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Fig. 7. The changes to the LPM patterning persist after temporally limited alterations in RA signaling. Experimental changes in RA signaling were limited to between stages 14–20 and the embryos were fixed at stage 34–36 for in situ hybridization for FoxF1 (A–C), Pitx2 (D–F), Hand1 (G–I), and HoxC-10 (J–L). The expression domain is reduced under treatment with RAA (A, D, and G), and expanded under RA (C, F, and I) as compared to the DMSO controls (B, E, and H) for all of FoxF1, Pitx2, and Hand1. While the domain of the posterior marker HoxC-10 was anteriorly displaced under RAA (J) as compared to DMSO controls (K), the domain is unaffected under treatment with RA. In each case, the lengths of the domains were measured as a ratio of the length from the cement gland to the most posterior point of LPM staining (x) to the length from the cement gland to the back of the body (y) for the anterior FoxF1, Pitx2, and Hand1 (M). The differences in the length of the staining domain were found to be significant (O, P and Q; p < 0.05; n > 15) between treatments (where *, **, and *** represent statistically significant groups). HoxC-10 was similarly measured (N) using the length of the body axis from the cement gland to the back of the body axis (y), however the length of the domain was measured from the back of the body axis to the anterior edge of the domain (z). The length was found to be significantly different between the DMSO controls and the RAA treatment (p < 0.05; n > 15) however no significant difference was found between RA treatments and controls (R). In all embryos the left lateral side is shown, with the anterior pole to the left, dorsal to the top. |
