XB-IMG-131091
Xenbase Image ID: 131091
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Fig. 10. Model for derrière activity. At the mid-blastula transition, we speculate that maternal transcription factors (such as VegT) and possibly
secreted factors activate derrière expression in the presumptive mesoderm and endoderm (wide hatching). During early gastrula, derrière
expression is maintained in the mesoderm by a positive feed-back loop that includes FGFs (such as eFGF), Xbra and zygotic VegT (close
hatching). derrière expression in the endoderm is not maintained presumably because such a feed-back loop cannot be established there. During
early gastrula stages, derrière may activate mesendodermal fates in both the future head region and more posteriorly. In particular, derrière may
play a role in activating posterolateral (paraxial) mesodermal fates at this time, before somite formation. By mid to late gastrula, derrière is
excluded from anterior mesoderm and from the dorsal midline (close hatching), and continues to promote posterolateral fates. An, animal pole;
Vg, vegetal pole; A, anterior; P, posterior; meso, mesodermal fates; endo, endodermal fates. Image published in: Sun BI et al. (1999) Copyright © 1999. 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 |