Fig. 1.

Cholera toxin causes proximal tubule defects. (A–D′) Xenopus embryos were treated with Pasteurella multocida toxin (Pmt), Pertussis toxin (Ptx) or Cholera toxin (Ctx) from stage 29/30 until stage 42 and analyzed by morphology (A–D) and H&E staining (A′–D′). Note that only Ctx causes edema formation. (E) Dose response curves for edema formation (red) and ectopic 4A6 staining (blue) of embryos treated with different doses of Ctx. Each individual data point is the summary of three independent experiments. The curve was obtained by fitting the data using non-linear regression and used to calculate the median effective doses (ED₅₀). (F and G) Whole mount in situ hybridization with aplnr comparing untreated and Ctx treated embryos at stage 39. (H) Bar diagram depicting the number of proximal tubular cells at stage 35 and 42 in untreated and Ctx treated embryos. (I–R) Ctx-treated embryos were analyzed using the 3G8 and 4A6 antibodies at stage 40 in whole mounts (I–N) or paraplast sections thereof (O–R). Single immunostainings were visualized with DAB, while double stainings were carried out using fluorescent labeled secondary antibodies visualizing 3G8 in red and 4A6 in green. Nuclei were counterstained using DAPI (blue). Ectopic 4A6 staining is indicated by red arrowheads (L).