Functionality of the GAL4/UAS system in Tribolium requires the use of endogenous core promoters

Here we report the establishment of the GAL4/UAS binary expression system in Tribolium castaneum. Both GAL4Δ and GAL4VP16 driven by the endogenous heat shock inducible promoter of the Tribolium hsp68 gene are efficient in activating reporter gene expression under the control of the Upstream Activating Sequence (UAS). UAS driven ubiquitous tGFP fluorescence was observed in embryos within four hours after activation while in-situ hybridization against tGFP revealed expression already after two hours. The response is quick in relation to the duration of embryonic development in Tribolium - 72 hours with segmentation being completed after 24 hours - which makes the study of early embryonic processes possible using this system. By comparing the efficiency of constructs based on Tribolium, Drosophila, and artificial core promoters, respectively, we find that the use of endogenous core promoters is essential for high-level expression of transgenic constructs.With the established GAL4/UAS binary expression system, ectopic misexpression approaches are now feasible in Tribolium. Our results support the contention that high-level transgene expression usually requires endogenous regulatory sequences, including endogenous core promoters in Tribolium and probably also other model systems.The red flour beetle Tribolium castaneum has become established as an important model system, from a group of insects - the Coleoptera - that comprises one fourth of all described animal species [1] including numerous pests (boll weevil, corn rootworm, Colorado potato beetle and Asian longhorn beetle). While the technical amenability of the fruit fly Drosophila melanogaster remains unmatched, there are topics which cannot be readily addressed in the fly. On one hand, evolutionary questions require comparative functional data from several species. Moreover, many processes are derived in Drosophila and data from more insect typical taxa is needed. For instance, segments are specified all at one tim