Figure 2.

Two Surges of Maternal Wnt/β-Catenin Target Gene Expression

(A) First surge of maternal Wnt/β-catenin-regulated gene expression initiates between stage 7 and stage 7.5 (gray box), although sia1 is slightly delayed (lighter gray box) relative to the other genes in this class (sia2, nodal3.1, nodal 5, nodal 6).

(B) Second surge of maternal Wnt/β-catenin-regulated gene expression initiates between stage 8 and stage 9.5 (gray box), although admp and gadd45g are slightly earlier (lighter gray box) than the other genes in this class (e.g., eomes, gsc, chrd, frzb, noggin, nodal 2, and others as indicated). Data were mined from Owens et al. (2016) using the online tool http://genomics.crick.ac.uk/cgi-bin/profile-search.exe?dbe=http&dbs=INFO-PUBLIC&uid=guest&species=Xt&profiles=KBAP&src=search&tgt=main&menu=main_images&option=images&dataset=KBAP&project_key=0&version=0. The graphs shown are framed between zero and 1 million transcripts per embryo and between fertilization and stage 10.25. Of the ten maternal Wnt/β-catenin-regulated genes identified as a first surge of expression in our analysis (using version 9 of the Xenopus tropicalis genome assembly, Figure 1D and Table S1A), the transcriptomics data from Owens et al. (2016, analyzed using version 7) contained information for five (see Table S1D), whereas of the 112 maternal Wnt/β-catenin-regulated genes expressed exclusively as part of the second surge of expression (118 minus the 10 genes already expressed from the first surge), 22 were used in this analysis both because transcriptomics data from Owens et al. (2016) were available and induction could be defined between low initial gene expression (less than 10k transcripts per embryo before st.6) and increased expression (more than 100k by stage 10, see Table S1D). The gray boxes indicate the first (in A) and second surge (in B) of expression, defined by 20,000 transcripts per embryo in the transcriptomics data from Owens et al. (2016).