Stable, germ-line transformation of Culex quinquefasciatus (Diptera: Culicidae).
A Hermes-based transposable element transformation system incorporating an enhanced green fluorescent protein (EGFP) marker was used to produce 2 transgenic lines of Culex quinquefasciatus. The transformation frequency was ∼12% and transformation of Culex was shown to be dependent on the presence of Hermes transposase. Injected Culex embryos were treated with 4 different heat shock regimes, 2 of which produced transformed individuals. These individuals were mated with wild-type mosquitoes and produced offspring which expressed the dominant EGFP gene in Mendelian ratios predicted for the stable integration of a gene at a single locus. The 2 transformed lines displayed distinct patterns of phenotypic expression, the expression of which has remained stable after 15 generations. In these transgenic lines, both the Hermes element and flanking plasmid DNA integrated into the Culex genome, as has been previously seen in Hermes-mediated transgenic strains of Aedes aegypti. The high frequency of Culex transformation together with the dependence on the presence of Hermes transposase suggests that, as for A. aegypti, this mode of transposition into the germ-line genome occurs by an alternate mechanism to the cut and paste type of transposition seen for this element in other insect species and in the somatic nuclei of mosquitoes. This is the first report of the genetic transformation of a species in the genus Culex and demonstrates that this medically important mosquito species can now, along with several other Culicine and Anopheline mosquito species, be genetically manipulated.