Fig. 2.

Sage is required for SG viability and normal lumenal morphology. (A) PH4αSG2 endoplasmic reticulum staining in sage^ko SGs was reduced relative to WT through stage 14 (large arrows), when staining in small puncta in the region of the SG was first visible (small arrows). By embryonic stage 15, most of the PH4αSG2 staining in sage mutants was in small puncta in the region of the SGs (small arrows). (B) Large cells with irregular PH4αSG2 staining (arrows) are likely to be macrophages that have engulfed dying SG cell debris. (C) Cleaved caspase 3 (CC3) staining at stage 15 reveals extensive apoptotic cell death in sage^ko compared with WT SGs. (D) rpr mRNA levels are upregulated (arrowheads) in stage 14 sage^ko and sens^E2 SGs. (E) Expression of the anti-apoptotic P35 gene in sage^ko rescues SG cell death associated with sage loss. Arrowheads indicate the secretory portion of the SG. (F) SGs stained with antibodies to the apical membrane protein Stranded at second (Sas), the basolateral protein α-Spectrin and nuclear CrebA reveal lumen irregularities in P35-rescued sage^ko SGs.