Interference of a synthetic C18 juvenile hormone with mammalian cells in vitro. II. Effects on cell cycle.

Interference of a synthetic C18 juvenile (JH) with the cell cycle of mouse embryo cells (ME-cells) and mouse cells of established cell line (L-cells) was examined. After 3 hour in the medium with JH (20 mg/ml) the cells were transfered to the regular culture medium and labelled with H3-thymidine then incubated for 1 to 48 hours before processing them for autoradiography. The percentage of labelled mitosis was then calculated for all cells samples examined and the labelled mitosis curves were drown and analyzed. It was shown that in contrast to the solvent which had no effect on duration of any of the component phases of the cell cycle of ME-cells, the juvenile hormone under conditions of these experiments prolonged G1 and G2 intervals what resulted in prolongation of the total cell cycle of these cells. On the other hand it shortened G1 and prolonged G2 intervals of L-cells without changing duration of the total cell cycle. Thus, in the examined mouse cells, they were the G1 and G2 intervals which are affected by JH. This findings are considered as an argument for pleiotropic nature of the juvenile hormone interference with mouse cells, the more so as it interfered with both protein and DNA synthesis in these cells.