EXTRACELLULAR NUCLEOTIDES ARE ACTIVE IN EVOKING THE WINGED MORPH OF EUPLOTES-OCTOCARINATUS

Extracellular nucleosidephosphates and -deoxyphosphates at micromolar concentrations induce Euplotes octocarinatus to change its ovoid cells hape into a ''winged'' morph. ATP/dATP and adenosine-tetraphosphate ar e most active, followed by CTP/dCTP, UTP/dTTP, and GTP/dGTP; ADP has l ess, while AMP, adenosine, cAMP, pyrophosphate and tripolyphosphate ha ve no morphogenetic activity. Euplotes changes morphogenetically a few hours after being exposed to these compounds; changes are completed w ithin 24-36 hr. Cell division is regularly stopped during this time. T ransformed Euplotes are protected from certain predators which is remi niscent of the response triggered by predator-released proteins.