Expression of two highly regulated subfamilies of the complex multigene family encoding IL-17 cytokines in the purple sea urchin are sequentially activated in a larval gut-associated inflammation model and modulate downstream gene expression in the gut epithelium.
Eph receptor signaling commonly excludes migrating embryonic cells from regions of high ligand density; however, in sea urchin embryos pigmented immunocytes are attracted to regions expressing high levels of Ephrin.
A gene duplication event has permitted the functional specialization of a homeodomain transcription factor through changes in exon-intron organization and these changes have supported the evolution of a major, phylum-level morphological novelty.
A conserved alternative splicing program is specific to planarian stem cells and is controlled by the highly conserved splicing factors CELF and MBNL; therefore, this mode of regulating stem cells is likely ancestral to all animals.
During early embryogenesis of the sea urchin, asymmetrical positioning of the dorsal/ventral organizer relies upon the suppression of organizer activities in dorsal blastomeres by the Hbox12 homeodomain-containing repressor.