Urchin, meet starfish

Comparative genomic analysis is increasingly used to provide evidence for phylogenetic relationships and the relative importance of both coding and noncoding DNA sequences. However, simple sequence comparison may not reveal all the relationships among organisms, particularly when they have been separated by vast amounts of evolutionary time. By viewing the interactions of genes as integrated multitasking networks, Veronica Hinman and colleagues at the California Institute of Technology report in the October 27 PNAS that a gene regulatory network (GRN) architecture controlling embryonic endomesoderm development in the sea urchin is strongly conserved in the starfish, despite half a billion years of divergent evolution. Such networks, the authors report, provide another tool for the understanding of genomic regulatory control, functions of noncoding DNA sequences, and mechanisms in evolution (PNAS, DOI:10.1073/pnas.2235868100, October 27, 2003).

Hinman et al. used genes involved in endomesodermal specification in the early embryo in the sea...