Abstract
Hydroxyurea inhibits mitotic activity in cells of the antheridial filaments of Chara vulgaris by blocking phase S and phase G2. Blocking of cells in phase G2 also occurs in the case of the root meristem cells of Helianthus annuus and Vicia faba var. minor. 3H-thymidine incorporation confirmed autoradiographically the blocking of cells of the antheridial filaments in Chara vulgaris at phase S and slowing down of the rate of DNA replication. Incubation with 3H-phenylalanine demonstrated that hydroxyurea inhibits protein synthesis.