Cell cycle control in synchronously dividing antheridial filaments of Chara vulgaris L. as revealed by cycloheximide pulse treatment.

In antheridial filaments of Chara vulgaris L. (cell cycle S+G2+M type) cycloheximide (2.5 micrograms/ml) totally inhibits protein synthesis after 2 h. The protein synthesis is resumed after the removal of the inhibitor from the medium. The inhibition of protein synthesis in the second half of G2 phase causes supercontraction of mitotic chromosomes, whereas in the late G2 phase it induces diminishing of tubulin content and the inhibition of the initiation of DNA synthesis in the next generation of antheridial filaments. The inhibition of protein synthesis in G2 phase does not affect the mitotic index. The inhibition of protein synthesis during S phase results in a lower rate of DNA replication and the prolongation of S phase. The inhibition of protein synthesis in the second half of G2 phase of the previous generation and in the S phase of the given generation causes mitotic delay which increases in proportion to the duration of G2 phase in the given generation.