The rapid spread of West Nile virus has emphasized the role mosquitoes play as vectors for microbes and? viruses that cause human infectious diseases. Some of these diseases such as malaria, dengue fever,? yellow fever and various forms of viral encephalitis affect millions of people each year and are of great? public health concern. A multi-component strategy is necessary to effectively combat and control these? diseases. A important component of this strategy is the control of mosquito populations. Our long term goal? is to understand the transcriptional mechanisms that control mosquito metamorphosis. This molecular? information will be used to model and test more effective, and specific, mosquito control agents. In addition,? this information will be used in the construction of transgenic mosquitoes that will reduce wild populations of? adult female mosquitoes, and in protocols that drive specific genetically engineered genes into indigenous? mosquito populations. This proposal concerns the expression of genes that may play a central role in? mosquito metamorphosis. The conserved transcription factor gene AaHR3 is expressed early during? mosquito metamorphosis and may play a central role in this process. Application of the juvenile hormone? analogue methoprene to larvae causes lethality by interfering with metamorphosis. Methoprene also? interferes with AaHR3 expression during metamorphosis. The coincidence of these effects suggest that? methoprene interferes with mosquito metamorphosis by inhibiting induction of transcription factor AaHR3.? In vitro culture of larval midguts will be used to determine if methoprene directly, or indirectly interferes with? the expression of this transcription factor gene during ecdysone induced metamorphic midgut remodeling.? In addition RNA interference (RNAi) will be used to determine if induction of AaHR3 controls mosquito? metamorphosis. AaHR3 specific RNAi will be injected into larvae, or will be ingested by larvae. The effect of? this RNAi will be assayed microscopically and biochemically by in situ hybridization and real time PCR. The? role of other transcription factor genes, such as Aa75b, AaBetaFTZ-F1 and Broad complex, in midgut? metamorphosis will also be investigated by the technique of RNA interference.
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