XB-IMG-24454
Xenbase Image ID: 24454
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Fig. 3. A dominant negative derrière cleavage mutant (CM-der) inhibits mesoderm induction in Xenopus embryos. The effect of CM-der on mesoderm formation is similar to that of the short form of cerberus (cer-S) but differs markedly from the activity of the xnr2 cleavage mutant (CM-xnr2). Embryos were injected with either 2 ng of CM-der, 2 ng of CM-xnr2, or 500 pg of cer-S mRNA into a single blastomere at the four-cell stage along with 200 pg of a β-galactosidase lineage tracer. Stage 11 embryos were stained with red-gal to mark the site of injection and analyzed by whole-mount in situ hybridization. (A-D) Expression of the mesodermal marker xbra is inhibited in a similar manner by CM-der and cer-S; CM-xnr2 causes expansion of xbra into the animal hemisphere. (E-G) Expression of derrière is significantly diminished by cer-S but is expended into the animal hemisphere by CM-xnr2. (H-J) Xnr2 expression is strongly inhibited by cer-S and appears to be partially attenuated in the presence of CM-der. In H-J, embryos have been oriented with the site of mRNA injection at the top. (K) Mechanism of inhibition by cleavage mutant constructs. (L) derrière activity is blocked by both CM-der and cer-S in animal caps. Animal poles were injected at the one-cell stage with 200 pg derrière mRNA and co-injected with either 2 ng CM-der or 500 pg cer-S. By itself, derrière induces xbra and xnr1, as well as upregulating its own transcription. CM-der shows no mesoderm-inducing activity on its own and significantly reduces mesoderm induction by wild-type derrière. cer-S also blocks mesoderm formation in animal caps expressing derrière. Image published in: Eimon PM and Harland RM (2002) Copyright © 2002. 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.
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