Xenbase Image ID: 78821

Fig. 2. Otx2 and Gbx2 participate as transcriptional repressors in the positioning of the isthmus organizer. Embryos were injected in one blastomere of two-cell stage embryos with 2 ng of Gbx2 (A,D,G,J), 2 ng of the Gbx2 repressor fusion (Gbx-EnR) (B,E,H,K) or 0.3 ng Gbx2 activator fusion (Gbx2-E1A) (C,F,I,L) mRNAs. The expression of Otx2, Fgf8, En2 and Pax2 were analyzed at stage 17 and the injected sides were detected by X-Gal stain. (A-C) Otx2 expression is inhibited in embryos injected with Gbx2 or Gbx2-EnR mRNAs (A,B, broken lines), while is displaced caudally in those injected with Gbx2-E1A mRNA (C, broken lines). (D-F) A rostral shift of Fgf8 isthmic expression territory is observed upon Gbx2 or Gbx2-EnR overexpression (D,E, broken lines), and inhibition and caudal shift of this expression domain occurs in Gbx2-E1A-injected embryos (F, arrowhead). (G-I) En2 is displaced anteriorly in Gbx2- or Gbx2-EnR-injected embryos (G,H, broken lines), while is repressed and shift caudally in those injected with Gbx2-E1A mRNA (I, broken lines). (J-L) Pax2 expression is displaced rostrally in embryos injected with Gbx2 or Gbx2-EnR mRNAs (J,K, broken lines), while a caudal shift occurs in Gbx2-E1A-injected embryos (L, broken lines). The injection at the two-cell stage of 5 ng of Otx2 (M,P,S,V), 2 ng of Otx2-EnR (N,Q,T,W) or 1 ng of Otx2-E1A (O,R,U,X). The expression of Gbx2, Fgf8, En2 and Pax2 were analyzed at stage 17. (M-O) Overexpression of Otx2 or Otx2-EnR mRNAs produce repression and caudal shift of Gbx2 (broken lines) and injection of Otx2-E1A mRNA caused an anterior shift and diffusion of Gbx2 (O, broken lines). (P-R) Fgf8 is shifted posteriorly in embryos injected with Otx2 or Otx2-EnR mRNAs (P,Q, broken lines) while injection of Otx2-E1A mRNA causes inhibition of the isthmus expression of Fgf8 (R, arrowhead). (S-U) En2 is shifted caudally in Otx2 and Otx2-EnR injected embryos (S,T, broken lines), while there is a decrease in En2 expression with an anterior displacement in embryos injected with Otx2-E1A mRNA (U, broken lines). (V-X) Pax2 is shifted caudally in Otx2- and Otx2-EnR-injected embryos (V,W broken lines), while its expression decrease in the Otx2-E1A-injected embryos (X, arrowhead). Arrowheads point to the injected sides. Each experiment was performed at least twice with a minimum of 30 embryos. The percentage of effect for each experiment was ∼ 70%. Image published in: Glavic A et al. (2002) Copyright © 2002. Image reproduced with permission of the publisher and the copyright holder. This is an Open Access article distributed under the terms of the Creative Commons Attribution License. Gene Synonyms Species Stage(s) Tissue gbx2.2.L XGBX-2 X. laevis Throughout NF stage 17 midbrain-hindbrain boundary fgf8.L AIGF, FGF-8, fgf-8b, fgf8a, fgf8b, MGC79739, Xfgf-8, Xfgf8 X. laevis Throughout NF stage 17 midbrain-hindbrain boundary cardiac mesoderm anterior neural ridge en2.L En-2, en2-a, en2-b, eng2, engrailed 2, engrailed homolog 2, engrailed-2, maben, xen2 X. laevis Throughout NF stage 17 midbrain-hindbrain boundary pax2.L LOC108697493, pax-2, pax2-a, pax2-b, XPax-2, XPax2 X. laevis Throughout NF stage 17 midbrain-hindbrain boundary optic field Image source: Published Larger Image Printer Friendly View

Return to previous page