... Goosecoid Xnot Frzb Transcription Repressor Notochord Xwnt-8 BMP Xenopus Embryo Axial development in vertebrates is initiated and co-ordinated during gastrulation by a dorsal territory called the organiser. In amphibia, on the basis of molecular and embryological data ( Lemaire...

.... Wnt signalling in very early embryos leads to a dorsalising response, which establishes the endogenous dorsal axis. Only a few hours later in development, almost the opposite happens: Xwnt-8 functions to pattern the embryonic mesoderm by promoting ventral and lateral mesoderm. The specificity...

... and decreased skeletal muscle. This phenotype is nearly identical to the effect of injection of either frzb or dominant negative Xwnt-8. Injection of human RGS2, which selectively deactivates Gq, had similar effects. rRGS4 inhibited the ability of early Xwnt-8 but not Xdsh misexpression to cause axis...

... of endogenous Xwnt-8 is regulated, in part, at a post-transcriptional level. We have identified a novel sequence element in the 3′ untranslated region of the Xwnt-8 RNA that controls the polyadenylation status of reporter and endogenous Xwnt-8 RNAs, directs rapid RNA degradation beginning precisely at the early...

.... * Author for correspondence at address 2 23 07 1996 © 1996 by Company of Biologists 1996 Siamois noggin goosecoid chordin brachyury Xwnt-8 Xnr-3 Xenopus dorsalisation embryonic axis Spemann organiser Nieuwkoop centre late blastula organiser Wnt signalling neural...

... comparable to that seen in neural crest of normal embryos. We suggest that the prospective neural crest is induced in normal embryos in the ectoderm that overlies the junction of the domains that express noggin and Xwnt -8. In support of this, we show animal cap explants from blastulae and gastrulae, treated...

... separated by closely spaced, sharp dose thresh-olds. Here we investigate this multithreshold activin response further using probes for genes expressed at early gastrula stages, namely Xbra, goosecoid, noggin, Xwnt-8 and Mix . 1 . We show that initial dose-response profiles are broad and smooth in contrast...

... and Xwnt-8 , in Xenopus gastrulae in which cell-cell communication, and therefore mesoderm induction, has been prevented by frequent cell dispersion. Although neither the early panmesodermal marker Xbra nor the muscle-specific α-actin gene were activated under these conditions, goosecoid and Xwnt-8 were...

... signals are required to generate pattern in this tissue. We have isolated a Xenopus cDNA for a Wnt-1 related gene, designated Xwnt-8 , which is activated in ‘response to mesoderm-inducing growth factors. Xwnt-8 transcripts are transiently expressed, being most abundant during gastrulation at which time...