Abstract: The mosquito Anopheles gambiae ( An. gambiae ) is the major vector of human malaria in sub-Saharan Africa. Malaria is spread to humans while the female infected mosquitoes bite people for blood meal. Significant physiological changes occur after blood ingestion and over 50% of all genes show significant variation in transcript accumulation. We hypothesize that microRNAs (miRNAs) may contribute to this tightly controlled tissue- and stage-specific gene expression.

To systematically assess the role of miRNAs, mosquito samples were collected at six time points after blood feeding to evaluate their dynamic changes. In addition, we measured the associations of miRNAs with Argonaute 1 (Ago1) and Argonaute 2 (Ago2) to assess the functional status of individual miRNA species. Overall, 167 mature miRNAs were detected in this study including 13 new miRNAs. While homologs of 12 new miRNAs were found in 19 other Anopheles species with well-sequenced genomes, miR-N5 was likely an An. gambiae -specific miRNA. Ago1 interacted with a majority of miRNAs, compared with Ago2. T

he expression of most of the 167 miRNAs were relatively stable after blood ingestion. However, 23 miRNAs showed differential expression, including the miR-309/286/2944 cluster, which was dramatically upregulated after blood feeding. Injection of the antagomir for miR-309 resulted in smaller developing oocytes and ultimately fewer eggs, suggesting that miR-309 plays an important role in regulating egg development. 

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