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Development of the body plan is controlled by large networks of regulatory genes. A gene regulatory network that controls the specification of endoderm and mesoderm in the sea urchin embryo is summarized here. The network was derived from large-scale perturbation analyses, in combination with computational methodologies, genomic data, cis-regulatory(More)
Several lines of evidence suggest that micromere signaling plays a key role in endo-mesoderm differentiation along the animal-vegetal (A-V) axis in sea urchin embryos. A recent study has suggested that the activity of micromeres of inducing endoderm differentiation of mesomere descendants is, unexpectedly, maximal at the hatching blastula stage in the(More)
Blastomere composition and expression profiles of wnt8 and hox11/13b orthologues were examined in the primitive indirect-developing echinoid Prionocidaris baculosa. We found that blastomere composition in the 16-cell-stage Prionocidaris embryos was different from that of the indirect-developing echinoids belonging to Euechinoidea, a derived group of the(More)
Concerning the evolution of deuterostomes, enteropneusts (acorn worms) occupy a pivotal role as they share some characteristics with chordates (e.g., tunicates and vertebrates) but are also closely related to echinoderms (e.g., sea urchin). The nervous system in particular can be a highly informative organ system for evolutionary inferences, and advances in(More)
In the ascidian embryo, the nerve cord and notochord of the tail of tadpole larvae originate from the precursor blastomeres for both tissues in the 32-cell-stage embryo. Each fate is separated into two daughter blastomeres at the next cleavage. We have examined mechanisms that are responsible for nerve cord and notochord specification through experiments(More)
Two wnt8 orthologs, Smwnt8 and Pjwnt8, were isolated from an indirect developing sand dollar, Scaphechinus mirabilis, and a direct developing sand dollar, Peronella japonica, respectively. The expression patterns of two genes during early development were examined by whole mount in situ hybridization. The expression of Smwnt8 was initiated in the micromeres(More)
We investigated the inductive signals originating from the vegetal blastomeres of embryos of the sand dollar Peronella japonica, which is the only direct developing echinoid species that forms micromeres. To investigate the inductive signals, three different kinds of experimental embryos were produced: micromere-less embryos, in which all micromeres were(More)
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