Spicule Formation by Isolated Micromeres of the Sea Urchin Embryo

Spicule formation by cultured embryonic cells from the sea urchin.

Small micromeres contribute to the germline in the sea urchin.

Many indirect developing animals create specialized multipotent cells in early development to construct the adult body and perhaps to hold the fate of the primordial germ cells. In sea urchin embryos, small micromeres formed at the fifth division appear to be such multipotent cells: they are relatively quiescent in embryos, but contribute significantly to the coelomic sacs of the larvae, from w...

Pattern formation during gastrulation in the sea urchin embryo.

The sea urchin embryo follows a relatively simple cell behavioral sequence in its gastrulation movements. To form the mesoderm, primary mesenchyme cells ingress from the vegetal plate and then migrate along the basal lamina lining the blastocoel. The presumptive secondary mesenchyme and endoderm then invaginate from the vegetal pole of the embryo. The archenteron elongates and extends across th...

The transcriptome of the sea urchin embryo.

The sea urchin Strongylocentrotus purpuratus is a model organism for study of the genomic control circuitry underlying embryonic development. We examined the complete repertoire of genes expressed in the S. purpuratus embryo, up to late gastrula stage, by means of high-resolution custom tiling arrays covering the whole genome. We detected complete spliced structures even for genes known to be e...

R11: a cis-regulatory node of the sea urchin embryo gene network that controls early expression of SpDelta in micromeres.

A gene regulatory network (GRN) controls the process by which the endomesoderm of the sea urchin embryo is specified. In this GRN, the program of gene expression unique to the skeletogenic micromere lineage is set in train by activation of the pmar1 gene. Through a double repression system, this gene is responsible for localization of expression of downstream regulatory and signaling genes to c...