Action de l'actinomycine D sur la diff�renciation cellulaire au cours de la r�g�n�ration de Planaires qui viennent d'�clore: II. Etudes autoradiographiques histologiques et ultrastructurales de l'action de l'antibiotique sur les synth�ses d'ARN

Effects of serotonin and catecholamines on RNA synthesis in planarians; in vitro and in vivo studies

The effects of serotonin, dopamine and noradrenaline on RNA synthesis, estimated by the incorporation of [3H]orotic acid, were studied on regenerating fragments of planarians. Serotonin was observed to inhibit, whereas dopamine and noradrenaline had no apparent action. These three neurohormones and their antagonists were also tested on planarian cell cultures, using [3H]-uridine as tracer. RNA synthesis, inhibited by serotonin, methiothepine (serotonin antagonist) and fluphenazine (dopamine antagonist), was shown to be restored by dopamine. The effects of serotonin, dopamine and their antagonists, are discussed in relation to the adenylate cyclase system.

[The head regeneration ofLineus sanguineus Rathke (Nemertini) under the influence of actinomycin-D. Chemomorphological data]

Fragments ofLineus sanguineus were incubated in seawater, which contained different concentrations of actinomycin-D (1.9 μg/ml, 0.95 μg/ml and 0.48 μg/ml). After 4, 5, 6 and 10 days the regenerates were studied by histological and histochemical methods (glycogen, glucose-6-phosphate-dehydrogenase and RNA). Corresponding to actinomycin-D concentration certain phases of regeneration are inhibited. The phases of proliferation are less sensitive to actinomycin-D than the phases of differentiation. If morphogenetic areas are inhibited, the normally demonstrable histochemical characteristics: accumulation of glycogen and later, the increase of G-6-P-DH activity and RNA concentration do not appear.