Fig. 6. Model of Ago1-dependent miRNAs in GSC fate determination. In the tip of the Drosophila germarium, BMP/Dpp, as short-range signals from niche cells perceived directly by GSCs, represses bam transcription and results in Bam/Bgcn complex activity loss, thereby depressing both the Pumilio/Nanos complex (Nos, Pum) and GSC-specific miRNA activities. The Pumilio/Nanos complex and GSC-specific miRNAs could function together to repress the translation of mRNAs for GSC/CB differentiation (A), or they might function separately to repress the translation of different groups of mRNA for GSC/CB differentiation (B).