Fig. 3.

Developmental principal cell mesh knockdown in the Drosophila Malpighian tubule using mesh RNA interference (RNAi) line 6867 causes morphological defects in adult fly tubules. A and B: bright-field images with depiction of major morphological segments of the anterior Malpighian tubules from a 1-day-old adult control female fly [w;UAS-mesh^RNAi (II)/+; A] and developmental principal cell mesh knockdown fly [w;UAS-mesh^RNAi (II)/+;c42-GAL4/+; B]. The mesh knockdown tubules appear enlarged compared with control tubules, and their initial segments contain opaque concretions (A and B, arrows). C–E: in control tubules, Mesh immunolocalizes to the smooth septate junctions between the epithelial cells throughout all segments. F–H: in mesh knockdown tubules, only trace levels of Mesh immunofluorescence are observed in the initial/transitional, main, and lower segments. Nuclei were counterstained blue with DAPI in C–H. Ten samples per genotype were examined. Scale bars, 100 µm (A and B) and 50 μm (C–H).