XB-IMG-42241
Xenbase Image ID: 42241
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Figure 6. xHtrA1 Activates Long-Range FGF Signaling(A) Western blot analysis of stage 14 embryos. Injection of xHtrA1 mRNA (80 pg) induces diphosphorylated ERK (dpERK). xHtrA1-MO (8 pmol), but not control-MO, reduces endogenous dpERK.(B–D) Whole-mount immunohistochemistry of early gastrula embryos probed for diphosphorylated ERK (dpERK). xHtrA1 mRNA (80 pg) induces ectopic dpERK in the animal cap. XFD mRNA (220 pg) blocks endogenous and xHtrA1-induced dpERK expression.(E–J) Whole-mount in situ hybridization of early neurula embryos (lateral view). xHtrA1 mRNA (80 pg) induces robust expression of FGF8 and FGF4. The effects of xHtrA1 on FGF8 and FGF4 are reverted by coinjection of DnFGFR4a (110 pg) and XFD mRNA (220 pg), respectively.(K) Reciprocal stimulation of xHtrA1 and FGF gene activities.(L) Experimental design of animal cap conjugate assay. The doses of mRNAs injected into each blastomere at the 4-cell stage were FGF4 (16 pg) and xHtrA1 (130 pg).(M) Control animal cap conjugates with nlacZ mRNA-injected inducer cap (blue), and uninjected responder cap remain round and do not express Xbra.(N) Slight elongation and narrow Xbra expression (red) in the responder cap at the interface to the inducer cap injected with FGF4 mRNA.(O and P) xHtrA1 mRNA alone has only little effect but, when coinjected with FGF4 into the inducer cap, induces significant elongation and robust Xbra expression in the responder cap.(Q and R) FGF4 in the inducer cap juxtaposed to an xHtrA1-injected responder cap causes significant elongation of the conjugate and Xbra expression far away from the signaling source.Frequency of specimen with the indicated phenotype was B, 11/11; C, 21/21, D, 26/26; E, 10/10; F, 26/27; G, 25/27; H, 16/16; I, 12/12; J, 10/12; M, 16/16; N, 12/12; O, 10/12; P, 15/18; Q, 10/10; and R, 22/25. Image published in: Hou S et al. (2007) Copyright © 2007. Image reproduced with permission of the Publisher, Elsevier B. V. Larger Image Printer Friendly View |