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The mesoderm of amphibian embryos such as Xenopus laevis arises through an inductive interaction in which cells of the vegetal hemisphere of the embryo act on overlying equatorial and animal pole cells. Three classes of 'mesoderm-inducing factor' (MIF) that might be responsible for this interaction in vivo have been discovered. These are members of the(More)
The Xolloid secreted metalloprotease, a tolloid-related protein, was found to cleave Chordin and Chordin/BMP-4 complexes at two specific sites in biochemical experiments Xolloid mRNA blocks secondary axes caused by chordin, but not by noggin, follistatin, or dominant-negative BMP receptor, mRNA injection. Xolloid-treated Chordin protein was unable to(More)
A complete fate map has been produced for the 32-cell stage of Xenopus laevis. Embryos with a regular cleavage pattern were selected and individual blastomeres were injected with the lineage label fluorescein-dextran-amine (FDA). The spatial location of the clones was deduced from three-dimensional (3D) reconstructions of later stages and the volume of each(More)
We have identified a novel Tolloid-like metalloprotease, called Xolloid-related (Xlr), that is expressed during early Xenopus development. Transcripts for xlr are localized to the marginal zone of mid-gastrulae and are most abundant in ventral and lateral sectors. At neurula stages xlr is strongly expressed around the blastopore and in the pharyngeal(More)
To examine whether a BMP signaling pathway functions in specification of cell fates in sea urchin embryos, we have cloned sea urchin BMP2/4, analyzed its expression in time and space in developing embryos and assayed the developmental consequences of changing its concentration through mRNA injection experiments. These studies show that BMP4 mRNAs accumulate(More)
Growth differentiation factor 9 (GDF-9) is a transforming growth factor-beta family member that is required for normal folliculogenesis in female mice, but its role as a regulator of human fertility is still unclear. We determined here by in situ hybridization and immunohistochemical analyses the localization of the GDF-9 messenger ribonucleic acid (mRNA)(More)
Injection of RNA encoding BMP-4 into the early Xenopus embryo suppresses formation of dorsal and anterior cell types. To understand this phenomenon, it is necessary to know the stage at which BMP-4 acts. In this paper, we present three lines of evidence showing that BMP-4 misexpression has no effect on the initial steps of mesoderm induction, either dorsal(More)
BMP-4 is an extracellular signalling molecule belonging to the TGF-beta superfamily that plays a central role in dorsoventral patterning in vertebrate gastrulae. We review the evidence indicating that BMP-4 acts as a morphogen, specifying dorsoventral positional values in a concentration-dependent manner. An activity gradient of BMP-4 is established not by(More)
We have further analysed the roles of mesoderm induction and dorsalization in the formation of a regionally specified mesoderm in early embryos of Xenopus laevis. First, we have examined the regional specificity of mesoderm induction by isolating single blastomeres from the vegetalmost tier of the 32-cell embryo and combining each with a lineage-labelled(More)
Activin and Vg1, two members of the TGF-beta family, are believed to play roles in mesoderm induction and axis formation in the amphibian embryo. Both molecules are provided maternally, either as protein (activin) or as RNA and protein (Vg1), and experiments with a truncated form of a type IIB activin receptor have led to the conclusion that activin is(More)