Inherent in the idea of gene regulatory networks was the concept that genome sequences that provided information about how genes should be expressed would be as important as the genome sequences that coded for the proteins themselves. Although non-protein-coding DNA was long considered to be “junk,” Davidson recognized that the key regulatory code resided in this genetic material. In 2006, Davidson co-led a group of 240 researchers from more than 70 institutions that sequenced the purple sea urchin’s genome. In 2008, a consortium of institutions led by Davidson’s lab characterized the 23,000 genes of that genome.
In parallel, the Davidson group systematically created a comprehensive functional testing strategy to detect all of the control connections between the genes involved in the key events in the earliest stages of sea urchin embryo development, and to determine how the activity of each gene affected the ability of every other gene in that part of the embryo to be expressed. The network model, first described in 2002 and elucidated and extended over the next 13 years, revealed that the regulatory networks governing high-level processes such as the formation of a specific type of cell are built from gene circuits that can have striking similarities even when the identities of the genes in the circuits are different. These circuits can be viewed as a few dozen types of modules that perform specific functions. Because similar modular systems appear to exist in flies, frogs, chicks, mice, and zebrafish, they may be a universal feature of higher organisms.More.
Requiescat in lucem pacis aeternitatis
See also: The Myth of Junk DNA