Fig. 7.

Notch activation in the PFCs rescues multilayered follicle cell phenotype. (A) Ovaries stained using DAPI to label DNA before and after NICD expression. NICD expression partially rescued the multi-layered posterior follicle cell phenotype. Scale bars: 20 µm. (B) Quantification of the ovarioles that have single-layered posterior follicle cells. Number of ovarioles (n) are indicated above the bar graphs. (C) Schematic summarizing RpS5b mutant phenotype during the egg chamber development. Wild-type germ cells express both RpS5a and RpS5b to maintain normal ribosome biogenesis and microtubule organization. However, the absence of RpS5b results in elevated rDNA transcription and increases in the translation efficiency of several RP transcripts, resulting the upregulation of global translation. In addition, translation of genes associated with microtubule function is downregulated upon loss of RpS5b, leading to their mis-organization. As a result, Delta and Mindbomb1 protein do not localize to the interface between the oocyte and posterior follicle cells, resulting in a failure to activate Notch signaling. In turn, disruption of the Notch pathway leads to abnormal cell divisions within posterior follicle cells after stage 6 of egg chamber development.