The sea urchin's siren.

This issue of Developmental Biology features articles that constitute a new wave of insights into how a genome interacts with itself (as DNA) and with effectors-proteins and probably RNAs, collectively operating as a kind of "cis-trans" dualism. We learned a test for allelism in genetics class that bore that Latin name but now it comes as a new day for biological science-a welcome era in which a phenomenon as complex as development can be envisioned from principles of chemical binding energy and specificity. The buzzword (the term is just-as there is deserved buzz) is that the genome is hard-wired, in the sense that it has been shaped to both encode and react to a regulatory network, of which it is itself a part. I here review some of the milestones of embryology in which the sea urchin was the key player, segueing into the modern era in which this organism launched an entirely new intellectual construct of genome organization and gene expression during development. This essay also contains a number of personal perspectives as well as some views on the overall epistemological fabric of developmental biology. Like all of us, I am excited to see the S. purpuratus genome appear and heartily congratulate, by writing this essay, the trailblazers whose intellectual courage and persistence has brought us to this happy position.