XB-IMG-132151
Xenbase Image ID: 132151
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Fig. 4. Induction of endodermal markers by activin and Vg1 protein. (A) At the 1-cell
stage synthetic mRNA encoding a TGF-b ligand was injected into the animal pole.
Animal caps were dissected from blastula stage embryos (stage 9) and cultured in
isolation until the mid-tailbud period (Stage 33-36). Gene expression was monitored by
RT-PCR. (B) To express the mature forms of Vg1 and BMP-2, mRNA encoding chimeric
forms of each gene were used in our injections. In the case of Vg1, a chimeric mRNA was
used where the pro region of BMP-2 was fused to the mature region of Vg1 (B-Vg1)
(Thomsen and Melton 1993). For BMP-2, the pro region of activin bB was fused to the
mature region of BMP-2 (A-BMP-2). The B-Vg1 chimera induces expression of cardiac
actin, IFABP and Xlhbox-8 in animal caps consistent with previously published results
that demonstrated the ability of B-Vg1 to induce axial mesoderm (Thomsen and Melton
1993). The A-BMP-2 chimera induces expression of globin, a ventral mesodermal
marker, in animal caps. Neither IFABP nor Xlhbox-8 expression is efficiently induced in
animal caps by BMP-2. The amount of RNA injected is indicated in picograms.
(C) Activin can induce cardiac actin, IFABP (data not shown) and Xlhbox-8 in animal
caps. The amount of injected RNA is indicated in femtograms. WE lanes represent RTPCR
products where mRNA from an unmanipulated embryo was used for cDNA
synthesis. The WE-RT lanes represent assays in which reverse transcriptase was left out
of the cDNA synthesis step with whole embryo RNA as a template. This serves as a
control for DNA contamination. Elongation factor 1 alpha (EF-1a) is included as a
control to insure that similar amounts of RNA are used in each lane. Image published in: Henry GL et al. (1996) Copyright © 1996. 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. Larger Image Printer Friendly View |