Induction of Chk2 signaling in the germarium is sufficient to cause oogenesis arrest inDrosophila

The conserved RNA helicase Vasa is required for germ cell development in many organisms. It is established that in Drosophila loss of piRNA pathway components, including Vasa, causes Chk2-dependent oogenesis arrest, however the stage at which Chk2-signaling is triggered was unknown. We found that absence of Vasa during the germarial stages arrests oogenesis due to Chk2 activation. Importantly, once induced in the germarium, Chk2-mediated arrest of oogenesis cannot be overcome by restoration of Vasa to the arrested egg-chambers. We conclude that Vasa activity specifically in the germarium is essential for germ cell lineage development.