In the November issue of Genes & Development, Jan Lohmann and Thomas Bosch report their discovery that a novel peptide, HEADY, is a potent inducer of head formation in lower metazoans. Axis formation is one of the first and most important steps in animal development. Many of the signaling peptides responsible for axis specification in flies, worms and mammals are known. However, scientists have long been unsure as to the extent to which signaling peptides play a role in the body axis formation of lower eukaryotic animals.
Using grafting experiments, Lohmann and Bosch show that a secondary head can be induced by HEADY. Donor tissue is treated with HEADY and labeled using fluorescent latex beads prior to transplantation into an unlabeled host. After five days, the transplanted tissue develops into a fluorescent secondary head.
That HEADY acts as a developmental switch to pattern the apical-basal axis of Hydra provides the first insight into how initial asymmetry is specified in lower metazoan animals. Furthermore, it supports the view that peptides have played a key role as developmental signals in metazoan evolution.
Genes & Development