Fig. 5

RA regulates CAC differentiation through action of Sox9b. (A) Experimental timeline of 4OHT-dependent induction of either Sox9b or truncated-Sox9b expression. 4OHT was applied from 2 to 3 dpf, and drugs (either DMSO (vehicle), RA, DAPT or RA+DAPT) from 3 to 5 dpf. (B-I, and K-R) Confocal images of 5 dpf dissected pancreata from larvae transgenic for the Notch-responsive creER^T2driver, a pan-endocrine marker neuroD:GFP and either the sox9b cre responder (B-I) or the truncated sox9b cre responder (K-R). All larvae were incubated from 2 to 3 dpf with either vehicle or 4OHT (as indicated). Next, vehicle and 4OHT treated larvae were incubated from 3 to 5 dpf with either: DMSO (B, C, K, L), RA (D, E, M, N), DAPT (F, G, O, P), or RA+DAPT (H, I, Q, R). 2° islet cellsn are marked by GFP (white arrow heads) and seen in the tail of the pancreas. White dashes outline the pancreata. Scale bar=100 µm. Average number of 2° islet cells/pancreas in larvae transgenic for the Notch-responsive creER^T2driver and Tg(neuroD:GFP)^nl1 and either the sox9b cre responder (J) or the truncated sox9b cre responder (S). N=number of larval pancreata quantified. Error bar represents SE; *p<0.01, **p<0.001.