Fig. 1

Fig. 1 Time course of the transcriptional response in the zebrafish tailbud following activation of Wnt signaling or inhibition of Fgf signaling. (A) Graphical representation of the experimental protocol. (B) DIC images of embryos after 3 h treatment of DMSO, LiCl, and SU5402. (C) Time course of chemical treatment. LiCl activation of Wnt signaling was measured by monitoring transcription of known direct Wnt targets dkk1 and axin2. (D) Time course of SU5402 treatment, an inhibitor of Fgfr1. Fgf signal inhibition was assayed by quantifying transcription of direct Fgf targets sef and spry4. (E) A reduction of presomitic mesoderm cells upon 7 h SU5402 treatment is revealed by reduction in her1, her7, and tbx6 expression. (F) Microarray analysis at the early time point (3 h) and later time point (7 h) suggests that many secondary changes in gene expression are observed at the later time point due to alterations in cell fate and/or cell survival. The data were processed via Agilent′s Feature Extraction software version 10.7.3.1. Samples were normalized using the percentile shift algorithm. No baseline transformation was performed. A 2-fold change cutoff was used to define regulated transcripts. (G) Gene Ontology classification based on Biological Processes Fat indicates that genes representing many more processes are differentially expressed at the later time point than the early, suggesting a loss of cell fates. Fat clustering is a version of Gene Ontologies (GO) that filters out the broadest GO terms so that they do not overshadow more specific GO terms. Fat contrasts to Slim, which provides a broader overview of the ontology content. Error bars are SEM, n=3.