HEADY Role in Hydra
Hydra, a multicellular, lower-eukaryotic, freshwater polyp, is known for its developmental idiosyncrasies. Slice off its head or its foot, and within two days either regenerates perfectly at the proper location. Although developmental biologists have some understanding of the molecular machinery involved in this feat, they have yet to isolate and prioritize many of the factors that play a role. In a recent paper, two scientists report the discovery of a signaling peptide called HEADY that appears to be very important for setting up axis formation in Hydra and other lower metazoans (J.U. Lohmann, T.C. Bosch, "The novel peptide HEADY specifies apical fate in a simple radially symmetric metazoan," Genes and Development, 14:2771-7, Nov. 1, 2000). Because Hydra does not lend itself to mutagenesis, investigators employed a screening strategy using differential display PCR. They split the organisms into balls of cells, let them form intact polyps,...