Fig. 5

Notch signaling acts between 25 hfp and 40 hpf to repress enteroendocrine cell differentiation and ascl1a expression. Ventral views with anterior to the left of embryos analyzed by visible (A, D and E) or fluorescent (C) WISH. (A) ascl1a expression is strongly increased in the primitive gut of 45 hpf mib embryos. (B) Quantification of the total number of enteroendocrine cells present in the whole intestine and labeled with a mixture of pyyb, gcga, sst and ghrelin. These positive cells have been directly counted under the microscope. Fold increase represents the mean (+S.EM.) of the enteroendocrine cells number in DAPT treated embryos versus DMSO treated embryos. Asterisks indicate that the difference between the cell number in control and embryos treated with DAPT is statistically significant by Student′s t-test. ***P<0.0001; **P<0.001; *P<0.05. (C) Confocal projections of 75 hpf embryos labeled with a mixture of pyyb, gcga, sst and ghrelin probes and treated with DAPT or DMSO from 30 hpf to 75 hpf. P, pancreas (D and E) ascl1a expression at 55 hpf is increased in the primitive gut of embryos treated with DAPT from 25 to 55 hpf (E) but not in embryos treated from 40 to 55 hpf (G).