Diversification of oral and aboral mesodermal regulatory states in pregastrular sea urchin embryos.
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gataC and prox1 are the first oral NSM-specific transcription factor genes, activated at 17-18 hpf.
"The first transcription factor genes specific to the oral NSM, prox1 and gataC, are transcriptionally activated in this region between 17 and 18 hpf (Fig. 1B,T), which is significantly later than the onset of Nodal transcription at about 8–9 hpf (Fig. 1B)."
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Knockdown of the aboral regulators gcm or gataE expands gataC expression into the whole NSM.
"If gcm or gataE expression are blocked by treatment with MASOs we see an expansion of ese, prox1, gataC, and erg expression (the same is seen for shr2 expression; not shown)."
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GataC knockdown has no effect on regulatory genes before gastrulation.
"GataC MASO treatment does not affect any regulatory genes pre-gastrulation (Supp. Fig. 4; Solek and Rast, personal communication)"
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The oral NSM gives rise to the blastocoelar cells, which have immune functions in the larva.
"About one-third of the NSM cells, located in a V-shaped sector directly beneath the oral ectoderm, give rise upon gastrulation to a particular mesenchymal cell type known as blastocoelar cells (Ruffins and Ettensohn, 1996)."