Storage of embryonically transcribed poly(A) RNA and its utilization during metamorphosis of the hydroidHydractinia echinata.

The formation of tentacles and stolons during metamorphosis is severely disturbed if inhibitors of mRNA metabolism are applied during certain phases of development. The periods of sensitivity to α-amanitin are late gastrulation and the disk stage of metamorphosis. A cordycepin sensitive phase exists during the first hour of metamorphosis. In all drug sensitive phases an enhanced poly(A) synthesis is found indicating increased mRNA metabolism in these stages. Pulse-chase experiments show that planula larvae store a poly(A)-rich RNA population sedimenting between 28-18s. These long living molecules are of embryonic origin, are located in RNP particles and are degraded during metamorphosis. The particles in question appear to be stored mainly in interstitial cells. In early metamorphosis no uridine is incorporated but labelled poly(A) is added to preexisting molecules.