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Fig. 5 Mosaic Analysis Demonstrates a Cell-Autonomous Requirement for RA Signaling during Forelimb Formation
(A–F) Experimental design for mosaic analysis. (A) Donor embryos were injected with fluorescein dextran at the one-cell stage. (B and C) At sphere stage, blastomeres from WT, Tg(hsp70:dnRARα), or BMS-treated donor embryos were transplanted into the margin of a WT host embryo. (D) At 48 hpf, progeny of donor-derived cells (arrows) were detected in the heart and fin by anti-fluorescein immunohistochemistry. (E) Mosaic embryo containing donor-derived cardiomyocytes. (F) Mosaic embryo containing donor-derived cells in pectoral fin. Only LPM-derived fin cartilage cells (yellow arrows), and not fin ectoderm (black arrow) or somite-derived fin muscle ([Haines and Currie, 2001] and [Neyt et al., 2000]), were scored as fin.
(G and H) Frequency of heart and fin contributions from heat-shocked Tg(hsp70:dnRARα), non-heat-shocked Tg(hsp70:dnRARα), WT, or BMS-treated donor-derived cells. Percentages reflect the number of mosaic embryos exhibiting donor-derived fin mesenchyme (F), atrial (A), or ventricular (V) cardiomyocytes relative to the total number of transplantation (TT) experiments. Asterisks indicate statistically significant differences from WT (p < 0.05).
Reprinted from Developmental Cell, 15(6), Waxman, J.S., Keegan, B.R., Roberts, R.W., Poss, K.D., and Yelon, D., Hoxb5b acts downstream of retinoic Acid signaling in the forelimb field to restrict heart field potential in zebrafish, 923-934, Copyright (2008) with permission from Elsevier. Full text @ Dev. Cell