oskar gene expression in the vector mosquitoes, Anopheles gambiae and Aedes aegypti

A disease control strategy based on the introduction into mosquito populations of a gene conferring a pathogen-refractory phenotype is currently under investigation. This population replacement approach requires a drive system that will quickly spread and fix antipathogen effector genes in target populations. Modified transposable elements containing the control sequences of developmentally regulated genes may provide the basis for a gene drive system that regulates gene mobilization in a sex- and stage-restrictive manner. Screening of a Drosophila melanogaster database for genes whose products localize exclusively in the future germ cells during early embryonic development resulted in the identification of several candidate genes. The regulatory sequences of these genes could be used to drive transposition. Mosquito orthologous genes of oskar were identified based on sequence homology and characterized further. The tissue- and sex-specific expression profiles and hybridizations in situ show that oskar orthologous transcripts in Anopheles gambiae and Aedes aegypti accumulate in developing oocytes of adult females and localize to the posterior poles of early embryos. These characteristics potentiate the use of the regulatory sequences of mosquito oskar genes for the control of modified transposable elements.