Fig. 3.

Delta-Gcm relationship on a cellular basis prior to and at endomesoderm diversification. (A) Schematic of the known Delta/Notch signaling-Gcm regulatory relationship. Delta through its interaction with Notch activates Gcm in the neighboring cells. Gcm is able at some point to maintain its own expression by a positive feedback loop onto its own promoter. (Ba-Gc) Expression profiles of Delta (olive) and Gcm (blue) by double fluorescent in situ hybridization from the 60-cell to the hatched blastula stage. First row shows two fluorescence channels and DIC pictures of vegetally viewed embryos. Second and third rows show confocal images of first row embryos with the nuclei in blue. On the third row, only the outlines of the gene expression domains have been kept to determine the number of cells expressing each gene (numbers color-coded at the bottom right corner), on how many cell layers those cells are distributed (data reported in H), how many cells express both genes simultaneously (number in white in the bottom left corner), or solely one or the other gene (dots on Gc and numbers in parentheses). (H) Summary of Delta (olive) and Gcm (blue) expression patterns throughout time and with respect to cell lineage.