How piRNA inheritance affects endogenous gene expression across generations. Alexandra A Erwin, Michelle Wickersheim, Justin Blumenstiel. University of Kansas, Lawrence, KS.

   Piwi-interacting RNAs (piRNAs) appear to have a dominant role in role in regulating transposable elements (TEs) in the germline. Recently, the role of piRNA regulation has been expanded to include endogenous gene control. We have identified unique clusters of piRNAs that target endogenous genes and that vary between two strains that cause the syndrome of hybrid dysgenesis in Drosophila virilis. We analyzed how the inheritance of these gene-targeting piRNAs influence gene expression across generations. This serves to test whether the requirement for piRNA priming through the maternal germline - as has been demonstrated for TEs - also applies to endogenous genes targeted by piRNAs. Preliminary studies have shown that there are diverse modes of action for gene-targetting piRNAs across generations. In addition, by filtering out the genes that may be regulated by the piRNA silencing pathway, we seek to identify genes whose expression is modified by the response to the hybrid dysgenic syndrome independent of changes in gene expression attributed to shifts in piRNA control.