Malaria is the world's most important tropical parasitic disease. It is responsible for 2 percent of all deaths worldwide and 9 percent of deaths in Africa. More than 3 billion people live under the threat of malaria. The ability of mosquitoes to transmit malaria parasites varies among different mosquito species, even between different geographical strains of the same species. Our long term goal is to identify mosquito genes that play central roles in imparting susceptibility or refractoriness of mosquitoes to the malaria parasite Plasmodium, and to use this knowledge to aid future efforts to control malaria transmission. Understanding molecular details of the parasite-vector interactions relies heavily on precise measurement of nascent protein synthesis in the mosquito during Plasmodium infection. Current expression profiling largely monitors alterations in steady-state levels of mRNA. However, due to various post-transcriptional and translational regulatory mechanisms, the abundance of each given mRNA in the transcriptome does not necessarily mirror the expression of the encoded proteins within the proteome. Some mosquito factors might have gone unrecognized because they are translationally rather than transcriptionally regulated after mosquitoes ingest a Plasmodium-infected blood meal. This research plan combines mRNA profiling with genome-wide analysis of mRNA translation states to simultaneously monitor changes in the transcriptome and nascent protein synthesis in the mosquito. We will use sucrose density gradient centrifugation to separate mRNAs associated with polyribosomes from those that are translationally inactive. The mRNA levels of individual mosquito genes in each of these two fractions will be determined using microarray hybridization. This approach will not only provide more accurate information regarding the rate of protein synthesis, it also will lead to the discovery of general and gene-specific translational regulation in response to Plasmodium infection. The specific aims of this project are: 1) To discover translational regulations of mosquito genes in the midgut in response to Plasmodium infection. 2) To determine whether the translational regulations of midgut mRNA differ between the Plasmodium falciparum-susceptible and -refractory mosquitoes during Plasmodium infection. PUBLIC HEALTH RELEVANCE: Project Narrative The malaria parasites must undergo a series of developmental transformations inside the mosquito vector to become infectious to vertebrate hosts. We will use a new genome-wide approach to study protein synthesis in mosquitoes after ingestion of parasites with a blood meal. The results from this study will advance our knowledge of mosquito-malaria parasite interaction and reveal genetic factors that determine the ability of the mosquitoes to transmit the parasites. The new insights in turn may lead to new strategies for malaria control.