EFFECTS OF HYDROXYUREA ON ACETABULARIA MEDITERRANEA

Effects of hydroxyurea on Acetabularia mediterranea. The effects of hydroxyurea, an inhibitor of DNA synthesis, on the morphogenesis, the synthesis of nucleic acids and the density of the cytoplasmic DNA's have been studied in nucleate and anucleate fragments of the unicellular alga Acetabularia mediterranea. It was found that: (1) the morphostatic effect of hydroxyurea is most marked at the beginning of cap formation; (2) in the presence of hydroxyurea, the synthesis of nucleic acids in the cytoplasm is inhibited in the whole algae as well as in anucleate fragments; (3) on the other hand, nuclear DNA synthesis which accompanies the formation of cysts, does not seem to be influenced by the presence of hydroxyurea in the culture medium; (4) no modifications of the density of the various cytoplasmic DNA's, as a result of treatment with hydroxyurea, have ever been observed. The significance of these results is discussed in the light of previous hypotheses concerning the mode of action of hydroxyurea. © 1969.