Functionality of the GAL4/UAS system in Tribolium requires the use of endogenous core promoters.
BACKGROUND
The red flour beetle Tribolium castaneum has developed into an insect model system second only to Drosophila. Moreover, as a coleopteran it represents the most species-rich metazoan taxon which also includes many pest species. The genetic toolbox for Tribolium research has expanded in the past years but spatio-temporally controlled misexpression of genes has not been possible so far.


RESULTS
Here we report the establishment of the GAL4/UAS binary expression system in Tribolium castaneum. Both GAL4 Delta 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.


CONCLUSIONS
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.
Schinko
Johannes B
JB
Ernst Caspari Haus, Georg-August-University Göttingen, Justus-von-Liebig-Weg11, 37077 Göttingen, Germany.
Weber
Markus
M
Viktorinova
Ivana
I
Kiupakis
Alexandros
A
Averof
Michalis
M
Klingler
Martin
M
Wimmer
Ernst A
EA
Bucher
Gregor
G
D000818:Animals; D030801:Animals, Genetically Modified; D004331:Drosophila melanogaster / Q000235:genetics; D049452:Green Fluorescent Proteins / Q000235:genetics; D011401:Promoter Regions, Genetic; D019076:Transgenes; D014231:Tribolium / Q000196:embryology* / Q000235:genetics* / Q000378:metabolism
D049452:Green Fluorescent Proteins