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Figure 4
(A–C) Fluorescent images of fixed (A) DMSO-treated, (B), DEAD-treated, and (C) RA-treated tg(ubb:lck-mNG) embryo trunks at the 12- and 15-somite stage. Yellow brackets indicate the distance between the notochord and underlying yolk cell. (D–F) DIC time-lapse images of the notochord and zebrafish trunk. Focal planes of the notochord and somites were overlaid to show the relative location to one another. Yellow brackets indicate the distance of the ventral notochord to the ventral-most portion of the embryo in (D) DMSO-treated embryos, (E) aldh1a2-/- embryos treated with DMSO, or (F) 0.1 μM RA-treated embryos. (G) Quantification of dorsal translocation of notochord from the ventral tissue. Black lines indicate the median and interquartile range. Wild-type are indicated by brown squares, while aldh1a2-/- and 0.1 μM RA embryos are shown by red circles and blue triangles, respectively. At t = 0, DMSO vs. RA is p<0.00001. At 150′, DMSO is p<0.00001 and p=0.005 vs. aldh1a2-/- and RA treatment, respectively. At 250′, DMSO is p=0.0001 and 0.054 vs. aldh1a2-/- and RA treatment, respectively. (H–J) Time-lapse image of a trunk explant from tg(actc1b:gfp), tg(tbxta:kaede) embryo at (H) 0′, (I) 60′, and (J) 120′. (H’–J’) Time-lapse image of explant showing tg(tbxta:kaede) only. (H’’–J’’) Time-lapse image of explant showing tg(actc1b:gfp) only. Time-lapse shows the notochord adjacent the yolk at time 0′, but moves dorsally from the yolk at time 120′. Scale bars, 25 µm.
Retinoic acid (RA) signaling promotes dorsal translocation of the notochord.