XB-IMG-158859
Xenbase Image ID: 158859
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Figure 3
Organizer formation is affected by siamois fusions. At the two-cell stage, both blastomeres were injected with 30 pg of β-galactosidase, siamois, VP16-Sia, or Eng-Sia mRNA, and embryos were harvested at stage 10.25 (early gastrula). (A–D) Vegetal view of injected embryos analyzed by in situ hybridization for goosecoid expression. (A) β-Galactosidase had no effect on the organizer-specific expression of goosecoid (n = 24). Siamois (B) and VP16-Sia (C) resulted in expansion of goosecoid expression in 79% (n = 24) and 88% (n = 24) of embryos, respectively. (D) Eng-Sia resulted in a reduction or loss of goosecoid expression in 83% (n = 24) of embryos. (E) Embryos were harvested at the gastrula stage and processed for reverse transcription–PCR analysis of the organizer genes noggin (Nog), Xnr3, chordin (Chd), follistatin (Xfs), and cerberus (Cer), the ventrolateral gene Xwnt8, the panmesodermal gene brachyury (Xbra), endogenous siamois (Sia), and the ubiquitous EF1α. Injection of siamois (lane 3) or VP16-Sia (lane 4) inhibited Xwnt8 expression and enhanced expression of noggin and chordin, without affecting Xnr3, follistatin, cerberus, siamois, or brachyury expression. Eng-Sia (lane 5) inhibited expression of noggin, Xnr3, chordin, follistatin, and cerberus, enhanced Xwnt8 expression, and had no effect on siamois or brachyury. EF1α is a control for RNA recovery and loading. β-Galactosidase-injected embryos (lane 2) served as a positive control, while an identical reaction without reverse transcriptase controlled for PCR contamination (lane 1). Image published in: Kessler DS (1997) Copyright © 1997. 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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