Transposons are mobile genetic elements that threaten the genome’s integrity of nearly every organism due to their mutagenic character. In the animal gonad, transposons are selectively silenced via the piRNA pathway, a specialized small RNA silencing pathway centered on PIWI proteins and their bound piRNAs. 
In stark contrast to other small RNA silencing pathways such as the siRNA pathway or the microRNA pathway, we entirely lack insight into biogenesis of piRNAs and the silencing mode of PIWI family proteins. We therefore established an RNAi assay that allows testing any gene of interest for its involvement in the piRNA pathway within a single genetic cross. 
Using this assay, we identified three key players acting in the biogenesis of piRNAs. These are the two RNA helicases Armitage and Yb and the putative nuclease Zucchini. While these three proteins are promising entry points towards a mechanistic understanding of piRNA biogenesis, the established RNAi assay will allow the conduction of a genome wide screen in conjunction with the VDRC RNAi library established at IMP/IMBA.

>>link to article on EMBO Journal website