Protein phosphorylation and the role of Ca2+ in planarian turbellarian regeneration

During planarian regeneration, relationships in timing were established between variations of calcium and calmodulin contents on one hand, and protein phosphorylation and stimulation of DNA and RNA synthesis on the other. Special attention was paid to changes in histone phosphorylation in regenerating fragments. Using in vitro experiments on dissociated planarian cells, we demonstrated causal relationships between these events. In particular, the key role of Ca²⁺ in the activation of protein kinases and in the initiation of DNA synthesis was emphasized.