Fig. 4. Introduction of mutations into the BSs for Lhx, Fox and T-box proteins resulted in a loss of lacZ transcription in the vegetal hemisphere. (A-D) Frequency of lacZ-positive cells for a given cell in 64-cell embryos injected with reporter constructs harboring the regulatory modules indicated on the left side. Red, yellow and blue ovals represent the binding sites for Lhx, Fox and T-box proteins, respectively. (E) Frequency of lacZ-transcribing cells for a given cell lineage in 64-cell embryos injected with reporter constructs harboring the DNA fragments shown on the left side. DNA fragment Lhx/Fox-BS contains the single Fox-binding site and the two Lhx-binding sites from regulatory module #6. DNA fragments Lhx-BS and Fox-BS include four binding sites for Lhx and Fox, respectively, which are from regulatory module #6. The DNA fragment T-box-BS includes four copies of the T-box-binding site present in the regulatory module #3. The nucleotides marked yellow, red and blue represent the putative binding sites for Fox, Lhx and T-box proteins, respectively. For color codes in histograms, see Fig. 1.