Safia El Jailani

Abstract The meiotic segregation pattern to generate haploid gametes is mediated by step-wise cohesion removal by separase, first from chromosome arms in meiosis I, and then from the centromere region in meiosis II. In mammalian oocytes, separase is tightly controlled during the hours-long prometaphase and until chromosome segregation in meiosis I, activated for a short time window, and again inhibited until metaphase II arrest is lifted by fertilization.

Highlights • Aurora B/C kinases are required for bivalent separation in mammalian oocyte meiosis • Aurora B/C kinases promote cleavage of the meiotic cohesin subunit Rec8 by separase • Requirement for phosphorylation of Rec8 for cleavage is evolutionarily conserved • Only a fraction of centromeric Rec8 is protected from separase in meiosis I Summary 1 Sato M. Kakui Y. Toya M. Tell the difference between mitosis and meiosis: interplay Between chromosomes, cytoskeleton, and cell cycle regulation.