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Fig. 3. The expression domains of Nkx-2.5, FoxF1, Hand 1 and Xsal-1 are altered by RA signaling. Embryos were treated with RAA (left panel), RA (right panel) or DMSO (center panel) and were allowed to develop until stage 20/22. Whole-mount in situ hybridization for Nkx-2.5 (A–C) demonstrates little change under the RA treatment (C), as compared to the DMSO control (B). In contrast, the expression domain of the anterior-dorsal marker FoxF1 (D–F) extends further to the posterior end of the embryo under exogenous RA conditions (F) and reduced under treatment with the RAA (D) as compared to the DMSO control (E). Similarly, the middle marker Hand1 (G–L) demonstrates a reduced expression domain under the RAA treatment (G), while the domain is expanded when treated with RA (I) as compared to the DMSO control (H). Note that when viewed from the side (G–I), the greatest expansion in the Hand1 domain is on the dorsal edge, where there is also increased staining intensity (arrowhead), when treated with RA. In contrast, when viewed from the side (M–O), the lateral Xsal-1 domain is virtually absent under treatment with RA (O) when compared to either RAA-treated (M) or control embryos (N). When viewed from the anterior end (Q–S), other areas of Xsal-1 expression are also affected by RA. The banded expression in the developing brain is reduced and there is increased expression in staining in presumptive ganglia when compared to RAA-treated (Q) or control embryos (R). |
