Résumé
Cyclin-dependent kinase (Cdk) mutations that prevent entry into the mitotic cell cycle of budding yeast fail to block meiotic DNA replication, suggestingthere may be fundamental differences between these pathways. However, S phase in meiosis was found to depend on the same B-type cyclins (Clb5 andClb6) as it does in mitosis. Meiosis differs instead in the mechanism that controls removal of the Cdk inhibitor Sicl. Destruction of Sicl and activationof a Clb5-dependent kinase in meiotic cells required the action of the meiosisspecific protein kinase Ime2, thereby coupling early meiotic gene expression to control of DNA replication for meiosis.