Figure 2

mtm zebrafish have dilated bile ducts with reduced branching.

(A) Whole-mount immunostaining of 7 dpf zebrafish larvae with 2F-11, an antibody that stains bile ducts. The mtm biliary tree was simplified and dilated as compared with the WT sibling. Scale bars: 20 μm. (B) Live-image analysis of Tp1:GFP bile duct transgenic line at 5 dpf and 7 dpf. The simplified and dilated mtm bile ducts seen with 2F-11 staining were also observable by this technique. Defects were more severe at 7 dpf compared with 5 dpf. Scale bars: 20 μm. (C) Quantification of biliary tree segment length and thickness using the Imaris filaments module. The segment length was unchanged at 5 dpf (WT median = 22.22, mtm median = 24.24, P = 0.43) but increased in mtm larvae by 7 dpf (WT median = 8.14, mtm median = 15.0, ****P < 0.0001), suggesting a reduction in branch complexity. Segments were thicker in mtm larvae as early as 5 dpf (WT median = 2.27, mtm median = 7.60, ****P < 0.0001), and this trend continues at 7 dpf (WT median = 2.24, mtm median = 5.15, ****P < 0.0001). Statistical significance was determined by Mann-Whitney U test.