nanos gene control DNA mediates developmentally regulated transposition in the yellow fever mosquito Aedes aegypti.

Transposable elements (TEs) are proposed as a basis for developing drive systems to spread pathogen resistance genes through vector mosquito populations. The use of transcriptional and translational control DNA elements from genes expressed specifically in the insect germ line to mediate transposition offers possibilities for mitigating some of the concerns about transgene behavior in the target vector species and eliminating effects on nontarget organisms. Here, we describe the successful use of the promoter and untranslated regions from the nanos (nos) orthologous gene of the yellow fever mosquito, Aedes aegypti, to control sex- and tissue-specific expression of exogenously derived mariner MosI transposase-encoding DNA. Transgenic mosquitoes expressed transposase mRNA in abundance near or equal to the endogenous nos transcript and exclusively in the female germ cells. In addition, MosI mRNA was deposited in developing oocytes and localized and maintained at the posterior pole during early embryonic development. Importantly, four of five transgenic lines examined were capable of mobilizing a second MosI transgene into the mosquito genome, indicating that functional transposase was being produced. Thus, the nos control sequences show promise as part of a TE-based gene drive system.

Nanos (nos) genes of the vector mosquitoes, Anopheles gambiae, Anopheles stephensi and Aedes aegypti.

A number of genetics-based strategies for the control of vector-borne diseases require the development of genetic drive systems for introgressing antipathogen effector genes into wild populations of insects. Modified transposons whose mobilization is controlled by the DNA elements of developmentally regulated genes offer a potential solution for introducing effector genes into mosquitoes. Such elements could exhibit sex-, stage- and species-specific transposition, thus mitigating some of the concerns associated with autonomous transposition. Hybridizations in situ show that the transcription products of the nanos orthologous genes of Anopheles gambiae (Anga nos), An. stephensi (Anst nos) and Aedes aegypti (Aeae nos) accumulate in developing oocytes in adult females and localize to the posterior pole in early embryos. These features make nos genes promising candidates for donating control sequences to modified transposons.