Extended Data Fig. 4: hesC appears to have lost its ancestral role of repressing larval skeletal cell specification in H. erythrogramma.

Derived expression patterns of hesC in H. erythrogramma at a, cleavage; b, blastula; and c, d, larva stage embryos. Micrographs derive from a single round of in-situ experiments. e, f, Control and MASO knock-down of HesC in H. erythrogramma (early larva; scale bar 100 µm). Polarized light illuminates skeletal elements. HesC knockdown appears to show no phenotype, a dramatic change from the ancestral dGRN. Injection experiments were replicated twice.