to purify and characterize the 3-hydroxykynurenine transaminase from mosquitoes by various biochemical techniques, (II) to initiate studies concerning the genetic regulation of this transaminase in mosquitoes during development with various molecular techniques, which includes preparation of a cDNA library from mosquito larvae, isolation of 3-hydroxykynurenine transaminase cDNA from the library, and study of gene expression of the 3-hydroxykynurenine transaminase in mosquitoes during development, and (III) to study the transamination pathway of 3-hydroxykynurenine to xanthurenic acid in Anopheles mosquitoes. Our hypotheses are that this transamination pathway is critical for the normal development of mosquitoes and also may play a critical role in stimulating Plasmodium development; consequently, understanding the mechanism controlling its regulation could have a significant impact on future efforts to negatively interfere with vector development through innovative mosquito control strategies and also may provide insight into developing novel tools for the control of malaria parasites by interrupting gametogenesis of Plasmodium in mosquito vectors.