Fig. 5

Aldh1-expressing cells are derived from Notch-responsive progenitor cells.

(A) Schematic timeline for 4OHT-induced lineage labeling. Tp1bglob:CreER ^T2/βactin:loxp-stop-loxp-hmgb-mCherry fish were treated with either 1% EtOH (B and D; negative controls) or with 4-hydroxy-tamoxifen (4OHT) between either 3-5 dpf (B and C) or 18-20 dpf (D and E), and then sacrificed for analysis at 25 dpf. Cells carrying the Tp1bglob:CreER^T2 lineage label display red nuclei. (C) 2F11 ^pos/Aldh1^pos cells arise from Notch-responsive cells labeled between 3-5 dpf (blue arrows). (E) Notch-responsive cells labeled between 18-20 dpf give rise to Aldh1^pos (blue arrows), Pax6:eGFP+ endocrine cells (green arrows) and ductal cells (white arrows). F, Schematic depiction of proposed lineage relationships between Notch-responsive progenitors (Notch-ON) and cells expressing 2F11, Aldh1, NeuroD and Pax6b during secondary islet formation. Notch-ON cells expressing 2F11 (red) give rise to Notch-OFF, 2F11^pos, NeuroD^pos, Aldh1^pos cells (blue), which then inactivate Aldh1 and activate Pax6 expression (green) prior to undergoing terminal endocrine differentiation (orange).