Inhibition of RNA Synthesis in Meiotic Cells and Its Effect on Meiotic Development

Using toyocamycin (TYM), an antimetabolite of RNA synthesis, we examined the significance of RNA synthesis during meiotic prophase. Lily microsporocytes at various stages of meiotic prophase were cultured for discrete intervals in the presence of the inhibitor at various concentrations. Cytological observations showed strong interference with the meiotic process of the inhibition of RNA synthesis at all meiotic stages up to early diakinesis. The main effects of inhibiting RNA synthesis were the suppression of meiotic development and abnormal chromosome segregation. When this inhibitor was applied to cells in leptonema or zygonema, zygonema arrest occurred. When it was applied in pachynema or diplonema, the cells did not progress beyond prophase, but remained suspended in some stage of late prophase. When the inhibitor was administered at half the concentration that induced suppression of meiotic development, the response of the cells was a delay in meiotic progression, but chiasma formation and chromosome segregation were almost always affected. These results demonstrate that RNA synthesis during meiotic prophase is essential to meiotic development.