GOF TRPP2 rescues the dorsal axis curvature (curly tail) phenotype in zebrafish embryos better than WT TRPP2. (A) Representative images of zebrafish embryos showing the range of severity in curly tail used for scoring. Normal: no curvature; mild: <90°; moderate: >90°; severe: tail tip crossing the body axis. (B) Bar graph represents the percentage of embryos with normal, mild, moderate, and severe curvature at 48 hpf. Embryos were injected at the one-cell stage with zebrafish TRPP2 MO or indicated combinations of MO and RNA. Statistical significance is determined by the χ² test. Data used in the Left bar graph were pooled from five independent experiments, whereas data used in the Right bar graph were pooled from two experiments. (C) Diagram showing fish pronephric kidney at around 48 hpf. (Right) Glomerulus and pronephric tubule are labeled on the zoom-in diagram. (D) Representative fluorescence images showing the area of the glomerulus (circled with dashed lines) of zebrafish embryos with different severity in dorsal axis curvature as shown in A. The transgenic line wt1b:EGFP [Tg(wt1b:eGFP)^li1] with pronephros-specific GFP expression was used in this experiment. (E) Scatter plot showing the correlation between glomerulus area and indicated curly tail severity. The glomerulus area was selected as shown with the dashed lines in D, and was measured with ImageJ. The mean and SD are indicated in the plot. *P < 0.05; ***P < 0.001.

Zebrafish with severe curly tail had a diluted glomerulus (cyst) in the pronephric kidney. (A) Diagram showing zebrafish pronephric kidney at around 48 hpf. The red line indicates the position of the virtual section shown in C. (B) Confocal images of the Tg(wt1b:eGFP)^li1 fish embryos with normal and severe curly tail phenotypes. GFP-positive tissues show the glomerulus and pronephric tubule. Dilation (cyst) was clearly observed in the glomerulus of the fish with the severe curly tail phenotype. (C) Virtual sections were made after 3D reconstructions of the GFP expression in the glomerulus shown in B. Red arrows indicate the dilated glomerulus (cyst) in fish with the severe curly tail phenotype.

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