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Evolutionary change in morphological features must depend on architectural reorganization of developmental gene regulatory networks (GRNs), just as true conservation of morphological features must imply retention of ancestral developmental GRN features. Key elements of the provisional GRN for embryonic endomesoderm development in the sea urchin are here compared with those operating in embryos of a distantly related echinoderm, a starfish. These animals diverged from their common ancestor 520-480 million years ago. Their endomesodermal fate maps are similar, except that sea urchins generate a skeletogenic cell lineage that produces a prominent skeleton lacking entirely in starfish larvae. A relevant set of regulatory genes was isolated from the starfish Asterina miniata, their expression patterns determined, and effects on the other genes of perturbing the expression of each were demonstrated. A three-gene feedback loop that is a fundamental feature of the sea urchin GRN for endoderm specification is found in almost identical form in the starfish: a detailed element of GRN architecture has been retained since the Cambrian Period in both echinoderm lineages. The significance of this retention is highlighted by the observation of numerous specific differences in the GRN connections as well. A regulatory gene used to drive skeletogenesis in the sea urchin is used entirely differently in the starfish, where it responds to endomesodermal inputs that do not affect it in the sea urchin embryo. Evolutionary changes in the GRNs since divergence are limited sharply to certain cis-regulatory elements, whereas others have persisted unaltered.
Brown,
New computational approaches for analysis of cis-regulatory networks.
2002, Pubmed,
Echinobase
Brown,
New computational approaches for analysis of cis-regulatory networks.
2002,
Pubmed
,
Echinobase Cripps,
Control of cardiac development by an evolutionarily conserved transcriptional network.
2002,
Pubmed Croce,
ske-T, a T-box gene expressed in the skeletogenic mesenchyme lineage of the sea urchin embryo.
2001,
Pubmed
,
Echinobase Davidson,
Regulatory gene networks and the properties of the developmental process.
2003,
Pubmed Davidson,
A genomic regulatory network for development.
2002,
Pubmed
,
Echinobase Davidson,
A provisional regulatory gene network for specification of endomesoderm in the sea urchin embryo.
2002,
Pubmed
,
Echinobase Fuchikami,
T-brain homologue (HpTb) is involved in the archenteron induction signals of micromere descendant cells in the sea urchin embryo.
2002,
Pubmed
,
Echinobase Hinman,
Expression and function of a starfish Otx ortholog, AmOtx: a conserved role for Otx proteins in endoderm development that predates divergence of the eleutherozoa.
2003,
Pubmed
,
Echinobase Hinman,
Expression of AmKrox, a starfish ortholog of a sea urchin transcription factor essential for endomesodermal specification.
2003,
Pubmed
,
Echinobase Hinman,
Expression of a gene encoding a Gata transcription factor during embryogenesis of the starfish Asterina miniata.
2003,
Pubmed
,
Echinobase Maduro,
Making worm guts: the gene regulatory network of the Caenorhabditis elegans endoderm.
2002,
Pubmed Maruyama,
A Sea Cucumber Homolog of the Mouse T-Brain-1 is Expressed in the Invaginated Cells of the Early Gastrula in Holothuria leucospilota.
2000,
Pubmed
,
Echinobase Oliveri,
Activation of pmar1 controls specification of micromeres in the sea urchin embryo.
2003,
Pubmed
,
Echinobase Oliveri,
A regulatory gene network that directs micromere specification in the sea urchin embryo.
2002,
Pubmed
,
Echinobase Patient,
The GATA family (vertebrates and invertebrates).
2002,
Pubmed Rast,
brachyury Target genes in the early sea urchin embryo isolated by differential macroarray screening.
2002,
Pubmed
,
Echinobase Rast,
Recovery of developmentally defined gene sets from high-density cDNA macroarrays.
2000,
Pubmed
,
Echinobase Reuter,
The gene serpent has homeotic properties and specifies endoderm versus ectoderm within the Drosophila gut.
1994,
Pubmed Richardson,
Expression of an embryonic spicule matrix gene in calcified tissues of adult sea urchins.
1989,
Pubmed
,
Echinobase Shoguchi,
A starfish homolog of mouse T-brain-1 is expressed in the archenteron of Asterina pectinifera embryos: possible involvement of two T-box genes in starfish gastrulation.
2000,
Pubmed
,
Echinobase Smith,
The phylogeny of echinoderm classes based on mitochondrial gene arrangements.
1993,
Pubmed
,
Echinobase Stathopoulos,
Dorsal gradient networks in the Drosophila embryo.
2002,
Pubmed Tagawa,
T-Brain expression in the apical organ of hemichordate tornaria larvae suggests its evolutionary link to the vertebrate forebrain.
2000,
Pubmed Wang,
Very early and transient vegetal-plate expression of SpKrox1, a Krüppel/Krox gene from Stronglyocentrotus purpuratus.
1996,
Pubmed
,
Echinobase Wray,
The origin of spicule-forming cells in a 'primitive' sea urchin (Eucidaris tribuloides) which appears to lack primary mesenchyme cells.
1988,
Pubmed
,
Echinobase Yuh,
Patchy interspecific sequence similarities efficiently identify positive cis-regulatory elements in the sea urchin.
2002,
Pubmed
,
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