Fig. 2. Gene silencing by RNA interference. (A) Scheme for transgenic RNA interference used in this work to knock down the expression of the TPR subunits of Drosophila APC/C. Inverted exon repeats of these genes (white bars) were cloned into pWIZ transformation vector under the control of the UAS promoter (white circles) and transgenic lines were made. These were crossed to the Act5C-GAL4 driver lines that constitutively expressed the GAL4 transcription activator in all cells throughout development. Progeny that contained both Act5C-GAL4 and UAS transgenic constructs expressed double-stranded hairpin RNAs that triggered gene silencing. (B) Monitoring TPR transcript levels in RNAi induced larvae (I) relative to uninduced controls (C). The rpL17A transcript was used as a calibration control. TPR gene-specific transcript levels appeared significantly lower in all RNAi induced samples.