Not perturbation disrupts oral NSM specification A) Transcript levels of oral NSM genes are significantly lower in Not MASO injected embryos compared to controls by 24 hpf but only a few ectodermal genes are affected (e.g., gsc, nk1). Labels, symbols and cutoffs as in Fig. 2. B,C) gcm expression is restricted to aboral NSM at 24 hpf in controls. B’,C’) In Not MASO treated embryos gcm is consistently expressed throughout the entire ring of NSM cells. Asterisks mark the vegetal pole. D,D’) At 3 dpf a normal number of pigment cells have embedded themselves in the aboral ectoderm in controls and Not MASO injected embryos (white arrowheads). However, a dense group of pigment cells accumulates ectopically below the apical plate region (dashed circle in D’). Skeletogenesis and gut development are delayed postgastrulation. Embryos oriented with their oral side to the left. VV – vegetal view.