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Fig. 1
The NTR/Mtz system induces selective liver damage in larval zebrafish. (A) Upper panel, cartoon of transgenic larva expressing cyan fluorescent NTR fusion protein in the liver. Lower panel, scheme of experimental timeline. Black arrows/numbers indicate how long fish were bathed in 5 mM Mtz or DMSO carrier prior to live imaging. Blue arrows indicate time window of larval feeding. Feeding was stopped one day prior to imaging to reduce autofluorescence. (B) Haemotoxylin & Eosin (H&E) staining of 8 dpf TG(fabp10:NTR-mTq2; casper) larvae exposed to 0.2% DMSO (Ctr) or 5 mM Mtz (48 h NTR/Mtz). The “Ctr” image is representative for the H&E staining pattern in 4 of 5 larvae. The “48 h NTR/Mtz” image is representative for the H&E staining pattern in 3 of 4 larvae. Dashed line, liver outlines. Scale bars, 50 μm. (C) TG(fabp10:NTR-mTq2; fabp10:PM2-eGFP-P2A-mTq2-NES) larvae reveal morphological abnormalities after Mtz exposure. Representative confocal z-slices of hepatocyte cytoplasm (NTR-mTq2, cyan fluorescence, left column) or plasma membranes (PM2-eGFP, green fluorescence, middle column) highlight liver morphology. Maximum intensity projections (MIP, right column) of confocal z-slices show overall liver shape and morphology in both channels. Scale bars, 50 µm. Top row: No/Mild damage in control. Insets, regularly arranged hepatocytes with distinct cell boundaries are in close contact. Inset scale bars, 10 μm. Middle rows: Moderate damage in larvae exposed to Mtz for either 24 h (second row) or 48 h (third row). Inset, rounded hepatocytes that have lost close cell-cell contact. Inset scale bars, 10 μm. Bottom row: Severely damaged liver in larva treated with Mtz for 48 h. Insets, severely disturbed hepatocyte morphology. Scale bars, 10 μm.