Action of foot activator on growth and differentiation of cells in hydra.

Foot activator is a small peptide found in hydra and specifically activates foot formation. I present a method for the further purification of foot activator by high-pressure liquid chromatography. The morphogenetically active fractions were assayed for their effect at the cellular level. Foot activator acts as a mitogen by pushing epithelial and interstitial cells, which are arrested in G2, into mitosis. In the presence of foot activator, epithelial stem cells are stimulated to differentiate into foot mucus cells, and interstitial nerve precursor cells differentiate into mature nerve cells. The interaction of foot activator with head activator in the development of hydra is discussed.