Fig. 7

Failed slit-diaphragm formation correlates with loss of barrier function in the glomerulus. 500 kDa FITC-dextran was injected into the circulation of 80 hpf larvae and the larvae were fixed the next morning (96 hpf) and sectioned. Dye uptake by endocytosis from the pronephric duct lumen was assessed at the level of the swim bladder (sb). Arrowheads indicate the position of pronephric ducts in the cross-sections. In wild-type control larvae (A), FITC fluorescence is present in the vasculature surrounding the pronephric ducts; however, no endosomes containing filtered dye are visible (arrowheads) in the pronephric duct epithelial cells. In nephrin (B) and podocin (C) morpholino injected embryos, dye uptake is detectable in the form of small apical endosomes adjacent to the duct lumen. Wild-type moe heterozygous larvae (D) show no dye uptake in the pronephric ducts, while moe homozygous mutant larvae (E) exhibit abundant dye uptake (arrowheads) at the same position in the ducts. (F) The plane of section for cross-sections in panels A–E is shown. The table represents the number of larvae examined/number of larvae positive for endocytosed dye in the pronerphic duct. 500 kDa FITC-dextran (green), autofluorescence (red).