Regulation der zeitlichen Aufeinanderfolge von Differenzierungsvorgängen bei Acetabularia

Abstract

Regulation of the temporal sequence of differentiation events in the unicellular and uninucleated green alge Acetabularia mediterranea was studied. In this organism formation of a cylindrical stalk is succeeded by the formation of a cap. Experiments with actinomycin show, that the genes which control stalk and cap formation are active at the same time in producing carriers of genetic information responsible for these two different processes. These carriers of genetic information are also transferred from the nucleus into the cytoplasm side by side (experiments with enucleated plants). But at first only genetic information for stalk formation is activated in the cytoplasm, while the cap specific carriers of genetic information remain stored and inactive. The temporal sequence of stalk and cap formation depends upon the fact, that the two informational stores, which are present at the same time in the cytoplasm, are realized one after another. This regulation apparently takes place at the level of translation. It was further shown, that the nucleus exerts an inhibitory influence on the realization of the cap specific genetic information in the cytoplasm.