Xenbase Image ID: 116366

Figure 1. Lefty Antagonizes Nodal and Vg1 Signaling, but Not Activin Signaling, in Zebrafishntl mRNA expression (A–C) and gsc mRNA expression (D–O) in wild-type zebrafish embryos at shield stage, animal pole view. Embryos were injected with low levels (1 pg) of activin βB mRNA (A–C), high levels (10 pg) of activin βB mRNA (D–F), 200 pg of activin βA mRNA (G–I), 75 pg of sqt mRNA (J–L), or 200 pg of Vg1 (M–O). Embryos were further double-injected with either 500 pg of LacZ mRNA (A, D, G, J, and M), 100 pg of lefty1 and 400 pg of LacZ mRNAs (B, E, H, K, and N), or 500 pg of lefty1 mRNA (C, F, I, L, and O). Ectopic ntl expression (arrowheads) in activin βB mRNA-injected embryos was not inhibited by Lefty1 (B and C) when compared with LacZ mRNA-coinjected controls (A). Note the dorsal expression of ntl (asterisks)—that is, dependent on endogenous Nodal signaling—is inhibited by Lefty1 in these embryos (B and C). Ectopic gsc expression in activin βB and activin βA mRNA-injected embryos was not inhibited by Lefty1 (E and F and H and I, respectively). In contrast, ectopic gsc expression in sqt and Vg1 mRNA-injected embryos was inhibited by both levels of Lefty expression (K and L and N and O, respectively). Wild-type embryos (P) were injected with 10 pg (low) and 20 pg (high) of activin βB/HA, 75 pg of sqt, or 200 pg of Vg1 mRNA. Embryos were further double-injected with 500 pg of LacZ mRNA, 100 pg of lefty1, and 400 pg of LacZ mRNAs, or 500 pg of lefty1 mRNA. Smad2 pathway activation was measured by an Activin response element luciferase reporter, A3-luc. Values are folds over wild-type control injected with 500 pg of LacZ mRNA and A3-luc reporter. An asterisk indicates a significant difference from the level of activation with ligand and LacZ expression alone (Student's t-test, p < 0.05). Image published in: Cheng SK et al. (2004) Copyright: ©2004 Cheng et al. Creative Commons Attribution license Larger Image Printer Friendly View

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