Regulatory Blueprint for a Chordate Embryo
Imai, K.S., Levine, M., Satoh, N., and Satou, Y. Science, 312, 1183-1187 (May 26, 2006).
Studies of gene networks have provided tantalizing glimpses into the mechanisms that have evolved to control developmental processes in such species as the sea urchin and fruit fly. The latest research, involving the sea squirt Ciona intestinalis, provides an extensive map of interactions between 76 regulatory genes that control tissue and body formation of this simple vertebrate during embryogenesis. Among the key findings is evidence that dynamic signaling interactions between cells and autoregulation determine gene expression temporally and geographically within the embryo. Transcriptional repression, in particular, appears to be a crucial feature of gene networks, as one phase of the investigation found that 22 of 27 genes for transcription factors and signal transduction molecules negatively regulate themselves either directly or indirectly. In all, the research team examined more than 3,000 combinations of expression to create gene circuit diagrams describing the formation of larval tissues.
The results expand upon our knowledge of gene networks in vertebrates, and set the stage for future research into ancestral mechanisms of regulation in hemichordates and echinoderms, as well as evolutionarily more advanced systems of higher vertebrates.
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